Sustainable production of 1,4-butynediol and downstream products thereof

Abstract

A process and a system to produce sustainable, especially renewable or recycling-based 1,4-butynediol as well as downstream products thereof are provided.

Description

BASF SE 241076W0011Sustainable Production of 1,4-Butynediol and Downstream Products ThereofField of the InventionThis invention relates to a process and a system to produce 1 ,4-butynediol as well as downstream products thereof.Background of the InventionFor decades, fossil carbon resources like coal, oil, and gas have been extensively used as the predominant raw material for energy production and petrochemical processes. This has led to an enormous increase of the carbon dioxide (CO2) concentration in the atmosphere causing global warming and climate change. In view of the finite availability of fossil resources and the urgency to reduce CO2 emissions, there is a high need to replace fossil carbon resources by renewable and recycled carbon resources and to use intermediates and products derived therefrom as efficiently as possible.Thus, chemical starting materials made from waste and biomass as well as chemical processes using sustainable energy sources and efficient recycling steps are becoming increasingly important for the transition to a more sustainable use of resources in the (petro-)chemical industry.1 ,4-Butanediol (BDO) is a versatile and important molecule for the chemical industry. It may be used as a solvent and as a precursor for important compounds and solvents like tetrahydrofuran (THF), gamma-butyrolactone (GBL) and N-methy l-2-pyrrolidone (NMP). BDO and said downstream products are also important monomers for a variety of polymers produced at large scale, e.g., polyesters such as polybutylene terephthalate (PBT) and polybutylene adipate terephthalate (PBAT), polyethers such as polytetrahydrofuran (polyTHF, PTMEG), and copolymers derived therefrom such as thermoplastic polyurethanes (TPU), thermoplastic elastomers (TPE) and polyether polyurea copolymers (e.g., spandex).BDO is commonly synthesized by the reaction of acetylene with two equivalents of formaldehyde (Reppe process). The resulting 1 ,4-butynediol (i.e., but-2-yne-1 ,4-diol; BYD) is subsequently hydrogenated to BDO. Conventionally, acetylene is obtained by partial oxidation of natural gas. Formaldehyde is typically manufactured by oxidation of methanol which is produced through catalytic processes from syngas originating from fossil feedstocks such as natural gas or coal. Also, hydrogen for the BDO reduction to BYD is frequently obtained from natural gas via steam reforming. Thus, conventional ways to produce BYD and BDO, respectively, employ fossil resources in different aspects and more sustainable ways to produce BYD and BDO are highly desired.While natural gas may in principle be replaced by biogas as a raw material, the availability of biogas may be fluctuating and overall limited. Novel pathways towards bio-based BDO like fermentative routes starting from sugars are being established but come along with their own technical and economic challenges. Thus, the use of existing production pathways and existing (large-scale) production facilities to obtain sustainable BYD and BDO without being dependent on biogas appears especially advantageous.Summary of the InventionIn a first aspect, the present invention relates to a process to produce 1 ,4-butynediol, the process comprising the steps S1) providing at least one sustainable feedstock comprising at least one component selected from the groupBASF SE 241076W0012 consisting of bio-oils, pyrolysis oils, and pyrolysis gases;52) converting at least a portion of said at least one sustainable feedstock to acetylene, wherein said conversion comprises the utilization of a steam cracking unit or a part thereof;53) providing formaldehyde;54) reacting at least a portion of the acetylene obtained in step S2) with at least a portion of the formaldehyde provided in step S3) to obtain 1 ,4-butynediol.In a second aspect, the invention relates to a system for producing 1 ,4-butynediol, the system comprising the units U1) sustainable feedstock unit;U2) acetylene unit comprising a steam cracking subunit;U3) formaldehyde unit; andU4) 1 ,4-butynediol unit; and optionallyU2*) Sachsse-Bartholome acetylene subunit.In a third aspect, the invention relates to the use of a steam cracking unit in a process to produce 1 ,4-butynediol, wherein the steam cracking unit is used inP1) production of acetylene and / or of one or more C1-4 alkanes from at least one sustainable feedstock comprising at least one component selected from the group consisting of bio-oils and pyrolysis oils, optionally after upgrading said sustainable feedstock, and separation of at least one fraction comprising acetylene or one or more C1-4 alkanes, and / orP2) separation of at least one fraction comprising one or more C1-4 alkanes from a sustainable feedstock comprising pyrolysis gas.Further aspects of the present invention will become apparent to the person skilled in the art directly from the foregoing and following description.The sets of preferred embodiments described in the following for the different aspects of the invention are intended to further illustrate, but in no way to restrict the present invention as described herein. They represent a suitably structured part of the description and thus support, but do not represent the claims of the present invention.General Terms and DefinitionsThe term ''sustainable'', as used herein, mainly refers to environmental sustainability. It relates to practices, actions, and attributes suited to maintain and preserve the health and balance of natural ecosystems and resources over the long term such that their capacities to regenerate are not exceeded, e.g., by minimizing resource depletion, pollution, waste production, and greenhouse gas emissions. When referring to resources and energy sources, the term "sustainable” includes, but is not limited to the terms "renewable” (e.g., derived from biomass, "bio-based”), "recycled” (e.g., derived from waste, "recycling-based”), and "non-fossil” (e.g., not derived from natural gas, oil, coal etc.).BASF SE 241076W0013The term ''equipped to”, as used herein, means that a device, unit, or system has the necessary components, tools, mechanisms, features, or capabilities that enable it to carry out the specified operations, tasks, or functions and that it may be configured to do so.The term “fluidically connected to” in respect to at least two units means that a fluid can flow from one unit to the other, e.g., through a system of one or more pipes, e.g., driven by screw conveyors, extruders, or pumps.The terms ''downstream of” and ''upstream of”, respectively, refer to a relationship of at least two operations or units within a sequence of operations or units and designate a connection of said operations or units in or against the direction, respectively, of material streams passing said sequence.The terms ''at least in part”, ''at least a part of”, or ''at least a portion of” refer to a fraction that is nonzero. It includes any fractions larger than 0 %, in particular it means a fraction of > 10 %, preferably > 20 %, more preferably > 30 %, more preferably > 40 %, more preferably > 50 %, more preferably > 60 %, more preferably > 70 %, more preferably > 80 %, more preferably > 90 %, most preferably 100 %.The terms “comprise(s)”, ''comprising” etc. are inclusive of and may, in a preferred embodiment, be replaced by the terms "consist(s) of”, "consisting of” etc.The term "to provide” includes, but is not limited to the term "to produce”. Thus, e.g., steps of providing a substance or composition and units for providing a substance or composition are inclusive of and may, in a preferred embodiment, be replaced by steps of producing said substance or composition and units for producing said substance or composition."Syngas” also known as "synthesis gas” refers to a mixture of predominantly CO and H2, which in addition may comprise minor amounts of CO2 and further components such as water and methane."Biogas”, a mixture of mainly methane and carbon dioxide, may be obtained by anaerobic digestion of organic matter. As used herein, the term "biogas” includes pretreated and upgraded biogas. In the pretreatment step, water vapor as well as hydrogen sulfide, if present, are removed to obtain pretreated biogas. In the upgrading step, carbon dioxide is removed by absorption in water, by amines, by membranes, or the application of pressure swing adsorption to obtain upgraded biogas which is almost pure methane (bio-methane). Thus, "biogas” refers in particular to bio-methane. Details on said biogas-related processes are described for example in E.-J. Nyns et al., Ullmann's Encyclopedia of Industrial Chemistry, 2014, Chapter "Biogas”, and the references cited therein."Biomass” is biological material derived from living or recently living organisms. In particular, the term "biomass” comprises plants or parts thereof like crops, energy crops, wood, wood waste, wood pellets, wood chips, forestry and agricultural residues, straw, lignocellulosic biomass, or residues thereof, marine organisms (like algae), biobased oils, biobased fats (preferably hydrated), and biowaste such as organic food waste."Bio-oil” designates a liquid compound mixture mainly comprising highly oxygenated compounds (e.g., glycerides, esters, carboxylic acids, phenols, alcohols, ketones, aldehydes, furans, and sugars) and water, while its exact composition depends on the biomass feedstocks and the processing steps applied. The term bio-oil includes in particular vegetable oils like rapeseed oil, sunflower oil, soybean oil, corn oil, castor oil, jatropha oil, carinata oil, palm oil, and macauba palm (kernel or pulp) oil, and processing residues thereof (like palm fatty acid distillate or oil mill effluents), waste cooking oil, tall oil, animal fats, and oils obtained by thermochemical conversion of biomass, e.g. biomass- derived pyrolysis or hydrothermal liquefaction oils, as well as mixtures thereof.BASF SE 241076W0014"Pyrolysis oil'' designates the liquid fraction obtained by pyrolysis of solid feedstocks like biomass or waste. In particular, it may refer to waste pyrolysis oils, more specifically to plastic waste pyrolysis oils. Pyrolysis oils are typically complex compound mixtures. Depending on the input material, they may comprise paraffins, isoparaffins, olefins, naphthenes, and aromatics in different amounts, but also various oxygenated compounds"Pyrolysis gas” designates the non-condensable, i.e., gaseous fraction obtained by pyrolysis of solid feedstocks like biomass or waste. In particular, it may refer to waste pyrolysis gases, more specifically to plastic waste pyrolysis gases. Pyrolysis gas mainly comprises C1-4 alkanes, C2-4 alkenes, and hydrogen.The term "waste” comprises fossil-based waste, biobased waste, and mixtures thereof. Examples for waste are agri- cultural / farming residues such as wood processing residues, waste wood, logging residues, switch grass, discarded seed corn, corn stover and other crop residues, municipal solid waste (MSW), industrial waste, hazardous waste, textiles, industrial waste, sewage sludge, (mixed) plastic waste, packaging waste, end-of-life tires, shredder residues such as automotive shredder residues, pyrolysis oils, and mixtures thereof."Plastic waste” comprises polyalkenes, polystyrene, and copolymers thereof, polyvinylchloride (PVC), polyvinylidene chloride (PVDC), polyamides (PA), polyurethanes (PU), acrylonitrile butadiene styrene (ABS), polyesters, polycarbonate (PC), rubbers, caprolactam-based waste and mixtures thereof, preferably polyalkenes. Polyalkenes comprise polyethylene (LDPE, HDPE) and polypropylene. Plastic waste can be for example derived from automotive shredder residue, and / or mixed plastic waste. Also rubber waste, e.g., end-of-life tires, is considered "plastic waste” in the sense of the present disclosure.The terms "fossil feedstock”, "fossil origin”, "fossil source” and the like include, but are not limited to coal, oil, natural gas, petcoke, carbonaceous products from crude oil refining, extra heavy crude oil, tar sand, bitumen, coke, high vacuum residues (HVRs), methane and mixtures thereof."Sustainable energy” or "sustainable electrical power” comprises wind energy, solar energy (thermal, photovoltaic, and concentrated solar energy), hydropower (tidal power, wave power, hydroelectric dams, in-river-hydrokinetics), geothermal energy, ambient or industrial heat captured by heat pumps, bioenergy (biofuel, biomass), the renewable part of waste energy sources, and nuclear energy (fission), as well as combinations thereof.Brief Description of the DrawingsFIG 1 : Flow diagram showing a process to produce BYD with acetylene as a product of steam cracking sustainable oil FIG 2: Flow diagram showing a process to produce BYD with acetylene obtained from C1-4 alkanes as products of steam cracking sustainable oilFIG 3: Flow diagram showing a process to produce BYD with acetylene obtained from C1-4 alkanes separated with the help of a steam cracking unit from a biomass-based or waste-based pyrolysis gasFIG 4: Flow diagram showing a process to produce BYD from one single sustainable steam cracking feedstock FIG 5: Flow diagram showing a process to produce BYD with formaldehyde obtained from sustainable raw material FIG 6: Flow diagram showing a process to produce BYD with formaldehyde obtained from CO2 captured from a steam cracking processFIG 7: Flow diagram showing a process to produce BYD with H2 as a product of steam cracking sustainable oil and / or as a product of pyrolysis gas fractionationBASF SE 241076W0015FIG 8: Flow diagram showing a process to produce BDO and cracking products from polymers based on BDO and / or cracking productsFIG 9: Flow diagram showing a process to produce polyurethane from polyurethane-containing wasteFIG 10: System in which a steam cracking unit (including its fractionation subunit) is connected to various units of the BDO production chainFIG 11 : System in which a steam cracking fractionation subunit is connected to various units of the BDO production chainFIG 12: System in which a steam cracking carbon capture subunit is connected to various units of the BYD production chainDetailed Description of the InventionThe present invention provides a process and a system to produce 1 ,4-butynediol (BYD) and downstream products thereof from sustainable feedstocks.According to this disclosure, BYD is synthesized via the Reppe process, i.e., by the reaction of acetylene with 2 equivalents of formaldehyde. Both reaction partners are advantageously obtained from one or more sustainable feedstocks, preferably waste or biomass, which are provided in a first step of the process.The route from such feedstocks to formaldehyde comprises the production of methanol from said feedstocks, e.g., via syngas that may be obtained through gasification of the feedstock, pyrolysis of the feedstock, followed by gasification of the obtained pyrolysis oil, reforming or partial combustion of light hydrocarbons, e.g., obtained from fermentation or pyrolysis of the feedstock or pyrolysis followed by steam cracking of the pyrolysis oil, reverse water gas shift reaction of hydrogen with CO2, obtained by incineration, fermentation, or reforming of the feedstock or from flue gas of the steam cracker.Also, methanol may be formed directly from hydrogen and CO2 obtainable from the above-mentioned sources.The favorable sustainability attributes are thus transferred onto methanol. Methanol is converted to formaldehyde with favorable sustainability attributes, which may be accomplished according to different oxidation or dehydrogenation processes. The process sequence proceeds with the formation of 1 ,4-butynediol (BYD) from said formaldehyde and acetylene.Within the scope of this disclosure, acetylene is obtained using a steam cracker facility. Advantageously, said acetylene exhibits favorable sustainability properties because it originates from sustainable feedstocks. For instance, acetylene is obtained by steam cracking of (optionally upgraded) bio-oils and pyrolysis oils derived from biomass and waste, respectively. Also, acetylene is produced by partial combustion of light hydrocarbons, in particular C1-4 alkanes. Said C1-4 alkanes are available by steam cracking of the above-mentioned sustainable oils or may be separated from the gas fraction of waste or biomass pyrolysis wherein advantageously the fractionation section of a steam cracker is used. According to this disclosure, BYD is optionally hydrogenated in the presence of H2 to form 1 ,4-butanediol (BDO). Said H2 originates advantageously from sustainable sources, in particular it is conceived within this disclosure that H2 is obtained from steam cracking of (optionally upgraded) bio-oils or pyrolysis oils.BASF SE 241076W0016Further downstream products, in particular polymers, may be generated based on BDO and optionally on olefins and / or aromatics from the steam cracking step. After the end of their lifespan, said downstream products may be recycled to the process of this disclosure by pyrolyzing or gasifying them to obtain pyrolysis oil, pyrolysis gas, or syngas to be used in the BYD synthesis as described above.The process according to this disclosure enables the production of BYD in which all carbon atoms originate from sustainable sources, preferably from one single sustainable feedstock. Of note, this is achieved without the use of biogas as a raw material. Furthermore, the process allows for keeping these renewable carbons in the value circle by providing options for recycling downstream products obtained from said BYD, in particular polymers like thermoplastic polyurethanes. Also, the process may be carried out with existing chemical infrastructure, in particular by using the cracking and fractionation capabilities of a steam cracker, originally designed for cracking fossil naphtha, but employed here for handling intermediates from sustainable feedstocks to provide sustainable BYD, BDO, and downstream products thereof. Also, biomass and waste resources may be used flexibly depending on supply, quality, economic, and sustainability considerations.Furthermore, BYD, BDO, and downstream products derived therefrom are provided with favorable and improved sustainability attributes, e.g., they are characterized by fully bio-based and / or recycling-based carbon atoms, a low carbon footprint, in the case of bio-based feedstocks and long-lived products even by net-negative CO2 emissions.Thus, in a first aspect, the present invention provides a process to produce 1 ,4-butynediol, the process comprising the steps51) providing at least one sustainable feedstock comprising at least one component selected from the group consisting of bio-oils, pyrolysis oils, and pyrolysis gases;52) converting at least a portion of said at least one sustainable feedstock to acetylene, wherein said conversion comprises the utilization of a steam cracking unit or a part thereof;53) providing formaldehyde;54) reacting at least a portion of the acetylene obtained in step S2) with at least a portion of the formaldehyde provided in step S3) to obtain 1 ,4-butynediol.Likewise, in the first aspect, the present invention relates to a process to produce 1 ,4-butynediol, the process comprising step S4)S4) reacting acetylene with formaldehyde to obtain 1 ,4-butynediol, whereby at least a portion of said formaldehyde is obtained from step S3)S3) providing formaldehyde, and whereby at least a portion of said acetylene is obtained from step S2)S2) converting at least a portion of at least one sustainable feedstock to acetylene, wherein said conversion comprises the utilization of a steam cracking unit or a part thereof, whereby said at least one sustainable feedstock is obtained from step S1)S1) providing at least one sustainable feedstock comprising at least one component selected from the group consisting of bio-oils, pyrolysis oils, and pyrolysis gases.BASF SE 241076W0017Preferred Embodiments1.1) The process according to the first aspect of the invention.In step S1 ), a sustainable feedstock is provided in sufficient amounts and quality to be used for obtaining acetylene therefrom as described below. Said feedstock may be liquid or gaseous and may comprise, preferably consist of one or more materials of bio-based or recycling-based origin. Also, it may comprise, but not exclusively consist of liquid and / or gaseous components of fossil origin, e.g., fossil naphtha. Preferably, said liquid feedstocks may comprise one or more of bio-oils and pyrolysis oils. Preferably, said gaseous feedstocks may comprise pyrolysis gases.Biomass and waste are considered main raw materials for said sustainable feedstocks.Biomass-based sustainable feedstocks comprise bio-oils like vegetable oils and processing residues thereof, waste cooking oil, tall oil, animal fats, and oils obtained by thermochemical conversion of biomass. The biomass is converted to a bio-oil by a processing that may comprise both mechanical and physical operations, like harvesting and collecting as well as crushing, cracking, cutting, shredding, grinding, chipping, milling, extrusion, irradiation, squeezing, pressing, bleaching, desodoration, filtering, sieving, adsorption, and thermal treatments such as drying and torrefaction, and chemical processes, like extraction, distillation, thermochemical conversions like pyrolysis or hydrothermal liquefaction, gasification followed by Fischer-Tropsch processes, hydrolysis, saponification, neutralization, ketonization, or hydrogenation. Also, the mechanical, physical, and / or chemical separation of the products and by-products of said operations and processes, in particular the separation of gaseous, liquid, and solid fractions, forms part of the biomass processing. The right choice of suitable process steps and operating conditions is mainly dependent on the biomass to be processed; but the one skilled in the art will be familiar with such considerations, in particular when it comes to the production and processing of edible oils, vegetable oils, tall oils and the like.Biomass and waste, in particular plastic waste, may be subjected to a pyrolysis reaction to obtain pyrolysis oil and pyrolysis gas. The pyrolysis of said raw materials yields a liquid fraction, commonly referred to as pyrolysis oil, as well as a non-condensable, gaseous fraction (pyrolysis gas) and a solid residue (pyrolysis char; normally composed of fixed carbon and inorganic compounds such as glass, metals, ash, etc.).Pyrolysis processes are known and described, e.g. for plastics, in EP 0713906 A1 , WO 95 / 03375 A1 , V. K. Son! et al., Energy Fuels 2021 , 35, 12763-12808, and J. Woidasky, Ullmann's Encyclopedia of Industrial Chemistry, 2020, Chapter "Plastics Recycling”, pp. 15-17, and e.g. for biomass in G. Wang et al., Energy Fuels 2020, 34, 12, 15557-15578. Pyrolysis oils are also commercially available.Typically, plastic waste comprises additives, such as processing aids, plasticizers, flame retardants, pigments, light stabilizers, lubricants, impact modifiers, antistatic agents, antioxidants, etc. These additives may comprise elements other than carbon and hydrogen. For example, bromine is mainly found in connection to flame retardants. Heavy metal compounds may be used as lightfast pigments and / or stabilizers in plastics. Cadmium, zinc, and lead may be present in heat stabilizers and slip agents used in plastics manufacturing. The plastic waste can also contain residues. Residues in the sense of the invention are contaminants adhering to the plastic waste. The additives and residues are usually present in an amount of less than 50 wt.