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

Abstract

A process and a system to produce 1,4-butanediol as well as downstream products thereof are provided.

Description

Sustainable Production of 1,4-Butanediol and Downstream Products ThereofField of the InventionThis invention relates to a process and a system to produce 1 ,4-butanediol 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.Syngas, being mainly a mixture of hydrogen (H2) and carbon monoxide (CO) in varying molar ratios, but also comprising CO2, is among the most important of such starting materials. Sustainable production pathways for syngas start, for instance, from waste or biomass and may include hydrogen and carbon oxides of sustainable origin. Syngas is an essential starting material to synthesize downstream products which are produced in large quantities, in particular methanol, but also synthetic natural gas (mainly methane) and Fischer-Tropsch hydrocarbons.However, to date, the H2 comprised in syngas is often of fossil origin either due to the origin of the carbon-containing syngas production feedstock or due to the admixture of H2 which is predominantly based on fossil fuels. Thus, greenhouse gas emissions of the syngas-using processes and thus the product carbon footprints (carbon intensities) of the products obtained on the basis of said syngas are increasedMethanol can be used as a fuel, to produce fuels like biodiesel, or for fuel applications, such as dimethylether, methyl- tert-butylether, tert-amylmethylether, and gasoline blending. In the chemical industry methanol serves as a raw material in the production of olefins, formaldehyde, acetaldehyde, acetic acid, methyl acetate, acetic anhydride, vinyl acetate, sodium methylate, methylation products like dimethylphenols, methyl amines, methyl mercaptane, dimethylterephthalate, aromatics, and fuels. The conventional production method involves a catalytic process using fossil feedstock such as natural gas or coal.Formaldehyde is widely used in the chemical industry due to its versatility and range of applications. It is produced by the oxidation or dehydrogenation of methanol and is an important intermediate in many chemical reactions. Formaldehyde is used in the production of a wide range of downstream products, including monomers (like butanediol, neopentyl glycol, methylendiphenyldiisocyanate, acrylic acid, methacrylic acid), polymers (like polyoxymethylene), polymers derived from the mentioned monomers (like polyethers, polyesters, polyurethanes, polyacrylates), resins (like phenol formaldehyde resins, urea condensation resins, melamine resins and acetone resins), plastics, textiles, and coatings. It is also used as a preservative in many consumer products such as cosmetics and household cleaners.1 ,4-Butanediol (BDO) is commonly synthesized by the reaction of acetylene with two equivalents of formaldehyde. The resulting 1 ,4-butynediol (i.e., but-2-yne-1,4-diol; BYD) is subsequently hydrogenated to BDO. BDO may be used in chemical industry as a solvent and as a precursor for important compounds and solvents like tetrahydrofuran (THF), gamma-butyrolactone (GBL) and N-methyl-2-pyrrolidone (NMP). BDO and said downstream products are 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 polytetrahydrofurane (polyTHF, PTMEG), and copolymers derived therefrom such as thermoplastic polyurethanes (TPU), thermoplastic elastomers (TPE) and polyether polyurea copolymers (e.g., spandex).The above-mentioned conversion of methanol to formaldehyde may also deliver a by-product gas stream, I. a. comprising hydrogen and carbon oxides, which is often used energetically only, see, e.g., A. W. Franz et al., Ullmann's Encyclopedia of Industrial Chemistry (2016), Chapter “Formaldehyde”. However, in particular in cases where sustainable carbon and hydrogen sources are employed for syngas production, a material use of by-product streams would be desirable to use the sustainable resources most efficiently and to obtain products with improved sustainability attributes.CN 109 651 110 A relates to a production method of high-purity 1,4-butanediol. The production method mainly comprises the working sections of formaldehyde, ethynylation, hydrogenation and product rectification, wherein according to the working section of formaldehyde, raw materials methyl alcohol and air generate formaldehyde under the effect of a catalyst; according to the working section of ethynylation, ethyne and formaldehyde are subjected to an alkynal reaction to generate refined 1 ,4-butynediol under the effect of a catalyst; according to the working section of hydrogenation, under the certain pressure, 1 ,4-butynediol and hydrogen from the upstream burner gas purification working section generate crude 1,4-butanediol under the effect of a catalyst; according to the working section of rectification, rectification treatment is performed on the 1,4-butanediol to obtain the high-purity 1 ,4-butanediol product.CN 112 457 161 provides a system and process for preparing 1 , 4-butanediol from acetylene and formaldehyde, the system comprises a formaldehyde preparation device, a 1, 4-butanediol preparation device, a 1, 4-butanediol preparation device and a rectification device which are sequentially and correspondingly connected, and the system further comprises an intelligent control device.GB 2 618 418 B relates to a method of producing formaldehyde comprising: providing a feedstock gas stream comprising electrolytic hydrogen generated from the electrolysis of water and one or both of carbon monoxide and carbon dioxide; converting at least a portion of the feedstock gas to methanol; converting at least a portion of the methanol to formaldehyde and hydrogen; separately recovering at least some of the formaldehyde and at least some of the hydrogen; and recycling at least some of the recovered hydrogen to the feedstock gas stream. Preferably, the feedstock gas comprises electrolytic hydrogen and a syngas comprising H2, CO and CO2. The syngas may have been formed by reforming with steam or by gasification with oxygen and steam. The gasification step may use oxygen generated from electrolysis of water. Preferably, the MeOH is purified using distillation before conversion of methanolto methanal. Converting the methanol to formaldehyde and hydrogen may comprise use of a silver catalyst and, preferably, is performed in the substantial absence of an oxidant.Summary of the InventionIn a first aspect, the present invention relates to a process to produce 1 ,4-butanediol, the process comprising the stepsA) providing methanol;B) converting at least a part of said methanol to formaldehyde, wherein a formaldehyde by-product gas stream comprising H2 is obtained;C) separating H2 from said formaldehyde by-product gas stream;D) providing acetylene;E) reacting at least a part of said acetylene with at least a part of the formaldehyde obtained in step B) to obtain1 ,4-butynediol;F) providing H2, wherein at least a part of said H2 is obtained from step C); andG) reacting at least a part of said 1 ,4-butynediol with at least a part of the H2 provided in step F) to obtain 1,4-bu- tanediol.In a second aspect, the invention relates to a system for producing 1 ,4-butanediol, the system comprising the unitsI) methanol providing unit;II) formaldehyde production unit;III) H2 recovery unit;IV) acetylene providing unit;V) 1,4-butynediol production unit;VI) H2 providing unit; andVII) 1,4-butanediol production unit.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.).The 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” or “at least a part 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.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 is considered “plastic waste” in the sense of the present invention.