Process for manufacture of propylene-derived chemicals of interest, in particular acrylates, from ethanol of renewable origin

Abstract

A process for making an acrylate selected from n-butyl acrylate and 2-ethylhexyl acrylate includes subjecting a feedstock comprising ethanol of a renewable source to dehydration to produce an ethylene stream of a renewable source. Mutually converting the ethylene stream of renewable source with olefins to obtain propylene of renewable source; the interconversion of olefins comprises dimerization of ethylene to obtain n-butene; and obtaining propylene according to (i) a metathesis reaction between the obtained n-butenes and ethylene. Subjecting the propylene of renewable origin to a series of chemical conversions including alpha), beta), delta) and epsilon) or alpha), gamma), delta) and epsilon) to obtain an acrylate selected from n-butyl acrylate and 2-ethylhexyl acrylate: alpha) hydroformylation of the propylene to produce n-butyraldehyde; beta) a hydrogenation reaction of the n-butyraldehyde obtained in alpha) to produce n-butanol; gamma) condensation of the n-butyraldehyde obtained in alpha) to produce 2-ethyl-3-hydroxyhexanal, and subjecting the 2-ethyl-3-hydroxyhexanal to a hydrogenation reaction to produce 2-ethylhexanol; delta) an oxidation reaction of the propylene to produce acrylic acid; epsilon) the esterification reaction of the acrylic acid with one of the n-butanol obtained in beta) or the 2-ethylhexanol obtained in gamma) to produce an acrylate. The process provides a reaction scheme for n-butyl acrylate and 2-ethylhexyl acrylate of renewable sources.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a process for the manufacture of propylene-derived chemicals, in particular acrylates selected from n-butyl acrylate and 2-ethylhexyl acrylate, from ethanol of renewable origin.

[0002] Ethylene is the cornerstone of the modern petrochemical industry. Important ethylene derivatives (at the end of their respective chains) include (meth)acrylic acid, (meth)acrylates, isononanol, ethylhexanol and ethylene glycol. One of the problems faced in the manufacture of chemicals and intermediates from ethylene is that the starting raw materials are derived from fossil fuels such as natural gas or crude oil, which are non-renewable feedstocks. Steam cracking using petroleum fractions and natural gas liquids as feedstocks is the main method for large-scale ethylene production worldwide.

[0003] Lower olefins such as isobutylene or propylene are of great interest for industrial and chemical applications. Isobutylene (also known as isobutene or 2-methylpropene) is a hydrocarbon of great interest which is widely used as an intermediate in the production of industrially important products including para-xylene, jet fuel blendstock, gasoline oxygenate, isooctane, methacrolein, methyl methacrylate and butyl rubber. Propylene is a hydrocarbon of great interest which is widely used as an intermediate in the production of acrylic acid. Historically, lower olefins have been obtained by catalytic cracking or steam cracking of fossil fuel feedstocks.

[0004] The Applicant has recognized that the production of ethylene and ethylene derivative compounds would benefit from replacing at least a portion of the carbon-containing raw materials of fossil origin with renewable resources such as carbonaceous materials derived from biomass. Of particular interest is an ethanol feedstock produced from renewable resources. Such ethanol from renewable origin (also known as "bioethanol" or "hydrous fuel alcohol") can be produced in large quantities from organic waste or biomass via fermentation. Different feedstocks for the production of ethanol can be sucrose-containing feedstocks such as sugar cane, starchy 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.

[0005] Even after the purification process, the advantages of bioethanol are often reduced due to the small amount of impurities it contains. Bioethanol impurities can include oxygenated organic compounds such as other alcohols such as isopropanol, n-propanol and isobutanol and / or aldehydes such as acetaldehyde. Bioethanol impurities can further include sulfur-containing impurities such as inorganic sulfur compounds dialkyl sulfides, dialkyl sulfoxides, alkyl mercaptans, 3-methylthio-1-propanol and / or sulfur-containing amino acids.

[0006] It would be desirable to integrate ethanol from renewable sources into existing processes designed to convert fossil-derived ethylene or its intermediates. However, some of the impurities may interfere with downstream processes that use bioethanol as a feedstock and produce chemical products, especially when some of the downstream steps are catalytic conversions.

[0007] If no effort is made to remove at least some of these impurities, the yields of the desired intermediates and final products and the efficiency of the overall process may be reduced.

[0008] US2008 / 0312485 discloses a process for the continuous production of propylene by dehydrating ethanol obtained from biomass to obtain ethylene and reacting ethylene with 1-butene in a metathesis reaction. The 1-butene is made by dimerization of ethylene obtained from biomass-derived ethanol,

[0033] and

[0061] .