-%, preferably less than 30 wt.-%, more preferably less than 20 wt.-%, even more preferably less than 10 wt.-%, based on the total weight of the dry weight plastic.BASF SE 241076W0018Examples of rubber waste include end-of-life tires, rubber waste produced during manufacturing processes and discarded rubber containing products such as latex examining gloves and gaskets. End-of-life tires comprise further ingredients such as textiles and organic and inorganic additives which may be separated from the rubber portion of end- of-life tires prior to pyrolysis. Pyrolysis oils obtained by pyrolysis of (predominantly) end-of-life tires are also known as tire pyrolysis oils (TPO).Biomass waste like green waste, food waste, human waste, manure, sewage, sewage sludge and slaughterhouse waste may also be comprised and pyrolyzed.To obtain a plastic waste pyrolysis oil, the plastic waste is inserted into a pyrolysis reactor using a dosing unit such as a screw or an extruder or a rotary valve or a pneumatic conveyor or a liquid injector. The plastic waste is optionally pre-heated in e.g., a heat exchanger prior to insertion into the pyrolysis reactor and / or subjected to a pre-pyrolysis at a temperature in the range of, for example, from about 200 to about 360 °C. Next, the plastic waste is heated in the pyrolysis reactor to a temperature in the range of from about 350 to about 900 °C, more preferably in the range of from 400 to about 600 °C, and a pressure in the range of from about 0.5 to about 2 bar(abs), more preferably in the range of from 0.9 to about 1.5 bar(abs). The pyrolysis reactor is preferably selected from the group comprising fluidized bed reactors, fixed-bed reactors, moving bed reactors, entrained flow reactors, screw reactors, extruders, stirred tank reactors and rotary kiln reactors. Preferably, the pyrolysis is performed in the pyrolysis reactor under an inert atmosphere exempt of 02 or air.The pyrolysis process according to this disclosure comprises the fractionation or separation of the reaction products according to processes known to the one of skill in the art, in particular into pyrolysis gas, pyrolysis oil, and pyrolysis char fractions.Preferred Embodiments1.2) The process according to any of the preceding embodiments, wherein in step S1), said at least one sustainable feedstock comprises at least one bio-oil, preferably selected from the group consisting of vegetable oils and processing residues thereof, waste cooking oil, tall oil, animal fats, and oils obtained by thermochemical conversion of biomass.1.3) The process according to any of the preceding embodiments, wherein in step S1), said at least one sustainable feedstock comprises at least one pyrolysis oil derived from biomass or waste, preferably derived from plastic waste, more preferably derived from plastic waste comprising polyurethanes and / or polyalkenes.1.4) The process according to any of the preceding embodiments, wherein in step S1), said at least one sustainable feedstock comprises at least one pyrolysis gas derived from biomass or waste, preferably derived from plastic waste, more preferably derived from plastic waste comprising polyurethanes and / or polyalkenes.1.5) The process according to any of the preceding embodiments, wherein in step S1), the total mass fraction of the one or more components selected from the group consisting of bio-oils, pyrolysis oils, and pyrolysis gases is more than 5 %, preferably more than 10 %, more preferably more than 20 %, more preferably more than 30 %, more preferably more than 40 %, more preferably more than 50 %, more preferably more than 60 %, more preferably more than 70 %, more preferably more than 80 %, more preferably more than 90 %.BASF SE 241076W00191.6) The process according to any of the preceding embodiments, wherein in step S1), said at least one sustainable feedstock further comprises at least one component of fossil origin, preferably fossil naphtha.1.7) The process according to any of the preceding embodiments, wherein in step S1), the total mass fraction of the one or more components of fossil origin is not more than 95 %, preferably not more than 90 %, more preferably not more than 80 %, more preferably not more than 70 %, more preferably not more than 60 %, more preferably not more than 50 %, more preferably not more than 40 %, more preferably not more than 30 %, more preferably not more than 20 %, more preferably not more than 10 %.1 .8) The process according to any of the preceding embodiments, wherein in step S1 ), providing at least one sustainable feedstock comprises subjecting at least one raw material selected from biomass and waste to pyrolysis to obtain a pyrolysis product stream and subjecting said pyrolysis product stream to fractionation to obtain at least one fraction selected from pyrolysis gas and pyrolysis oil.In step S2), acetylene is obtained from the feedstock provided in step S1 ) by chemical conversion.For liquid feedstocks comprising bio-oils and / or pyrolysis oils, said conversion optionally starts with the upgrading of said feedstock. Said upgrading process is preferably selected from the group comprising washing, extraction, absorption, adsorption, distillation, hydrotreatment, catalytic cracking, catalytic aromatization, and combinations thereof. Such optional upgrading processes are for example described in WO 2021 / 224287, WO 2023 / 061834, EP 0713906, and WO 95 / 03375 which are incorporated herein by reference. A skilled person knows how and in which cases to use upgrading processes disclosed in said documents and comparable upgrading processes disclosed elsewhere.In particular, said liquid feedstock may be subjected to a hydrotreatment process, i.e., to the reaction with hydrogen in the presence of at least one catalyst, preferably at least one heterogeneous catalyst, preferably at high temperatures and pressures to form a hydrotreated feedstock. For instance, temperatures from 100°C to 600°C and pressures from 5 bar to 200 bar may be applied.Catalytic hydrotreatment is a well-established upgrading technology, e.g., for processing feedstocks such as bio-oils or pyrolysis oils, and comprises different hydrogen-induced chemical transformations. More specifically, catalytic hydrotreatment comprises the processes of hydrodeoxygenation, hydrodenitrogenation, hydrodehalogenation, hydrodesulfurization, hydrodemetallation, hydrocracking, hydroisomerization, and hydrogenation (e.g., of C-C double bonds, C-C triple bonds, conjugated C-C double bonds).Hydrotreatment of feedstocks provided in step S1) may be required to obtain a more valuable or better suitable feedstock for successive processing, e.g., for cracking processes such as a steam cracking to produce olefins and aromatics, or for partial oxidation reaction and / or gasification processes for producing syngas. Such steam cracking processes are known in the art and for example disclosed in H. Zimmermann, R. Walzl, Ullmann's Encyclopedia of Industrial Chemistry, Vol. 13 "Ethylene”, pp. 469-494, 2012, and the references cited therein. Such partial oxidation reactions are known in the art and are for example disclosed in WO 2022 / 200532, Ullmann's Encyclopedia of Industrial Chemistry, Vol. 16, Chapter: Gas Production, 2. Processes”, pages 443-455, 2012, and the references cited therein.Each of the aforementioned successive processes has certain specifications in respect to amount of C-C double bonds, amount of C-C triple bonds, amount of dienes, amount of aromatics, amount of heteroatoms like oxygen,BASF SE 241076W00110 nitrogen, halogens, sulfur, and metals, amount of organic compounds comprising at least one heteroatom, the heteroatoms preferably selected from the group comprising nitrogen, oxygen, halogens, sulfur, and the final boiling point. The final boiling point is affected by the chain length of hydrocarbons present in said feedstock. Upgrading by hydrotreatment may be needed or advisable to better meet such process requirements.Other reasons for a hydrotreatment of such feedstocks comprise the prevention of fouling in further process steps, increasing the physical and chemical (storage) stability of such feedstocks, and providing feedstocks which are within required specifications for successive unit operations. Such specifications may comprise final boiling point, chemical composition, concentration limits for heteroatoms such as nitrogen, oxygen, or sulfur, viscosity, miscibility, and the like. The desired chemical reactions during a hydrotreatment of such feedstocks comprise the removal of heteroatoms such as for example nitrogen, oxygen, halogens, and sulfur in organic compounds, in particular of oxygen, hydrodemetallation for removal of metal atom impurities in such feedstocks, hydrogenation of C-C double and C-C triple bonds, hydrogenation of conjugated C-C double bonds in dienes and aromatics, hydroisomerization, and hydrocracking reactions in which longer chain hydrocarbons are cracked to smaller chain hydrocarbons to reduce the final boiling point of such feedstocks.Hydrotreatment methods for plastic waste derived pyrolysis oils as feedstock are for example disclosed in WO 2023 / 073059, WO 2017 / 083018, FR 3 103 822 A1 , and US 2019 / 062646 A1. Hydrotreatment methods for bio-oils are described, e.g., in M. Zhang et al., Molecular Catalysis 2021 , 504, 111438, and the references cited therein. The methods, catalysts and process parameters can also be used for the method according to the present invention or used by the operator as a starting point for further optimization in respect to a given feedstock composition and / or a given set of specifications (e.g., concentration of olefins, dienes, sulfur compounds) to be reached by the hydrotreatment.Hydrocracking is used to break long-chain hydrocarbons into shorter hydrocarbons. Catalytic hydrocracking is typically carried out over bifunctional catalysts in a hydrogen atmosphere at pressures between 40 bar and 200 bar and temperatures between 300 °C and 600 °C. If the process takes place at medium pressure between 40 bar to 80 bar, it is referred to as mild hydrocracking (MHC). The bifunctional catalysts contain a de- / hydrogenation and an acid functionality, e.g., nickel, molybdenum or noble metals on alumina, zeolites, or other aluminosilicates. Hydrocracking methods are for example disclosed in WO 2019 / 229072, EP 2770040 and US 2013 / 0116491 .Alkanes or alkyl residues having a length n with 10 < n < 30 present in the feedstock provided in step S1) are at least partially converted, in case step S2) comprises a hydrocracking reaction, into alkanes or alkyl residues having a chain length m with m < n wherein 1 < m < 18, preferably 2 < m < 16, more preferably 2 < m < 12, most preferably 3 < m < 9. Such hydrotreatment reactions can be single-phase reactions or multi-phase reactions (e.g., one or more liquid feedstock reacts with gaseous hydrogen; one or more liquid feedstock reacts with gaseous hydrogen in the presence of at least one heterogeneous catalyst; one or more gaseous feedstock reacts with gaseous hydrogen; one or more gaseous feedstock reacts with gaseous hydrogen in the presence of at least one heterogeneous catalyst and so on).Accordingly, different types of reactors can be used for such hydrotreatment reactions, depending for example on the number of phases which must be brought to a reaction. Examples for suitable reactors in case one or more liquid feedstock reacts with gaseous hydrogen in the presence of at least one (solid) heterogeneous catalyst comprise trickle-BASF SE 241076W00111 bed reactors. Examples for suitable reactors in case one or more gaseous feedstock reacts with gaseous hydrogen in the presence of at least one (solid) heterogeneous catalyst comprise fixed bed reactors.A hydrotreatment can be conducted in a single stage (reactor) or in successive stages (successive reactors) in which case different process conditions, reactor types and catalysts may be employed to achieve an improved result compared to a single stage hydrotreatment.Heterogeneous catalysts employed in hydrotreatment reactions of such feedstocks comprise solid catalyst; said solid catalysts typically comprise at least one active metal and a support. The at least one active metal is preferably selected from nickel, cobalt, molybdenum, tungsten, palladium, rhodium, and the like. Combinations of said active metals such as for example nickel-molybdenum, cobalt-molybdenum and the like can also be used.The support in such heterogeneous catalysts is preferably selected from the group comprising alumina, silica, silica- aluminas, zeolites, silica-alumina phosphates, magnesium oxide, clays, carbon, and mixtures thereof. The supports may also comprise support-dopants such as zirconium dioxide, cerium dioxide, titanium dioxide, and mixtures thereof. The temperature, pressure residence time, reactor type, catalyst type and other parameters depend for example on the type of feedstock (composition) used for the hydrotreatment reaction and the type of the desired hydrotreatment reaction (kind of feedstock components to be depleted). The one of skill the art will be familiar with such considerations and will find sufficient guidance in the prior art to select suitable process parameters.Hydrotreatment of bio-oils and pyrolysis oils delivers sustainable hydrocarbons of different chain lengths, ranging from diesel and aviation fuel to naphtha and LPG (liquefied petroleum gas, mainly C2-4 alkanes) fractions, depending on the raw material and hydrotreatment conditions applied.The production of acetylene from the feedstock provided in step S1) may be accomplished by steam cracking to form acetylene. The feedstock may be used as provided in step S1 ), after hydrotreatment as described hereinbefore, and / or in admixture with other feedstocks suitable for steam cracking, e.g., fossil naphtha or fossil LPG. In any case, the input mixture for steam cracking must meet the relevant process specifications.Steam cracking is a chemical process used in the petrochemical industry to break down larger hydrocarbon molecules into smaller ones. Steam cracking processes and steam cracking units ("steam crackers”, i.e., the petrochemical plants in which steam cracking is performed) are for example described in H. Zimmermann, R. Walzl, Ullmann's Encyclopedia of Industrial Chemistry, 2012, chapter "Ethylene”, and the references cited therein. The process involves heating hydrocarbons, in particular naphtha, in (typically gas-fired) furnaces to high temperatures (around 750 °C to 850 °C) in the presence of steam. This causes the hydrocarbons to break apart into smaller molecules, especially into short-chain olefins like ethylene, propylene, and butadiene. These smaller molecules are used as building blocks to produce a wide range of chemical products, such as plastics, synthetic rubber, and other industrial chemicals. Further products of the steam cracking process include aromatics (e.g., benzene, toluene, xylenes), but also C1-4 alkanes, hydrogen, and acetylene. The broad product spectrum obtained is separated into fractions and pure compounds predominantly using cryogenic separation techniques with the help of an elaborated fractionation section.Also, the steam cracker furnaces being fired mainly with natural gas emit large amounts of carbon dioxide which is preferably captured and stored and / or utilized as a chemical raw material.BASF SE 241076W00112While the most important feedstocks for steam cracking are of fossil origin, e.g., fossil naphtha and fossil LPG, sustainable steam cracker feedstocks are gaining more importance to produce downstream products with improved carbon footprints. The sustainable feedstocks provided in step S1) may be suited for that purpose as such, after hydrotreatment, or by dilution, i.e., as a blend, with other suitable feedstocks, in particular with naphtha.Acetylene is one of the products obtained by steam cracking (see, e.g., P. Passler et al., Ullmann's Encyclopedia of Industrial Chemistry, 2012, Chapter "Acetylene”, pp. 310-312, and the references cited therein). In the case of naphtha cracking, higher cracking severities (in terms of lower propylene to ethylene ratios) typically lead to an increase of the acetylene formation. Even higher acetylene yields are obtainable by steam cracking of LPG. While normally being hydrogenated to increase the ethylene yield, acetylene may be recovered according to processes known in the art, e.g., by solvent extraction from the C2 fraction of the steam cracker.The production of acetylene from the feedstock provided in step S1) may also be accomplished by steam cracking, as described hereinbefore, to form C1-4 alkanes, in particular methane, followed by partial combustion, i.e., partial oxidation, of said alkanes to produce acetylene.C1-4 alkanes are routinely separated from other cracking products using the fractionation section of the steam cracker (see, e.g., H. Zimmermann, R. Walzl, Ullmann's Encyclopedia of Industrial Chemistry, 2012, chapter "Ethylene”, and the references cited therein).Acetylene may be formed from said alkanes, especially from methane, by processes known in the art, for example, described in P. Passler et al., Ullmann's Encyclopedia of Industrial Chemistry, 2012, Chapter "Acetylene”, and the references cited therein. The partial combustion with oxygen or air (e.g., Sachsse-Bartholome process) delivers acetylene and also a relatively carbon-rich syngas which may be used after the possibly required adjustment of the stoichiometric number S, e.g., for methanol synthesis as described below. Such process sequence hence allows for the formation of acetylene on the one hand and formaldehyde (via syngas and methanol) on the other hand from one single feedstock, preferably a sustainable feedstock.Also, the non-condensable, gaseous fraction obtainable from pyrolysis of solid feedstocks (pyrolysis gas), as described for step S1 ), contains light hydrocarbons, in particular C1-4 alkanes and C1-4 alkenes, e.g., as reported for a fixed- bed reactor pyrolysis by P. K. Ghodke et al., Processes 2023, 11, 71. However, said pyrolysis gas as such may not be fit for the partial combustion process due to the presence of components, e.g., olefins, that may, for instance, pose a safety risk when introduced into the process. Thus, it may be beneficial to subject the pyrolysis gas to a separation process that delivers a gas mixture that is well suited for the partial combustion to acetylene. The fractionation section of a steam cracker plant may serve this purpose very well.Hence, according to this disclosure, the fractionation section of a steam cracker is used advantageously to obtain from a pyrolysis gas one or more gas fractions suitable for partial combustion to form acetylene. To this end, the pyrolysis gas is fed, optionally after compression, into the hydrocarbon fractionation section of a steam cracking unit where, depending on the specific design, construction, and process, different fractions comprising C1-4 alkanes are separated. These fractions may be used in separated or combined form as feedstocks for the above-mentioned partial combustion process to acetylene. In addition, one or more fractions containing olefins are obtained as well as a hydrogen fraction.BASF SE 241076W00113Said processing route of pyrolysis gas improves the overall material use of sustainable pyrolysis products: It does not only deliver further acetylene of sustainable origin, but at the same time increases the output of sustainable olefins of the steam cracker. Thus, altogether a process with high efficiency is provided.Preferred Embodiments1 .9) The process according to any of the preceding embodiments, wherein step S2) comprises upgrading, e.g., catalytic hydrotreatment, of said at least one sustainable feedstock, wherein said catalytic hydrotreatment preferably comprises a hydrocracking step.1.10) The process according to any of the preceding embodiments, wherein in step S2) said conversion comprises steam cracking of at least a portion of said at least one sustainable feedstock to obtain a cracking product mixture comprising acetylene and separating acetylene therefrom.1.11) The process according to any of the preceding embodiments, wherein in step S2) said steam cracking unit or a part thereof is utilized for steam cracking of at least a portion of said at least one sustainable feedstock to obtain a cracking product mixture comprising acetylene and for separating acetylene therefrom.1.12) The process according to any of the preceding embodiments, wherein in step S2) said conversion comprises steam cracking of at least a portion of said at least one sustainable feedstock to obtain a cracking product mixture comprising one or more C1-4 alkanes, separating therefrom at least one fraction comprising one or more C1-4 alkanes, and subjecting said at least one fraction to partial combustion to obtain acetylene.1.13) The process according to the preceding embodiment, wherein said partial combustion further delivers syngas, at least a portion of which is used for producing methanol according to step S3a).1.14) The process according to any of the preceding embodiments, wherein