Production of ethylene-derived chemicals of interest in combination with generation of thermal energy

Abstract

A process for the manufacture of a chemical of interest comprises subjecting a feedstock comprising ethanol of renewable origin to dehydration to produce an ethylene stream of renewable origin, the ethylene stream of renewable origin to mutual olefin conversion to obtain one or more C3-4-olefins of renewable origin selected from the group consisting of propylene, n-butene and isobutene. Further, the C3-4-olefin of renewable origin is subjected to a chemical conversion or series of chemical conversions to obtain the chemical of interest, the chemical conversion or series of chemical conversions producing one or more crude product streams and optionally one or more crude intermediate product streams. Subsequently, at least one of the one or more crude product streams and optionally one or more intermediate crude product streams is subjected to purification, producing one or more purified product streams, one or more waste streams, and optionally one or more purified intermediate product streams. At least one of the waste streams is then incinerated to produce thermal energy. The process provides a reaction scheme that provides a renewable source of ethylene-derived chemicals of interest while minimizing fossil carbon dioxide emissions and consumption of renewable source of feedstocks.

Description

[0001] The present invention relates to a process for the production of ethylene-derived chemicals of interest in conjunction with the generation of thermal energy.

[0002] The manufacture of many chemical derivatives is typically carried out using a multi-step chemical reaction process that produces a crude product stream containing not only the desired chemical derivative, but also other compounds, including but not limited to unreacted starting materials, intermediate reaction products, by-products, and impurities. Therefore, one of the final or intermediate steps in a multi-step process for the manufacture of chemical derivatives involves purifying (e.g., by distillation) the crude product stream to separate the desired product from most of the other compounds.

[0003] In cases where other compounds do not require further separation or recycling to one or more steps of the multi-step process, the waste stream is discarded or incinerated and thus utilized for its calorific value. Since the carbon-containing feedstocks currently used to manufacture most chemical derivatives are almost entirely of fossil origin, such as natural gas or crude oil, the incineration of waste streams is a source of CO₂ emissions that contribute to the carbon footprint of chemical production sites. This situation is exacerbated by chemical reactions that inherently have high rates of by-product formation, as the yield losses caused by these by-products are accompanied by high, climate-damaging emission rates when these by-products are burned.

[0004] Regulatory pressure to reduce CO2 emissions, particularly fossil CO2 emissions, is increasing. For example, producers can choose to actually reduce their CO2 emissions, pay a carbon tax under a carbon tax system, or some combination of the two. By utilizing biogenic carbon as fuel, the CO2 emissions associated with combustion do not contribute to taxable carbon emissions because the carbon is recycled to produce more biomass.

[0005] Ethylene is the cornerstone of the modern petrochemical industry. Important ethylene derivatives (at the ends of their respective chains) include (meth) acrylic acid, (meth) acrylic esters, isononanol, ethyl hexanol, and ethylene glycol. One of the problems faced in manufacturing chemicals and intermediates from ethylene is that the starting materials come from fossil fuels, such as natural gas or crude oil, which are non-renewable raw materials. Steam cracking, which uses petroleum fractions and natural gas liquids as feedstock, is the leading method for large-scale production of ethylene worldwide.

[0006] Lower olefins, such as isobutylene or propylene, are of great importance for industrial and chemical applications. Isobutylene (Isobutylene), also known as isobutylene (isobutene) or 2-methylpropylene, is a hydrocarbon of great importance, which is widely used as an intermediate in the production of industrially important products, including p-xylene, jet fuel mixtures, gasoline oxygenates, isooctane, methacrolein, methyl methacrylate and butyl rubber. Propylene is a hydrocarbon of great importance that is widely used as an intermediate in the production of acrylic acid. Historically, lower olefins are obtained by catalysis or steam cracking of fossil fuel feedstocks.

[0007] The production of ethylene and ethylene derivative compounds will benefit from replacing at least a portion of the carbonaceous raw materials of fossil origin with renewable resources (such as carbonaceous materials derived from biomass). Particularly interesting is the ethanol raw material produced by renewable resources. This renewable source of ethanol (also referred to as "bioethanol" or "aqueous fuel alcohol") can be prepared in large quantities by organic waste or biomass via fermentation. The different raw materials for producing ethanol can be raw materials containing sucrose, such as sugar cane, starch materials, such as corn, starch, wheat, cassava, lignocellulosic biomass, such as switchgrass, and / or agricultural waste. The purification or separation of bioethanol is often carried out by complex multi-stage distillation.

[0008] The present invention seeks to propose a reaction scheme that provides renewable sourced ethylene-derived chemicals of interest while minimizing fossil carbon dioxide emissions and consumption of renewable sourced feedstock.

[0009] The present invention relates to a method for producing a chemical of interest, comprising the following steps:

[0010] a) subjecting a feedstock comprising ethanol of renewable origin to dehydration to produce an ethylene stream of renewable origin;

[0011] b) subjecting the renewable source ethylene stream to olefin interconversion to obtain one or more renewable source C 3-4 - olefins; the olefin interconversion comprises (i) and, where necessary, one or both of (ii) and (iii):

[0012] (i) ethylene dimerization to obtain n-butene;

[0013] (ii) a metathesis reaction between the n-butene obtained according to (i) and ethylene to obtain propylene; and

[0014] (iii) isomerizing the n-butene obtained according to (i) to obtain isobutene; and

[0015] c) making the C of the renewable source 3-4- the olefin is subjected to a chemical transformation or a series of chemical transformations, which chemical transformation or series of chemical transformations produces one or more crude product streams and optionally one or more crude intermediate product streams, to obtain the chemical of interest,

[0016] d) subjecting at least one of the one or more crude product streams and optionally one or more intermediate crude product streams to purification to produce one or more purified product streams, one or more waste streams and optionally one or more purified intermediate product streams,

[0017] e) Incineration of at least one of these waste streams to produce thermal energy.

[0018] At least one purified product stream constitutes a chemical of interest.

[0019] It is understood that the complete or partial replacement of fossil ethylene and C with their renewable counterparts at the beginning of the process chain is 3-4 -Olefins reduce the emission of fossil-based carbon dioxide produced by the combustion of downstream by-products. If olefins from renewable sources are used as the starting material for the reaction sequence that produces the chemical of interest, then the incineration of the associated waste streams and the production of CO2 can be considered as the combustion of ethanol from renewable sources and transferred to the incineration step. The key feature of this preferred embodiment is the specific combination of olefin production from renewable sources with the incineration of unavoidable waste streams. The thermal energy thus produced can be considered "green energy" because the heat used for its production can be attributed to the combustion of ethanol from renewable sources, so no fossil resources are required.

[0020] Of course, it is also possible to directly burn a certain amount of ethanol from renewable sources (i.e., to use it as a biofuel) to generate the required heat. However, once burned, the ethanol from renewable sources can no longer be used as a starting material for chemical synthesis. This amount of ethanol from renewable sources can be saved by a specific combination according to this preferred embodiment. In other words, burning part of the ethanol from renewable sources to generate heat is transferred to a later production step, i.e., to incinerate the waste stream, as a part of the inevitable yield loss there. Therefore, this embodiment combines the use of ethanol from renewable sources as a starting material for chemical synthesis and simultaneously as a biofuel.

[0021] In a preferred embodiment, the ethanol to olefin production steps a) and b) are combined with downstream chemical conversions that have limited or no selectivity for the chemical of interest, or in other words, are accompanied by a large number of undesirable reactions. Such chemical conversions have relatively low yields of the desired chemical of interest and, after purification of the crude product stream, produce a large amount of waste stream in addition to the purified product stream.