[0009] WO 2010 / 066830 discloses the conversion of bioethanol to ethylene. The bioethanol is produced by fermentation of carbohydrates or synthesis gas made from gasification of biomass. Subsequently, the ethylene is dimerized or oligomerized to, for example, 1-butene and / or 1-hexene. The dimerized or oligomerized α-olefins are converted to internal olefins, which are then subjected to metathesis with ethylene.

[0010] WO 2011 / 085223 discloses an integrated process for preparing renewable hydrocarbons. The process includes dehydrating renewable isobutanol to form a mixture of linear butenes and isobutene and dehydrating renewable ethanol to ethylene. Subsequently, the butene mixture and ethylene react to form one or more renewable C 3 -C 16 olefins.

[0011] EP 3 067 340 A discloses a process that includes: fermenting a renewable carbon source to produce an alcohol mixture containing ethanol, isopropanol, and 1-butanol; co-dehydrating the alcohols to produce an olefin mixture that mainly contains ethylene, propylene, and linear butenes in addition to water and by-products, the linear butenes being a mixture of 1-butene and 2-butene (cis and trans isomers); removing water, oxygenated compounds, and other by-products from the olefin mixture to produce an olefin mixture mainly containing ethylene, propylene, and linear butenes; and passing the olefin mixture through an isomerization bed such that 1-butene is isomerized to 2-butene, and subsequently passing the olefin mixture mainly containing ethylene, propylene, and 2-butene through a metathesis bed for the reaction between ethylene and 2-butene to produce additional propylene.

[0012] WO 2009 / 098268 discloses a process for dehydrating an alcohol to produce an olefin. The alcohol can be ethanol obtainable from carbohydrates. For this purpose, a stream comprising ethanol and an inert component is contacted with a catalyst to obtain ethylene. It indicates that ethylene can be dimerized to butene and then isomerized to isobutene; dimerized to 1-butene, which is isomerized to 2-butene and further converted to propylene by metathesis with ethylene; or converted to ethylene oxide and diols. Only experimental details of the ethanol dehydration are provided. A similar process is disclosed in WO 2011 / 089235.

[0013] WO 2009 / 098269 discloses a process for converting ethanol obtainable from carbohydrates to propylene. The ethanol is dehydrated to ethylene, and the ethylene is reacted with an olefin having four or more carbon atoms to obtain propylene. WO 2009 / 098267 discloses a similar process.

[0014] WO 2021 / 067294 discloses a process for simultaneously dehydrating, dimerizing, and metathesizing C 2 -C 5 alcohols in a reactor to produce C 2 -C 7 olefins.

[0015] WO 2009 / 070858 discloses an integrated process for producing an ethylene-butene copolymer. The ethylene is obtained by dehydrating ethanol produced by fermentation of sugars. A process for obtaining 1-butene for polymerization indicates dimerizing the ethylene produced by ethanol dehydration, where the ethanol is produced by fermentation of sugars. No details about the dimerization are given.

[0016] In the examples, the present invention seeks to propose a reaction scheme for providing light olefins (such as ethylene and propylene) from renewable sources, which partially or completely replace the light olefins output from a steam cracker. These light olefins are used as building blocks for producing various chemicals of interest. It is desirable that the light olefins from renewable sources can be blended with or interchanged with fossil-derived intermediates having the same chemical structure without adjustment in downstream processes. This includes that the starting olefins for all branches of the value chain historically provided by the steam cracker output can be supplied simultaneously on a renewable source basis. In this way, at least the greenhouse gas footprint and / or carbon footprint of producing the chemicals of interest is reduced. Detailed Description

[0017] For this purpose, the present invention relates to a process for manufacturing a chemical of interest selected from chemicals derived from propylene, said process comprising the following steps:

[0018] a) Subjecting a feedstock containing ethanol from renewable sources to dehydration to produce an ethylene stream from renewable sources;

[0019] b) Subjecting the ethylene stream from renewable sources to olefin metathesis to obtain propylene from renewable sources; the olefin metathesis includes (i) and (ii):

[0020] (i) Ethylene dimerization to obtain n-butene;

[0021] (ii) A metathesis reaction between the n-butene obtained according to (i) and ethylene to obtain propylene; and

[0022] c) Subjecting the propylene from renewable sources to one chemical transformation or a series of chemical transformations to obtain a chemical of interest.