in step S2) said steam cracking unit or a part thereof is utilized for steam cracking of at least a portion of said at least one sustainable feedstock to obtain a cracking product mixture comprising one or more C1-4 alkanes and for separating therefrom at least one fraction comprising one or more C1-4 alkanes.1.15) The process according to any of the preceding embodiments, wherein in step S1) said at least one sustainable feedstock comprises pyrolysis gas and wherein in step S2) said conversion comprises feeding into the fractionation section of a steam cracking unit said at least one sustainable feedstock, separating therefrom at least one fraction comprising one or more C1-4 alkanes, and subjecting said at least one fraction to partial combustion to obtain acetylene.1.16) The process according to any of the preceding embodiments, wherein in step S2) said steam cracking unit or a part thereof is utilized for separating from at least one sustainable feedstock comprising pyrolysis gas at least one fraction comprising one or more C1-4 alkanes.1.17) The process according to any of the preceding embodiments, wherein in step S2) said steam cracking unit or a part thereof is utilized for separating from at least one sustainable feedstock comprising pyrolysis gas at least one fraction comprising one or more C1-4 olefins.1.18) The process according to any of the preceding embodiments, wherein in step S2) said steam cracking unit or a part thereof is utilized for separating from at least one sustainable feedstock comprising pyrolysis gas a fraction comprising hydrogen.BASF SE 241076W001141.19) The process according to any of the preceding embodiments, wherein in step S2) CO2 that is emitted by the steam cracking subunit is captured and optionally stored and / or utilized.Step S3)In step S3), formaldehyde is provided in sufficient amounts and quality (e.g., purity) to facilitate the later reaction to BYD described hereinafter. Formaldehyde may be provided according to any conceivable production route that is known to the one of skill in the art. In particular, formaldehyde may be produced from methanol which in turn is obtainable from syngas. Preferably, the process and the obtained formaldehyde are characterized by favorable sustainability attributes, e.g., resulting from the use of bio-based or recycling-based feedstocks.Thus, step S3) may comprise the following substeps:S3a) providing methanol; andS3b) converting at least a portion of said methanol to formaldehyde, wherein substep S3a) optionally comprises the substeps S3aa) providing syngas; andS3ab) converting at least a portion of said syngas to methanol.Substep S3a)Methanol is provided in sufficient amounts and quality (e.g., purity) for further use in the conversion to formaldehyde. While said methanol may in principle originate from any conceivable source that is known to the one of skill in the art, methanol may in particular be produced from syngas, preferably as described hereinafter. Preferably, at least a portion of said methanol exhibits favorable sustainability properties, for instance, it originates from sustainable, in particular bio-based or recycling-based sources or it has a reduced product carbon footprint.Substep S3aa)Syngas is provided in sufficient amounts, quality (e.g., purity), and H2-to-CO and H2-to-CO2 ratios, respectively, (together: H2-to-COx ratio) to facilitate the later conversion to methanol. Providing syngas may include the substeps of producing syngas from a feedstock, purifying the raw syngas, and adjusting the H2-to-COx ratio in the (optionally purified) syngas. As a part of the last-mentioned substep, the coproduced CO2 may be captured from the resulting gas stream and preferably stored (carbon capture and storage, CCS) or utilized as a chemical feedstock (carbon capture and utilization, CCU) to avoid CO2 emissions to the atmosphere.Producing Syngas from FeedstockSyngas may be produced from a plethora of carbon-containing feedstocks, virtually from any hydrocarbon feedstock, using a variety of technological approaches. In particular, syngas production may be accomplished by reaction of gaseous and liquid feedstocks with steam (steam reforming), CO2 (dry reforming), or 02 (partial oxidation) or by reaction of solid feedstocks with oxidants like 02 and / or steam (partial oxidation: gasification). Syngas may also be obtainedBASF SE 241076W00115 from CO2 and H2 as input materials via reverse water gas shift (reverse WGS, rWGS) reaction, in which CO and H2O are formed from CO2 and H2.Traditionally, mainly fossil feedstocks like natural gas, naphtha, heavy vacuum residues, and coal have been used for the generation of syngas. Syngas production processes based on fossil feedstocks may be made more sustainable by capturing and storing the formed CO2 (e.g., as a by-product of complete oxidation and / or the WGS reaction) such that greenhouse gas emissions are limited. Nowadays, in view of the finite availability of fossil resources and the urgency to reduce net CO2 emissions, there is a high need to replace fossil carbon resources by sustainable, preferably renewable, carbon resources. Thus, non-fossil, sustainable sources of syngas have been attracting increasing interest. Thus, preferably, the provided syngas originates from bio-based or recycling-based carbon-containing feedstocks like biomass or waste that may be converted to syngas through processes like gasification, pyrolysis, and partial oxidation, or fermentation followed by steam reforming. Also, syngas may be obtained from CO2 and H2 through (partial) rWGS reaction, wherein, preferably, said CO2 had been captured from biomass or waste incineration, from other industrial processes, or from the atmosphere and said H2 had been produced sustainably, e.g., as described below, in particular by processes driven by renewable energy like water electrolysis. Further, syngas with reduced CO2 emissions and thus a reduced carbon intensity may be generated by reforming of natural gas or gasification of coal wherein the formed CO2 is captured and stored or used as a feedstock in the chemical industry. In particular, steam reforming, autothermal reforming, or dry reforming of biogas, gasification of biomass or waste, and rWGS reaction of CO2 and H2 are contemplated within the scope of this disclosure as sustainable syngas sources.Reforming of Gaseous or Liquid FeedstocksReforming of hydrocarbons is a mature process to produce syngas. The main hydrocarbon reforming technologies are steam (methane) reforming (SMR), partial oxidation, and autothermal reforming (ATR) (the last-mentioned being basically a combination of the former two processes), all of which are well-known to the one of skill in the art. Said processes to produce syngas are described for example in H. Hiller et al., Ullmann's Encyclopedia of Industrial Chemistry, 2012, Chapter "Gas Production, 1. Introduction”, R. Reimert et al., Ullmann's Encyclopedia of Industrial Chemistry, 2012, Chapter "Gas Production, 2. Processes”, and the references cited therein.The most Important gaseous feedstock for reforming processes is methane, e.g., provided as natural gas, synthetic natural gas (SNG), or biogas. Also other low-boiling gaseous hydrocarbons like ethane or propane and liquid hydrocarbons, such as light naphtha cuts, can be reacted, e.g., after optional sulfur removal with water vapor via steam reforming.For instance, in steam reforming, methane (or other low-boiling hydrocarbons) is reacted with steam in the presence of a catalyst under high temperature and high-pressure conditions, whereas in partial oxidation, methane is reacted with sub-stoichiometric amounts of oxygen.Partial oxidation of hydrocarbons, in particular of natural gas, SNG, biogas, ethane and the like, may be carried out according to various routes. Among them is the partial combustion with oxygen or air to obtain acetylene along with a relatively carbon-rich syngas (e.g., Sachsse-Bartholome process). Said process is, for example, described in P. Passler et al., Ullmann's Encyclopedia of Industrial Chemistry, 2012, Chapter "Acetylene”, and the references cited therein.BASF SE 241076W00116Another reforming approach uses CO2 as an oxidant (dry reforming), wherein methane and CO2 are converted in an endothermic reaction in the presence of a catalyst. Dry reforming is reviewed for example by D. Pakhare et al., Chem. Soc. Rev. 2014, 43, 7813-7837, Z. Alipour et al. Chem. Eng. J. 2023, 452, 139416, and the references cited therein.Gasification of Solid or Liquid FeedstocksGasification of solid or liquid feedstocks like fossil feedstocks (such as coal), biomass, waste, or mixtures thereof involves heating the feedstock to high temperatures in the presence of limited supplies of oxygen or steam. The conversion proceeds via thermal decomposition and subsequent heterogeneous reaction of the solid residue with reactive gases like 02, steam, CO2, or H2. Solid biomass feedstocks suitable for gasification include wood or residues thereof, (energy) crops or residues thereof, agricultural waste, and sewage sludge. Solid waste feedstocks suitable for gasification include municipal waste, hazardous waste, industrial waste, mixed plastic waste, caprolactam-based waste, or end-of-life tires.Syngas is for example produced from solid feedstocks via coal gasification. Coal is reacted thereby in a mixture of partial oxidation with air or pure 02 and gasification with water vapor to give a mixture of CO and H2. Via the Boudouard equilibrium carbon monoxide is in equilibrium with carbon and carbon dioxide.Furthermore, the WGS reaction must be taken into account.CO + H2O ^ CO2+ H2,The exothermic reaction with oxygen provides the necessary energy to achieve the high reaction temperatures for the endothermic gasification reaction of carbon with water vapor.Also, more sustainable solid feedstocks like biomass (e.g., wood or straw) or waste may be converted to syngas through gasification techniques. These feedstocks may need to be pre-treated according to a suitable pre-treatment method or a suitable combination of pre-treatment methods with the aim to homogenize the physical and chemical properties of the feedstock, to meet certain requirements for a specific type of gasifier, and / or to meet certain requirements for further downstream process steps to produce chemical compounds.Suitable pre-treatment methods for a given feedstock are preferably selected from the group comprising drying, comminution, classification, sorting, agglomeration, (thermo-)chemical methods, and biological methods.Drying methods comprise belt drying, fluidized bed drying, drum drying, spray drying, hearth drying, rotary tray drying, and radiation drying.Comminution methods comprise pressure, impact, shearing, grinding, milling, shredding, crushing, and cutting. Grinding a feedstock may be carried out, e.g., in rod mills and ball mills, closed circuited with classification. Milling is preferably performed in a wet state. Accordingly, a grinding pre-treatment is preferably combined with a drying method in a single pre-treatment unit. Crushing may be performed in jaw-crushers, gyratory crushers, and cone crushers. Crushing is preferably performed in a dry state. Accordingly, a crushing pre-treatment is preferably combined with a drying method prior to crushing in a single pre-treatment unit.Classification methods comprise screening (e.g., with revolving drum screens, surface screens, fixed and movable gratings), winnowing, flotation, zigzag classification, and air table classification. Screening systems preferably compriseBASF SE 241076W00117 one or more of bar screens, wedge wire screens, radial sieves, banana screens, multi-deck screens, vibratory screens, fine screens, flip flop screens, and wire mesh screens. Screens can be static, or they can incorporate mechanisms to shake or vibrate the screen(s).Sorting methods comprise manual sorting, pneumatic sorting, sensor-based sorting (e.g., NIR-assisted sorting, induc- tive-assisted sorting, and X-ray-assisted sorting), and metal separation (e.g., magnetic separation, eddy current separation).Agglomeration methods comprise pelletizing, briquetting, and extrusion. Such methods usually comprise a means for compressing the feedstock and optionally a further means for heating ("baking”) the compressed feedstock. Such pretreatment methods often provide better physical characteristics than the initial feedstock, improve the transportability of the feedstock, e.g., to another location, and improve the thermochemical behavior.Thermochemical methods comprise pyrolysis, converting the feedstock into char, and torrefaction. Thermochemical pre-treatment may be carried out in pyrolysis reactors in which the feedstock is heated to e.g., 500 °C in an inert atmosphere to obtain a pyrolysis oil having an improved calorific value compared to the untreated feedstock and a reduced volume which improves the transportability of the feedstock, e.g., to another facility.In particular, biomass is preferably torrefied or converted by pyrolysis into a pyrolysis oil prior to gasification.Municipal solid waste (MSW) is optionally pre-treated by methods such as drying, shredding, sorting, inert removal and may be used in the form of refuse-derived fuel (RDF).Biological methods comprise fermentation such as anaerobic fermentation.The gasification step is performed in a gasifier to produce raw syngas from the (optionally pre-treated) feedstock.The selection of reactor type and size depends on several parameters, including the composition of the carbonaceous feedstock, physical and / or chemical properties of the feedstock like water content, ash content, elemental composition, size, and calorific value, the demand of products, and the availability of the carbonaceous feedstock. It also depends on the pre-treatment method applied to the feedstock. An overview of gasifier types is for example provided in J. G. Speight, Handbook of Gasification Technology, Scrivener Publishing and Wiley, 2020, ch. 8.4.2, pp. 259-262. Preferably, the gasifier is selected from the group comprising counter-current fixed bed reactors, co-current-fixed bed reactors, bubbling fluidized bed reactors, circulating fluidized bed reactors, dual fluidized bed reactors, downdraft entrained flow reactors, updraft entrained flow reactors, and plasma gasifiers like fixed-bed plasma gasifiers, more preferably from the group comprising bubbling fluidized bed reactors, circulating fluidized bed reactors, dual fluidized bed reactors, downdraft entrained flow reactors, updraft entrained flow reactors, and fixed-bed plasma gasifiers.While gasifiers typically rely on heat generation by (partial) oxidation, in particular plasma gasifiers, e.g., their plasma torches, may be operated with electrical power, preferably sustainable electrical power.Preferred combinations of pre-treatment methods and gasifier types comprise:- screening and / or agglomeration with counter-current or co-current-fixed bed reactors;- crushing and / or shredding with bubbling, circulating, or dual fluidized bed reactors;- grinding with downdraft or updraft entrained flow reactors.The gasification reaction in a gasifier is typically carried out at a temperature > 700 °C in the presence of a sub- stoichiometric amount of an oxidant such as 02, air, steam, supercritical water, CO2, or a mixture of the aforementioned. Oxygen is the most common oxidant used for gasification because of its easy availability and low cost.BASF SE 241076W00118Preferably, the gasifier is an "oxygen blown" gasifier, i.e., 02 is preferably used as the oxidant in suitable gasifiers listed above. For example, the molar ratio "oxygen: oxygen required for a total oxidation of the feedstock” can range from 0.3 to less than 1. It is particularly advantageous for any of the oxygen-consuming process steps described herein in terms of sustainability if as much of the needed 02 as possible is supplied with the help of renewable energy sources, e.g., via water electrolysis driven by renewable energy as described below. If steam acts as an oxidant, the raw syngas has a higher molar ratio H2-to-CO in comparison to the use of air as an oxidant. Gasification yields a raw syngas which has a molar ratio H2-to-CO when leaving the gasifier which ranges from about 0.1 : 1 to about 3:1 and depends on the type of solid and / or liquid feedstock used, the oxidant and other reaction conditions applied such as temperature and / or residence time of the reactants in the gasifier. A gasification reaction usually results in further reaction products such as solid and / or highly viscous carbonaceous residues (e.g., ash, char, and / or tar).Pyrolysis of Solid FeedstocksPyrolysis processes of solid feedstocks like waste and biomass to obtain pyrolysis oils are described hereinbefore.Pyrolysis oils (and similarly pyrolysis chars) may be converted in a gasifier and / or partial oxidation reaction unit into syngas. Such gasifiers and partial oxidation reactions are known in the art and are for example disclosed in R. Reimert et al., Ullmann's Encyclopedia of Industrial Chemistry, 2012, Chapter: "Gas Production, 2. Processes”, pp. 443-455, and J. G. Speight, Handbook of Gasification Technology, Scrivener Publishing and Wiley, 2020, and the references cited therein. The skilled person can select suitable reactors and reaction conditions to convert the pyrolysis oil into syngas by a partial oxidation reaction and / or gasification. Preferably, the pyrolysis oil is converted in an entrained-flow gasifier into syngas. rWGS of CO2 and H2CO2 may form the basis of syngas either by being used itself as the carbon-containing component of syngas (i.e., syngas consisting essentially of CO2 and H2) or by being converted with H2 to syngas consisting essentially of CO and H2 (e.g., through the rWGS reaction) or with CH4 of fossil or biobased origin (e.g., through dry reforming). rWGS reactions are described in Y. A. Daza et al., RSC Adv. 2016, 6, 49675-49691 , E. Rezaei et al., Chemical Engineering Research and Design, 2019, 144, 354-369, EP2175986, CN103183346, US8946308and the references cited therein. Preferably the CO2 and the H2 for said processes are of sustainable origin, more preferably the CO2 is captured from flue gases (most preferably derived from biomass) or the atmosphere and H2 is obtained with reduced or without CO2 emissions.- CO2 CaptureCO2 may be captured from the atmosphere (direct air capture, DAC), from the ocean (direct ocean capture, DOC; indirect ocean capture, IOC), or from industrial point sources of CO2 emissions (via pre-combustion capture, oxyfuel combustion, or post-combustion capture routes). Such industrial point sources include power plants based on combustion of organic material like coal, natural gas, biogas, oil, waste, or biomass (wood or residues thereof, (energy) crops or residues thereof, agricultural waste, sewage sludge) and industrial facilities like plants for cement production, steel manufacturing, chemical manufacturing, biogas production and processing, and refineries. In the area of chemicalBASF SE 241076W00119 manufacturing, steam crackers, steam reformers (especially to produce hydrogen), partial oxidation plants (e.g., to obtain ethylene oxide, acetylene, or syngas), and facilities for the hydrotreatment of bio-oils or waste-derived pyrolysis oils are among the main facilities that emit significant amounts of CO2. Capturing CO2 is most cost-effective at point sources, such as large carbon-based energy facilities, industries with major CO2 emissions (e.g., cement production, steelmaking), natural gas processing, synthetic fuel plants, and fossil fuel-based hydrogen production plants. Extracting CO2 from air is possible, although the lower concentration of CO2 in air compared to combustion sources complicates the engineering and makes the process therefore more expensive. Thus, preferably, the CO2 is captured from industrial flue gases.Processes for capturing CO2 are described for examples in S. Topham et al., Ullmann's Encyclopedia of Industrial Chemistry, 2014, Chapter "Carbon dioxide”, and the references cited therein.In post combustion capture, the CO2 is removed after combustion of the fossil fuel - this is the scheme that would apply to fossil-fuel power plants. CO2 is captured from flue gases at power stations or other point sources. Absorption or carbon scrubbing with amines is the dominant capture technology. It is the only carbon capture technology so far that has been used industrially. CO2 adsorbs to a MOF (metal-organic framework) through physisorption or chemisorption based on the porosity and selectivity of the MOF leaving behind a CO2 poor gas stream. The CO2 is then stripped off the MOF using temperature swing adsorption (TSA) or pressure swing adsorption (PSA) so the MOF can be reused.DAO is a process of capturing CO2 directly from the ambient air and generating a concentrated stream of 002 for sequestration or utilization or production of carbon-neutral fuel. 002 removal is achieved when ambient air contact chemical media, typically an aqueous alkaline solvent or sorbents. These chemical media are subsequently stripped of 002 through the application of energy (namely heat), resulting in a 002 stream that can undergo dehydration and compression, while simultaneously regenerating the chemical media for reuse.Dilute 002 can be efficiently separated using an anionic exchange polymer resin called Marathon MSA, which absorbs air 002 when dry, and releases it when exposed to moisture. A large part of the energy for the process is supplied by the latent heat of phase change of water. Other substances which can be used are metal-organic frameworks (or MOF’s). Membrane separation of 002 rely on semi-permeable membranes.