[0022] Chemical transformations with limited selectivity or no selectivity are considered to be transformations with selectivity less than 95%, preferably 90% or less. Selectivity is defined as the percentage of renewable sources of C that are converted to the desired chemical of interest. 3-4 - olefins (or mixed renewable / fossil C 3-4 The overall selectivity of a series of chemical transformations to obtain the chemical of interest can be calculated by multiplying the partial selectivities of each individual transformation. Preferably, the selectivity is in the range of 60% to 90% or 70% to 85%. The lower end of such a range constitutes a compromise for obtaining a large amount of waste for incineration while still having a significant yield of the chemical of interest.

[0023] It is particularly preferred when the waste generated in the production of the corresponding chemical of interest and subjected to incineration according to step e) has a high lower heating value ("LHV"). The lower heating value is the gross calorific value minus the latent heat of vaporization of the water vapor formed by the combustion of components of the waste, including elemental hydrogen. Taking into account the energy losses required to vaporize the water, the lower heating value is the thermal energy generated by burning 1 kg of waste. This energy loss is not released as heat. The LHV is measured in a bomb calorimeter. The combustion of a stoichiometric mixture of a specific amount of waste and oxygen at 25°C in a steel container is initiated by an ignition device and the reaction is allowed to complete. After the reaction is complete, the steel container (including the burned waste) is cooled to 150°C. The LHV is therefore defined as the amount of heat released by burning a specific amount of waste (initially at 25°C) and returning the temperature of the combustion products to 150°C.

[0024] Preferably, the waste stream incinerated according to step e) has a lower heating value LHW in the range of 10 to 45 MJ, preferably 15 to 45 MJ, more preferably 20 to 40 MJ per kg of waste.

[0025] In a preferred embodiment the percentage of biogenic carbon in the waste incinerated according to step e) is in the range of 20 to 100, preferably 40 to 90, more preferably 50 to 85 wt.-%, based on the total carbon (biogenic and fossil) in the waste.

[0026] Based on carbon isotope fingerprints and / or 14 C(fM), biogenic carbon can be distinguished from fossil carbon. There are three naturally occurring carbon isotopes: 12 C. 13 C and 14 C. These isotopes are present in the total carbon in the ground at fractions of 0.989, 0.011, and 10-12, respectively. 12 C and 13 C is stable, and 14 C decays naturally into 14N, half-life is 5730 years. 14 C originates from the atmosphere, mainly due to cosmic radiation that eventually 14 N neutron bombardment. 14 C has a relatively short half-life (in geological terms) and its levels in fossil carbon are extremely low.

[0027] Alternatively, the ratio of fossil carbon to biogenic carbon can of course be assessed based on the biogenic carbon / fossil carbon ratio of the stream entering the reaction that produces the waste stream.

[0028] Preferably, the method includes f) transferring at least a portion of the thermal energy to a water stream to generate a heated steam stream. Conveniently, the heated steam stream is used to provide heat to one or more heated processes. Modern industrial chemical production sites are integrated with a variety of processes and equipment to produce a variety of chemical products. A "heated process" can be any process in the corresponding industrial chemical production site that requires steam. The steam can be used in equipment such as heat exchangers, steam turbines, reboilers, etc. This can be, for example, any or all of steps a), b)-(i), b)-(ii), and b)-(iii), but is not limited thereto. A "distributed steam grid" is used for heat transfer between different processes within the site and is therefore used to integrate and efficiently utilize heat. The thermal energy can be generated by evaporating water to produce steam, preferably in the form of steam condensate. The steam is fed into the steam grid. The thermal energy can also be used to raise the steam to a high pressure level of 4 bar gauge or higher, as typically provided in steam lines in industrial plants.

[0029] In an embodiment, the heated steam stream is used to provide at least a portion of the heat consumed in at least one of steps a) and b), more specifically in at least one of steps a), b)-(i), b)-(ii), and b)-(iii). Thus, the economic viability of the ethanol dehydration and olefin conversion steps can be improved because less fossil energy is required for steam generation.

[0030] Purification can relate to distillation one or more crude product streams or one or more crude intermediate product streams to obtain one or more purified product streams or one or more purified intermediate product streams.The various substances encountered in chemical reactions or reaction sequences can undergo many side reactions that produce color-forming substances, oligomers and various decomposition products, etc. These are removed during post-processing usually, such as by distillation, except for the desired product, to produce light boilers and / or high boiler fractions. Light boilers or high boiler fractions are used because of their calorific value, i.e., as fuel combustion. Due to their generally higher calorific value, high boilers or distillation bottoms stream are preferred waste streams that are directed to incineration.

[0031] In an embodiment of the method according to the invention, the C of renewable origin3-4 The olefin is propylene, and step c) comprises hydroformylation of the propylene to produce a crude aldehyde stream comprising n-butyraldehyde and isobutyraldehyde; and step d) comprises purifying the crude aldehyde stream to produce a purified aldehyde stream and a waste stream.

[0032] In another embodiment of the method according to the invention, the C 3-4 - the olefin is isobutylene, and step c) comprises (ci) to (cv), and step d) comprises (di) to (d-iii):

[0033] (ci) reacting isobutylene with formaldehyde to produce a crude isopentenol stream, and (di) purifying the crude isopentenol stream to produce a purified isopentenol stream and a first waste stream;

[0034] (c-ii) oxidation reaction of the purified prenylaldehyde stream to produce a crude prenylaldehyde stream, (d-ii) purifying the crude prenylaldehyde stream to produce a purified prenylaldehyde stream and a second waste stream;

[0035] (c-iii) isomerizing the purified prenol stream to produce prenols,

[0036] (c-iv) isomerizing the purified prenylaldehyde stream to produce pentenals,

[0037] (cv) reacting the pentenols with pentenals to produce a crude citral stream, and (d-iii) purifying the crude citral stream to produce a purified citral stream and a third waste stream. The first, second, and third waste streams can be combined and directed to incineration.

[0038] The expressions "renewable" or "of renewable origin" with respect to chemical compounds are used synonymously and mean chemical compounds that contain a certain amount of renewable carbon, i.e. have a reduced carbon content of fossil origin or no carbon content of fossil origin. Renewable carbon relates to all carbon sources that avoid or replace the use of any additional fossil carbon from the lithosphere. Renewable carbon can come from the biosphere, the atmosphere or the technosphere - but not from the lithosphere. Thus, the expressions "renewable" or "of renewable origin" specifically include chemical compounds derived from biomass. It also includes compounds derived from waste (such as polymer residues) or from waste streams of chemical production processes.

[0039] The expression "chemicals of interest" refers collectively to any desired compound occurring in the value chain starting from ethylene.

[0040] Bioethanol is the preferred form of renewable sourced ethanol, although the scope of the present invention is not limited to the use of bioethanol.

[0041] In the present invention, bioethanol refers to ethanol obtained from biomass feedstocks (e.g., plants or non-crop feedstocks containing carbon sources that can be converted to ethanol, for example, through microbial metabolism). Typical examples of carbon sources are starch, sugars such as pentoses or hexoses, such as glucose, fructose, sucrose, xylose, and arabinose, or plant degradation products, cellulose hydrolyzates, or juices such as sugarcane and sugar beets, which contain large amounts of these components.

[0042] Biomass feedstocks can be derived from several sources. Bioethanol production can be based on food crop feedstocks such as corn and sugarcane, bagasse, cassava (first generation biomass feedstocks).

[0043] Another source of biomass feedstock is lignocellulosic material from agricultural crops (second-generation biomass feedstock). Potential feedstocks include agricultural residue byproducts such as rice, straw (such as wheat, oat, and barley straw), rice husks, and corn stover. Biomass feedstock can also be waste from the forest products industry (wood waste) and sawdust, or waste from specialized ethanol crop production. Switchgrass and elephant grass can be used as dedicated crops for conversion into ethanol.