[0023] In particular, the present invention relates to a process for manufacturing an acrylate selected from n-butyl acrylate and 2-ethylhexyl acrylate, the process comprising the following steps:

[0024] a) Subjecting a feedstock containing ethanol from renewable sources to dehydration to produce an ethylene stream from renewable sources;

[0025] b) Subjecting the ethylene stream from renewable sources to olefin metathesis to obtain propylene from renewable sources; the olefin metathesis includes (i) and (ii):

[0026] (i) Ethylene dimerization to obtain n-butene; and

[0027] (ii) A metathesis reaction between the n-butene obtained according to (i) and ethylene to obtain propylene; and

[0028] c) Subjecting the propylene from renewable sources to a series of chemical transformations to obtain an acrylate selected from n-butyl acrylate and 2-ethylhexyl acrylate, the series of chemical transformations including α), β), δ) and ε) or α), γ), δ) and ε):

[0029] α) Hydroformylation of the propylene to produce n-butanal;

[0030] β) Hydrogenation reaction of the n-butanal obtained in α) to produce n-butanol;

[0031] γ) Condensation of the n-butanal obtained in α) to produce 2-ethyl-3-hydroxyhexanal, and subjecting the 2-ethyl-3-hydroxyhexanal to a hydrogenation reaction to produce 2-ethylhexanol;

[0032] δ) Oxidation reaction of the propylene to produce acrylic acid;

[0033] ε) Esterification reaction of the acrylic acid with one of the n-butanol obtained in β) or the 2-ethylhexanol obtained in γ) to produce an acrylate.

[0034] The process of the present invention is preferably a continuous process in the sense that the upstream steps of the reaction route that at least produce the chemical of interest (including step a) and steps b-(i) and b-(ii)) are carried out continuously. In an even more preferred embodiment, all steps of the reaction route that produce the chemical of interest are carried out continuously. This does not exclude the presence of buffer volumes between subsequent reaction steps in the reaction route.

[0035] The present invention is based on the idea of eliminating impurities inherently present in ethanol from renewable sources during the process of manufacturing ethylene itself. Thus, the ethylene from renewable sources or propylene from renewable sources produced therefrom can be blended with or interchanged with fossil-derived intermediates having the same chemical structure without adjustment in downstream processes.

[0036] It is contemplated that the olefins from renewable sources involved in the process according to the present invention can be blended with supplementary olefins from other sources. This can ensure the efficient utilization of downstream processes, for example, during a transitional period when the supply of olefins from renewable sources is limited. These supplementary olefins (including supplementary ethylene, supplementary propylene, and supplementary 1-butene) can be fossil-based, partially from renewable sources, or renewable sources via another production route.

[0037] Thus, in an embodiment, the process comprises:

[0038] blending the ethylene from renewable sources with supplementary ethylene before step b), the supplementary ethylene not being obtained from ethanol from renewable sources according to step a); and / or

[0039] blending the propylene from renewable sources with supplementary propylene before steps c) and d), the supplementary propylene not being obtained from ethanol from renewable sources according to steps a) and b); and / or

[0040] blending the 1-butene from renewable sources with supplementary 1-butene before step b)-(ii), the supplementary 1-butene not being obtained from ethanol from renewable sources according to steps a) and b)-(i).

[0041] Examples of supplementary ethylene are ethylene obtained by steam cracking of fossil-based feeds such as naphtha, natural gas, or crude oil. Examples of supplementary propylene are propylene obtained by steam cracking of fossil-based feeds such as naphtha, natural gas, or crude oil. Examples of supplementary 1-butene are 1-butene obtained by steam cracking of fossil-based feeds such as naphtha, natural gas, or crude oil.

[0042] On the other hand, the present invention also relates to a method for enhancing the environmental sustainability of an acrylate selected from n-butyl acrylate and 2-ethylhexyl acrylate by blending or replacing fossil-derived propylene with propylene from renewable sources to obtain sustainability-enhanced propylene, and subjecting the sustainability-enhanced propylene to a series of chemical transformations to obtain the acrylate, wherein the propylene from renewable sources is obtained by:

[0043] a) subjecting a feedstock containing ethanol from renewable sources to dehydration to produce an ethylene stream from renewable sources; and

[0044] b) subjecting the ethylene stream from renewable sources to olefin metathesis to obtain propylene from renewable sources; the olefin metathesis includes (i) and (ii):

[0045] (i) ethylene dimerization to obtain n-butene; and

[0046] (ii) a metathesis reaction between the n-butene obtained according to (i) and ethylene to obtain propylene;

[0047] The series of chemical transformations includes α), β), δ) and ε) or α), γ), δ) and ε):

[0048] α) hydroformylation of the propylene to produce n-butanal;

[0049] β) hydrogenation of the n-butanal obtained in α) to produce n-butanol;

[0050] γ) condensation of the n-butanal obtained in α) to produce 2-ethyl-3-hydroxyhexanal, and subjecting the 2-ethyl-3-hydroxyhexanal to a hydrogenation reaction to produce 2-ethylhexanol;

[0051] δ) oxidation of the propylene to produce acrylic acid;

[0052] ε) esterification of the acrylic acid with one of the n-butanol obtained in β) or the 2-ethylhexanol obtained in γ) to produce an acrylate.