- H2 ProductionHydrogen, e.g., for use in the rWGS reaction or to adjust the H2-to-COx ratio of syngas as described below, may be obtained according to processes known in the art. Production process are for example described in P. Haussinger et al., Ullmann's Encyclopedia of Industrial Chemistry, 2012, Chapter "Hydrogen, 2. Production” and the references cited therein. In particular, starting from natural gas, biogas, or other light hydrocarbons, steam reforming, autothermal reforming, or other syngas-producing processes (especially if followed by a WGS reaction and hydrogen separation) and pyrolysis of hydrocarbons provide substantial amounts of H2. Further important H2 production technologies comprise water electrolysis and chlor-alkali electrolysis as well as H2 generation by decomposition of H2 carriers like ammonia. H2 with favorable sustainability attributes may be obtained by separation from syngas with favorable sustainability attributes according to gas separation processes known in the art, e.g., as described in P. Haussinger et al., Ullmann's Encyclopedia of Industrial Chemistry, 2012, Chapter "Hydrogen, 2. Production”, Chapter "Hydrogen, 3. Purification”,BASF SE 241076W00120 and the references cited therein, in particular by pressure-swing adsorption. Said syngas may be produced according to any of the above-mentioned syngas-producing processes starting from sustainable, i.e., renewable or recycled, feedstocks. H2 with favorable sustainability attributes may be produced also from fossil sources, e.g., via steam reforming or autothermal reforming of natural gas, when the formed CO2 is captured and stored. Alternatively, it may be obtained through methane pyrolysis of natural gas, synthetic natural gas, or biogas, wherein solid carbon, but no CO2 is formed as a by-product. Sustainable H2 may also be manufactured by electrolysis of water and chlor-alkali electrolysis in which at least a part of the needed electrical power is generated from non-fossil, renewable sources.In methane pyrolysis (also referred to as "methane decomposition”), light hydrocarbons, in particular methane, e.g., in the form of natural gas or biogas, is decomposed without the involvement of oxygen into H2 and solid, high-purity carbon (e.g., as carbon black, carbon powder, or granular carbon). In contrast to reforming, however, no gaseous CO2 is produced, but solid carbon is formed as a by-product, which has a positive effect on economic efficiency and ecologic impact. Further, compared to water electrolysis, methane pyrolysis requires significantly less energy. Therefore, methane pyrolysis is considered a promising sustainable technology for future hydrogen production.Methane pyrolysis may be carried out in different ways known to the one skilled in the art (Muradov et al., International Journal Hydrogen Energy 2008, 33, 6804-6839; Abbas et al., International Journal Hydrogen Energy 2010, 35, 1160- 1190); Dagle et al.: An Overview of Natural Gas Conversion Technologies for Co-Production of Hydrogen and Value- Added Solid Carbon Products, Report by Argonne National Laboratory and Pacific Northwest National Laboratory (ANL-17 / 11, PNNL-26726, November 2017): catalytically or thermally, and with heat input via plasma, microwave, heated carrier gas, resistance heating, induction, liquid metal processes, or autothermally, in particular via plasma pyrolysis (WO 2015 / 116797, WO 2015 / 116800), metal melting / metal salt melting (WO 2020 / 161192, WO 2021 / 183959), moving bed process (US 2982622, WO 2019 / 145279, WO 2020 / 200522, WO 2023 / 057242), (fluidized bed) catalytic process (WO 2011 / 029144, WO 2016 / 154666), or partial / pulsed combustion (WO 2020 / 118417 and US 2022 / 0185664), the moving bed process being particularly advantageous due to its high efficiency, heat integration, flexibility, and favorable product carbon footprint. These processes differ I. a. in the form of the energy used (thermal, electrical, etc.), the process conditions (temperature, pressure, etc.), the catalysts, and / or auxiliary materials used. The pyrolysis process is preferably heated electrically, even more preferably by resistive heating (Joule heating) of the substrate material (US 2982622, WO 2019 / 145279, and WO 2020 / 200522).The solid carbon type generated in the methane decomposition depends on the reaction conditions, reactor, and heating technology. Examples are carbon black from plasma processes carbon powder from liquid metal processes granular carbon from thermal decomposition in fixed, moving, or fluidized bed reactors.The processing and separation of solid carbon depends on the chosen pyrolysis technology and is known by the person skilled in the art. Thus, solid carbon may be separated by a cyclone or a filter and may be post-treated, e.g., to achieve agglomeration; further, the carbon may be purified by washing and / or evaporation techniques to remove, for instance, residual metal contamination. The resulting gas stream comprising hydrogen may be finally purified by a PSA processBASF SE 241076W00121 to remove remaining impurities like hydrogen sulfide, carbon oxides, hydrocarbons, and inert gases like nitrogen, to yield purified hydrogen.Electrolysis of water is an environmentally friendly method to produce hydrogen because it may use H2O as a sustainable resource and produces only pure 02 as by-product. Within the present invention, said 02 may be used advantageously in oxygen-consuming processes like partial oxidation, autothermal reforming, gasification, or methanol oxidation as described herein. Additionally, water electrolysis utilizes direct current (DC), preferably from sustainable energy sources, for example solar, wind, hydropower, and biomass.One suitable water electrolysis process is alkaline water electrolysis. Hydrogen production by alkaline water electrolysis is a well-established technology up to the megawatt range for a commercial level. Alkaline electrolysis operates at lower temperatures such as 30-80°C with alkaline aqueous solution (KOH / NaOH) as the electrolyte, the concentration of the electrolyte being about 20% to 30 %. However, alkaline electrolysis has negative aspects such as limited current densities (below 400 mA / cm2), low operating pressure and low energy efficiency.Polymer electrolyte membrane (PEM) water electrolysis was developed to overcome the drawbacks of alkaline water electrolysis. Variants of PEM water electrolysis are proton exchange membrane water electrolysis (PEMWE) and anion exchange membrane water electrolysis (AEMWE). PEM water electrolysis technology is similar to the PEM fuel cell technology, where solid polysulfonated membranes (Nation®, fumapem®) are used as an electrolyte (proton conductor). These proton exchange membranes have many advantages such as low gas permeability, high proton conductivity (0.1 ± 0.02 S cm-1), low thickness (20-300 pm), and allow high-pressure operation. In terms of sustainability and environmental impact, PEM water electrolysis is one of the most favorable methods for conversion of sustainable energy to highly pure hydrogen. PEM water electrolysis has great advantages such as compact design, high current density (above 2 A cm-2), high efficiency, fast response, operation at low temperatures (20-80°C) and production of ultrapure hydrogen. The state-of-the-art electrocatalysts for PEM water electrolysis are highly active noble metals such as Pt / Pd for the hydrogen evolution reaction (HER) at the cathode and lrO2 / RuO2 for the oxygen evolution reaction (OER) at the anode.One of the largest advantages of PEM water electrolysis is its ability to operate at high current densities. This can result in reduced operational costs, especially for systems coupled with very dynamic energy sources such as wind and solar power, where sudden spikes in energy output would otherwise result in uncaptured energy. The polymer electrolyte allows the PEM water electrolyzer to operate with a very thin membrane (ca. 100-200 pm) while still allowing high operation pressure, resulting in low ohmic losses, primarily caused by the conduction of protons across the membrane (0.1 S / cm), and a compressed hydrogen output.An overview of hydrogen production by PEM water electrolysis is given in S. Kumar and V. Himabindu, Material Science for Energy Technologies 2 (2019), pp. 4442 - 4454. An overview of hydrogen production by anion exchange membrane water electrolysis is given in H. A. Miller et al., Sustainable Energy Fuels, 2020, 4, pp. 2114 - 2133.Hydrogen may be furthermore obtained by the chlor-alkali electrolysis process which is known to the one of skill in the art. The process is for example described in P. Schmittinger et al., Ullmann's Encyclopedia of Industrial Chemistry, 2011 , Chapter "Chlorine”, pp. 538-595, and the references cited therein.BASF SE 241076W00122Also, generation of H2 by decomposition of ammonia is contemplated within the scope of this invention. Such processes are known to the one of skill in the art and have been reviewed, e.g., by I. Lucentini et al., Ind. Eng. Chem. Res. 2021 , 60, 51 , 18560-18611.Within the present invention, the production of hydrogen is preferably not associated with CO2 emissions from fossil sources. Thus, preferred processes are steam reforming, autothermal reforming, and other syngas-producing processes in which the formed by-product carbon dioxide is captured and sequestered or used as a chemical raw material and is thus not released to the atmosphere. Further preferred processes are steam reforming, autothermal reforming, and other syngas-producing processes based on renewable resources like biogas or other biomass-derived light hydrocarbons. Even more preferred processes are those with net-negative CO2 emissions, e.g., steam reforming, autothermal reforming, and other syngas-producing processes based on renewable resources and combined with CCS or CCU, or methane pyrolysis based on renewable resources like biogas or other biomass-derived light hydrocarbons.Other preferred processes to produce H2 are electrolysis of water and chlor-alkali electrolysis in which at least a part of the needed electrical power is generated from non-fossil, renewable sources. The term "at least in part” means that another part of the electrical power can still be produced from fossil fuels (preferably from natural gas, since combustion of natural gas causes much lower carbon dioxide emission per Megajoule of electrical energy produced than combustion of coal). However, the portion of electrical energy produced from fossil fuels should be as low as possible, preferably < 50%, more preferably < 30%, most preferably < 20%, further most preferably < 10%, ideally < 1 %. Preferably, the electrical power is at least in part, preferably exclusively, sustainable energy, as defined hereinbefore.Various methods for certification and tracking of the "energy source mix” have been set up based on local legislations, e.g., Guarantees of Origin (Gos: Europe), Renewable Electricity Cerficates (RECs: USA, Canada), or international RECs (l-RECs: China, India, Brazil, Mexico, Indonesia, South Africa, etc). Certificates such as "Non-Fossil Certificate Contracts” are common practice for tracking the ratio of non-fossil energy used in industrial processes and related products (e.g., https: / / www.ekoenergy.org / ecolabel / criteria / tracking / ).Purification of SyngasThe raw syngas obtained by any one or more of the processes described hereinbefore may be further treated to obtain purified syngas.In such purification steps, impurities and other undesired components are removed. Typical impurities in the raw syngas, e.g., as obtained from gasification processes, comprise acid gases, chlorides, sulfur-containing organic compounds such as sulfur dioxide, ammonia, trace heavy metals like mercury (e.g., as respective salts), tars / condensable hydrocarbons, and particulate residues like dust. Various chemical and / or physical methods for removal of such impurities from said raw syngas such as filtration, scrubbing, condensation and ab- / adsorption are known and can be chosen and adapted according to the type and respective concentration of the impurities in said raw syngas and the tolerance to such impurities in the successive process steps. E.g., bulk particulate impurities can be removed from the raw syngas by a cyclone and / or filters, fine particles, ammonia, and chlorides by wet scrubbing, trace heavy metals by solid absorbents, and sulfur-containing organic compounds (e.g., COS) by catalytic hydrolysis to H2S and acid gas removal. Bulky and fine particles such as dust in the syngas may also be removed with a quench in a soot water washing unit.BASF SE 241076W00123Purification of raw syngas is preferred to improve the lifetimes and to maintain the activities of catalysts utilized in successive process steps and to meet environmental emission regulations.Adjusting the H2-to-COx ratioTo facilitate the further syngas use, it will be typically necessary to adjust the H2-to-COx ratio in the obtained syngas to fulfill the stoichiometric requirements for subsequent syngas-utilizing processes like methanol synthesis. These are typically described by the stoichiometric number S, defines as S = ([H2]-[CO2]) / ([CO2]+[CO]). For instance, SMR may provide a stoichiometric number of approximately 2.8 while biomass gasification may deliver syngas with a stoichiometric number of only slightly above 1. To produce methanol, the ratio of carbon oxides to hydrogen in the synthesis gas is adjusted to meet the reaction equationsCO + 2 H2 — > CH3OHCO2 + 3 H2 ^ CH3OH + H2OThus, a H2-to-CO molar ratio of approximately 2 will be needed for methanol production and even higher values in case the syngas comprises substantial amounts of CO2 that have to be converted. A stoichiometric number of slightly above 2 has been proven to be optimal. Such adjustment may be achieved, for instance, by carrying out the WGS reaction or by admixing H2 and CO2, respectively, from external sources, i.e., from processes other than those to produce said syngas, e.g., from water electrolysis or carbon capture.The WGS equilibrium allows to adjust the stoichiometric number according to the following reaction equation:CO + H2O H2 + CO2Thus, the H2 content in the syngas is increased by reacting at least a portion of the CO comprised in the raw syngas with water to form additional H2 and CO2 and thereby a H2-enriched syngas stream is generated. Hence, CO-rich syngas can be H2-enriched or CO-depleted via the WGS reaction by adding water and removing CO2. I.e., syngas having a first molar ratio H2-to-CO is converted in the WGS reaction to a H2-enriched syngas having a second molar ratio H2-to-CO, wherein said second molar ratio is larger than said first molar ratio.The WGS reaction is an exothermic reaction. It is preferably performed according to processes known in the art, such as those defined in W.-H. Chen, et al, Applied energy 2020, 258, 114078. It can be conducted with a variety of catalysts (such as copper-zinc-aluminum catalysts and chromium or copper promoted iron-based catalysts) in the temperature range between about 200 °C and about 480 °C. The type of WGS reaction can be adapted to the general conditions and requirements of the process, e.g., how much additional H2 obtained by the WGS reaction is desired.Vice versa, the rWGS reaction, starting from H2-rich syngas, yields H2-depleted or CO-enriched syngas by adding CO2 and removing water.Details on the WGS equilibrium are described, e.g., in H. Hiller et al., Ullmann's Encyclopedia of Industrial Chemistry, 2012, Chapter "Gas Production, 1. Introduction” and R. Reimert et al., Ullmann's Encyclopedia of Industrial Chemistry, 2012, Chapter "Gas Production, 2. Processes”, and the references cited therein.CO2 formed in substep S3aa), during the syngas production process and / or the WGS reaction, may be removed at least in part from syngas. A variety of processes to capture CO2 is available to the one of skill in the art; suitable methods for CO2 removal from syngas include membrane separation, cryogenic separation, absorption, adsorption, e.g., with PSA or MOFs, and combinations thereof. In particular, CO2 may be removed from the syngas by absorption.BASF SE 241076W00124The syngas is contacted with an aqueous solution of alkylamines such as monoethanolamine, diethanolamine, methyldiethanolamine and the like or methanol ("amine wash” or "methanol wash”). CO2 is captured in such solutions / liq- uids in a chemical reaction and then directed to a "regenerator” (e.g., a stripper with a boiler) where the absorption reaction is reversed such that CO2 and the recovered alkylamine are obtained.Processes for the separation and storage of carbon dioxide are described, e.g., in Topham et al., Ullmann's Encyclopedia of Industrial Chemistry, 2014, Chapter "Carbon Dioxide”, pp. 1-43, and the references cited therein.As an alternative or addition to the WGS reaction, H2 and CO2, respectively, from external, preferably non-fossil sources may be admixed to the syngas to adjust the H2-to-COx ratio according to the needs of the overall process and to allow for a maximum conversion of carbon oxides to downstream chemicals. Said external sources of H2 and CO2 are described above and include water electrolysis and methane pyrolysis to produce H2 and carbon capture to produce CO2.In that sense CO2 from different bio-based sources can be included into the syngas. The biogenic source of CO2 could be from fermentation processes of biomass, combustion processes of biomass or waste of biobased materials, or from extractive processes of atmospheric CO2. Of course, mixtures of CO2 from biogenic and fossil carbon sources can be used, too.Substep S3ab)Methanol production from syngasThe conversion of syngas to methanol is well-known in the art. Details on the methanol synthesis and various options thereof suitable to be combined with the processes described herein are disclosed, e.g., in Ott et al., Ullmann's Encyclopedia of Industrial Chemistry (2012), Chapter "Methanol”, p. 3 to 13, and the references cited therein.In particular, methanol may be produced from syngas by a catalytic gas phase reaction in a low-pressure process at about 5-10 MPa and about 200-300 °C, e.g., in adiabatic reactors or quasi-isothermal reactors. The catalyst is for example a mixture of copper and zinc oxides on alumina support. Typically, a stoichiometric number of slightly above 2 has proven beneficial to achieve high conversion rates.Alternatively, methanol may be formed directly by reaction of CO2 and H2 in the presence of a catalyst. Overviews on the reaction and suitable catalyst systems are given, e.g., by M. Ren et al., Catalysts 2022, 12, 403 and K. Stangeland et al., Energ. Ecol. Environ. 2020, 5, 272-285.Also, a process for the CO2-to-methanol synthesis can be carried out, for example, by the method known from DE-A- 42 20 865, which produces methanol under the influence of silent electrical discharges. Alternatively, methanol synthesis can also be carried out in a thermal reactor under pressure and elevated temperature and in the presence of a copper-based catalyst (DE 43 32 789 A1 ; DE 19739773 A1).Typical catalysts are described, for example, by N. Kanoun et al., Catalysis Letters 1992, 15, 231-235. Potential catalysts like CuO / ZnO and Cu-ZnO-AI2O3 are also described by R. M. Navarro et al., Materials 2019, 12, 3902 and by S. G. Jadhav et al., Chem. Eng. Res. Des. 2014, 92 2557-2567.Promising catalyst systems for large-scale industrial processes are Cu-based and In-based due to their superior catalytic performance. Recently a high selective catalysts ln2O3 / ZrO2 was described for industrial relevant conditions. ABASF SE 241076W00125 typical range of industrially relevant conditions for the hydrogenation of CO2 to methanol are T=200-300°C, p = IQ- 50 MPa, and gas hourly space velocity (GHSV) of 16000-48000 h-1 (O. Martin et al., Angew. Chem. Int. Ed. 2016, 55, 6261 -6265).The conversion can be carried out in the presence of a copper-zinc-alumina catalyst. If copper-zinc-alumina catalysts are employed, the preferred temperature is in the range of from 150 to 300°C, preferably 175 to 300°C, and the preferred pressure is in the range of from 10 to 150 bar (abs).The synthesis of methanol from CO2 is less exothermic than that starting from syngas, and it also involves as a secondary reaction the rWGS reaction. To facilitate methanol synthesis, the CO in syngas is converted to CO2 through the WGS reaction:CO2 + 3 H2 CH3OH + H2O AH(298K) = -49.5 kJ mol-1CO2 + H2 CO + H2O AH(298K) = 41 .2 kJ mol-1The water-gas equilibrium mentioned above provides the basis to produce CO2-neutral methanol if the CO2 originates from appropriate direct or indirect biogenic sources. According to the rWGS reaction, there is the opportunity of including biogenic CO2 directly to an adapted syngas-to-methanol process. Syngas is then converted to methanol, e.g., in the ranges of temperature of 250-300°C and pressure of 5-10 MPa, using CuO / ZnO / AI2O3 catalyst.Step S3ab) includes the separation and purification of methanol by processes known to the one of skill in the art, for instance, by distillation.Substep S3b)Formaldehyde production from methanolFormaldehyde is produced industrially from methanol via catalytic oxidation and / or dehydrogenation processes. Details on the formaldehyde production routes are described, e.g., in A. W. Franz et al., Ullmann's Encyclopedia of Industrial Chemistry (2016), Chapter "Formaldehyde”, in H. I. Mahdi et al., Mol. Catalysis 2023, 537, 112944, and the references cited therein.In the so-called FORMOX process, oxidation of methanol is effected with excess air in the presence of an iron molybdenum oxide catalyst at 250-400°C: 2 CH3OH + 02 2 CH2O + 2 H2OOther processes use air as an oxidant, silver catalysts, and an excess of methanol at temperatures of 600-720 °C and atmospheric pressure. In this setup, in addition to partial oxidation, also a dehydrogenation reaction occurs:CH3OH ^ CH2O + H2Further, formaldehyde may be obtained by non-oxidative dehydrogenation of methanol. Such processes have been reviewed by and are known from, e.g., N. Ya. Usachev et al., Pet. Chem. 2004, 44, 379-394. In particular, catalytic systems based on aluminum (e.g., aluminum oxide, alkali metal aluminate, alkaline earth metal aluminate), silver (e.g., silver, silver oxide), copper, zinc, indium, platinum, and alkali metals have been investigated and proven to show good activities. Preferably the catalyst system comprises silver, copper, zinc, and / or alkali metals, more preferably sodium or sodium compounds, most preferably sodium carbonate. The reaction is carried out preferably under anaerobic conditions, i.e., substantially in the absence of oxygen to minimize hydrogen oxidation to water and to reduce safety risks. Typical reaction temperatures may range from about 450-500 °C for copper-based catalysts, over 500-600 °C for zinc- containing catalysts and 650 °C for silver-containing catalysts to 650-900 °C for alkali metal-containing catalysts. TheBASF SE 241076W00126 reaction may be carried out in membrane reactors. Also, electrically heated reactors may be employed, e.g., including