[0044] First-generation bioethanol is produced in four basic steps:

[0045] (1) Enzymatic saccharification or hydrolysis of starch into sugars

[0046] (2) Microbial fermentation of sugars

[0047] (3) Purification by distillation to obtain hydrous ethanol

[0048] (4) Dehydration (water removal) to produce anhydrous ethanol

[0049] Second generation raw materials are considered to be renewable and sustainable carbon sources. The pretreatment of this raw material is a basic prerequisite for subjecting it to enzymatic hydrolysis, fermentation, distillation and dehydration. Pretreatment involves grinding and being exposed to acid and heat to reduce the size of plant fiber and a part of hydrolyzed material to produce fermentable sugars. Saccharification utilizes enzymes to hydrolyze another part into sugar. Finally, various sugars (pentoses and hexoses) are converted into ethanol by fermentation of bioengineered microorganisms. The production of bioethanol is well known and is carried out on an industrial scale.

[0050] Ethanol from renewable sources can also be obtained from carbon-containing waste materials (such as waste products from the chemical industry, garbage, and sewage sludge). Ethanol production from waste materials can be achieved by gasifying them into syngas and catalytically converting them into ethanol, see, for example, Recent Advances in Thermo-Chemical Conversion of Biomass, 2015, pp. 213-250, https: / / doi.org / 10.1016 / B978-0-444-63289-0.00008-9 and Nat Commun, 11, 827 (2020), https: / / doi.org / 10.1038 / s41467-020-14672-8.

[0051] Dehydration of ethanol from renewable sources

[0052] As a first step, the present invention relates to the dehydration of ethanol from a renewable source. The production of ethylene by catalytic dehydration of ethanol is a well-known method. The reaction is typically carried out at 300°C to 400°C and at moderate pressure in the presence of a catalyst. Catalysis is reviewed in Ind & Eng Chem Research, 52, 28, 9505-9514 (2013), Materials, 6, 101-115 (2013), and ACS Omega, 2, 4287-4296 (2017). Examples of catalysts are activated alumina or silica, phosphoric acid impregnated on coke, heteropolyacids (HPA salts), silica-alumina, molecular sieves such as ZSM-5 or SAPO-11 zeolites, other zeolites, or modified zeolites of various molecular structures, with zeolites and HPA salts being preferred.

[0053] Ethanol dehydration is described, for example, in WO 2009 / 098268, WO 2010 / 066830, WO 2009 / 070858 and the prior art discussed therein, WO 2011 / 085223 and the prior art discussed therein, US 4,234,752, US 4,396,789, US 4,529,827 and WO 2004 / 078336.

[0054] The ethanol dehydration reaction is usually carried out in a gas phase in contact with a heterogeneous catalyst bed using a fixed bed or fluidized bed reactor. For a fixed bed reactor, the operation can be isothermal (with an external heating system) or adiabatic (in the presence of a heat transfer fluid). The raw material is vaporized and heated to the desired reaction temperature; as the reaction proceeds in the reactor, the temperature drops. Multiple reactor beds are usually used in series to maintain the temperature drop in each bed to a controllable range. The cooled effluent from each bed is further heated to reach the desired inlet temperature of the subsequent bed. In addition, a portion of the water is recycled together with the fresh and unreacted ethanol. The presence of water helps to moderate the temperature drop in each bed.

[0055] In some embodiments, the ethanol feedstock of renewable source can be sent to the pre-treatment section to remove mineral contaminants, otherwise this will be harmful to the downstream catalytic reaction. Pre-treatment can involve contacting the ethanol feedstock of renewable source with cation and / or anion exchange resin. After the operation of a certain period of time, resin can be regenerated to recover its ion exchange capacity by passing one or more resin beds through a regenerant solution. Two groups of beds are preferably operated in parallel to keep continuous operation. One group of resin bed is suitably regenerated, and another group of resin bed is used to pre-treatment.

[0056] In isothermal design, catalyst is placed in the tube of the shell-and-tube fixed bed reactor that is arranged vertically and surrounded by a shell (shell-and-tube design). Heat transfer medium (such as molten salt or oil) circulates in the shell to provide the required heat. Baffles can be set on the shell side to promote heat transfer. The cooled heating medium is heated externally and recycled. Compared with the adiabatic reactor, the temperature drop on the process side can be reduced. Better control of temperature leads to an increase in the selectivity of ethylene formation and a reduction in the amount of undesirable by-products. The temperature is maintained at a roughly constant level within the range of 300°C to 350°C. The ethanol conversion rate is typically between 98% and 99%. The selectivity to ethylene is preferably greater than 90mol-%, more preferably greater than 93mol-%, most preferably greater than 95mol-%, such as 95 to 99mol-%. Due to the rate of coke deposition, the catalyst must be regenerated frequently. Depending on the type of catalyst used, the cycle life is between 3 weeks and 4 months, followed by regeneration, for example, for 3 days.

[0057] In an adiabatic design, the endothermic heat of the reaction is supplied by a preheated inert diluent such as steam. Typically, three fixed-bed reactors are used, with an intermediate furnace used to reheat the ethanol / steam mixed feed stream to each reactor. Feeding ethanol along with steam results in less coke formation, longer catalyst activity, and higher yields.

[0058] Another approach is the fluidized bed process. Fluidized bed systems provide excellent temperature control in the reactor, minimizing byproduct formation. Fluidized bed operation distributes heat at rates close to isothermal conditions. The heat absorbed by the reaction is supplied by the hot, recycled silica-alumina catalyst returned from the catalyst regenerator. Therefore, external heating of the reactor is not required.

[0059] After dehydration, the reaction mixture is subjected to a separation step. A general separation scheme includes rapidly cooling the reaction gas, for example in a water quench tower, which separates most of the by-product water and unreacted ethanol from ethylene and other light components, which leave, for example, the top of the quench tower. In one type of separation scheme, the water-washed ethylene stream is immediately subjected to an alkali wash (for example, in a column) to remove trace amounts of CO2. The gaseous stream can enter the compressor directly or first pass through a buffer gas cabinet and then enter the gas compressor. After compression, the gas is cooled by refrigeration and then passed through an adsorber with, for example, activated carbon to remove trace amounts of heavy components (for example, C4) (if they exist). Before the ethylene product leaves the equipment, the adsorber is followed by a desiccant drying and dust filtration step. This separation scheme produces ethylene with a purity of 99%+. If necessary, the ethylene is further purified by alkali washing and desiccant drying and is graded in a cryogenic tower to obtain the final product.

[0060] Several commercial processes are currently in operation, developed by Braskem, Chematur, British Petroleum (BP), and Axens, in collaboration with Total and the French Institute for Renewable Energy in Petroleum (IFPEN). These processes differ, for example, in their process conditions, catalysts, and the heat integration scheme employed. BP's (now Technip) process is called Hummingbird. In this process, a heteropolyacid is used as a catalyst, and the reactor is operated at 160°C to 270°C and 1 to 45 bar. Unreacted ethanol is recycled to the reactor. The process developed by Axens is called Atol. It uses two fixed-bed adiabatic reactors operating at 400°C to 500°C. Zimut's process operates with four adiabatic tubular reactors. This process uses a Syndol catalyst (primarily composed of Al2O3-MgO / SiO2), developed by American Halcon Scientific Design, Inc. in the 1980s. In the Braskem process, the adiabatic reactor feed is diluted to a significant extent with steam. In this process, the reactor is operated at temperatures between 180°C and 600°C, preferably between 300°C and 500°C, and at a pressure of 1.9 to 19.6 bar. Alumina or silica-alumina catalysts are used. The Braskem process is described in more detail in US Pat. No. 4,232,179. Process control according to the Braskem process is particularly preferred.