[0053] A key advantage of the method according to the present invention is that it can be easily integrated into existing production sites where one or more chemicals of interest are manufactured based on fossil raw materials (especially naphtha). This means that fossil-based ethylene and propylene can be completely or partially replaced by ethylene and propylene from corresponding renewable sources. Thereby, the corresponding chemicals of interest are obtained, the carbon atoms of which are completely or partially based on carbon from renewable sources (so-called "green" carbon).

[0054] Reducing carbon dioxide emissions provides additional benefits. The chemical conversions involved in reaction routes to produce individual chemicals of interest are typically less than 100% selective. The yield losses themselves manifest as the formation of by-products, which vary depending on the type of reaction involved. For example, oxidation reactions of substrates to the desired product almost always to some extent are accompanied by over-oxidation of the substrate to form carbon oxides, especially carbon dioxide. By completely or partially replacing fossil ethylene and propylene with their counterparts from renewable sources, the fossil-based carbon dioxide emissions across the production site can be reduced, since the corresponding emissions caused by yield losses along the value chain are at least partially based on green carbon. Thus, the carbon dioxide emissions generated do not impact the greenhouse emissions of the production site. For example, in the production of acrylic acid (as further described below), carbon dioxide is formed due to the complete oxidation of propylene. Thus, using propylene from renewable sources such as obtained by the method according to the invention prevents the formation of fossil-based carbon dioxide emissions resulting from such production.

[0055] Furthermore, in non-oxidation reactions, the various substances present may undergo many side reactions that generate color-forming substances, oligomers, and various decomposition products, etc. In addition to the desired product, these are typically removed during post-treatment, for example by distillation, thereby generating light boiler and / or high boiler fractions. The light boiler or high boiler fractions are conventionally used for their calorific value, i.e., burned as fuel or exploited as a hydrocarbon source, such as for steam cracker feed. It should be understood that completely or partially replacing fossil ethylene and propylene with their counterparts from renewable sources at the start of the processing chain reduces the fossil-based carbon dioxide emissions resulting from the combustion of downstream by-products.

[0056] Thus, it is expected that both direct and indirect benefits are associated with the method of the invention with respect to any chemical of interest manufactured via the method according to the invention.

[0057] The expressions "renewable" or "from renewable sources" with respect to compounds are used synonymously and mean compounds containing a certain amount of renewable carbon, i.e., having a reduced or no carbon content from fossil sources. Renewable carbon requires that all carbon sources avoid or replace the use of any additional fossil carbon from the geosphere. Renewable carbon can come from the biosphere, the atmosphere, or the technosphere - not from the geosphere. Thus, the expressions "renewable" or "from renewable sources" specifically include biomass-derived compounds. It also includes compounds derived from waste (such as polymer residues) or waste streams from chemical production processes.

[0058] The term "chemicals of interest" collectively refers to any desired compounds that occur in the value chain starting from and including ethylene. Thus, the term includes any intermediates and end products. In some cases, a compound can be both an intermediate and an end product. For example, n-butyl acrylate can be an end product of the value chain and, if desired, can also be an intermediate when it is further processed.

[0059] All patents and literature documents mentioned below are incorporated herein by reference in their entirety.

[0060] Bioethanol is a preferred form of ethanol from renewable sources, but the scope of the present invention is not limited to the use of bioethanol.

[0061] In the present invention, bioethanol refers to ethanol obtained from biomass feedstocks (such as plant or non-crop feedstocks) containing a carbon source that can be converted into ethanol, for example, by microbial metabolism. Typical examples of carbon sources are starch, sugars such as pentoses or hexoses (such as glucose, fructose, sucrose, xylose, arabinose), or degradation products of plants, hydrolysis products of cellulose, or sugarcane juice, beet juice, etc. containing a large amount of the above components.

[0062] Biomass feedstocks can be derived from several sources. Bioethanol production can be based on food crop feedstocks such as corn and sugarcane, sugarcane bagasse, cassava (first-generation biofeedstocks).