alkali metal (especially sodium)-based catalysts on conducting supports like SiC (DE19814285A1 ), which is particularly beneficial when electric power of sustainable origin is available.Step S4) includes the separation of formaldehyde from the product mixture that is obtained from the methanol conversion. This may be achieved by processes known to the one of skill in the art which may include, for instance, absorption, distillation, and anion exchange steps.Preferred Embodiments1.20) The process according to any of the preceding embodiments, wherein in step S3) at least a portion of said formaldehyde originates from bio-based or recycling-based sources.1 .21) The process according to any of the preceding embodiments, wherein step S3) comprises producing formaldehyde.1.22) The process according to any of the preceding embodiments, wherein step S3) comprises the substeps S3a) providing methanol; andS3b) converting at least a portion of said methanol to formaldehyde.1 .23) The process according to embodiment 1 .22, wherein in substep S3a) at least a portion of said methanol originates from bio-based or recycling-based sources.1 .24) The process according to any of embodiments 1 .22 to 1 .23, wherein substep S3a) comprises producing methanol.1 .25) The process according to any of embodiments 1 .22 to 1 .24, wherein substep S3a) comprises the substeps S3aa) providing syngas; andS3ab) converting at least a portion of said syngas to methanol.1 .26) The process according to embodiment 1 .25, wherein in step S3aa) at least a portion of said syngas originates from bio-based or recycling-based sources.1 .27) The process according to any of embodiments 1 .25 to 1 .26, wherein step S3aa) comprises producing syngas.1 .28) The process according to any of embodiments 1 .25 to 1 .27, wherein in substep S3aa), said syngas comprises CO and H2.1 .29) The process according to any of embodiments 1 .25 to 1 .27, wherein in substep S3aa), said syngas comprises CO2 and H2.1 .30) The process according to any of embodiments 1 .25 to 1 .29, wherein in substep S3aa), said syngas comprises CO, 002, and H2.1.31) The process according to any of embodiments 1.25 to 1.30, wherein substep S3aa) comprises producing syngas comprising CO and / or 002 and comprising H2 and wherein substep S3aa) preferably comprises purifying said syngas.1.32) The process according to any of embodiments 1.25 to 1.31, wherein substep S3aa) further comprises adjusting the stoichiometric number by carrying out the WGS reaction and / or by addition of H2, and optionally of 002, from external sources.BASF SE 241076W001271 .33) The process according to any of embodiments 1 .25 to 1 .32, wherein in substep S3aa), said syngas has a stoichiometric number in the range from 1 .9 to 3.0, preferably in the range from 2.0 to 2.5, more preferably in the range from 2.0 to 2.2, most preferably of approximately 2.1 or approximately 2.2.1 .34) The process according to any of embodiments 1 .25 to 1 .33, wherein in substep S3aa), at least a portion of said syngas originates from a sustainable production process, preferably comprising carbon capture and / or using renewable energies.1 .35) The process according to any of embodiments 1 .25 to 1 .34, wherein in substep S3aa), at least a portion of said CO and / or of said CO2 originates from sustainable sources, preferably from bio-based or recycling-based carbon-containing raw materials.1 .36) The process according to any of embodiments 1 .25 to 1 .35, wherein in substep S3aa), at least a portion of said H2 originates from sustainable sources, preferably from water electrolysis, chlor-alkali electrolysis, methane pyrolysis, or decomposition of ammonia, or from step S2).1 .37) The process according to any of embodiments 1 .25 to 1 .36, wherein in substep S3aa), at least a portion of said syngas originates from steam reforming or autothermal reforming of at least one gaseous and / or liquid feedstock, preferably selected from the group consisting of methane, biogas, ethane, propane, light naphtha cuts, and biomass-derived light hydrocarbons, more preferably at least a portion of said syngas originates from steam reforming or autothermal reforming of methane, optionally followed by water-gas shift reaction, wherein CO2 that is formed in the steam reforming or autothermal reforming process and / or in the water-gas shift reaction is captured and optionally stored and / or utilized.1 .38) The process according to any of embodiments 1 .25 to 1 .37, wherein in substep S3aa), at least a portion of said syngas originates from steam reforming or autothermal reforming, optionally followed by water-gas shift reaction, of one or more C1-4 alkanes, said one or more C1-4 alkanes being obtained from steam cracking of at least one sustainable, optionally upgraded feedstock according to step S2), wherein more preferably CO2 that is formed in the steam cracking, steam reforming, autothermal reforming process, and / or in the water-gas shift reaction is captured and optionally stored and / or utilized.1 .39) The process according to any of embodiments 1 .25 to 1 .38, wherein in substep S3aa), at least a portion of said syngas originates from steam reforming or autothermal reforming, optionally followed by water-gas shift reaction, of one or more C1-4 alkanes, said one or more C1-4 alkanes being preferably obtained from pyrolysis gas, more preferably by utilizing the fractionation section of a steam cracker unit.1 .40) The process according to any of embodiments 1 .25 to 1 .39, wherein in substep S3aa), at least a portion of said syngas originates from partial oxidation or autothermal reforming of at least one gaseous and / or liquid feedstock, preferably selected from the group consisting of methane, biogas, ethane, propane, light naphtha cuts, and biomass-derived light hydrocarbons, wherein preferably said partial oxidation or autothermal reforming is carried out in the presence of oxygen at least a portion of which is obtained from water electrolysis, more preferably from water electrolysis driven by renewable energies.1.41) The process according to any of embodiments 1.25 to 1.40, wherein in substep S3aa), at least a portion of said syngas originates from partial combustion of one or more C1-4 alkanes, said one orBASF SE 241076W00128 more C1-4 alkanes being obtained from steam cracking of at least one sustainable, optionally upgraded feedstock according to step S2), wherein more preferably CO2 that is formed in the steam cracking and / or partial combustion is captured and optionally stored and / or utilized.The process according to any of embodiments 1.25 to 1.41, wherein in substep S3aa), at least a portion of said syngas originates from partial combustion of one or more C1-4 alkanes, said one or more C1-4 alkanes being preferably obtained from pyrolysis gas, more preferably by utilizing the fractionation section of a steam cracker unit.1 .42) The process according to any of embodiments 1 .25 to 1 .42, wherein in substep S3aa), at least a portion of said syngas originates from dry reforming of at least one gaseous feedstock, preferably of methane or biogas, and CO2, wherein preferably at least a portion of said CO2 is obtained via DAC, DOC, and / or IOC or is obtained via carbon capture from industrial point sources.1 .43) The process according to any of embodiments 1 .25 to 1 .43, wherein in substep S3aa), at least a portion of said syngas originates from gasification, optionally after a pre-treatment step, of at least one solid and / or liquid raw material, preferably comprising biomass and / or waste, more preferably comprising plastic waste comprising polyurethanes and / or polyalkenes, wherein preferably said gasification is carried out in the presence of oxygen at least a portion of which is obtained from water electrolysis, more preferably from water electrolysis driven by renewable energies.1 .44) The process according to any of embodiments 1 .25 to 1 .44, wherein in substep S3aa), at least a portion of said syngas originates from gasification, optionally after a pre-treatment step, of at least one sustainable feedstock comprising bio-oils and / or pyrolysis oils provided in step S1 ), more preferably comprising pyrolysis oil obtained from plastic waste comprising polyurethanes and / or polyalkenes, wherein preferably said gasification is carried out in the presence of oxygen at least a portion of which is obtained from water electrolysis, more preferably from water electrolysis driven by renewable energies.1 .45) The process according to any of embodiments 1 .25 to 1 .45, wherein in substep S3aa), at least a portion of said syngas originates from gasification, optionally after a pre-treatment step, of a pyrolysis char obtained in the course of step S1 ), wherein preferably said gasification is carried out in the presence of oxygen at least a portion of which is obtained from water electrolysis, more preferably from water electrolysis driven by renewable energies.1 .46) The process according to any of embodiments 1 .25 to 1 .46, wherein in substep S3aa), at least a portion of said syngas originates from pyrolysis of at least one solid feedstock, preferably comprising biomass, more preferably selected from the group consisting of wood or residues thereof, crops or residues thereof, agricultural waste, and sewage sludge, and / or waste, more preferably selected from the group consisting of municipal waste, hazardous waste, industrial waste, mixed plastic waste, caprolactam- based waste, and end-of-life tires, most preferably plastic waste comprising polyurethanes and / or polyalkenes, to obtain a pyrolysis oil, and subsequent partial oxidation and / or gasification of said pyrolysis oil, wherein preferably said partial oxidation and / or gasification is carried out in the presence of oxygen at least aBASF SE 241076W00129 portion of which is obtained from water electrolysis, more preferably from water electrolysis driven by renewable energies.1 .47) The process according to any of embodiments 1 .25 to 1 .47, wherein in substep S3aa), at least a portion of said syngas originates from rWGS reaction of CO2 and H2, wherein preferably at least a portion of said CO2 originates from biomass and / or is obtained via DAC, DOC, and / or IOC or is obtained via carbon capture from industrial point sources, in particular from a steam cracking unit, and / or wherein preferably at least a portion of said H2 originates from water electrolysis, chlor-alkali electrolysis, methane pyrolysis, decomposition of ammonia, step S2), or syngas production processes the CO2 emissions of which are captured and optionally stored and / or utilized.1 .48) The process according to any of embodiments 1 .25 to 1 .48, wherein in substep S3aa), at least a portion of said syngas originates from rWGS reaction of CO2 and H2, wherein at least a portion of said CO2 originates from incineration of biomass and / or waste in a power plant and is obtained via carbon capture from said power plant, and wherein preferably at least a portion of said H2 originates from water electrolysis, chlor-alkali electrolysis, methane pyrolysis, decomposition of ammonia, step S2), or syngas production processes the CO2 emissions of which are captured and optionally stored and / or utilized.1.49) The process according to any of embodiments 1.36, 1.40, and 1.44 to 1.49, wherein in substep S3aa), electrical power is used for said water electrolysis, chlor-alkali electrolysis, and / or methane pyrolysis and the fraction of said electrical power that originates from fossil energy sources is < 50%, preferably < 30%, more preferably < 20%, even more preferably < 10%, most preferably < 1 %.1.50) The process according to any of embodiments 1.36, 1.40, and 1.44 to 1.50, wherein in substep S3aa), electrical power is used for said water electrolysis, chlor-alkali electrolysis, and / or methane pyrolysis and at least a part, preferably all, of said electrical power originates from non-fossil energy sources, preferably selected from the group consisting of wind energy, solar energy, hydropower, geothermal energy, ambient or industrial heat captured by heat pumps, bioenergy (biofuel, biomass), the renewable part of waste energy sources, or nuclear energy.1.51) The process according to any of embodiments 1 .25 to 1.51, wherein in substep S3ab), said conversion is carried out in the presence of a copper-zinc-alumina-based catalyst, e.g., CuO / ZnO / AI2O3.1.52) The process according to any of embodiments 1 .25 to 1.51, wherein in substep S3ab), said conversion is carried out in the presence of an indium-based catalyst, e.g., I n2O3 / ZrO2.1.53) The process according to any of embodiments 1.25 to 1.53, wherein step S3ab) includes the purification of methanol.1 .54) The process according to any of embodiments 1 .22 to 1 .54, wherein in step S3b), said conversion is carried out with air in the presence of an iron molybdenum oxide catalyst or of a silver catalyst.1 .55) The process according to any of embodiments 1 .22 to 1 .54, wherein in step S3b), said conversion is carried out with oxygen-enriched air in the presence of an iron molybdenum oxide catalyst or of a silver catalyst, whereinBASF SE 241076W00130 said oxygen is preferably obtained from water electrolysis, more preferably from water electrolysis driven by renewable energy.1 .56) The process according to any of embodiments 1 .22 to 1 .54, wherein in step S3b), said conversion is carried out under anaerobic conditions, preferably using an electrically heated reactor, and in the presence of a silver, copper, zinc, or alkali metal catalyst, preferably a sodium-based catalyst such as sodium carbonate.1 .57) The process according to any of embodiments 1 .22 to 1 .57, wherein step S3b) includes the separation of formaldehyde.Step S4)1 ,4-butynediol (BYD) is synthesized according to processes known in the art from acetylene obtained in step S2) and from formaldehyde provided in step S3), for example, as described in H. Grafje et al., Ullmann's Encyclopedia of Industrial Chemistry, 2019, Chapter "Butanediols, Butenediols, and Butynediol”, pp. 1-4, and the references cited therein.In the Reppe process, acetylene is reacted under pressure (1-8 bar absolute pressure) with 2 equivalents of formaldehyde, provided in the form of a 30-50 % aqueous solution, at elevated temperature (80-100 °C) in the presence of an activated catalyst like a transition metal acetylide, the transition metal being preferably selected from copper, silver, gold, and mercury. Preferred is an activated catalyst in the form of copper (I) acetylide, formed in the reactor by an activation process known to the person skilled in the art which includes acetylene, formaldehyde, and a pre-catalyst, e.g., copper(ll) oxide and optionally bismuth(lll) oxide on silica support. Alternative catalyst systems include copper carbonate, e.g., malachite-based, catalysts with and without carrier and / or bismuth as promotor. Moreover, various carriers can be used as catalyst support, e.g., AI2O3 or magnesium silicate.Preferably, acetylene and formaldehyde originate from the same, preferably sustainable, raw material. This may be achieved, for instance, by steam cracking a sustainable feedstock as described in step S2) to deliver acetylene and C1-4 alkanes, the latter of which may be used as a basis for the formaldehyde production chain, e.g., as a source of syngas via SMR or ATR. Also, partial combustion of C1-4 alkanes as described for step S2) provides acetylene and a syngas, wherein said C1-4 alkanes may originate from steam cracking of sustainable feedstocks and / or from pyrolysis gases. Similarly, syngas may be obtained via gasification of a portion of sustainable raw material while pyrolysis of another portion of the raw material provides pyrolysis oil (for steam cracking and / or gasification to syngas) and pyrolysis gas (for syngas production and / or partial combustion to acetylene). Finally, CO2 captured from the steam cracking process may be used for syngas and / or methanol production.By such reaction sequences, the processes starting from one single raw material or feedstock and leading to BYD or even BDO and derivatives thereof, as described below, can be collocated, i.e., all the process steps may be in fluid communication and hence do not require any transport measures (e.g., by ship, railroad, truck, or the like). This is particularly advantageous since acetylene is highly reactive which comes along with challenges for storage and transport. Thus, typically, acetylene's reaction partners are transported to the acetylene production site. However, this causes additional financial and logistic efforts and is often associated with a negative environmental impact, e.g., by transport-related additional greenhouse gas emissions. Also, the additional time delay until next process steps, the contact with different storage materials, and the exposure to varying environmental conditions may require the use ofBASF SE 241076W00131 stabilizing agents (being additional cost drivers and increasing overall process complexity, e.g., due to efforts for admixing and possibly removing them), parts of which may end up as undesired impurities or contaminants in downstream process steps and products.Preferred Embodiments1 .58) The process according to any of the preceding embodiments, wherein step S4) is carried out in the presence of a catalyst comprising at least one transition metal acetylide, preferably a copper (I) acetylide.1 .59) The process according to any of the preceding embodiments, wherein step S4) is carried out in the presence of a copper (I) catalyst, preferably of a copper (I) acetylide catalyst.1 .60) The process according to any of the preceding embodiments, wherein step S4) is carried out in the presence of a pre-catalyst comprising copper(ll) oxide, preferably further comprising bismuth(lll) oxide.1 .61) The process according to any of the preceding embodiments, wherein step S4) is carried out in the presence of a pre-catalyst comprising a copper carbonate species such as malachite, preferably further comprising bis- muth(lll) oxide.1.62) The process according to any of the preceding embodiments, wherein in step S4) at least a portion of said formaldehyde and at least a portion of said acetylene originate from the same raw material.1.63) The process according to any of the preceding embodiments, wherein in step S4) at least a portion of said formaldehyde and at least a portion of said acetylene originate from the same sustainable feedstock provided in step S1 ), in particular they are obtained via partial combustion of C1-4 alkanes.1.64) The process according to any of the preceding embodiments, wherein in step S4) at least a portion of said formaldehyde and at least a portion of said acetylene originate from a steam cracking process, e.g., acetylene as a cracking product and formaldehyde as being derived from captured CO2.Further process stepsThe process according to this disclosure may comprise further optional steps where needed or advisable to improve the overall performance of the process. In particular, purification steps may be applied to the product and intermediate streams obtained to improve their properties or to meet certain specifications for further process steps.Also, steps S5) and S6), described hereinafter, may be comprised by the process of the disclosure.The process according to the present invention enables the production of BYD in which all carbon atoms originate from sustainable sources. Therefore, the present invention further relates to 1 ,4-butynediol (BYD) obtained by the process of the present invention.Step S5)BDO is produced by hydrogenation of BYD obtained in step S4), e.g., as described in H. Grafje et al., Ullmann's Encyclopedia of Industrial Chemistry, 2019, Chapter "Butanediols, Butenediols, and Butynediol”, pp. 4-6, and the references cited therein.BASF SE 241076W00132Typically, a 30-50% aqueous solution of BYD is hydrogenated continuously at 80-170 °C and 250-300 bar hydrogen atmosphere. Mainly nickel on zirconium oxides support or on aluminum support is employed as a catalyst system, but also Raney nickel may be used as a fixed-bed or slurry catalyst. Also, palladium-based catalyst systems have been reported as being effective for the BYD hydrogenation.For the hydrogenation, preferably H2 of sustainable origin is used. In particular, H2 obtained as a by-product of the steam cracking process of step S2), i.e., originating from the sustainable feedstock of step S1), may be used advantageously to obtain BDO with favorable sustainability properties. Also, sustainable hydrogen for the BYD hydrogenation may be obtained from fractionation of pyrolysis gas in the fractionation section of a steam cracking unit.To increase the purity of the produced BDO, an additional fractional distillation step may be carried out. Thus, water, other alcohols like methanol, propyl alcohols, and (other) butyl alcohols, and further impurities (e.g., aldehydes, acetals, lactones) may be removed, e.g., in a multi-step process, from the reactor effluent to obtain pure BDO.Preferred Embodiments1.65) A process to produce 1 ,4-butanediol, the process comprising the process to produce 1 ,4-butynediol according to any of the preceding embodiments and further comprising step S5)S5) hydrogenating at least a portion of said 1 ,4-butynediol to obtain 1 ,4-butanediol.1 .66) The process according to the preceding embodiment, wherein in step S5) at least a portion of the H2 needed is obtained from the steam cracking of step S2).1.67) The process according to any of embodiments 1.66 to 1.67, wherein in step S5) at least a portion of the H2 needed is obtained by separation from at least one sustainable feedstock comprising pyrolysis gas according to step S2).1.68) The process according to any of embodiments 1.66 to 1.68, wherein step S5) is carried out in the presence of a nickel catalyst.1 .69) The process according to any of embodiments 1 .66 to 1 .69, wherein step S5) is carried out in the presence of a palladium catalyst.1.70) The process according to any of embodiments 1.66 to 1.70, wherein step S5) includes a fractional distillation step to obtain purified BDO.The present invention further relates to 1 ,4-butanediol (BDO) obtained by the process of the present invention.Within the scope of this invention, the BDO obtained in step S5), respectively, may be converted further to downstream products.The publication Prior Art Disclosure; Issue 684; paragraphs