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 1 ,4-butanediol.FIG 2: Flow diagram showing a process to produce 1 ,4-butanediol from one single carbon-containing feedstock.FIG 3: Flow diagram showing a process to produce 1 ,4-butanediol in connection with water electrolysis.FIG 4: System for performing the process according to FIG 1FIG 5: System for performing the process according to FIG 2FIG 6: System for performing the process according to FIG 3Legend for FIG 1-6:0: carbon-containing feedstock; 1: methanol; 2: water; 3: 02; 4: H2; 5: by-product gas stream; 6: formaldehyde; 7: acetylene; 8: 1 ,4-butynediol; 9: 1 ,4-butanediol10 / 10a: methanol production; 11 : formaldehyde production; 12: 1 ,4-butynediol production; 13: H2 recovery; 14 / 14a: H2 production; 15: hydrogenation; 16: downstream process101 : methanol providing unit; 102 / 102a: H2 production unit; 103: formaldehyde production unit; 104: H2 recovery unit; 105: acetylene providing unit; 106: 1,4-butynediol production unit; 107: 1,4-butanediol production unit; 108: downstream conversion unitDetailed Description of the InventionThe present invention provides a process and a system to produce 1,4-butanediol (BDO) and downstream products thereof.Said process starts with the provision of methanol that preferably exhibits favorable sustainability attributes. In particular, favorable sustain ability refers to limited net CO2 emissions, which can be achieved, e.g., by employing sustainablefeedstocks, sustainable process schemes, sustainable energy sources, and / or by capturing and storing or utilizing CO2 formed in the course of the methanol synthesisMethanol is converted to formaldehyde with favorable sustainability attributes, which may be accomplished according to different oxidation or dehydrogenation processes. In any case, a by-product gas stream of the formaldehyde synthesis is obtained that contains H2. Because of the reaction sequence, said H2 carries the favorable sustainability attributes of the originally provided syngas. However, said by-product stream is often used energetically only (see, e.g., A. W. Franz et al., Ullmann's Encyclopedia of Industrial Chemistry (2016), Chapter "Formaldehyde"), i.e., the hydrogen is oxidized to water to produce energy, e.g., in the form of heat; instead, from an overall sustainability perspective, it should be more advantageous to incorporate said hydrogen into value products while providing energy through other, more efficient routes.Along these lines, the next process step comprises the separation of H2 from said by-product gas stream. The thus obtained H2 is then available for further utilizationThe process sequence proceeds with the formation of 1,4-butynediol (BYD) from said formaldehyde and acetylene. Preferably, also said acetylene exhibits favorable sustainability properties, e.g., it may have been synthesized from non-fossil resources. Finally, BYD is hydrogenated in the presence of H2 to form BDO. Within the scope of the invention, at least a part of said H2 originates from the above-mentioned H2 recovery from the formaldehyde by-product gas stream.By recovering H2 from the formaldehyde synthesis and using it for the BDO production, the process described herein allows for a more complete conversion of, preferably sustainable, feedstocks to value products in terms of atom economy. Hence, the overall process efficiency is increased. The process is at least in part self-supplying in respect of the H2 demand such that the need and costs for H2 from other sources are reduced. For instance, less H2 from external sources may be required, which results in a lower dependency on external, possibly fluctuating H2 supply, in particular in view of fluctuating renewable energy supplies. Also, the reduced need for external H2 production may lead to a lower demand of H2 production feedstock, to a lower energy consumption, and to lower greenhouse gas emissions The sustainability of the process chain is thus enhanced. Such advantages may outweigh the additional efforts for H2 separation or - in the case of a methanol dehydrogenation - the lower process efficiency (e.g., higher temperatures, lower conversions) compared to an oxidative process.Furthermore, BDO and downstream products derived therefrom are provided with favorable and improved sustainability attributes, e.g., they are characterized by 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-butanediol, the process comprising the stepsA) providing methanol;B) converting at least a part of said methanol to formaldehyde, wherein a formaldehyde by-product gas stream comprising H2 is obtained;C) separating H2 from said formaldehyde by-product gas stream;D) providing acetylene;E) reacting at least a part of said acetylene with at least a part of the formaldehyde obtained in step B) to obtain 1 ,4-butynediol;F) providing H2, wherein at least a part of said H2 is obtained from step C); andG) reacting at least a part of said 1 ,4-butynediol with at least a part of the H2 provided in step F) to obtain 1 ,4-bu- tanediol.Likewise, in the first aspect, the present invention relates to a process to produce 1 ,4-butanediol, the process comprising step G)G) reacting 1 ,4-butynediol with H2 to obtain 1 ,4-butanediol, whereby in step G) at least a part of said 1 ,4-butynediol is obtained from step E)E) reacting acetylene with formaldehyde to obtain 1 ,4-butynediol, whereby at least a part of said acetylene is obtained from step D)D) providing acetylene; and whereby at least a part of said formaldehyde is obtained from step B)B) converting methanol to formaldehyde, wherein a formaldehyde by-product gas stream comprising H2 is obtained; whereby at least a part of said methanol is obtained from step A)A) providing methanol; and whereby in step G) at least a part of said H2 is obtained from step F)F) providing H2, wherein at least a part of said H2 is obtained from step C)C) separating H2 from the formaldehyde by-product gas stream obtained in step B).Preferred Embodiments1 1) The process according to the first aspect of the invention.Step A)In a first step of the process according to the invention, methanol is provided in sufficient amounts and quality (e.g., purity) for further use in chemical processes, in particular for 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 part 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.Preferred Embodiments1 .2) The process according to any of the preceding embodiments, wherein in step A) at least a part of said methanol originates from bio-based or recycling-based sources.1 .3) The process according to any of the preceding embodiments, wherein step A) comprises producing methanol.1 4) The process according to any of the preceding embodiments, wherein step A) comprises the substeps A1) and A2)A1) providing syngas comprising CO and / or CO2 and comprising H2; andA2) converting at least a part of said syngas to methanol.Substep AltSyngas 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 obtained from C02 and H2 as input materials via reverse WGS (rWGS) reaction, in which CO and H20 are formed from C02 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 C02 (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 C02 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 C02 and H2 through (partial) rWGS reaction, wherein, preferably, said 002 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 C02 emissions and thus a reduced carbon intensity may be generated by reforming of natural gas or gasification of coal wherein the formed 002 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 002 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. Another 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, C02, 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.The exothermic reaction with oxygen provides the necessary energy to achieve the high reaction temperatures for the endothermic gasification reaction of carbon with water vaporAlso, 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 comprise 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, 002, or a mixture of the aforementioned. Oxygen is the most common oxidant used for gasification because of its easy availability and low cost. Preferably, 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 FeedstocksBiomass and waste, in particular plastic waste, may also be used to produce syngas via a pyrolysis reaction to obtain a pyrolysis oil and subsequent partial oxidation and / or gasification of said oil. Pyrolysis processes as such are known. They are described, e.g. for plastics, in EP 0713906 A1 , WO 95 / 03375 A1, 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 elementsother 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.Examples 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, moving bed reactors, entrained flow reactors, screw reactors, extruders, stirred tank reactors and rotary kiln reactor. Preferably, the pyrolysis is performed in the pyrolysis reactor under an inert atmosphere exempt of 02 or air. Optionally, pyrolysis oils are subjected to an upgrading process. 