[0061] Dimerization of ethylene

[0062] The process of the present invention involves dimerizing ethylene to obtain n-butene according to steps b) to (i) above. Any known method can be used to dimerize ethylene to produce n-butene. A review of dimerization and oligomerization chemistry and technology is provided in Catalysis Today, Vol. 14 (Issue 1), April 10, 1992.

[0063] Suitably, steps b)-(i) comprise:

[0064] - contacting the renewable sourced ethylene stream with a dimerization catalyst in a dimerization zone;

[0065] - operating the dimerization zone under conditions effective to produce an effluent consisting essentially of n-butenes, a stream consisting essentially of heavier olefins and optionally an unconverted ethylene stream; and

[0066] - Fractionating the effluent to recover a stream consisting essentially of n-butenes, a stream consisting essentially of heavier olefins, and optionally an ethylene stream.

[0067] Dimerization catalyst can be homogeneous or heterogeneous.Typical dimerization catalyst is titanium or nickel compound activated with alkyl aluminum compound.Usually, the Ti(IV) valence is stabilized by selecting appropriate ligand, alkyl aluminum compound, solvent polarity and Al / Ti ratio.The nickel compound that can catalyze the selective production of butene is typically based on the cationic nickel salt that is stabilized with phosphine and activated with alkyl aluminum compound.

[0068] In one embodiment, the oligomerization of ethylene is carried out in the liquid phase comprising a nickel compound and an aluminum compound in the presence of a catalytic system. Such catalytic systems are described in documents FR 2 443 877 and FR 2 794 038. Dimersol E TM A process is based on this technology and leads to the industrial production of olefins.

[0069] Thus, in one embodiment, the oligomerization of ethylene is carried out in the presence of a catalytic system comprising:

[0070] i) at least one divalent nickel compound,

[0071] ii) at least one hydrocarbyl aluminum dihalide having the formula AlRX2, wherein R is a hydrocarbyl group containing from 1 to 12 carbon atoms, such as an alkyl, aryl, aralkyl, alkaryl or cycloalkyl group, and X is a chlorine or bromine atom, and

[0072] iii) optionally a Bronsted organic acid.

[0073] As the divalent nickel compound, preferably used is a compound having the general formula (R 1 COO)2Ni carboxylate nickel, where R 1 is an optionally substituted hydrocarbon radical containing up to 20 carbon atoms, for example an alkyl, cycloalkyl, alkenyl, aryl, aralkyl or alkaryl radical, preferably a hydrocarbon radical having 5 to 20 carbon atoms, preferably 6 to 18 carbon atoms. Suitable divalent nickel compounds include chlorides, bromides, carboxylates such as octoate, 2-ethylhexanoate, decanoate, oleate, salicylate, hydroxydecanoate, stearate, phenate, cycloalkanoate and acetylacetonate. Nickel 2-ethylhexanoate is preferably used.

[0074] Hydrocarbyl aluminum dihalide compounds correspond to the formula AlRX2, wherein R is a hydrocarbon radical containing 1 to 12 carbon atoms, such as an alkyl, aryl, aralkyl, alkaryl or cycloalkyl radical, and X is a chlorine or bromine atom. As examples of such compounds, mention may be made of sesquiethylaluminum chloride, ethylaluminum dichloride, isobutylaluminum dichloride, diethylaluminum chloride or mixtures thereof.

[0075] According to a preferred method, a Bronsted organic acid is used. The Bronsted acid compound corresponds to the formula HY, wherein Y is an organic anion, such as a carboxyl group, a sulfonic acid group or a phenol group.2 COOH halogenated carboxylic acid (where R 2 is a haloalkyl group) are preferred, in particular those containing at least one α-halogen atom of a group —COOH and having 2 to 10 carbon atoms in total. Preferably, a group having the formula CX is used p H 3-p A haloacetic acid containing —COOH, wherein X is fluorine, chlorine, bromine or iodine, and wherein p is an integer from 1 to 3. For example, trifluoroacetic acid, difluoroacetic acid, fluoroacetic acid, trichloroacetic acid, dichloroacetic acid and chloroacetic acid may be mentioned. Arylsulfonic acids, alkylsulfonic acids and fluoroalkylsulfonic acids may also be used, as well as picric acid and nitroacetic acid. Trifluoroacetic acid is preferably used.

[0076] The three components of the catalytic formulation can be mixed in any order. However, it is preferred to mix the nickel compound with the Bronsted organic acid first and then introduce the aluminum compound. The molar ratio of the hydrocarbyl aluminum dihalide to the nickel compound, expressed as the Al / Ni ratio, is from 2 / 1 to 50 / 1, and preferably from 2 / 1 to 20 / 1. The molar ratio of the Bronsted acid to the nickel compound is from 0.25 / 1 to 10 / 1, and preferably from 0.25 / 1 to 5 / 1.

[0077] According to a preferred method, the hydrocarbyl aluminum dihalide may be enriched with aluminum trihalide, the mixture of the two compounds then corresponding to the formula AlR n X 3-n , wherein R is a hydrocarbon group containing 1 to 12 carbon atoms, such as an alkyl, aryl, aralkyl, alkaryl or cycloalkyl group, X is a chlorine or bromine atom, and n is a number between 0 and 1. Suitable mixtures include: ethylaluminum dichloride enriched with aluminum chloride, the mixture having the formula AlEt 0.9 Cl 2.1 ; Dichloroisobutylaluminum rich in aluminum chloride, the mixture having the formula AliBu 0.9 Cl 2.1 ; and dibromoethylaluminum rich in aluminum bromide, the mixture having the formula AlEt 0.9 Br 2.1 .

[0078] The reaction for the oligomerization of ethylene can be carried out at a temperature of -20°C to 80°C, preferably 40°C to 60°C, under pressure conditions such that the reagents remain at least predominantly in the liquid or condensed phase. The pressure is generally between 0.5 and 5 MPa, preferably between 0.5 and 3.5 MPa. The contact time is generally between 0.5 and 20 hours, preferably between 1 and 15 hours.

[0079] The oligomerization stage can be carried out in a reactor having one or more reaction stages connected in series, wherein the ethylene feedstock and / or the preferably preconditioned catalytic composition are continuously introduced in the first stage or in the first stage and any of the other stages. At the outlet of the reactor, the catalyst can be deactivated, for example, by injection of ammonia and / or aqueous soda solution and / or aqueous sulfuric acid solution. Unconverted olefins and alkanes, which may be present in the feedstock, are then separated from the oligomers in a separation stage, for example by distillation or by means of a washing cycle with caustic soda and / or water.

[0080] The conversion per pass is typically 85% to 98%. The selectivity of the n-butenes formed is typically between 50% and 80%. The n-butenes consist of butene-2 (cis- and trans-) and butene-1.

[0081] The effluent typically contains less than 0.2% by weight of isobutylene, or even less than 0.1% by weight of isobutylene.

[0082] Separation of n-butene-rich streams

[0083] The effluent obtained by dimerization of ethylene is subjected to a separation stage in such a way as to obtain a fraction rich in n-butenes.

[0084] Separation can be carried out by evaporation, distillation, extractive distillation, by solvent extraction or by a combination of these techniques. These methods are known to those skilled in the art. Preferably, the separation of the effluent obtained by the oligomerization of ethylene is carried out by distillation.

[0085] Preferably, the oligomerization effluent is sent to a distillation column system comprising one or more columns which, on the one hand, enable the n-butenes to be separated from the ethylene (which can be returned to the oligomerization reactor) and from the heavier olefins having 5 and more carbon atoms.