[1000] to

[8005] ; ISSN: 2198-4786; published: February 12, 2024, will be regarded as Reference RF1 , which is incorporated herein by reference in its entirety. Preferably, the downstream product PRF1 is a product as described in Reference RF1 ; paragraphs

[1000] to

[8005] , Preferably, the process described herein is further a process for the production of a downstream product, preferably product PRF1 .BASF SE 241076W00133The converting step to obtain the product PRF1 preferably comprises one or more step(s) as described below and can be performed by conventional methods well known to a person skilled in the art. The converting step preferably comprises one or more step(s) selected from: recycling, preferably depolymerizing, gasifying, pyrolyzing, and / or steam cracking; and / or purifying, preferably crystallizing, (solvent) extracting, distilling, evaporating, hydrotreating, absorbing, adsorbing and / or subjecting to ion exchanger; and / or assembling, preferably foaming, synthesizing, chemical conversion, chemically transforming, polymerizing and / or compounding; and / or forming, preferably foaming, extruding and / or molding; and / or finishing, preferably coating and / or smoothing.In addition, the one or more step(s) are described in detail in Reference RF1 ; paragraphs

[1000] to

[8005] ,The term "building block”, as used herein, comprises compounds, which are in a gaseous or liquid state under standard conditions of 0°C and 0.1 MPa. Building blocks are typically used in chemical industry to form secondary products, which provide a higher structural complexity and / or higher molecular weight than the building block on which the secondary product is based. The building block is preferably selected from the group consisting of hydrogen, carbon monoxide, carbon dioxide, ethylene oxide, ethylene glycols, syngas comprising a mixture of hydrogen and carbon monoxide, alkanes, alkenes, alkynes and aromatic compounds. The alkanes, alkenes, alkynes and aromatic compounds comprise in particular 1 to 12 carbon atoms, respectively.The term "monomer”, as used herein, comprises molecules, which can react with each other to form polymer chains by polymerization. The monomer is preferably selected from the group consisting of (meth)acrylic acid, salts of (meth)acrylic acid; in particular sodium, potassium and zinc salts; (meth)acrolein and (meth)acrylates. (Meth)acrylates comprising 1 to 22 carbon atoms are preferred, in particular comprising 1 to 8 carbon atoms. The terms (meth)acrylic acid, (meth)acrolein or (meth)acrylate relate to acrylic acid, acrolein or acrylate and also to methacrylic acid, methacrolein or methacrylate, where applicable. Further, the monomer can be selected from hexamethylenediamine (HMD) and adipic acid.The building block can further be an intermediate compound. The term "intermediate compound”, as used herein, comprises organic reagents, which are applied for formation of compounds with higher molecular complexity. The intermediate compound can be selected for example from the group consisting of phosgene, polyisocyanates and propylene oxide. The polyisocyanates are in particular aromatic di- and polyisocyanates, preferably toluene diisocyanate (TDI) and / or diphenylmethane diisocyanate (MDI).The building block and the monomer and typical converting step(s) to obtain the building block or monomer are described in more detail in paragraphs

[1000] to

[1012] of Reference RF1.The term "polymer A”, as used herein, comprises thermoplastic, e.g., polyamide or thermoplastic polyurethane, thermoset, e.g., polyurethane, elastomer, e.g., polybutadiene, or a copolymer or a mixture thereof and is defined in more detail in paragraphs

[2001] to

[2007] of Reference RF1.The term "polymer composition A”, as used herein, comprises all compositions comprising a polymer as described above and one or more additive(s), e.g. reinforcement, colorant, modifier and / or flame retardant, and is defined in more detail in paragraph

[2008] of Reference RF1.BASF SE 241076W00134The term "polymer product A”, as used herein, comprises any product comprising the polymer A and / or polymer composition A as described above and is defined in more detail in paragraphs

[2009] and

[2010] of Reference RF1.The step(s) to obtain the polymer, preferably polymer A, polymer composition, preferably polymer composition A or polymer product, preferably polymer product A is / are described in more detail in paragraph

[2011] of Reference RF1 . The term "industrial use polymer”, as used herein, comprises rheology, polycarboxylate, alkoxylated polyalkylenamine, alkoxylated polyalkylenimine, polyether-based, dye inhibition and soil release cleaning polymers defined in more detail in paragraphs

[3035] to

[3044] of Reference RF1. The term "industrial use surfactant”, as used herein, comprises nonionic, anionic and amphoteric industrial use surfactants defined in more detail in paragraphs

[3008] to

[3034] of Reference RF1. The term "industrial use descaling compound”, as used herein, comprises non-phosphate-based builders (NPB) and phosphonates (CoP) described in more detail in paragraphs

[3001] to

[3005] of Reference RF1. The term "industrial use biocide”, as used herein, refers to a chemical compound that kills microorganisms or inhibits their growth or reproduction defined in more detail in paragraphs

[3006] to

[3007] of Reference RF1. The term "industrial use solvent”, as used herein, comprises alkyl amides, alkyl lactamides, alkyl esters, lactate esters, alkyl diester, cyclic alkyl diester, cyclic carbonates, aromatic aldehydes and aromatic esters defined in more detail in paragraphs

[3045] to

[3055] of Reference RF1 . The term "industrial use dispersant”, as used herein, comprises anionic and non-ionic industrial use dispersants defined in more detail in paragraphs

[3056] to

[3058] of Reference RF1. The term "composition and / or formulation thereof” with reference to the industrial use polymers, industrial use surfactants, descaling compounds and / or industrial use biocides refers to industrial use compositions and / or institutional use products and / or fabric and home care products and / or personal care products defined in more detail in paragraph

[3059] of Reference RF1. The converting step(s) to obtain the industrial use polymer, industrial use surfactant, descaling compound and / or industrial use biocide are defined in more detail in paragraph

[3060] of Reference RF1. The converting steps to obtain the industrial use composition or formulation of the industrial use polymer, industrial use surfactant, descaling compound and / or industrial use biocide are defined in more detail in paragraph

[3061] of Reference RF1.The term "agrochemical composition”, as used herein, typically relates to a composition comprising an agrochemically active ingredient and at least one agrochemical formulation auxiliary. Examples of agrochemical compositions, active ingredients and auxiliaries are described in more detail in Reference RF1 , paragraph

[4001] ,The agrochemical composition may take the form of any customary formulation. The agrochemical compositions are prepared in a known manner, e.g. described by Mollet and Grubemann, Formulation technology, Wiley VCH, Weinheim, 2001 ; or Knowles, New developments in crop protection product formulation, Agrow Reports DS243, T&F Informa, London, 2005. The converting step(s) to obtain the agrochemically active ingredients and auxiliaries may be conducted in analogy to the production step(s) of their analogues that are based on petrochemicals or other precursors that are not gained by recycling processes. In addition, conversion to compounds mentioned in sections "Polymer” and "Cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter, further cosmetic ingredient or compositions or formulations thereof' may be performed as described in these sections as well as the respective paragraphs in Reference RF1.The term active pharmaceutical ingredients and / or intermediates thereof, as used herein, comprises substances that provide pharmacological activity or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease, or to affect the structure or any function of the body. Intermediates thereof are isolated products that areBASF SE 241076W00135 generated during a multi-step route of synthesis of an active pharmaceutical ingredient. The term pharmaceutical excipients, as used herein, comprises compounds or compound mixtures used in compositions for various pharmaceutical applications, which are not substantially pharmaceutically active on itself. Active pharmaceutical ingredients and / or intermediates thereof and pharmaceutical excipients are defined in more detail in paragraph

[5001] of Reference RF1. The converting step(s) to obtain the active pharmaceutical ingredients and / or intermediates thereof and pharmaceutical excipients may comprise one or more synthesis steps and can be performed by conventional synthesis and techniques well known to a person skilled in the art.The terms animal feed additives, human food additives, dietary supplements, as used herein, comprises Vitamins, Pro- Vitamins and active metabolites thereof including intermediates and precursors, especially Vitamin A, B, E, D, K and esters thereof, like acetate, propionate, palmitate esters or alcohols thereof like retinol or salts thereof and any combinations thereof; Tetraterpenes, especially isoprenoids like carotenoids and xanthophylls including their intermediates and precursors as well as mixtures and derivates thereof, especially beta carotene, Canthaxanthin, Citranaxanthin, Astaxanthin, Zeaxanthin, Lutein, Lycopene, Apo-carotenoids, and any combinations thereof; organic acids, especially formic acid, propionic acid and salts thereof, such as sodium, calcium or ammonium salts, and any combinations thereof, such as but not limited to mixtures of formic acid and sodium formiate, propionic acid and ammonium propionate, formic acid and propionic acid, formic acid and sodium formiate and propionic acid, propionic acid and sodium propionate and formic acid and sodium formiate; glycerides of carboxylic acids and short and medium chain fatty acids, conjugated linoleic acids, such as omega-6 fatty acid (C18:2) methyl ester and 1 ,2-propandiol and beverage stabilizers, such as polyvinylpyrrolidone-polymer or polyvinylimidazole / polyvinylpyrrolidone-copolymer. Animal feed additives, human food additives and dietary supplements are defined in more detail in paragraph

[5002] of Reference RF1.The converting step(s) to obtain the animal feed additives, human food additives, dietary supplements may comprise one or more synthesis steps and can be performed by conventional synthesis and techniques well known to a person skilled in the art.The terms aroma chemical and aroma composition as used herein, comprise a volatile organic substance with a molecular weight between 70-250 g / mol comprising a functional group with a carbon skeleton of C5-C16 carbon atoms comprising linear, branched, cyclic, for example with a ring size of C5-C18, bicyclic or tricyclic aliphatic chains and but not necessarily one or more unsaturated structural elements like double bonds, triple bonds, aromatics or heteroaromatics and preferably the one or more additional functional groups are selected from alcohol, ether, ester, ketone, aldehyde, acetal, carboxylic acid, nitrile, thiol, amine. In one aspect, the aroma chemical is a terpene-based aroma chemical, for example selected from monoterpenes and monoterpenoids, sesquiterpenes and sesquiterpenoids, diterpenes, triterpenes or tetraterpenes. Aroma chemicals can be combined with further aroma chemicals to give an aroma composition. Aroma chemicals and aroma compositions are defined in more detail in paragraph