[0063] Another source of biomass feedstocks is lignocellulosic materials from crops (second-generation biofeedstocks). Potential feedstocks include agricultural residual by-products such as rice, straw (such as wheat, oat, and barley straw), rice husks, and corn stover. Biomass feedstocks can also be waste materials from the forest products industry (wood waste) and sawdust, or produced specifically as ethanol crops. Switchgrass and elephant grass can be used as dedicated crops for conversion to ethanol.

[0064] First-generation bioethanol is produced in four basic steps:

[0065] (1) Enzymatic saccharification or hydrolysis of starch into sugars

[0066] (2) Microbial fermentation of sugars

[0067] (3) Purification by distillation to obtain hydrous ethanol

[0068] (4) Dehydration (water removal) to produce anhydrous ethanol.

[0069] The second-generation feedstocks are considered renewable and sustainable carbon sources. Pretreatment is a necessary prerequisite before the feedstocks are subjected to enzymatic hydrolysis, fermentation, distillation, and dehydration. The pretreatment involves milling and exposure to acids and heat to reduce the size of the plant fibers and hydrolyze a portion of the material to produce fermentable sugars. Saccharification utilizes enzymes to hydrolyze another portion into sugars. Finally, fermentation by bioengineered microorganisms converts the various sugars (pentoses and hexoses) into ethanol. The production of bioethanol is well-known and carried out on an industrial scale.

[0070] 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. The production of ethanol from waste materials can be accomplished by gasification to syngas and its catalytic conversion to 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.

[0071] Dehydration of Ethanol from Renewable Sources

[0072] As a first step, the present invention relates to the dehydration of ethanol from renewable sources. 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 moderate pressure in the presence of a catalyst. The catalytic effects are 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 zeolites of the ZSM-5 type or SAPO-11 type, other zeolites or modified zeolites with various molecular structures, where zeolites and HPA salts are preferred.

[0073] The dehydration of ethanol 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.

[0074] The ethanol dehydration reaction is typically carried out in the 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 carrier fluid). The feedstock is vaporized and heated to the desired reaction temperature; as the reaction proceeds in the reactor, the temperature drops. Multiple reactor beds are typically used in series to keep the temperature drop of each bed within a manageable range. The cooled effluent from each bed is further heated to bring it to the desired inlet temperature of the subsequent bed. In addition, a portion of the water is recycled together with fresh and unreacted ethanol. The presence of water helps to moderate the temperature drop in each bed.

[0075] Prior to dehydration, the ethanol feedstock from renewable sources can be sent to a pretreatment section to remove mineral contaminants that would otherwise be harmful to the downstream catalytic reaction. The pretreatment can involve contacting the ethanol feedstock from renewable sources with cationic and / or anionic exchange resins. After a period of operation, the resins can be regenerated by passing a regenerant solution through the resin bed to restore their ion exchange capacity. Two sets of beds are preferably operated in parallel to maintain continuous operation. One set of resin beds is being properly regenerated while the other set of resin beds is being used for pretreatment.

[0076] In an isothermal design, the catalyst is placed inside the tubes of a multitubular fixed bed reactor, which are arranged vertically and surrounded by a shell (tube and shell design). A heat transfer medium (such as molten salt or oil) circulates inside the shell to provide the required heat. Baffles can be provided on the shell side to promote heat transfer. The cooled heating medium is heated externally and recycled. Compared with an adiabatic reactor, the temperature drop on the process side can be reduced. The better control of the temperature results in an increase in the selectivity of ethylene formation and a decrease in the amount of undesired by-products. The temperature is maintained at a substantially constant level within the range of 300 °C to 350 °C. The ethanol conversion is between 98% and 99%, and the selectivity to ethylene is between 94 mol% and 97 mol%. 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, for example, 3 days.

[0077] In the adiabatic design, the heat of absorption of the reaction is supplied by preheated inert diluents (such as steam). Typically, three fixed-bed reactors can be used, where an intermediate furnace is used to reheat the ethanol / steam mixed feed stream entering each reactor. Feeding steam together with ethanol results in less coke formation, longer catalyst activity, and higher yields.

[0078] Another method is the fluidized-bed method. The fluidized-bed system provides excellent temperature control in the reactor, thus minimizing by-product formation. The heat distribution rate of fluidized-bed operation approaches isothermal conditions. The heat of absorption of the reaction is supplied by the heat-recovered silica-alumina catalyst returned from the catalyst regenerator. Therefore, external heating of the reactor is not necessary.