[0086] Higher olefins can be hydrogenated to obtain naphtha of renewable origin. "Naphtha of renewable origin" shall mean naphtha produced from renewable sources. It is a hydrocarbon composition composed primarily of paraffin waxes. The molecular weight of such naphtha of renewable origin can range from hydrocarbons having 5 to 8 carbon atoms. Naphtha of renewable origin can be used as a feedstock in steam cracking to produce light olefins, dienes, and aromatic compounds of renewable origin.

[0087] Thus, in an embodiment, steps b)-(i) comprise:

[0088] - contacting the renewable sourced ethylene stream with a dimerization catalyst in a dimerization zone;

[0089] - operating the dimerization zone under conditions effective to produce an effluent consisting essentially of n-butenes, a stream consisting essentially of heavier olefins and optionally an unconverted ethylene stream;

[0090] - fractionating the effluent to recover a stream consisting essentially of n-butenes, a stream consisting essentially of heavier olefins, and optionally an ethylene stream; and

[0091] - subjecting this stream consisting essentially of heavier olefins to hydrogenation in order to obtain naphtha of renewable origin.

[0092] Metathesis of ethylene and n-butene

[0093] Ethylene can undergo metathesis with n-butene to produce propylene. In one aspect of the present invention, steps b) to (ii) comprise a metathesis reaction between the n-butene obtained in step (i) and ethylene to produce propylene. The n-butene obtained by the ethylene dimerization (i) is a mixed stream comprising 1-butene and 2-butene. Essentially only 2-butene reacts in the metathesis reaction, while 1-butene is essentially inert.

[0094] In one embodiment, 1-butene is removed from the mixed stream of 1-butene and 2-butene and directed to other uses in the plant. Thus, in one embodiment, steps b) to (ii) comprise removing 1-butene from the mixed stream to obtain a 2-butene-rich stream, and subjecting the 2-butene-rich stream to a metathesis reaction. The 2-butene-rich stream may comprise at least 90 wt.% 2-butene, based on the total amount of n-butenes.

[0095] Alternatively, 1-butene can be converted to 2-butene by double bond isomerization. Double bond isomerization is an equilibrium limited reaction. Therefore, it is advantageous to subject a mixed stream of n-butenes to metathesis so that the 2-butenes react with ethylene before the double bond isomerization of the 1-butene. Thus, in one embodiment, the n-butenes are a mixed stream comprising 1-butene and 2-butene, and b)-(ii) include

[0096] b)-(iia) subjecting the mixed stream to the metathesis reaction to obtain propylene and unreacted 1-butene;

[0097] b)-(iib) subjecting the unreacted 1-butene to double bond isomerization to obtain 2-butene; and

[0098] b)-(iic) recycling the 2-butene obtained in steps b)-(iib) to be used in steps b)-(iia).

[0099] In another embodiment, 1-butene can be converted into 2-butene when metathesis reaction.For this purpose, metathesis catalyst and isomerization catalyst can be physically mixed or provided as different layers to allow two reactions to be carried out simultaneously.Therefore, in one embodiment, this n-butylene is a mixed stream comprising 1-butene and 2-butene, and step b)-(ii) comprises making this mixed stream pass through the metathesis / isomerization zone comprising metathesis catalyst and isomerization catalyst.Because 2-butene is consumed due to the metathesis reaction on metathesis catalyst, 2-butene is supplemented by making 1-butene be isomerized to 2-butene on isomerization catalyst.

[0100] The reaction is carried out in the presence of a metal-based metathesis catalyst selected from tungsten, molybdenum, rhenium, niobium, tantalum, vanadium, ruthenium, rhodium, iridium, osmium and nickel. Tungsten, molybdenum and rhenium are preferred and tungsten is particularly preferred. Typically, the tungsten catalyst is supported on silica, and molybdenum and rhenium are supported on a carrier based on aluminum oxide. Particularly preferred metathesis catalysts are WO3-based catalysts, such as WO3 supported on silica in the form of particles.

[0101] Suitable isomerization catalysts include magnesium-based catalysts, such as MgO-based catalysts, for example, pelletized MgO.

[0102] The metathesis is carried out under conditions effective to produce an effluent comprising propylene, unconverted ethylene, and optionally 1-butene.

[0103] Unconverted ethylene and / or unconverted n-butenes can be recycled and combined with new ethylene and n-butenes to provide a metathesis feedstock.

[0104] The reaction can be carried out at 340-375°C, 25-40 bar, 7.5-30 hours -1 The reaction was carried out at a weight hourly space velocity (WHSV) of 1:1 to 2:1 and a molar ratio of ethylene to 2-butene of 3:1 to 10:1.

[0105] The reactor effluent can be sent to a deethenizer to remove C2 and lighter materials. The bottoms from the deethenizer are sent to a depropylene tower. High purity, polymer grade propylene (>99.9% molar purity) is recovered from the depropylene tower overhead. The lighter materials from the deethenizer and the heavier C2 from the depropylene tower are removed. 4+ The material is partially recycled in the reactor. Purge flows are provided for lighter and heavier materials to prevent the accumulation of inerts.

[0106] It should be noted that no propane is produced during the metathesis reaction. Thus, polymer grade propylene can be produced by this process without the need for expensive propylene-propane superfractionators.

[0107] A commercial process for producing polymer grade propylene by metathesis from ethylene and butene feedstocks is available from CB&Lummus (trade name OCT TM ) and LyondellBasell.

[0108] Skeletal isomerization of n-butene

[0109] In one aspect, the process of the present invention involves isomerizing the n-butenes obtained according to (i) according to steps b) to (iii) to obtain isobutenes.

[0110] Since isomerization is an equilibrium reaction, the reaction mixture always contains unreacted n-butenes.

[0111] Suitably, steps b) to (iii) comprise:

[0112] - contacting the n-butenes with a skeletal isomerization catalyst in an isomerization zone to produce a mixture of n-butenes and isobutenes;

[0113] - recovering from the mixture a stream consisting essentially of n-butenes and a stream consisting essentially of isobutene; and

[0114] - recycling the stream consisting essentially of n-butenes to the isomerization zone.

[0115] A suitable recovery scheme utilizes the reaction of isobutylene with an alkanol to produce an alkyl tert-butyl ether. The etherification reaction is selective for isobutylene, while normal butenes are unreactive in the reaction. Therefore, this reaction can be used as a method for separating normal butenes from isobutylene.

[0116] Therefore, isobutylene can be recovered from a mixture of n-butene and isobutylene by the following steps:

[0117] (a) reacting a mixture of n-butenes and isobutenes with isobutanol in the presence of an acidic ion exchange resin in an etherification unit to form a mixture of isobutyl tert-butyl ether (IBTBE) and unconverted n-butenes;

[0118] (b) distilling the reaction mixture in a first distillation unit to obtain an overhead product stream consisting essentially of n-butenes and a bottoms product comprising IBTBE;

[0119] (c) feeding the bottom product to an ether cracking unit to decompose IBTBE to obtain isobutene and isobutanol;

[0120] (d) distilling the mixture of isobutene and isobutanol produced in step (c) in a second distillation unit to obtain an overhead product stream consisting essentially of isobutene and a bottoms product comprising isobutanol; and

[0121] (e) recycling the bottom product of step (d) to step (a).

[0122] Skeletal isomerization generally requires an acidic catalyst. Known skeletal isomerization catalysts include alumina and halogenated aluminas, particularly F- or Cl- promoted aluminas.