[5003] of Reference RF1.The converting step(s) to obtain the aroma chemical and aroma composition may comprise one or more synthesis steps and can be performed by conventional synthesis and techniques well known to a person skilled in the art.The term "aqueous polymer dispersion”, as used herein, comprises aqueous composition(s) comprising dispersed polymer(s) and is defined in more detail in the section

[6001] entitled "aqueous polymer dispersion” of Reference RF1. The dispersed polymer(s) may be selected from acrylic emulsion polymer(s), styrene acrylic emulsion polymer(s),BASF SE 241076W00136 styrene butadiene dispersion(s), aqueous dispersion(s) comprising composite particles, acrylate alkyd hybrid disper- sion(s), polyurethane(s) (including UV-curable polyurethanes) and polyurethane - poly(meth)acrylate hybrid poly- mer(s). The term "emulsion polymer”, as used herein, comprises polymer(s) made by free-radical emulsion polymerization. Aqueous polyurethane dispersion(s) are defined in more detail in the section

[6002] entitled "Polyurethane dispersions” of Reference RF1. UV-curable polyurethane(s) is / are defined in more detail in the section

[6017] of Reference RF1. Polyurethane - poly(meth)acrylate hybrid polymer(s) is / are defined in more detail in the section

[6016] of Reference RF1.The term "polymeric dispersant”, as used herein, comprises preferably polymer(s) comprising polyether side chain, in particular polycarboxylate ether polymer(s) and polycondensation product(s) defined in more detail in paragraph

[6020] entitled "Polymeric dispersant” of Reference RF1.The converting (polymerization) step(s) to obtain the aqueous polymer dispersion(s) comprising emulsion polymer(s) is / are defined in more detail in the section

[6003] entitled "Emulsion polymerization” of Reference RF1.The converting (polymerization) step(s) to obtain the aqueous polyurethane dispersion(s) is / are defined in more detail in the section

[6014] entitled "Process for the preparation of aqueous polyurethane dispersions” and section

[6017] entitled "Aqueous UV-curable polyurethane dispersions, their preparation and use and compositions containing them” of Reference RF1.Composition(s) and uses of aqueous polymer dispersion(s) and of polymeric dispersant(s) are defined in more detail in the following sections of Reference RF1 : section

[6004] entitled "Uses of aqueous polymer dispersions”, section

[6005] entitled "Binders for architectural and construction coatings” section

[6006] entitled "Binders for paper coating” section

[6007] entitled "Binders for fiber bonding” section

[6008] entitled "Adhesive polymers and adhesive compositions” section

[6015] entitled "Aqueous polyurethane dispersions suitable for use in coating compositions” section

[6016] entitled "Aqueous polyurethane - poly(meth)acrylate hybrid polymer dispersions suitable for use in coating compositions” section

[6017] entitled "Aqueous UV-curable polyurethane dispersions, their preparation and use and compositions containing them” section

[6018] entitled "Inorganic binder compositions comprising polymeric dispersants and their use”

[6019] 100% curable coating compositionsUV-crosslinkable poly(meth)acrylate(s) and its / their uses are defined in more detail in section

[6009] entitled "UV- crossli nkable poly(meth)acrylates for use in UV-curable solvent-free hotmelt adhesives and their use for making pressure-sensitive self-adhesive articles” of Reference RF1.Polyisocyanate(s), composition(s) comprising them and their uses are defined in more detail in section

[6010] entitled "Polyisocyanates” of Reference RF1.Hyperbranched polyester polyol(s) and its / their uses are defined in more detail in section

[6011] entitled "Organic solvent based hyperbranched polyester polyols suitable for use in coating compositions” of Reference RF1. The converting step(s) to obtain the hyperbranched polyester polyols is / are defined in more detail in the section

[6012] entitledBASF SE 241076W00137"Preparation of organic solvent based hyperbranched polyester polyols” of Reference RF1. Coating composition(s) comprising hyperbranched polyester polyol(s), polyisocyanate(s) and additive(s) and substrate(s) coated therewith are defined in more detail in section

[6013] entitled "Organic solvent based two component coating compositions comprising hyperbranched polyester polyols and polyisocyanates” of Reference RF1.Unsaturated polyester polyol(s), solvent-based coating composition(s) comprising said unsaturated polyester polyol(s) and substrate(s) for coating with said coating composition(s) are defined in more detail in section

[6018] entitled "Organic solvent-based coating composition comprising unsaturated polyester polyols” of Reference RF1.100% curable coating composition(s) is / are defined in more detail in section

[6019] of Reference RF1.Polymeric dispersant(s) for inorganic binder compositions is / are defined in more detail in section

[6020] of Reference RF1 . The inorganic binder composition (s) comprising the polymeric dispersants and their use are defined in more detail in section

[6021] of Reference RF1. The converting step(s) to obtain the polymeric dispersant(s) are defined in more detail in section

[6020] of Reference RF1. The term "inorganic binder composition” comprising the polymeric disper- sant(s), as used herein, comprises preferably in particular hydraulically setting compositions and compositions comprising calcium sulfate and is defined in more detail in section

[6021] of Reference RF1 entitled "Inorganic binder compositions comprising the polymeric dispersant and their use”. Specific building material formulation(s) comprising polymeric dispersant(s) or building product(s) produced by a building material formulation comprising a polymeric dispersant are disclosed in more detail in section

[6021] of Reference RF1.The term "cosmetic surfactant”, as used herein, comprises non-ionic, anionic, cationic and amphoteric surfactants and is defined in more detail in paragraph

[7002] of Reference RF1. The term "emollient”, as used herein, refers to a chemical compound used for protecting, moisturizing, and / or lubricating the skin and is defined in more detail in paragraph

[7003] of Reference RF1. The term "wax”, as used herein, comprises pearlizers and opacifiers and is defined in more detail in paragraph

[7004] of Reference RF1. The term "cosmetic polymer”, as used herein, comprises any polymer that can be used as an ingredient in a cosmetic formulation and is defined in more detail in paragraph

[7005] of Reference RF1. The term "UV filter”, as used herein, refers to a chemical compound that blocks or absorbs ultraviolet light and is defined in more detail in paragraph

[7006] of Reference RF1. The term "further cosmetic ingredient”, as used herein, comprises any ingredient suitable for making a cosmetic formulation. Several sources disclose cosmetically acceptable ingredients. E. g. the database Cosing on the internet pages of the European Commission discloses cosmetic ingredients and the International Cosmetic Ingredient Dictionary and Handbook, edited by the Personal Care Products Council (PCPC), discloses cosmetic ingredients. The term "composition and / or formulation thereof” with reference to the cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter and / or further cosmetic ingredient refers to personal care and / or cosmetic compositions or formulations defined in more detail in paragraph

[7007] of Reference RF1. The converting step(s) to obtain the cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter or further cosmetic ingredient is / are defined in more detail in paragraph

[7008] of Reference RF1.The terms "polymer B”, "polymer composition B”, "coating composition”, "other functional composition”, "foil”, "molded body”, "coating” and "coated substrate” are well known to the person skilled in the art and are defined in more detail from paragraph