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 A1 , WO 2023 / 061834 A1, EP 0713906 A1, and WO 95 / 03375 A1 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.Pyrolysis oils 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.WGS 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 COand 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, and 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 chemical 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 002 is captured from industrial flue gases.Processes for capturing C02 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. C02 adsorbs to a MOF (metal-organic framework) through physisorption or chemisorption based on the porosity and selectivity of the MOF leaving behind a C02 poor gas stream. The C02 is then stripped off the MOF using temperature swing adsorption (TSA) or pressure swing adsorption (PSA) so the MOF can be reused.DAC is a process of capturing C02 directly from the ambient air and generating a concentrated stream of C02 for sequestration or utilization or production of carbon-neutral fuel. C02 removal is achieved when ambient air contact chemical media, typically an aqueous alkaline solvent or sorbents. These chemical media are subsequently stripped of C02 through the application of energy (namely heat), resulting in a C02 stream that can undergo dehydration and compression, while simultaneously regenerating the chemical media tor reuse.Dilute C02 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 bythe 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 produced from fossil sources, e.g., via steam reforming or autothermal reforming of natural gas, when the formed 002 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 002 is formed as a byproduct. 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 C02 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 process 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 highoperation 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.Also, 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.Purification 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 part 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 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 A1), 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. The 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 / liquids 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.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.Preferred Embodiments1.5) The process according to embodiment 1.4, wherein in substep A1), said syngas comprises CO and H2.1.6) The process according to embodiment 1.4, wherein in substep A1), said syngas comprises CO2 and H2.1 .7) The process according to any of embodiments 1 .4 to 1.6, wherein in substep A1), said syngas comprises CO, CO2, and H2.1.8) The process according to any of embodiments 1.4 to 1.7, wherein substep A1) comprises producing syngas comprising CO and / or CO2 and comprising H2 and wherein substep A1) preferably comprises purifying said syngas.1.9) The process according to embodiment 1.8, wherein substep A1) 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.) The process according to any of embodiments 1 4 to 1.9, wherein in substep A1), 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.) The process according to any of embodiments 1.4 to 1.10, wherein in substep A1), at least a part of said syngas originates from a sustainable production process, preferably comprising carbon capture and / or using renewable energies. ) The process according to any of embodiments 1.4 to 1.11, wherein in substep A1), at least a part of said CO and / or of said CO2 originates from sustainable sources, preferably from bio-based or recycling-based carbon-containing feedstocks. ) The process according to any of embodiments 1.4 to 1.12, wherein in substep A1), at least a part of said H2 originates from sustainable sources, preferably from water electrolysis, chlor-alkali electrolysis, methane pyrolysis, or decomposition of ammonia. ) The process according to any of embodiments 1.4 to 1.13, wherein in substep A1), at least a part 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 part 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. ) The process according to any of embodiments 1 4 to 1.14, wherein in substep A1), at least a part 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 part of which is obtained from water electrolysis, more preferably from water electrolysis driven by renewable energies. ) The process according to any of embodiments 1.4 to 1.15, wherein in substep A1), at least a part 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 part of said CO2 is obtained via DAC, DOC, and / or IOC or is obtained via carbon capture from industrial point sources. ) The process according to any of embodiments 1.4 to 1.16, wherein in substep A1), at least a part of said syngas originates from gasification, optionally after a pre-treatment step, of at least one solid and / or liquid feedstock, preferably comprising biomass and / or waste, wherein preferably said gasification is carried out in the presence of oxygen at least a part of which is obtained from water electrolysis, more preferably from water electrolysis driven by renewable energies. ) The process according to any of embodiments 1.4 to 1.17, wherein in substep A1), at least a part 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, 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 a part of which is obtained from water electrolysis, more preferably from water electrolysis driven by renewable energies.1.19) The process according to any of embodiments 1.4 to 1.18, wherein in substep A1), at least a part of said syngas originates from rWGS reaction of CO2 and H2, wherein preferably at least a part 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 and / or wherein preferably at least a part of said H2 originates from water electrolysis, chlor-alkali electrolysis, methane pyrolysis, decomposition of ammonia, or syngas production processes the CO2 emissions of which are captured and optionally stored and / or utilized.1.20) The process according to any of embodiments 1.13 and 1.19, wherein in substep A1), 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 s 50%, preferably 30%, more preferably s 20%, even more preferably 10%, most preferably < 1 %.1.21) The process according to any of embodiments 1.13, and 1.19 to 1.20, wherein in substep A1), 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 energySubstep A2)The 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.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, methanolsynthesis 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 I n2O3 / ZrO2 was described for industrial relevant conditions. A typical range of industrially relevant conditions for the hydrogenation of CO2 to methanol are T=200-300°C, p = ID- 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.Preferred Embodiments1 .22) The process according to any of the preceding embodiments, wherein in substep A2), said conversion is carried out in the presence of a copper-zinc-alumina-based catalyst, e.g., CuO / ZnO / AI2O3.1 .23) The process according to any of the preceding embodiments, wherein in substep A2), said conversion is carried out in the presence of an indium-based catalyst, e.g., I n2O3 / ZrO2.Step B)Formaldehyde 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:CH30H -^ CH2O + H2Also, instead of air as an oxidant, oxygen-enriched air may be employed, the oxygen originating preferably from water electrolysis, e.g., from step F) described below, preferably from water electrolysis driven by renewable energy. Of note, the use of oxygen-enriched air allows for a reduction of the air flow (CN102757324).Further, 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. The 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 B) 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.In the above-mentioned processes, especially where a dehydrogenation reaction is involved, a by-product gas stream of the formaldehyde synthesis is obtained that contains H2, depending on the process conditions often in admixture with nitrogen, carbon oxides, unconverted methanol, or residual formaldehyde. Advantageously, the use of oxygen- enriched air instead of air as an oxidant leads to a reduction of the nitrogen content in the by-product gas stream such that the concentration of H2 in said gas-stream is increased which facilitates its separationPreferred Embodiments1.24) The process according to any of embodiments 1.1 to 1.23, wherein in step B), said conversion is carried out with air in the presence of an iron molybdenum oxide catalyst or of a silver catalyst.1.25) The process according to