[0079] After dehydration, the reaction mixture is subjected to a separation step. A general separation scheme consists of rapidly cooling the reaction gas (e.g., in a water quench tower), which separates most of the by-product water and unreacted ethanol from ethylene and other light components that leave from the top of the quench tower. In one type of separation scheme, the water-washed ethylene stream is immediately subjected to an alkali wash (e.g., in a column) to remove trace amounts of CO 2 . The gaseous stream can directly enter a compressor or first be transferred to a surge gas holder and then to a gas compressor. After compression, the gas is cooled with a refrigeration device and then passed through an adsorber with, for example, activated carbon to remove trace amounts of heavy components (e.g., C4), if they are present. After the adsorber are a desiccant drying and dust filtration step, after which the ethylene product leaves the plant. This separation scheme produces ethylene with a purity of 99%+. If desired, the ethylene is further purified by alkali washing and desiccant drying and fractionated in a cryogenic column to obtain the final product.

[0080] Currently, several commercial methods jointly developed by Braskem, Chematur, British Petroleum (BP), Axens, together with Total and IFPEN are in operation. These processes differ, for example, in their process conditions, catalysts, and the heat integration schemes employed. The process developed by BP (now Technip) is called Hummingbird. In this process, heteropolyacid is used as the catalyst, and the reactor operates 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. Two fixed-bed adiabatic reactors operating at 400 °C to 500 °C are used. Chematur's process operates with four adiabatic tubular reactors. The Syndol catalyst (the main component is Al2 O 3 -MgO / SiO 2 ) which was developed by American Halcon Scientific Design, Inc. in the 1980s. In the Blasco process, the adiabatic reactor feed is diluted to a large extent with steam. In this process, the reactor operates at 180 °C to 600 °C, preferably 300 °C to 500 °C and at 1.9 to 19.6 bar. Alumina or silica-alumina catalysts are used. A more detailed description of the Blasco process is given in US 4,232,179. Process control according to the Blasco process is particularly preferred.

[0081] Dimerization of ethylene

[0082] The process of the present invention relates to the dimerization of ethylene according to step b)-(i) to obtain n-butene. Any known process can be used for the dimerization of ethylene to produce n-butene. A review of dimerization and oligomerization chemistry and technology is given in Catalysis Today, Volume 14 (Issue 1), April 10, 1992.

[0083] Conveniently, step b)-(i) comprises:

[0084] - contacting the ethylene stream from the renewable source with a dimerization catalyst in a dimerization zone;

[0085] - operating the dimerization zone under conditions effective to produce an effluent consisting essentially of: n-butene, a stream consisting essentially of heavier olefins, and optionally an unreacted ethylene stream; and

[0086] - fractionating the effluent to recover a stream consisting essentially of n-butene, a stream consisting essentially of heavier olefins, and an optional ethylene stream.

[0087] The dimerization catalyst can be homogeneous or heterogeneous. Typical dimerization catalysts are titanium or nickel compounds activated with an alkylaluminum compound. Generally, the Ti(IV) valence is stabilized by selecting appropriate ligands, alkylaluminum compounds, solvent polarity, and Al / Ti ratio. Nickel compounds that can catalyze the selective production of butenes are typically based on cationic nickel salts stabilized with phosphines and activated with an alkylaluminum compound.

[0088] In one embodiment, the oligomerization of ethylene is carried out in the liquid phase in the presence of a catalytic system comprising a nickel compound and an aluminum compound. Such catalytic systems are described in the literature FR 2 443 877 and FR 2794 038. Dimersol E TM The process is based on this technology and leads to the industrial production of olefins.

[0089] Thus, in one embodiment, the oligomerization of ethylene is carried out in the presence of a catalytic system comprising:

[0090] i) at least one divalent nickel compound,

[0091] ii) at least one hydrocarbyl aluminum dihalide having the formula AlRX 2 wherein R is a hydrocarbyl group containing from 1 to 12 carbon atoms, such as an alkyl, aryl, aralkyl, alkaryl or cycloalkyl group, X is a chlorine or bromine atom, and

[0092] iii) optionally a Bronsted organic acid.

[0093] As the divalent nickel compound, nickel carboxylates having the general formula (R 1 COO) 2 Ni are preferably used, wherein R 1 is an optionally substituted hydrocarbyl group containing up to 20 carbon atoms, such as an alkyl, cycloalkyl, alkenyl, aryl, aralkyl or alkaryl group, preferably a hydrocarbyl group having 5 to 20 carbon atoms, preferably 6 to 18 carbon atoms. Suitable divalent nickel compounds include: chlorides, bromides, carboxylates (such as octanoate, 2-ethylhexanoate, decanoate, oleate, salicylate, hydroxydecanoate, stearate), phenolates, naphthenates and acetylacetonates. Nickel 2-ethylhexanoate is preferably used.