[8000] to

[8005] of Reference RF1.BASF SE 241076W00138Preferred embodiments1.71) A process to produce at least one downstream product, preferably at least one product PRF1 , the process comprising the process according to any of embodiments 1.66 to 1.71 and further comprising step S6)S6) converting 1 ,4-butanediol obtained in step S5) to obtain at least one downstream product.1 .72) The process according to embodiment 1 .72, wherein the product PRF1 is selected from: i) building block or monomer; or ii) polymer, preferably polymer A, polymer composition, preferably polymer composition A, or polymer product, preferably polymer product A; or iii) cleaning polymer, cleaning surfactant, descaling compound, cleaning biocide or composition or formulation thereof; or iv) agrochemical composition, agrochemical formulation auxiliary or agrochemically active ingredient; or v) active pharmaceutical ingredient or intermediate thereof, pharmaceutical excipient, animal feed additive, human food additive, dietary supplements, aroma chemical or aroma composition; or vi) aqueous polymer dispersion, preferably polyurethane or polyurethane - poly (meth)acryl ate hybrid polymer dispersion, emulsion, binder for paper and fiber coatings, UV-curable acrylic polymer for hot melts and coatings polyisocyanates, hyperbranched polyester polyol, polymeric dispersant for inorganic binder compositions, unsaturated polyester polyol or 100% curable composition; or vii) cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter, further cosmetic ingredient or composition or formulation thereof; or viii) polymer B, polymer composition B, coating composition, other functional composition, foil, molded body, coating or coated substrate.1 .73) The process according to any one of embodiments 1 .72 to 1 .73, wherein the content of said 1 ,4-butanediol in the product PRF1 is 1 weight-% or more, preferably 2 weight-% or more, more preferably 5 weight-% or more, more preferably 15 weight-% or more, more preferably 30 weight-% or more, more preferably 40 weight-% or more, more preferably 60 weight-% or more, more preferably 80 weight-% or more, more preferably 90 weight-% or more, more preferably 95 weight-% or more; and / or wherein the content of said 1 ,4-butanediol in the product PRF1 is 100 weight-% or less, preferably 95 weight- % or less, more preferably 90 weight-% or less, more preferably 50 weight-% or less, more preferably 25 weight-% or less, more preferably 10 weight-% or less; and preferably wherein the content is determined based on identity preservation and / or segregation and / or mass balance and / or book and claim chain of custody models, preferably based on mass balance, preferably the International Sustainability and Carbon Certification (ISCC) standard.Further embodiments of the first aspect of the invention are described by the combination of any and each of the above definitions and embodiments with one another, in particular by way of FIGs 1-9:- FIG 1 depicts the co-production of BYD and steam cracking products (in particular olefins and aromatics):BYD is synthesized from acetylene and formaldehyde, wherein acetylene is formed and separated in a steamBASF SE 241076W00139 cracking unit in which sustainable oil, i.e. , bio-oil and / or pyrolysis oil, optionally after upgrading, is used as a sustainable feedstock.- FIG 2 depicts the co-production of BYD and steam cracking products (in particular olefins and aromatics):BYD is synthesized from acetylene and formaldehyde, wherein acetylene is formed by steam cracking of sustainable oil, i.e., bio-oil and / or pyrolysis oil, optionally after upgrading, to obtain C1-4 alkanes and their subsequent partial combustion.Of note, FIG 2 may further comprise the features and embodiments of FIG 1 , although not reproduced explicitly.- FIG 3 depicts the co-production of BYD and steam cracking products (in particular olefins and aromatics):BYD is synthesized from acetylene and formaldehyde, wherein acetylene is formed by separation of C1-4 alkanes from a biomass-derived or waste-derived pyrolysis gas using the fractionation section of a steam cracking unit and their subsequent partial combustion. Other separated components of the pyrolysis gas, in particular light olefins, add to the separated product streams of the steam cracking unit.Of note, FIG 3 may further comprise the features and embodiments of FIG 1-2, although not reproduced explicitly.- FIG 4 depicts the co-production of BYD and steam cracking products (in particular olefins and aromatics) wherein BYD is formed from one single sustainable steam cracking feedstock:BYD is synthesized from acetylene and formaldehyde, wherein acetylene is formed as described for any one or more of FIG 1-3 (although reproduced explicitly only for FIG 2). Formaldehyde is obtained from the acetylene-off- gas which is used, optionally after adjustment of the stoichiometric number, as a syngas to produce methanol. Methanol is further oxidized and / or dehydrogenated in the presence of a silver catalyst or an iron molybdenum oxide catalyst to formaldehyde.Of note, FIG 4 may further comprise the features and embodiments of FIG 1-3, although not reproduced explicitly.- FIG 5 depicts the co-production of BYD and steam cracking products (in particular olefins and aromatics):BYD is synthesized from acetylene and formaldehyde, wherein formaldehyde is formed from syngas as described for FIG 4. Said syngas is obtained from sustainable raw material, i.e., biomass and / or waste, via- gasification of sustainable raw material,- reforming (e.g., SMR, ATR) of light hydrocarbons obtained as non-condensable fraction from pyrolysis of sustainable raw material (pyrolysis gas), and / or- gasification of bio-oil obtained from biomass or of pyrolysis oil obtained from sustainable raw material.Of note, FIG 5 may further comprise the features and embodiments of FIG 1-4, although not reproduced explicitly.- FIG 6 depicts the co-production of BYD and steam cracking products (in particular olefins and aromatics):BYD is synthesized from acetylene and formaldehyde, wherein formaldehyde is formed from syngas as described for FIG 4. Said syngas is obtained from carbon dioxide which is captured from burning fuels to fire the steam cracking furnaces and converted to syngas through a rWGS process using hydrogen, preferably sustainable hydrogen. Alternatively, said carbon dioxide and said hydrogen may be used to directly produce methanol.Of note, FIG 6 may further comprise the features and embodiments of FIG 1-5, although not reproduced explicitly.- FIG 7 depicts the co-production of BDO and steam cracking products (in particular olefins and aromatics):BDO is synthesized by hydrogenating BYD, obtained as described for FIGs 1-5. The needed hydrogen is formed and separated in a steam cracking unit using sustainable feedstock. Also, hydrogen may be obtained by separationBASF SE 241076W00140 of pyrolysis gas with the help of the fractionation section of a steam cracking unit.Of note, FIG 7 may further comprise the features and embodiments of FIG 1-6, although not reproduced explicitly.- FIG 8 depicts a circular process including the production of BDO and / or cracking products that are obtained from BDO-based and / or cracking product-based polymers which enter the processes described for FIG 1-7 as plastic waste.Of note, FIG 8 may further comprise the features and embodiments of FIG 1-7, although not reproduced explicitly.- FIG 9 depicts a circular process including the production of BDO and / or cracking products that are obtained from PU-based waste. PU may be synthesized, for instance, on the basis of aromatics from steam cracking (e.g., to produce aromatic diisocyanates like MDI and TDI) and BDO (e.g., to produce polyTHF).Only one of the depicted pathways to syngas and acetylene, respectively, needs to be embodied. The use of hydrogen originating from steam cracking is optional. Of note, FIG 9 may further comprise the features and embodiments of FIG 1-8, although not reproduced explicitly.The different embodiments described herein for the first aspect of the invention apply equally to the further aspects of the invention.Thus, in a second aspect, the present invention provides a system for producing 1 ,4-butynediol, the system comprising the unitsU1) sustainable feedstock unit;U2) acetylene unit comprising a steam cracking subunit;U3) formaldehyde unit; andU4) 1 ,4-butynediol unit; and optionallyU2*) Sachsse-Bartholome acetylene subunit.As used herein, the term system refers to an arrangement of units that allows for the exchange of material and / or energy streams between the different units. Said exchange may be accomplished by fluid connections, by pipelines, or by other means of transportation. In particular, said system may be embodied by a production plant, more specifically by an integrated production plant.Preferred Embodiments2.1) The system according to the second aspect of the invention.2.2) The system according to any of the preceding embodiments, wherein the system is a production plant, preferably an integrated production plant.BASF SE 241076W00141Unit U1)The sustainable feedstock unit U1) is equipped to perform process step S1) as described above, including its different embodiments. In particular, it is equipped to receive and store at least one sustainable feedstock as described herein and to provide it to an acetylene unit U2), in particular to its steam cracking subunit.Unit U1) may comprise a bio-oil subunit equipped to process biomass into bio-oil, as described for step S1 ).Also, it may comprise a pyrolysis subunit (and optionally a fractionation subunit) equipped to produce (and optionally separate) one or more of pyrolysis oil, pyrolysis gas, and pyrolysis char from biomass and / or waste, as described for step S1). The pyrolysis subunit may also provide pyrolysis gas to a steam cracker fractionation subunit of unit U2) and / or may provide pyrolysis oil and / or pyrolysis gas to the syngas unit U3aa).Thus, unit U1) may further comprise a raw material subunit equipped to receive and store raw material selected from the group consisting of biomass and waste and to provide it to the bio-oil and / or pyrolysis subunit.Also, unit U1) may comprise a blending subunit to blend different components of sustainable and / or fossil origin to obtain at least one sustainable feedstock.Preferred Embodiments2.3) The system according to any of the preceding embodiments, wherein unit U1) is fluidly connected and arranged upstream to unit U2).2.4) The system according to any of the preceding embodiments, wherein unit U1) is fluidly connected and arranged upstream to the steam cracking fractionation subunit of unit U2).2.5) The system according to any of the preceding embodiments, wherein unit U1) is fluidly connected and arranged upstream to unit U3aa).2.6) The system according to any of the preceding embodiments, wherein unit U1) comprises a raw material subunit.2.7) The system according to any of the preceding embodiments, wherein unit U1) comprises a bio-oil subunit.2.8) The system according to any of the preceding embodiments, wherein unit U1) comprises a pyrolysis subunit.2.9) The system according to any of the preceding embodiments, wherein unit U1) comprises a fractionation subunit.2.10) The system according to any of the preceding embodiments, wherein unit U1) comprises a blending subunit.Unit U2)The acetylene unit U2) is equipped to perform process step S2) as described above, including its different embodiments. In particular, it is equipped to receive from unit U1) at least one sustainable feedstock as described herein, and to store it, optionally to upgrade it, optionally to blend different feedstocks, and to convert said feedstock and to separate from the cracking product mixture acetylene and at least one fraction containing one or more C1-4 alkanes. Said acetylene is provided to the BYD unit U4) while co-produced hydrogen may be provided to BDO unit U5) and coproduced cracking products like olefins and / or aromatics may be provided to a downstream conversion unit U6). Said C1-4 alkanes may be used by unit U2) to produce additional acetylene by partial combustion or to produce syngas. Also, unit U2) may separate from pyrolysis gas C1-4 alkanes and hydrogen for the above-mentioned uses.BASF SE 241076W00142Preferred Embodiments2.11) The system according to any of the preceding embodiments, wherein unit U2) is fluidly connected and arranged downstream to unit U1).2.12) The system according to any of the preceding embodiments, wherein unit U2) is fluidly connected and arranged upstream to unit U4).2.13) The system according to any of the preceding embodiments, wherein unit U2) is fluidly connected and arranged upstream to unit U5).2.14) The system according to any of the preceding embodiments, wherein unit U2) is fluidly connected and arranged upstream to unit U6).2.15) The system according to any of the preceding embodiments, wherein unit U2) is fluidly connected and arranged upstream to unit U3aa).2.16) The system according to any of the preceding embodiments, wherein unit U2) further comprises an upgrading subunit, in particular a hydrotreatment subunit.2.17) The system according to any of the preceding embodiments, wherein unit U2) further comprises a feedstock blending subunit.2.18) The system according to any of the preceding embodiments, wherein unit U2) further comprises a steam cracker fractionation subunit.2.19) The system according to the preceding embodiment, wherein the steam cracker fractionation subunit of unit U2) is fluidly connected and arranged downstream to a pyrolysis subunit of unit U1).2.20) The system according to any of the preceding embodiments, wherein unit U2) further comprises a Sachsse- Bartholome acetylene subunit U2*).2.21) The system according to the preceding embodiment, wherein unit U2*) is fluidly connected and arranged downstream to the steam cracker fractionation subunit of unit U2) and fluidly connected and arranged upstream to unit U4) and / or fluidly connected and arranged upstream to unit U3ab).2.22) The system according to any of the preceding embodiments, wherein unit U2) further comprises a steam cracker carbon capture subunit.2.23) The system according to the preceding embodiment, wherein the steam cracker carbon capture subunit of unit U2) is fluidly connected and arranged upstream to a unit U3aa) and / or to a unit U3ab).Unit U3)The formaldehyde unit U3) is equipped to perform process step S3) as described above, including its different embodiments. In particular, it is equipped to receive or produce methanol, to store it, and to convert it to formaldehyde. Said formaldehyde is provided to the BYD unit U4).Thus, unit U3) may comprise a methanol subunit U3a), equipped to perform process step S3a) as described above, and a formaldehyde production subunit U3b), equipped to perform process step S3b) as described above.The methanol subunit U3a) may receive or produce syngas and convert it to methanol. Said methanol is provided to the formaldehyde production unit U3b), in which it is converted to formaldehyde.BASF SE 241076W00143Thus, unit U3a) may comprise a syngas subunit U3aa), equipped to perform process step S3aa) as described above, and a methanol production subunit U3ab), equipped to perform process step S3ab) as described above.The syngas subunit U3aa) may receive carbon-containing feedstock to produce syngas therefrom, like biomass and / or waste, pyrolysis oil and / or pyrolysis gas, e.g., from the pyrolysis subunit of U1), C1-4 alkanes, e.g., from the above- mentioned steam cracker fractionation subunit of U2), or CO2, e.g., from the above-mentioned steam cracker carbon capture subunit of U2). Optionally, U3aa) may also receive H2 from the steam cracker fractionation subunit of U2). U3aa) may convert said feedstocks to syngas and provide it to the methanol production subunit U3ab).The methanol production subunit U3ab) may further receive syngas from the Sachsse-Bartholome acetylene subunit U2*), CO2 from the steam cracker carbon capture subunit of U2), and / or H2 from the steam cracker fractionation subunit of U2).Preferred Embodiments2.24) The system according to any of the preceding embodiments, wherein unit U3) is fluidly connected and arranged upstream to unit U4).2.25) The system according to any of the preceding embodiments, wherein unit U3) comprises a methanol subunit U3a) and a formaldehyde production subunit U3b).2.26) The system according to embodiments 2.25, wherein subunit U3a) is fluidly connected and arranged upstream to subunit U3b).2.27) The system according to any of embodiments 2.25 to 2.26, wherein subunit U3a) comprises a syngas subunit U3aa) and a methanol production subunit U3ab).2.28) The system according to embodiment 2.27, wherein subunit U3aa) is fluidly connected and arranged upstream to subunit U3ab).2.29) The system according to any of embodiments 2.27 to 2.28, wherein subunit U3aa) is fluidly connected and arranged downstream to unit U1).2.30) The system according to any of embodiments 2.27 to 2.29, wherein subunit U3aa) is fluidly connected and arranged downstream to the steam cracker fractionation subunit of U2) and / or to the steam cracker carbon capture subunit of U2).2.31) The system according to any of embodiments 2.27 to 2.30, wherein subunit U3aa) comprises a syngas production subunit selected from the group of steam reforming subunit, an autothermal reforming subunit, a partial oxidation subunit, a partial combustion subunit, a dry reforming subunit, a gasification subunit, a pyrolysis subunit, and a rWGS subunit.2.32) The system according to any embodiments 2.27 to 2.31 , wherein subunit U3aa) comprises a syngas purification subunit and / or a subunit for the adjustment of the stoichiometric number like a WGS subunit.2.33) The system according to any of embodiments 2.27 to 2.32, wherein subunit U3ab) is fluidly connected and arranged downstream to subunit U3aa).BASF SE 241076W001442.34) The system according to any of embodiments 2.27 to 2.33, wherein subunit U3ab) is fluidly connected and arranged downstream to the steam cracker fractionation subunit of U2), to the steam cracker carbon capture subunit of U2), and / or to the Sachsse-Bartholome acetylene subunit U2*).2.35) The system according to any of embodiments 2.27 to 2.34, wherein subunit U3ab) comprises a methanol purification subunit.2.36) The system according to any of embodiments 2.25 to 2.35, wherein subunit U3b) is fluidly connected and arranged downstream to subunit U3a).2.37) The system according to any of embodiments 2.25 to 2.36, wherein subunit U3b) is fluidly connected and arranged upstream to unit U4).2.38) The system according to any of embodiments 2.25 to 2.37, wherein subunit U3b) comprises a formaldehyde separation subunit.Unit U4)The BYD unit U4) is equipped to perform process step S4) as described above, including its different embodiments. In particular, it is equipped to receive acetylene from unit U2) and formaldehyde from unit U3) and to convert them to BYD. Said BYD may be provided to the BDO unit U5) as described hereinafter.Preferred Embodiments2.39) The system according to any of the preceding embodiments, wherein unit U4) is fluidly connected and arranged downstream to unit U2) and to unit U3).2.40) The system according to any of the preceding embodiments, wherein unit U4) is fluidly connected and arranged downstream to the steam cracker fractionation subunit of U2) and / or to the Sachsse-Bartholome acetylene subunit U2*).2.41) The system according to any of the preceding embodiments, wherein unit U4) is fluidly connected and arranged upstream to unit U5).Further unitsThe system according to the invention may comprise further units and subunits, e.g., for performing the further process steps described above, like purification and separation steps.In particular, it may comprise units U5) and / or U6) as described hereinafter.Unit U5)The BDO unit U5) is equipped to perform process step S5) as described above, including its different embodiments. In particular, it is equipped to receive and store BYD from unit U4), to receive and store hydrogen, e.g., from unit U2), and to convert them to BDO. Said BDO may be purified, e.g., by fractional distillation, and may be provided to further downstream conversion units U6) as described hereinafter.BASF SE 241076W00145Preferred Embodiments2.42) A system for producing BDO according to any of the preceding embodiments, the system comprising the system for producing BYD according to any of the preceding embodiments and further comprising unit U5)U5) BDO unit.2.43) The system according to embodiment 2.42, wherein unit U5) is fluidly connected and arranged downstream to unit U4).2.44) The system according to any of embodiments 2.42 to 2.43, wherein unit U5) is fluidly connected and arranged downstream to unit U2), in particular to the steam cracker fractionation subunit of U2).2.45) The system according to any of embodiments 2.42 to 2.44, wherein unit U5) is fluidly connected and arranged upstream to unit U6).2.46) The system according to any of embodiments 2.42 to 2.45, wherein subunit U5) comprises a BDO purification subunit, in particular a distillation subunit.Unit U6)The downstream conversion unit U6) is equipped to perform process step S6) as described above, including their different embodiments. In particular, it is equipped to receive and store BDO from unit U5) and optionally to receive and store cracking products like olefins or aromatics from unit U2) and to convert them to a downstream product, in particular to a polymer. For this purpose, U6) may comprise multiple conversion subunits, in particular a polymerization subunit.Preferred Embodiments2.47) A system for producing at least one downstream product, the system comprising the system for producing BDO according to any of embodiments 2.42 to 2.46 and further comprising unit U6)U6) downstream conversion unit.2.48) The system according to embodiment 2.47, wherein unit U6) is fluidly connected and arranged downstream to unit U5).2.49) The system according to any of embodiments 2.47 to 2.48, wherein unit U6) is fluidly connected and arranged downstream to unit U2).Further embodiments of the second aspect of the invention are described by the combination of any and each of the above definitions and embodiments with one another, in particular by way of FIGs 10 to 12.FIG 10 depicts a system for producing BYD, and optionally BDO and downstream products thereof, in which a steam cracking unit (including its fractionation subunit) is connected to various units of the BDO production chain (dotted connections and units are optional): In particular, the steam cracking unit provides acetylene to the BYD unit, wherein said acetylene is obtained directly by fractionation of the cracking products and / or by partial combustion of C1-4 alkane fractions. Also, hydrogen may be provided to a syngas unit and a methanol unit (not depicted) and to a BDO unit. Further cracking products (olefins, aromatics) may be provided to a polymer unit. C1-4 alkanes may also be provided to a syngas unit and acetylene-off-gas to a methanol production unit.BASF SE 241076W00146FIG 11 depicts a system for producing BYD, and optionally BDO and downstream products thereof, in which a steam cracking fractionation subunit is connected to various units of the BDO production chain (dotted connections and units are optional): In particular, the steam cracking fractionation subunit is used to separate pyrolysis gas from a pyrolysis unit such that C1 -4 alkanes are provided to a Sachsse-Bartholome acetylene unit which in turn provides acetylene to the BYD unit. A portion of the 01-4 alkanes and / or pyrolysis oil from the pyrolysis unit may be provided to a syngas unit. The acetylene-off-gas may be sent to a methanol production unit. The further products of the pyrolysis gas fractionation (hydrogen, olefins) may be provided to a BDO unit and a polymer unit, respectively.FIG 12 depicts a system for producing BYD in which a steam cracking carbon capture subunit is connected to various units of the BYD production chain (dotted connections and units are optional): 002 captured from the steam cracker flue gas is provided to a syngas unit or to a methanol production unit.The different embodiments described herein for the second aspect of the invention apply equally to the third aspect of the invention.In a third aspect, the invention relates to the use of a steam cracking unit in a process to produce 1 ,4-butynediol, wherein the steam cracking unit is used inP1) production of acetylene and / or of one or more C1-4 alkanes from at least one sustainable feedstock comprising at least one component selected from the group consisting of bio-oils and pyrolysis oils, optionally after upgrading said sustainable feedstock, and separation of at least one fraction comprising acetylene or one or more C1-4 alkanes, and / orP2) separation of at least one fraction comprising one or more C1-4 alkanes from a sustainable feedstock comprising pyrolysis gas.The embodiments described for the first and second aspect of the invention, relating to operation modes, process steps, systems, units, and subunits, apply equally to the third aspect of the invention.The sets of preferred embodiments described in the following are intended to further illustrate, but in no way to restrict the present invention as described herein. They represent a suitably structured part of the description and thus support, but do not represent the claims of the present invention.Preferred Embodiments3.1) The use according to the third aspect of the invention.3.2) The use according to any of the preceding embodiments, wherein said steam cracking unit is a steam cracking subunit of unit U2) according to any of embodiments 2.11 to 2.23.3.3) The use according to any of the preceding embodiments, wherein said process to produce BYD is a process according to any of the embodiments of the first aspect of the invention.3.4) The use according to any of the preceding embodiments, wherein in P1), said production of acetylene and / or of one or more C1-4 alkanes and / or said separation is carried out by steam cracking according to step S2) described hereinbefore, in particular according to any of embodiments 1.9 to 1.14 and 1.19.BASF SE 241076W001473.5) The use according to any of the preceding embodiments, wherein in P2), said separation is carried out according to step S2) described hereinbefore, in particular according to any of embodiments 1.15 to 1.19.In further aspects, the invention relates to the products obtained by carrying out the processes described herein, in particular to downstream products like monomers, polymers, or polymer products as well as to any fractions and downstream products thereof.Further embodiments of the different aspects of the invention are described by the combination of any and each of the above definitions and embodiments with one another.

Claims

BASF SE 241076W00148Claims1 . A process to produce 1 ,4-buty nediol, the process comprising step S4)S4) reacting acetylene with formaldehyde to obtain 1 ,4-buty nediol, whereby at least a portion of said formaldehyde is obtained from step S3)S3) providing formaldehyde, and whereby at least a portion of said acetylene is obtained from step S2)S2) converting at least a portion of at least one sustainable feedstock to acetylene, wherein said conversion comprises the utilization of a steam cracking unit or a part thereof, whereby said at least one sustainable feedstock is obtained from step S1)S1) providing at least one sustainable feedstock comprising at least one component selected from the group consisting of bio-oils, pyrolysis oils, and pyrolysis gases.

2. The process according to any of the preceding claims, wherein in step S1) said at least one component is selected from the group consisting of vegetable oils and processing residues thereof, waste cooking oils, tall oils, animal fats, oils obtained by thermochemical conversion of biomass, pyrolysis oils derived from plastic waste, pyrolysis gases derived from plastic waste, wherein said plastic waste preferably comprises polyurethanes and / or polyalkenes.

3. The process according to any of the preceding claims, wherein step S2) comprises catalytic hydrotreatment, preferably comprising a hydrocracking step, of said at least one sustainable feedstock.

4. The process according to any of the preceding claims, wherein in step S2) said conversion comprises steam cracking of at least a portion of said at least one sustainable feedstock to obtain a cracking product mixture comprising acetylene and separating acetylene therefrom.

5. The process according to any of the preceding claims, wherein in step S2) said conversion comprises steam cracking of at least a portion of said at least one sustainable feedstock to obtain a cracking product mixture comprising one or more C1-4 alkanes, separating therefrom at least one fraction comprising one or more C1-4 alkanes, and subjecting said at least one fraction to partial combustion to obtain acetylene.

6. The process according to any of the preceding claims, wherein in step S1 ) said at least one sustainable feedstock comprises pyrolysis gas and wherein in step S2) said conversion comprises feeding into the fractionation section of a steam cracking unit said at least one sustainable feedstock, separating therefrom at least one fraction comprising one or more C1-4 alkanes, and subjecting said at least one fraction to partial combustion to obtain acetylene.BASF SE 241076W001497. The process according to any of the preceding claims, wherein step S3) comprises the substeps, S3a) providing methanol; andS3b) converting at least a portion of said methanol to formaldehyde; and wherein optionally substep S3a) comprises the substepsS3aa) providing syngas; andS3ab) converting at least a portion of said syngas to methanol.

8. The process according to claim 7, wherein in substep S3aa), at least a portion of said syngas originates from steam reforming, autothermal reforming, or partial combustion, optionally followed by water-gas shift reaction, of one or more C1-4 alkanes, said one or more C1-4 alkanes being obtained from pyrolysis gas, preferably by utilizing the fractionation section of a steam cracker unit; and / or wherein in substep S3aa), at least a portion of said syngas originates from partial combustion of one or more C1-4 alkanes, said one or more C1-4 alkanes being obtained from steam cracking of at least one sustainable, optionally upgraded feedstock according to step S2).

9. The process according to any of claims 7 to 8, wherein in substep S3aa), at least a portion of said syngas originates from gasification, optionally after a pre-treatment step, of at least one solid and / or liquid raw material, preferably comprising biomass and / or waste, more preferably comprising plastic waste comprising polyurethanes and / or polyalkenes.

10. The process according to any of claims 7 to 9, wherein in substep S3aa), at least a portion of said syngas originates from reverse water gas shift reaction of CO2 and H2, wherein preferably at least a portion of said CO2 originates from biomass and / or is obtained via direct air capture, direct ocean capture, and / or indirect ocean capture or is obtained via carbon capture from industrial point sources, in particular from a steam cracking unit.11 . The process according to any of the preceding claims, wherein in step S4) at least a portion of said formaldehyde and at least a portion of said acetylene originate from the same sustainable feedstock provided in step S1).

12. 1 ,4-butynediol obtained by a process according to any one of claims 1 to 11.

13. A process to produce 1 ,4-butanediol, the process comprising the process to produce 1 ,4-butynediol according to any of the preceding claims and further comprising step S5)S5) hydrogenating at least a portion of said 1 ,4-butynediol to obtain 1 ,4-butanediol; wherein preferably at least a portion of the H2 needed is obtained from the steam cracking of step S2).

14. 1 ,4-butanediol obtained by a process according to claim 13.BASF SE 241076W0015015. A process to produce at least one downstream product, preferably at least one product PRF1 , the process comprising the process according to claim 13 and further comprising step S6)S6) converting 1 ,4-butanediol obtained in step S5) to obtain at least one downstream product.

16. A system for producing 1 ,4-butynediol, the system comprising the unitsU1) sustainable feedstock unit;U2) acetylene unit comprising a steam cracking subunit;U3) formaldehyde unit; andU4) 1 ,4-butynediol unit; and optionallyU2*) Sachsse-Bartholome acetylene subunit.

17. The use of a steam cracking unit in a process to produce 1 ,4-butynediol, preferably in a process according to any of claims 1 to 11, wherein the steam cracking unit is used inP1) production of acetylene and / or of one or more C1-4 alkanes from at least one sustainable feedstock comprising at least one component selected from the group consisting of bio-oils and pyrolysis oils, optionally after upgrading said sustainable feedstock, and separation of at least one fraction comprising acetylene or one or more C1-4 alkanes, and / orP2) separation of at least one fraction comprising one or more C1-4 alkanes from a sustainable feedstock comprising pyrolysis gas.