any of embodiments 1.1 to 1.23, wherein in step B), said conversion is carried out with oxygen-enriched air in the presence of an iron molybdenum oxide catalyst or of a silver catalyst, wherein said oxygen is preferably obtained from water electrolysis, more preferably from water electrolysis driven by renewable energy.1.26) The process according to any of embodiments 1.1 to 1.23, wherein in step B), 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 .27) The process according to any of the preceding embodiments, wherein step B) includes the separation of formaldehyde.Step C)In step C), H2 is separated from the formaldehyde by-product gas stream. A number of well-known and established techniques are available to achieve this goal efficiently, in particular PSA, membrane separation, and cryogenic separation. Said gas separation techniques are described, for example, in W. Boll et al., Ullmann's Encyclopedia of Industrial Chemistry, 2012, Chapter "Gas Production, 3. Gas Treating”, and the references cited therein.For instance, PSA involves passing the gas mixture through a bed of adsorbent material that selectively adsorbs nitrogen and carbon oxides, allowing H2 to pass through. By cycling the pressure, the adsorbed gases can be desorbed and removed from the adsorbent bed, leaving behind purified H2. Another technique is membrane separation, which uses a selectively permeable membrane to separate hydrogen from the other gases in the mixture. Cryogenic separation is another method that involves cooling the gas mixture to very low temperatures, which causes the nitrogen and carbon oxides to condense and separate from the hydrogen.Such separation techniques typically deliver hydrogen of sufficient purity which can readily be used as a chemical feedstock for further process steps. Often, good to excellent H2 recovery rates (i.e., amount of H2 that can be recovered from a gas mixture in relation to the amount of H2 present in said gas mixture), e.g., beyond 90 %, even from gas mixtures with rather low H2 contents, are achieved using such techniques.Should higher purity requirements have to be met, step C) may comprise an additional step of further purifying the separated H2 to remove compounds and species that might detrimentally impact (e.g., poison catalysts) step G).Preferred Embodiments1 .28) The process according to any of embodiments 1 .1 to 1 .27, wherein in step C), said separation is carried out by pressure swing adsorption.1 29) The process according to any of embodiments 1 .1 to 1 .27, wherein in step C), said separation is carried out by membrane separation.1 30) The process according to any of embodiments 1 .1 to 1 .27, wherein in step C), said separation is carried out by cryogenic separation.1.31) The process according to any of the preceding embodiments, wherein in step C), the H2 recovery rate is above 60 %, preferably above 70 %, more preferably above 80%, most preferably above 90 %.Step D)In step D), acetylene is provided, e.g., produced, in sufficient amounts and quality to be used for step E) described below. Acetylene may be produced according to any conceivable production route that is known to the one of skill in the art. Such processes are, for example, described in P. Passler et al., Ullmann's Encyclopedia of Industrial Chemistry, 2012, Chapter “Acetylene", and the references cited therein.Among them is the partial combustion of hydrocarbons, in particular of natural gas, SNG, biogas, ethane and the like, with oxygen or air (e.g., Sachsse-Bartholome process). Said 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 the methanol synthesis according to substep A2). Such process sequence hence allows for the formation of acetylene onthe one hand and formaldehyde (via syngas and methanol) on the other hand from one single feedstock, preferably a sustainable feedstock.Preferably, the process and the obtained acetylene are characterized by favorable sustainability attributes, e.g., resulting from the use of bio-based feedstocks like biogas or the use of 02 sustainably produced from water electrolysis with renewable energy, e.g., obtained from step F) described below, as an oxidant.Preferred Embodiments1.32) The process according to any of the preceding embodiments, wherein step D) comprises producing acetylene by partial combustion of hydrocarbons, preferably of hydrocarbons of renewable origin, more preferably of biogas.1.33) The process according to any of the preceding embodiments, wherein step D) comprises producing acetylene and a syngas comprising CO, 002, and H2.1 .34) The process according to embodiment 1 .33, wherein at least a part of said syngas is used for producing methanol according to step A).1 .35) The process according to any of the preceding embodiments, wherein at least a part of the methanol provided in step A) and at least a part of the acetylene provided in step D) are produced from the same hydrocarbon feedstock, in particular by partial combustion of hydrocarbons, preferably of biogas, to obtain syngas according to substep A1) and to obtain acetylene according to step D).1 .36) The process according to any of embodiments 1 .32 and 1 .35, wherein said partial combustion is carried out in the presence of oxygen, preferably obtained from water electrolysis, more preferably from water electrolysis driven by renewable energy.Step E)1 ,4-butynediol (BYD) is synthesized according to processes known in the art from acetylene provided in step D) and from formaldehyde obtained in step B), 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, feedstock, e.g., by partial combustion of hydrocarbons as described for step D). By such reaction sequences, the processes starting from one single feedstock and leading to BYD or even BDO and derivatives thereof 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 thelike). 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 of 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 .37) The process according to any of the preceding embodiments, wherein step E) is carried out in the presence of a catalyst comprising at least one transition metal acetylide, preferably a copper (I) acetylide.1 .38) The process according to any of the preceding embodiments, wherein step E) is carried out in the presence of a copper (I) catalyst, preferably of a copper (I) acetylide catalyst.1 .39) The process according to any of the preceding embodiments, wherein step E) is carried out in the presence of a pre-catalyst comprising copper(ll) oxide, preferably further comprising bismuth(lll) oxide.1 .40) The process according to any of the preceding embodiments, wherein step E) 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 .41) The process according to any of the preceding embodiments, wherein in step E) at least a part of said formaldehyde and at least a part of said acetylene originate from the same hydrocarbon feedstock, in particular they are obtained via partial combustion of hydrocarbons, preferably of biogas, to obtain syngas according to substep A1) and to obtain acetylene according to step D).In step F), H2 is provided in sufficient amounts and quality to be used for step G) described below. Within the present invention, as much H2 as possible is provided from step C) described hereinbefore such that the need for externally produced H2 is minimized; preferably all of the H2 recovered in step C) is provided according to step F).However, though in theory the dehydrogenation of 2 equivalents of methanol to formaldehyde releases as much H2 as is required for the hydrogenation of one equivalent of BYD to BDO, the amount of H2 recoverable in practice in step C) will not suffice to fully supply step F) with H2.Thus, the H2 obtained from step C) must be supplemented with H2 from external sources, i.e., from processes other than step C). Such H2 may be obtained according to processes known in the art. Production process are for example disclosed in P. Haussinger et al., Ullmann's Encyclopedia of Industrial Chemistry, 2012, Chapter “Hydrogen, 2. Production” and the references cited therein. Preferred ways to produce H2 are already described above for substep A1); thus, the embodiments mentioned for substep A1) apply equally to step F), in particular methane pyrolysis, water electrolysis, chlor-alkali electrolysis, and ammonia decomposition, as well as their embodiments and features described above.Still, the amount of H2 needed from external sources may be reduced by the H2 recovery of step C) such that less feedstock and / or less energy for external H2 production