[0094] The hydrocarbyl aluminum dihalide compound corresponds to the formula AlRX 2 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. As examples of such compounds, sesquiethyl aluminum chloride, dichloroethyl aluminum, dichloroisobutyl aluminum, chloro diethyl aluminum or mixtures thereof may be mentioned.

[0095] According to a preferred method, a Bronsted organic acid is used. The Bronsted acid compound corresponds to the formula HY, where Y is an organic anion, such as carboxylate, sulfonate or phenolic. Halocarboxylic acids having the formula R 2 COOH (wherein R 2 is a haloalkyl group) are preferred, especially those containing at least one α-halogen atom of the group —COOH and having a total of 2 to 10 carbon atoms. Preferably, haloacetic acids having the formula CX p H 3-p —COOH are used, where X is fluorine, chlorine, bromine or iodine and p is an integer from 1 to 3. By way of example, trifluoroacetic acid, difluoroacetic acid, fluoroacetic acid, trichloroacetic acid, dichloroacetic acid and chloroacetic acid may be cited. Aryl sulfonic acids, alkyl sulfonic acids and fluoroalkyl sulfonic acids, as well as picric acid and nitroacetic acid, may also be used. Trifluoroacetic acid is preferably used.

[0096] The three components of the catalytic formulation can be mixed in any order. However, it is preferred to first mix the nickel compound with the Bronsted organic acid and then subsequently introduce the aluminum compound. The molar ratio of the hydrocarbyl aluminum dihalide to the nickel compound, expressed by 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.

[0097] According to a preferred method, the hydrocarbyl aluminum dihalide can be rich in aluminum trihalide, and the mixture of the two compounds corresponds to the formula AlR n X 3-n , where R is a hydrocarbyl group containing 1 to 12 carbon atoms, such as an alkyl group, an aryl group, an aralkyl group, an alkaryl group or a cycloalkyl group, X is a chlorine or bromine atom, and n is a number between 0 and 1. Suitable mixtures include: dichloroethylaluminum rich in aluminum chloride, which has the formula AlEt 0.9 Cl 2.1 ; dichloroisobutylaluminum rich in aluminum chloride, which has the formula AliBu 0.9 Cl 2.1 ; and dibromoethylaluminum rich in aluminum bromide, which has the formula AlEt 0.9 Br 2.1 .

[0098] The oligomerization of ethylene can be carried out under pressure conditions at a temperature of -20 °C to 80 °C, preferably 40 °C to 60 °C, such that at least most of the reagents remain in the liquid phase or the condensed phase. The pressure is generally between 0.5 and 5 MPa, preferably between 0.5 MPa and 3.5 MPa. The contact time is generally between 0.5 and 20 hours, preferably between 1 and 15 hours.

[0099] The oligomerization stage can be carried out in a reactor having one or more reaction stages in series, in which the ethylene feedstock and / or the catalytic composition, which is preferably pre-conditioned in advance, is continuously introduced in the first stage, or in the first stage and any other one of these stages. At the outlet of the reactor, the catalyst can be deactivated, for example, by injecting ammonia and / or an aqueous soda solution and / or an aqueous sulfuric acid solution. Then, the unreacted olefins and alkanes optionally present in the feedstock are separated from the oligomers by a separation stage, for example, by distillation or by means of a washing cycle with caustic soda and / or water.

[0100] The single-pass conversion rate is usually 85% to 98%. The selectivity for the formation of n-butene is generally between 50% and 80%. The n-butene consists of butene-2 (cis- and trans-) and butene-1.

[0101] The effluent typically contains less than 0.2% by weight of isobutene, or even less than 0.1% by weight of isobutene.

[0102] Separation of the stream rich in n-butene

[0103] The effluent obtained by ethylene dimerization is subjected to a separation stage in such a way as to obtain a fraction rich in n-butene.

[0104] The 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.

[0105] Preferably, the oligomerized effluent is sent to a distillation column system comprising one or more columns, which on the one hand makes it possible to separate n-butene from ethylene (which can be returned to the oligomerization reactor) and heavier olefins having 5 carbon atoms or more.

[0106] The higher olefins can be subjected to hydrogenation in order to obtain naphtha from renewable sources. "Naphtha from renewable sources" shall mean naphtha produced from renewable sources. It is a hydrocarbon composition mainly composed of paraffins. The molecular weight of naphtha from renewable sources can be in the range of hydrocarbons having 5 to 8 carbon atoms. Naphtha from renewable sources can be used as a feedstock for steam cracking to produce light olefins, dienes and aromatic compounds from renewable sources.