[0123] Certain zeolites have been shown to be highly effective in the skeletal isomerization of normal olefins. Such zeolites include those selected from the group consisting of zeolites having the framework structures of ZSM-22, ZSM-23, and ZSM-35.

[0124] Examples of highly selective, highly stable catalysts are chlorinated γ-Al2O3, ferrierite, SAPO-11 (silicoaluminophosphate molecular sieve), and MeAPO-11 (Me = Co, Mn, Mg) (molecular sieve). A particularly preferred catalyst is ferrierite. The typical elemental composition of ferrierite zeolite is Na2Mg2[Al6Si 30 O 72 ]·18H2O, as disclosed, for example, in US 6323384.

[0125] The spent catalyst may be regenerated by heating in an oxygen-containing gas, such as air, at a temperature ranging from about 200°C to about 700°C.

[0126] The skeletal isomerization of n-butene to isobutene is an equilibrium-controlled process, where the equilibrium conversion decreases with increasing temperature.

[0127] Skeletal isomerization is carried out by contacting the feed with the catalyst at a temperature at which skeletal isomerization of the n-butene feed occurs using any suitable contacting technique. The feed is preferably maintained in the vapor phase during contacting. The reactor temperature is preferably in the range of about 300° C. to about 650° C., more preferably about 400° C. to about 580° C. The weight hourly space velocity (WHSV) is not critical but will generally be in the range of about 0.1 to about 40 hr. -1 , preferably from about 1 to about 20 hr -1 Any convenient pressure may be used, with the lowest practical pressure being preferred in order to minimize side reactions such as polymerization. Preferred pressures are in the range of about 0.1 to about 10 atmospheres, more preferably about 1 to about 4 atmospheres.

[0128] In the case of a single contact of the feed with the catalyst, equilibrium may not be achieved. However, in a specific variant of the process, the product stream leaving the catalyst bed can be divided and only one part can be sent directly to the workup process, while the other part is redirected over the catalyst bed.

[0129] Several commercial processes for the isomerization of n-butenes are known. In one embodiment, the n-butene feedstock is vaporized, typically by heat exchange with the reactor effluent, and further heated to the reaction temperature. In the reactor, the vapor reacts with up to 44% of the n-butenes to convert them into isobutene, with a selectivity greater than 86%. Typically, two reactors are operated cyclically: one in reaction mode and the other in regeneration mode. The reactor effluent is cooled, compressed, and fractionated. The heavy fraction is separated and removed as bottoms from the overhead isobutene product.

[0130] For example, operating conditions, processes and catalyst modifications are disclosed in US 6,111,160 and US 6,323,384. Typical operating conditions are: 340°C-360°C reaction temperature, 2H -1 WHSV of 1-2 bar, olefin partial pressure of 1-2 bar, and total pressure of 1-3 bar.

[0131] Hydroformylation of propylene

[0132] In aspects of the present invention, the renewable source of C 3-4 - the olefin is propylene, wherein step c) comprises hydroformylation of propylene to produce n-butyraldehyde, isobutyraldehyde or a mixture thereof.

[0133] The hydroformylation of propylene can be carried out according to any known method. If necessary, the aldehyde produced can be separated by fractionation.

[0134] Hydroformylation or oxidation process is an important large-scale industrial process for preparing aldehydes from olefins, carbon monoxide and hydrogen. These aldehydes can alternatively be hydrogenated with hydrogen in the same operation or subsequently in a separate hydrogenation step, to produce the corresponding alcohol. Usually, hydroformylation is carried out in the presence of a catalyst that is uniformly dissolved in the reaction medium. The catalyst used is typically a carbonyl complex of a metal of transition group VIII (particularly Co, Rh, Ir, Pd, Pt or Ru), which can be unmodified or modified with, for example, an amine-containing or phosphine-containing ligand. A summary description of the processes practiced on an industrial scale is given in J. Falbe, “New Syntheses with Carbon Monoxide”, Springer Verlag 1980, pp. 162 ff., US Pat. Nos. 3,527,809; 3,917,661; 4,148,830; 4,742,178; 4,769,984; 4,885,401; 6,049,011.

[0135] Propylene is preferably hydroformylated using a ligand-modified rhodium carbonyl as a catalyst. The hydroformylation of propylene may be carried out at a temperature ranging from 50°C to 200°C, preferably from 60°C to 150°C, and more preferably from 70°C to 120°C.

[0136] In one embodiment, the hydroformylation reaction is carried out at low pressure, for example, in the range of 0.05 to 50 MPa (absolute), preferably in the range of about 0.1 MPa to 30 MPa, and most preferably at a pressure below 5 MPa. Desirably, the partial pressure of carbon monoxide is no more than 50% of the total pressure.

[0137] The ratios of carbon monoxide, hydrogen, and ethylene in the hydroformylation reaction medium can be selected within a wide range. In some embodiments, based on the total amount of CO, hydrogen, and propylene, CO is from about 1 mol% to 50 mol%, preferably from about 1 mol% to 35 mol%; H is from about 1 mol% to 98 mol%, preferably from about 10 mol% to 90 mol%; and ethylene is from about 0.1 to 35 mol%, preferably from about 1 to 35 mol%.

[0138] The hydroformylation reaction is preferably carried out in the presence of both a liquid phase and a gas phase. The reactants are usually in the gas phase. The catalyst is typically in the liquid phase. Because the reactants are gaseous compounds, a high contact surface area between the gas phase and the liquid phase is desirable to enhance good mass transfer. The high contact surface area between the catalyst solution and the gas phase can be provided in any suitable manner. In a batch process, the batch contents are fully mixed during the reaction process. In a continuous operation, the reactor feed gas can contact the catalyst solution in a stirred autoclave, for example, in a continuous flow, wherein the gas is preferably introduced and dispersed in the bottom of the container through a perforated inlet (for example, a sprayer). The high contact between the catalyst and the gas feed can also be provided by dispersing a solution of the Rh catalyst on a high surface area carrier, which is a well-known technique in the art as supported liquid phase catalysis, or Rh is provided as a part of a permeable gel.

[0139] The reaction can be carried out in batch mode or preferably on a continuous basis.One or more reactors can be used in continuous mode to carry out the reaction in one or more stages.

[0140] The ratio of H to CO in the synthesis gas used for hydroformylation is desirably in the range of 1.1:1 to 1.01:1, preferably 1.06:1 to 1.02:1. Typically, the synthesis gas can be produced or otherwise initially provided in a manner such that the ratio of hydrogen to CO is much higher than this. Excess hydrogen can be separated as needed and used in other reaction stages.

[0141] Hydroformylation processes inherently produce high-boiling liquid aldehyde condensation byproducts, such as dimers, trimers, and tetramers, which can serve as solvents for the hydroformylation process, as well as other liquid heavies. Consequently, even after separating the initial aldehyde product from its light products (e.g., carbon monoxide, hydrogen, unreacted olefins, alkane byproducts, etc.) in the case of continuous gas recycle hydroformylation processes, or after separating the initial aldehyde product from its solution containing light products and catalyst in the case of continuous liquid recycle hydroformylation processes, the resulting crude aldehyde product mixture always contains small amounts of these high-boiling products. Indeed, even after separating the lower-boiling branched-chain aldehydes from their higher-boiling normal-chain aldehyde counterparts to obtain purified branched-chain aldehydes (e.g., isobutyraldehyde) and retaining the straight-chain aldehydes (e.g., normal-butyraldehyde), the normal-aldehyde product can still contain higher amounts of these organic heavies than would be desirable for its ultimate end use.