are required. In case step B) is carried out under anaerobic conditions, up to approximately 70 % of H2 to be provided in step F) may be replaced by recovered H2, and up to approximately 40 % in case step B) is carried out as an oxidative process (in both cases assuming a constant process throughput).Preferred Embodiments1.42) The process according to any of the preceding embodiments, wherein in step F), at least 10 % of said H2 is obtained from step C), preferably at least 20 %, more preferably at least 30 %, more preferably at least 40 %, more preferably at least 50 %, more preferably at least 60 %, more preferably at least 70 %, more preferably at least 80 %.1 .43) The process according to any of the preceding embodiments, wherein at least 20 % of the H2 obtained in step C) is provided in step F), preferably at least 35 %, more preferably at least 50 %, more preferably at least 60 %, more preferably at least 70 %, more preferably at least 80 %, more preferably at least 90 %, most preferably all of the H2 obtained in step C).1.44) The process according to any of the preceding embodiments, wherein in step F), at least a part of said H2 originates from sustainable external processes, preferably from water electrolysis, chlor-alkali electrolysis, methane pyrolysis, or decomposition of ammonia, said sustainable external processes being preferably driven by renewable energy, or from syngas production processes the CO2 emissions of which are captured and optionally stored and / or utilized.1 45) The process according to any of the preceding embodiments, wherein in step F), the fraction of said H2 that is obtained from external sources is not more than 90 %, 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 %.Step G)BDO is produced by hydrogenation of BYD obtained in step E), 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.Typically, 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, the H2 as provided in step F) of the present invention is advantageously used to obtain BDO with favorable sustainability properties.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 46) The process according to any of the preceding embodiments, wherein step G) is carried out in the presence of a nickel catalyst.1 .47) The process according to any of the preceding embodiments, wherein step G) is carried out in the presence of a palladium catalyst.1.48) The process according to any of the preceding embodiments, wherein step G) includes a fractional distillation step to obtain purified BDO.Further process stepsThe process according to the invention 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 streams obtained in steps B), E), and G) to improve their properties or to meet certain specifications for further process steps.Also, step H), described hereinafter, may be comprised by the process of the invention.Step H)Within the scope of this invention, the BDO obtained in step G), 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.The 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 carbonmonoxide, 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.The 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 “compositionand / 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 are 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 sodiumpropionate 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), styrene butadiene dispersion (s), aqueous dispersion(s) comprising composite particles, acrylate alkyd hybrid dispersion^), polyurethane(s) (including UV-curable polyurethanes) and polyurethane - poly(meth)acrylate hybrid polymers). 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 poly carboxy I ate 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 hybride 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- crosslinkable 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] entitled “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) comprisingpolymeric 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.Preferred embodiments1 49) A process to produce at least one downstream product, preferably at least one product PRF1, the process comprising the process according to any of the preceding embodiments and further comprising step H)H) converting 1 ,4-butanediol obtained in step G) to obtain at least one downstream product.1.50) The process according to embodiment 1.49, wherein the product PRF1 is selected from:I) building block or monomer; orII) polymer, preferably polymer A, polymer composition, preferably polymer composition A, or polymer product, preferably polymer product A; or ill) 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 meltsand 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.1.51) The process according to any one of embodiments 1.49 to 1.50, 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 1-3:FIG 1 depicts the production of BDO (9) from methanol (1) and acetylene (7) with H2 recovery and utilization: Methanol (1 ) is synthesized (10) and oxidized and / or dehydrogenated (11) to formaldehyde (6). From the by-product gas stream (5) of the formaldehyde synthesis (11), H2 (4) is separated, i e., recovered (13). Formaldehyde (6) is reacted (12) with acetylene (7) to form BYD (8) which is hydrogenated (15) to BDO (9). For the hydrogenation (15), said separated H2 (4) is supplemented with externally produced (14) H2 to achieve the necessary amounts. Optionally, BDO (9) is further utilized in downstream processes (16) to produce downstream products.Preferred methanol syntheses (10) are described for step A) hereinbefore and include the synthesis of methanol from CO2 and H2 as well as the following syngas-producing processes, followed by optional adjustment of the stoichiometric number of the obtained syngas and by conversion to methanol:- partial oxidation of a gaseous feedstock like natural gas, SNG, or biogas;- SMR or ATR of a gaseous feedstock like natural gas, SNG, or biogas wherein CO2 that is formed as a by-product of the process or for heating the process is captured for later storage or utilization;- gasification of a solid or liquid feedstock like coal, biomass, or waste;- pyrolysis of a solid or liquid feedstock like biomass or waste and subsequent gasification of the obtained pyrolysis oil; and- rWGS of CO2 and H2 to obtain syngas.FIG 2 depicts the production of BDO (9) from one single carbon-containing feedstock (0) with H2 recovery and utilization:FIG 2 comprises all the features of FIG 1 as described above. Beyond, in FIG 2, methanol (1) and acetylene (7) are obtained from one single carbon-containing feedstock (0). To this end, preferably, said feedstock (0) comprises natural gas, SNG, or biogas and is partially oxidized (10a) to obtain acetylene (7) along with a carbon-rich syngas which is complemented with H2 (not explicitly depicted), e.g., obtained from an external source via water electrolysis and / or methane pyrolysis, to adjust the H2-to-COx ratio. Said adjusted syngas is then further converted to methanol (1).FIG 3 depicts the production of BDO (9) from methanol (1) and acetylene (7) with H2 recovery and utilization in connection with water electrolysis (14a): FIG 3 comprises all the features of FIG 1 as described above. Optionally, FIG 3 may also include all the features of FIG 2 as described above although not depicted explicitly. Beyond, in FIG 3, the external production of H2 (4) is embodied by the electrolysis (14a) of water (2). The co-produced 02 (3) may optionally be used for the methanol synthesis (10), e.g., for gasification or partial oxidation processes, or for the conversion (11) of methanol (1) to formaldehyde (6).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-butanediol, the system comprising the unitsI) methanol providing unit;II) formaldehyde production unit;III) H2 recovery unit;IV) acetylene providing unit;V) 1,4-butynediol production unit;VI) H2 providing unit; andVII) 1,4-butanediol production unit.