[0142] A conventional procedure for separating the branched-chain aldehyde products from the linear-chain aldehyde products of such crude aldehyde product mixtures produced by conventional continuous rhodium-catalyzed hydroformylation processes is by a two-step distillation procedure involving the use of two separate distillation columns. For example, the purified branched-chain aldehyde (isobutyraldehyde) is first separated from the crude aldehyde product mixture via distillation in an initial distillation column, and then the remaining normal (linear) aldehyde (n-butyraldehyde) is further refined or purified from any remaining higher-boiling by-products by a second distillation conducted in a second distillation column.

[0143] Alternatively, the distillation scheme can be modified to recover a portion of the linear aldehydes in the first distillation column. Thus, the crude aldehyde product mixture starting material can be fed to the distillation column and distilled therein to simultaneously obtain (i) a liquid aldehyde product stream withdrawn at or near the top of the distillation column and consisting essentially of purified branched-chain aldehydes, (ii) a volatilized aldehyde product stream consisting essentially of purified linear aldehydes as a vapor sidestream, the amount of which does not exceed about 70 weight percent of the amount of linear aldehydes present in the liquid crude aldehyde product mixture starting material, and (iii) the remaining liquid aldehydes consisting essentially of linear aldehydes are recovered from or near the bottom of the distillation column along with organic heavies present in the liquid crude aldehyde product mixture starting material. The remaining liquid aldehydes are directed to a butyraldehyde residue column, where the linear aldehydes are withdrawn from the top of the column and the remaining heavies are recovered from or near the bottom of the butyraldehyde residue column.

[0144] The organic heavies recovered from the crude aldehyde product mixture include any organic solvents and organic byproducts having a boiling point higher than that of the linear aldehyde product compound, such as liquid aldehyde condensation byproducts (dimers, trimers, tetramers, etc.), and other common high-boiling byproducts, such as the corresponding alkanols. Of course, it should be understood that such crude aldehyde product mixtures may also contain some small amounts of residual lights (e.g., unreacted olefins and byproduct alkanes) and organophosphorus contaminants, such as free organophosphorus ligands and / or their corresponding oxides.

[0145] According to the present invention, the organic heavies recovered from the crude aldehyde product mixture constitute a waste stream which is incinerated to produce thermal energy.

[0146] Isobutylene reacts with formaldehyde to produce prenol

[0147] In another aspect of the present invention, the renewable source of C 3-4 - the olefin is isobutene, and step c) comprises reacting the isobutene with formaldehyde to produce prenol.

[0148] The production of prenol (3-methyl-3-butene-1-ol) is well known. For example, it can be produced by the Prince reaction between isobutene and formaldehyde in the liquid phase at temperatures of 220°C to 280°C and pressures of 230 to 270 bar, with or without a catalyst. The reaction mixture can be fractionated to obtain prenol. Further details are provided in WO 2008 / 037693.

[0149] Purification of the crude prenol stream may include

[0150] (i) directing the crude isopentenol stream to a first low-boiler separation column operated at a pressure of 1.5 bar absolute or less to obtain a first bottom stream containing isopentenol and formaldehyde and a first distillate stream containing water and low-boilers;

[0151] (ii) directing the first bottom stream to a second low-boiler separation column operated at a pressure of 2 bar absolute or higher to obtain a second distillate stream containing aqueous formaldehyde and a second bottom stream containing prenol; and

[0152] (iii) the second bottom stream is directed to a refining column to obtain pure isopentenol as a distillate stream and a bottom stream containing high boilers.

[0153] Isomerization of isopentenol to prenol

[0154] In one embodiment of this aspect, step c) further comprises isomerizing the prenol to prenol.

[0155] The isomerization is carried out in the presence of hydrogen and a catalyst. A preferred catalyst is a fixed-bed catalyst containing palladium and selenium or tellurium, or a mixture of selenium and tellurium, supported on silica. The isomerization is carried out at a temperature of 50°C to 150°C to produce a reaction mixture of prenol and isopentenol. The isopentenol may be recycled. Further details are provided in WO 2008037693.

[0156] Oxidation of isopentenol to isopentenal

[0157] In another embodiment of this aspect, step c) further comprises oxidation of prenol to produce prenal.

[0158] The selective oxidation of primary alcohols such as prenol to corresponding aldehyde is a well-known reaction. Prenol can be oxidized to isopentanal by oxidative dehydrogenation with the aid of an oxygen-containing gas under catalysis (for example supported copper, silver and / or gold catalysts, preferably silver catalysts). Oxidation is carried out at a reaction temperature of 300 ℃ to 500 ℃ and produces a mixture of isopentanal (3-methyl-3-butenal) and pentenals (3-methyl-2-butenal) and unreacted isopentanal. This mixture contains excessive isopentanal, and for example a weight ratio of 2:1 to 5:1 is provided. Further details are provided in WO 2008037693.

[0159] Isomerization of isopentenal to pentenal

[0160] In another embodiment of this aspect, step c) further comprises isomerizing prenylaldehyde to pentenal.

[0161] Isopentenal is subjected to isomerization to produce other isopentenal, wherein isopentenal is preferably used in the form of the mixture obtained from step (b). Isomerization is carried out at a temperature of 100 ℃ to 200 ℃ in the presence of an isomerization catalyst (preferably sodium acetate) to produce a mixture of isopentenal and isopentenol. The mixture is fractionated to produce a stream of isopentenal and a stream of isopentenol. The isopentenol can be recycled. Further details are provided in WO 2008037693.

[0162] Pentenol reacts with pentenal to produce citral

[0163] In another embodiment of this aspect, step c) further comprises converting prenol, prenal to produce citral.

[0164] First, pentenol and pentenal are subjected to acetalization to produce the dipentenol acetal of pentenal, 3-methyl-2-butenal-dipentenyl acetal. The acetalization is carried out under vacuum and acidic catalyst (e.g., mineral acid such as nitric acid or sulfuric acid) at temperatures as high as 100° C. to 120° C. The water formed during the acetalization is continuously removed.

[0165] The acetal is then subjected to thermal cracking at temperatures of 150°C to 170°C in the presence of an acidic catalyst such as phosphoric acid to obtain cis / trans-pentenyl-(3-methyl-butadienyl) ether. Under the reaction conditions, the ether undergoes a Claisen and Cope rearrangement to give citral. Further details are provided in WO 2008037693.

[0166] Suitably, the cracking can be carried out in the lower part of a distillation column or in a sump serving as a cracking column. Preferably, the acetal is introduced into the lower part of the distillation column, into a sump of the distillation column, or into the evaporator of the distillation column. Typically, the bottoms from the cracking column are a mixture of high boilers, including C5 oligomers resulting from the thermal instability of the dipentenyl acetal. A portion of the bottoms from the cracking column is continuously discharged. This serves to prevent the accumulation of high boilers.

[0167] The present invention is further illustrated by the accompanying drawings and the following examples.

[0168] Figure 1 Schematic diagram of a production plant for the integrated production of butyraldehyde and citral starting from ethanol from renewable sources.

[0169] like Figure 1 As shown, an integrated production facility includes an ethanol-to-olefins platform having an ethanol dehydration unit, an ethylene dimerization unit, a metathesis unit, and a butene isomerization unit. The facility includes an isobutylene extraction unit that recovers a stream consisting essentially of n-butenes and a stream consisting essentially of isobutylene from a mixed stream of n-butenes and isobutylenes received from the butene isomerization unit, wherein the stream consisting essentially of n-butenes is recycled to the butene isomerization unit.

[0170] The propylene formed in the metathesis unit is subjected to hydroformylation with synthesis gas (CO / H2) in a hydroformylation unit. The crude hydroformylation product obtained is purified in a butyraldehyde purification unit, resulting in pure butyraldehyde and a waste stream. The waste stream is directed to an incineration unit.

[0171] The isobutylene and formaldehyde that take out from the isobutylene extraction unit are reacted in reaction unit to produce thick prenol stream, the thick prenol stream that obtains is subjected to purification in purification unit to produce the prenol stream and the first waste stream of purification.The isopentanal stream of purification is subjected to oxidation reaction in oxidation unit to produce thick prenol stream, the thick prenal stream that obtains is subjected to purification in purification unit to produce the prenal stream and the second waste stream of purification.After the isopentanal stream of purification is isomerized to produce pentenals, pentenals and pentenols are reacted in condensation unit to produce thick citral stream. Pentenols are obtained by the isomerization of the isopentanal of purification. The thick citral stream that obtains is subjected to purification in purification unit to produce the citral stream and the 3rd waste stream of purification. The first waste stream, the second waste stream and the 3rd waste stream are merged and directed to incineration unit.

[0172] In the incineration unit, the thermal energy generated by the incineration of the waste stream is used to evaporate and heat water to produce heating steam, which is fed to the steam grid.

[0173] Example (prophetic)

[0174] In accordance with Figure 1 At the facility, one ton each of butyraldehyde and citral was produced. 3.7 tons of ethanol from renewable sources was consumed for this purpose.

[0175] 0.6 tons of propene formed in the metathesis unit were subjected to hydroformylation in the hydroformylation unit with 0.4 tons of synthesis gas (fossil origin). Purification of the crude hydroformylation product obtained resulted in a total waste stream of 0.02 tons of mixed fossil / renewable origin, 0.015 tons of renewable origin.

[0176] 1.1 tons of isobutene taken from the isobutene extraction unit are reacted with 0.6 tons of formaldehyde (fossil origin) in a reaction unit, and the prenol obtained is further processed to produce citral, including purification of intermediates in a purification unit, resulting in a first waste stream, a second waste stream and a third waste stream totaling 0.4 tons of a combined stream of mixed fossil / renewable origin, 0.3 tons of which is of renewable origin.

[0177] Incineration of the combined waste streams from butyraldehyde purification and citral production produces 0.9 tonnes of mixed fossil / renewable CO2, 0.7 tonnes of renewable origin, equivalent to a reduction of approximately 70% of fossil CO2. In the incineration unit, 5.4 tonnes of heating steam (4 bar) are produced, corresponding to the thermal equivalent of incinerating 0.45 tonnes of ethanol.

Claims

1. A method for producing a chemical of interest, comprising the steps of: a) subjecting a feedstock comprising ethanol of renewable origin to dehydration to produce an ethylene stream of renewable origin; b) subjecting the renewable source ethylene stream to olefin interconversion to obtain one or more renewable source C 3-4 - olefins; the olefin interconversion comprises (i) and, where necessary, one or both of (ii) and (iii): (i) dimerization of ethylene to obtain n-butene; (ii) a metathesis reaction between the n-butene obtained according to (i) and ethylene to obtain propylene; as well as (iii) isomerizing the n-butene obtained according to (i) to obtain isobutene; as well as c) making the C of the renewable source 3-4 - the olefin is subjected to a chemical transformation or a series of chemical transformations, which chemical transformation or series of chemical transformations produces one or more crude product streams and optionally one or more crude intermediate product streams, to obtain the chemical of interest, d) subjecting at least one of the one or more crude product streams and optionally one or more intermediate crude product streams to purification to produce one or more purified product streams, one or more waste streams and optionally one or more purified intermediate product streams, e) Incineration of at least one of these waste streams to produce thermal energy.

2. The method according to claim 1, comprising f) transferring at least a portion of the thermal energy to a water stream to generate a heated steam stream.

3. The method according to claim 2, wherein: This heated steam stream is used to provide heat to the heated process.

4. The method according to claim 3, wherein: The heated steam stream is used to provide at least a portion of the heat consumed in at least one of steps a) and b).

5. A method according to any one of the preceding claims, wherein The waste incinerated according to step e) has a lower calorific value in the range of 10 to 45 MJ / kg of waste.

6. A method according to any one of the preceding claims, wherein The percentage of biogenic carbon in the waste stream incinerated according to step e) is in the range of 20% to 100%, based on the total carbon in the waste.

7. A method according to any one of the preceding claims, wherein Purification involves distilling the one or more crude product streams or one or more crude intermediate product streams.

8. The method according to claim 7, wherein: At least one of the waste streams directed to incineration is a distillation bottoms stream.

9. A method according to any one of the preceding claims, wherein Step b)-(i) comprises: - contacting the renewable sourced ethylene stream with a dimerization catalyst in a dimerization zone; - operating the dimerization zone under conditions effective to produce an effluent consisting essentially of n-butenes, a stream consisting essentially of heavier olefins and optionally an unconverted ethylene stream; - fractionating the effluent to recover a stream consisting essentially of n-butenes, a stream consisting essentially of heavier olefins, and optionally an ethylene stream; and - subjecting this stream consisting essentially of heavier olefins to hydrogenation in order to obtain naphtha of renewable origin.

10. A method according to any one of the preceding claims, wherein The n-butene is a mixed stream comprising 1-butene and 2-butene, and wherein b)-(ii) comprises removing 1-butene from the mixed stream to obtain a 2-butene-rich stream, and subjecting the 2-butene-rich stream to the metathesis reaction.

11. A method according to any one of the preceding claims, wherein The n-butene is a mixed stream comprising 1-butene and 2-butene, and wherein b)-(ii) comprises b)-(iia) subjecting the mixed stream to the metathesis reaction to obtain propylene and unreacted 1-butene; b)-(iib) subjecting the unreacted 1-butene to double bond isomerization to obtain 2-butene; and b)-(iic) recycling the 2-butene obtained in steps b)-(iib) to be used in steps b)-(iia).

12. The method according to any one of claims 1 to 10, wherein The n-butenes are a mixed stream comprising 1-butene and 2-butene, and wherein b)-(ii) comprise passing the mixed stream through a metathesis / isomerization zone comprising both a metathesis catalyst and an isomerization catalyst.

13. A method according to any one of the preceding claims, wherein Steps b) to (iii) comprise: - subjecting these n-butenes to skeletal isomerization to produce a mixture of n-butenes and isobutenes; - recovering from the mixture a stream consisting essentially of n-butenes and a stream consisting essentially of isobutene; and - recycling the stream consisting essentially of n-butenes to the skeletal isomerization.

14. The method according to any one of claims 1 to 12, wherein The renewable source of C 3-4 - the olefin is propylene, wherein step c) comprises hydroformylation of the propylene to produce a crude aldehyde stream comprising n-butyraldehyde and isobutyraldehyde; and step d) comprises purifying the crude aldehyde stream to produce at least one purified aldehyde stream and a waste stream.

15. A method according to any one of the preceding claims, wherein The renewable source of C 3-4 - the olefin is isobutylene, and step c) comprises (ci) to (cv), and step d) comprises (di) to (d-iii): (ci) reacting isobutylene with formaldehyde to produce a crude isopentenol stream, and (di) purifying the crude isopentenol stream to produce a purified isopentenol stream and a first waste stream; (c-ii) oxidation reaction of the purified prenylaldehyde stream to produce a crude prenylaldehyde stream, (d-ii) purifying the crude prenylaldehyde stream to produce a purified prenylaldehyde stream and a second waste stream; (c-iii) isomerizing the purified prenol stream to produce prenols, (c-iv) isomerizing the purified prenylaldehyde stream to produce pentenals, (cv) reacting the pentenols with pentenals to produce a crude citral stream, and (d-iii) purifying the crude citral stream to produce a purified citral stream and a third waste stream.

16. The method according to claim 15, wherein The first, second and third waste streams are combined and directed to incineration.

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