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.Unit I)The methanol providing unit I) is equipped to perform process step A) as described above, including its different embodiments. Thus, to perform substeps A1) and A2), it may comprise a syngas providing subunit la) and a methanol production subunit lb).The syngas providing subunit la) is equipped to perform process substep A1) as described above, including its different embodiments.In particular, it is equipped to receive and store syngas and / or a feedstock to produce syngas and to provide syngas to unit lb). In addition, it may receive and store H2 (optionally also oxygen) from a H2 production unit, e.g., unit VI). Similarly, it may receive and store CO2 from a CO2 production unit, e.g., a carbon capture unit.Unit la) may comprise a feedstock pretreatment subunit that is fed with feedstock and is equipped to process said feedstock as described for substep A1) above. Further, it may comprise a syngas production subunit, e.g., a reforming subunit, a gasification subunit, a pyrolysis subunit, and / or a rWGS subunit. Preferably, said syngas production subunit is connected to a CO2 production unit to capture 002 that is co-produced in the syngas production process. Also, subunit la) may comprise a syngas purification subunit as well as a subunit for adjusting the stoichiometric number, e.g., a WGS subunit.Subunit lb) is equipped to perform substep A2). In particular, it is equipped to receive a syngas stream, optionally to store syngas, to convert it to methanol, and to provide methanol to unit II). Unit I), in particular subunit lb), may also receive a syngas stream that is a by-product of the acetylene production (see the description of step D) above).Preferred Embodiments2 3) The system according to any of the preceding embodiments, wherein unit I) is fluidly connected and arranged upstream to unit II).2 4) The system according to any of the preceding embodiments, wherein unit I) is fluidly connected and arranged downstream to unit IV).2 5) The system according to any of the preceding embodiments, wherein unit I) comprises the subunits la) and lb) la) syngas providing subunit; and lb) methanol production subunit.2.6) The system according to any of the preceding embodiments, wherein subunit la) is fluidly connected and arranged upstream to subunit lb).2.7) The system according to any of the preceding embodiments, wherein subunit la) is fluidly connected and arranged downstream to unit VI).2.8) The system according to any of the preceding embodiments, wherein subunit la) is fluidly connected and arranged downstream to a C02 production unit.2.9) The system according to any of the preceding embodiments, wherein subunit la) comprises a feedstock pretreatment subunit.2.10) The system according to any of the preceding embodiments, wherein subunit la) comprises at least one syngas production subunit selected from the group consisting of a steam reforming subunit, a partial oxidation subunit,an autothermal reforming subunit, a dry reforming subunit, a gasification subunit, a pyrolysis subunit, and a rWGS subunit.2.11) The system according to any of the preceding embodiments, wherein subunit la) comprises a syngas purification subunit and / or a subunit for adjusting the stoichiometric number.2.12) The system according to any of the preceding embodiments, wherein subunit lb) is fluidly connected and arranged downstream to subunit la).2.13) The system according to any of the preceding embodiments, wherein subunit lb) is fluidly connected and arranged upstream to unit II).Unit II)The formaldehyde production unit II) is equipped to perform process step B) as described above, including its different embodiments.In particular, it is equipped to receive a methanol stream, optionally to store methanol, and to convert it to formaldehyde. It may further receive oxygen from a water electrolysis unit (e.g., unit VI)). Further, it is equipped to separate said formaldehyde from a formaldehyde by-product gas stream and to provide the latter to the H2 recovery unit III).Preferred Embodiments2.14) The system according to any of the preceding embodiments, wherein unit II) is fluidly connected and arranged downstream to unit I) and optionally to unit VI).2.15) The system according to any of the preceding embodiments, wherein unit II) is fluidly connected and arranged upstream to unit III) and unit IV).2 16) The system according to any of the preceding embodiments, wherein unit II) comprises an oxidation subunit.2 17) The system according to any of the preceding embodiments, wherein unit II) comprises a dehydrogenation subunit2 18) The system according to any of the preceding embodiments, wherein unit II) comprises a separation subunit.Unit ill)The H2 recovery unit III) is equipped to perform process step C) as described above, including its different embodiments.In particular, it is equipped to receive the formaldehyde by-product gas stream from unit II), to separate H2 therefrom, optionally to store H2, and to provide H2 to the BDO production unit VII) according to step F) as described above.Preferred Embodiments2.19) The system according to any of the preceding embodiments, wherein unit III) is fluidly connected and arranged downstream to unit II).2.20) The system according to any of the preceding embodiments, wherein unit III is fluidly connected and arranged upstream to unit VII).2 21) The system according to any of the preceding embodiments, wherein unit III) comprises a pressure swing adsorption subunit.2.22) The system according to any of the preceding embodiments, wherein unit III) comprises a membrane separation subunit.2.23) The system according to any of the preceding embodiments, wherein unit III) comprises a cryogenic separation subunit.2.24) The system according to any of the preceding embodiments, wherein unit III) comprises a H2 storage subunit.The acetylene providing unit IV) is equipped to perform process step D) as described above, including its different embodiments.In particular, it is equipped to receive, optionally store, and provide acetylene to unit V).Unit IV) may comprise an acetylene production subunit, e.g., a subunit equipped for partial combustion of hydrocarbons to produce acetylene. The thereby obtained syngas (see step D)) may be used as a feedstock for the optional methanol synthesis of substep A1). Thus, unit IV) may be equipped to receive and store a hydrocarbon feedstock for partial combustion.The acetylene providing unit IV) may further be operated advantageously with 02, preferably from water electrolysis using renewable energy.Preferred Embodiments2 25) The system according to any of the preceding embodiments, wherein unit IV) is fluidly connected and arranged upstream to unit V).2 26) The system according to any of the preceding embodiments, wherein unit IV) is fluidly connected and arranged upstream to unit I)2 27) The system according to any of the preceding embodiments, wherein unit IV) is fluidly connected and arranged downstream to unit VI), wherein unit VI) comprises a water electrolysis subunit.2.28) The system according to any of the preceding embodiments, wherein unit IV) comprises an acetylene production subunit, preferably a subunit for the partial combustion of hydrocarbons.Unit V)The BYD production unit V) is equipped to perform process step E) as described above, including its different embodiments.In particular, it is equipped to receive formaldehyde from unit II) and acetylene from unit IV), optionally to store one or both of them, to convert them to BYD, and to provide BYD to the BDO production unit VII).Preferred Embodiments2.29) The system according to any of the preceding embodiments, wherein unit V) is fluidly connected and arranged downstream to unit II) and to unit IV).2 30) Thus, unit V) is fluidly connected and arranged downstream to units II) and IV) and upstream to unit VII).Unit VI)The H2 providing unit VI) is equipped to provide to unit VII) H2 in sufficient amounts and quality for carrying out step G), including its different embodiments.Thus, unit VI) may be equipped to receive and store a feedstock for producing H2, to produce and optionally store H2, and to provide it to unit VII). In addition, if it comprises a water electrolysis subunit, unit VI) may be equipped to store the co-produced oxygen and provide it to units I), II), and / or IV). Unit VI) may consist of a syngas production subunit (i.e., comprising all the features and embodiments described for unit la)) along with optional WGS and carbon capture subunits and with a H2 separation subunit.Also, unit VI) may be equipped to receive and optionally store H2 obtained from external sources, i.e. from outside the process or system according to the invention, e.g., delivered via pipeline or other transport means, in a H2 storage subunit and to provide H2 to unit VII). Said H2 may also be received and stored in the form of H2 carriers. H2 carriers are substances or materials that can store and release H2 in a controlled manner; examples include ammonia, methanol, metal hydrides, organic hydrides, and liquid organic hydrogen carriers. In the case of H2 being received in the form of a H2 carrier, the unit VI) may comprise a H2 release subunit that is equipped to release H2 from a H2 carrier. Such processes are well-known to those of skill in the art and include, for instance, cracking of ammonia or cracking of methanol.Preferred Embodiments2 31) The system according to any of the preceding embodiments, wherein unit VI) is fluidly connected and arranged upstream to unit VII).2 32) The system according to any of the preceding embodiments, wherein unit VI) comprises at least one syngas production subunit selected from the group consisting of a steam reforming subunit, a partial oxidation subunit, an autothermal reforming subunit, a dry reforming subunit, a gasification subunit, a pyrolysis subunit, and a rWGS subunit, optionally comprises a WGS subunit and / or a carbon capture subunit, and comprises a H2 separation subunit.2.33) The system according to any of the preceding embodiments, wherein unit VI) comprises a water electrolysis subunit.2.34) The system according to embodiment 2.34, wherein unit VI) comprises an oxygen storage subunit.2.35) The system according to any of embodiments 2.34 to 2.35, wherein unit VI) is fluidly connected and arranged upstream to unit I) and / or unit IV).2.36) The system according to any of embodiments 2.34 to 2.36, wherein unit VI) is fluidly connected and arranged upstream to unit II).2.37) The system according to any of the preceding embodiments, wherein unit VI) comprises a chlor-alkali electrolysis subunit.2.38) The system according to any of the preceding embodiments, wherein unit VI) comprises a methane pyrolysis subunit.2 39) The system according to any of the preceding embodiments, wherein unit VI) comprises an ammonia decomposition subunit2.40) The system according to any of the preceding embodiments, wherein unit VI) comprises a H2 storage subunit.2.41) The system according to any of the preceding embodiments, wherein unit VI) comprises a storage subunit for storing one or more H2 carriers.2.42) The system according to any of the preceding embodiments, wherein unit VI) comprises a H2 release subunit for releasing H2 from one or more H2 carriers.The BDO production unit VII) is equipped to perform process step G) as described above, including its different embodiments.In particular, it is equipped to receive BYD from unit V) and H2 from units III) and / or VI) and to convert them to BDO, e.g., by continuous hydrogenation. Unit VII) may optionally provide BDO to the downstream conversion unit VIII) described hereinafter.Unit VII) may comprise a distillation subunit equipped to separate BDO from other components of the effluent stream of the reactor such that pure BDO is obtained.Preferred Embodiments2.43) The system according to any of the preceding embodiments, wherein unit VII) is fluidly connected and arranged downstream to units V) and to units III) and / or VI).2 44) The system according to any of the preceding embodiments, wherein unit VII) is fluidly connected and arranged upstream to unit VIII).2 45) Thus, unit V) is fluidly connected and arranged downstream to units II) and IV) and upstream to unit VII).Further unitsThe system according to the invention may comprise further units and subunits, e.g., for performing purification and separation steps where needed or advisable. Also, the system may comprise one or more downstream conversion units VIII), as described below.Unit VIII)The downstream conversion unit VIII) is equipped to perform process step H) as described above, including its different embodiments. In particular, it is equipped to receive and store BDO and to produce downstream products thereof.Preferred Embodiments2.46) The system according to any of the preceding embodiments, the system further comprising at least one unit VIII)VIII) downstream conversion unit.2 47) The system according to embodiment 2.47, wherein unit VIII) is fluidly connected and arranged downstream to unit VII).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 4-6.FIG 4 depicts a system for performing the processes according to FIG 1 :The methanol providing unit (101) supplies the formaldehyde production unit (103) with methanol (1) which is converted to formaldehyde (6) and a formaldehyde by-product gas stream (5). Formaldehyde (6) is provided to the BYD production unit (106) where it is reacted with acetylene (7) provided by the acetylene providing unit (105) to BYD (8). From the formaldehyde by-product gas stream (5), H2 (4) is separated in the H2 recovery unit (104); further H2 (4) is available from the H2 providing unit (102). In the BDO production unit (107), BYD (8) from (106) and H2 (4) from (102) and (104) are converted to BDO (9) which is optionally provided to the downstream conversion unit (108).FIG 5 depicts a system for performing the processes according to FIG 2:The system of FIG 5 comprises all the elements and features of the system of FIG 4. It goes beyond FIG 4 in that the acetylene providing unit (105) comprises an acetylene production subunit that provides a syngas comprising CO, CO2, and H2 to the methanol providing unit (101) where said syngas is used to produce methanol (1).FIG 6 depicts a system for performing the processes according to FIG 3:The system of FIG 6 comprises all the elements and features of the system of FIG 4. It goes beyond FIG 4 in that the H2 providing unit (102) comprises a water electrolysis unit (102a) that does not only provide H2 (4) to the BDO production unit (107), but may also provide oxygen (3) to a syngas production subunit of (101) selected from the group consisting of a partial oxidation subunit, an autothermal reforming subunit, and a gasification subunit, to the formaldehyde production unit (103), and / or to an acetylene production subunit of (105).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.ExamplesThe following examples are for the purpose of illustration of the invention only and are not intended in any way to limit the scope of the present invention.) Typical product composition obtained from partial combustion of low-boiling alkanesTypical volume ratios of components of the cracked gas composition obtained from the Sachsse-Bartholome process (oil quench) are displayed in the following table (see P. Passler et al., Ullmann's Encyclopedia of Industrial Chemistry, 2012, Chapter "Acetylene”):The data show that the partial combustion of low-boiling alkanes yields syngas and acetylene as main reaction products that may be used as feedstocks and starting materials for further reaction sequences. ) Syngas composition obtained from partial combustion of low-boiling alkanesTypical volume ratios of H2 and carbon oxides (normalized to CO) and stoichiometric numbers S in gas streams obtained from the Sachsse-Bartholome process (oil quench) are displayed in the following table (see P. Passler et al., Ullmann's Encyclopedia of Industrial Chemistry, 2012, Chapter “Acetylene”):The data show that partial combustion of low-boiling alkanes delivers a relatively carbon-rich syngas which - after H2 admixture - may be suitable for the synthesis of methanol. ) Composition of a formaldehyde by-product gas streamA typical composition of a by-product gas stream is summarized in the following table (see, e.g. , DE 2655321). This gas stream is obtained from a silver-catalyzed conversion of about 61 t of raw methanol (in admixture with about 30 1 of water) to formaldehyde using about 100 t of air as an oxidant at temperatures of about 650-720°C and atmospheric pressure.The data show that relevant amounts of H2 are found in the formaldehyde by-product gas stream, which underlines the technical feasibility and reasonableness of the H2 separation.) Production of BDO from Methanol and Acetylene101 t of methanol are partially oxidized with 166 1 of air in the presence of a silver catalyst. Thus, 831 of formaldehyde and a by-product gas stream of 180 1, comprising 2.31 of hydrogen, are obtained. From said by-product gas stream, 2.1 1 of H2 are recovered via pressure-swing-adsorption. Said 831 of formaldehyde are reacted with 33 1 of acetylene using steam to give BYD. BYD is further hydrogenated consuming 5.7 1 of H2 at 300 bar and utilizing steam to yield crude BDO, whereby 2.1 1 of said 5.7 1 of H2 originate from the mentioned H2 recovery process. Said crude BDO may be distilled using steam to deliver 100 1 of distilled BDO.Thus, this exemplary process shows that the demand for external H2 to hydrogenate BYD to BDO may be reduced by about 30 - 40 % by utilizing H2 recovered from the formaldehyde by-product gas stream.

Claims

Claims1. A process to produce 1 ,4-butanediol, the process comprising step G)G) reacting 1,4-butynediol with H2 to obtain 1 ,4-butanediol, whereby in step G) at least a part of said 1,4-butynediol is obtained from step E)E) reacting acetylene with formaldehyde to obtain 1,4-butynediol, whereby at least a part of said acetylene is obtained from step D)D) providing acetylene; and whereby at least a part of said formaldehyde is obtained from step B)B) converting methanol to formaldehyde, wherein a formaldehyde by-product gas stream comprising H2 is obtained; whereby at least a part of said methanol is obtained from step A)A) providing methanol; and whereby in step G) at least a part of said H2 is obtained from step F)F) providing H2, wherein at least a part of said H2 is obtained from step C)C) separating H2 from the formaldehyde by-product gas stream obtained in step B).

2. The process according to claim 1 , wherein step A) comprises the substeps A1 ) and A2)A1) providing syngas comprising CO and / or CO2 and comprising H2; and A2) converting at least a part of said syngas to methanol.

3. The process according to claim 2, wherein in substep A1), at least a part of said CO and / or of said CO2 originates from bio-based or recycling-based carbon-containing feedstocks.

4. The process according to any of claims 2 to 3, wherein in substep A1), at least a part of said H2 originates from water electrolysis, chlor-alkali electrolysis, methane pyrolysis, or decomposition of ammonia.

5. The process according to any of claims 2 to 4, wherein in substep A1), at least a part 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.

6. The process according to any of claims 2 to 5, wherein in substep A1 ), at least a part of said syngas originates from partial oxidation or autothermal reforming of at least one gaseous and / or liquid feedstock, selected from the group consisting of methane, biogas, ethane, propane, light naphtha cuts, and biomass-derived light hydrocarbons.

7. The process according to any of claims 2 to 6, wherein in substep A1 ), at least a part of said syngas originates from gasification, optionally after a pre-treatment step, of at least one solid and / or liquid feedstock, comprising biomass and / or waste.

8. The process according to any of claims 2 to 7, wherein in substep A1 ), at least a part of said syngas originates from pyrolysis of at least one solid feedstock, comprising biomass and / or waste, to obtain a pyrolysis oil, and subsequent partial oxidation and / or gasification of said pyrolysis oil.

9. The process according to any of claims 2 to 8, wherein in substep A1 ), at least a part of said syngas originates from reverse water gas shift reaction of CO2 and H2, wherein preferably at least a part 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 and / or wherein preferably at least a part of said H2 originates from water electrolysis , chlor-alkali electrolysis, methane pyrolysis, decomposition of ammonia, or syngas production processes the CO2 emissions of which are captured and optionally stored and / or utilized.

10. The process according to any of the preceding claims, wherein in step B), said conversion is carried out with air in the presence of an iron molybdenum oxide catalyst or of a silver catalyst.

11. The process according to any of claims 1 to 9, wherein in step B), said conversion is carried out under anaerobic conditions and in the presence of a silver, copper, zinc, or alkali metal catalyst, preferably a sodium-based catalyst such as sodium carbonate.

12. The process according to any of the preceding claims, wherein step D) comprises producing acetylene by partial combustion of hydrocarbons.

13. The process according to any of the preceding claims, wherein in step E) at least a part of said formaldehyde and at least a part of said acetylene originate from the same hydrocarbon feedstock via partial combustion of hydrocarbons to obtain syngas according to substep A1) and to obtain acetylene according to step D).

14. The process according to any of the preceding claims, wherein step G) is carried out in the presence of a nickel catalyst or a palladium catalyst.

15. A process to produce at least one downstream product, preferably at least one product PRF1 , the process com- prising the process according to any of the preceding claims and further comprising step H)H) converting 1 ,4-butanediol obtained in step G) to obtain at least one downstream product.

16. A system for producing 1 ,4-butanediol, the system comprising the unitsI) methanol providing unit; II) formaldehyde production unit;III) H2 recovery unit;IV) acetylene providing unit;V) 1,4-butynediol production unit;VI) H2 providing unit; and VII) 1,4-butanediol production unit.

17. The system according to claim 16, wherein unit III) is fluidly connected and arranged upstream to unit VII).

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