[0107] Thus, in an embodiment, step b)-(i) comprises:

[0108] - contacting the ethylene stream from renewable sources with a dimerization catalyst in a dimerization zone;

[0109] - operating the dimerization zone under conditions effective to produce an effluent consisting essentially of: n-butene, a stream consisting essentially of heavier olefins and optionally an unreacted ethylene stream;

[0110] - fractionating the effluent to recover a stream consisting essentially of n-butene, a stream consisting essentially of heavier olefins and an optional ethylene stream; and

[0111] - optionally subjecting the stream consisting essentially of heavier olefins to hydrogenation in order to obtain naphtha from renewable sources.

[0112] Metathesis of ethylene and n-butene

[0113] Ethylene can undergo metathesis with 1-butene to produce propylene. Step b)-(ii) includes a metathesis reaction between the 1-butene obtained according to step (i) and ethylene to obtain propylene. The 1-butene obtained during ethylene dimerization (i) is a mixed stream containing 1-butene and 2-butene. Essentially only 2-butene reacts in the metathesis reaction, while 1-butene is essentially inert.

[0114] In one embodiment, 1-butene is removed from the mixed stream of 1-butene and 2-butene and directed elsewhere in the plant for use. Thus, in one embodiment, step b)-(ii) includes 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. The 2-butene-rich stream can contain at least 90 wt.-% 2-butene based on the total amount of 1-butene.

[0115] Alternatively, 1-butene can be converted to 2-butene by double bond isomerization. Double bond isomerization is an equilibrium-limited reaction. Thus, it is advantageous to subject the mixed stream of 1-butene to metathesis so that 2-butene reacts with ethylene before the double bond isomerization of 1-butene. Thus, in one embodiment, the 1-butene is a mixed stream containing 1-butene and 2-butene, and b)-(ii) includes

[0116] b)-(iia) subjecting the mixed stream to the metathesis reaction to obtain propylene and unreacted 1-butene;

[0117] b)-(iib) subjecting the unreacted 1-butene to double bond isomerization to obtain 2-butene; and

[0118] b)-(iic) recycling the 2-butene obtained in step b)-(iib) to step b)-(iia).

[0119] In another embodiment, 1-butene can be converted to 2-butene while the metathesis reaction is taking place. For this purpose, the metathesis catalyst and the isomerization catalyst can be physically mixed or provided as separate layers to allow both reactions to occur simultaneously. Thus, in one embodiment, step b)-(ii) is carried out by passing the mixed stream through a metathesis / isomerization zone comprising both the metathesis catalyst and the isomerization catalyst. Since 2-butene is consumed by the metathesis reaction on the metathesis catalyst, 2-butene is replenished by isomerizing 1-butene to 2-butene on the isomerization catalyst.

[0120] The reaction is carried out in the presence of a metal-based metathesis catalyst, the metal being selected from tungsten, molybdenum, rhenium, niobium, tantalum, vanadium, ruthenium, rhodium, iridium, osmium, nickel, etc. 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 an alumina-based support. A particularly preferred metathesis catalyst is based on WO 3 catalysts, such as silica-supported WO 3 .

[0121] Suitable isomerization catalysts include magnesium-based catalysts, such as MgO-based catalysts, e.g., tableted MgO.

[0122] The metathesis is carried out under conditions effective to produce an effluent comprising propylene, unreacted ethylene and optionally 1-butene.

[0123] The unreacted ethylene and / or unreacted n-butene can be recycled and combined with fresh ethylene and n-butene to provide the metathesis feedstock.

[0124] The reaction can be carried out at 340 °C - 375 °C, 25 - 40 bar, a weight hourly space velocity (WHSV) of 7.5 - 30 h -1 and an ethylene to 2-butene molar ratio of 3:1 to 10:1.

[0125] The reactor effluent can be sent to a deethenizer to remove C2 and lighter materials. The bottom residue from the deethenizer is sent to a depropanizer. High-purity, polymer-grade propylene (>99.9% molar purity) is recovered from the overhead distillate of the depropanizer. The lighter materials from the deethenizer and the heavier C 4+ materials from the depropanizer are partially recycled to the reactor. A purge stream is provided for the lighter and heavier materials to prevent the accumulation of inert substances.

[0126] It should be noted that propane is not produced during the metathesis reaction. Thus, polymer-grade propylene can be produced by this process without the need for an expensive propylene - propane superfractionator.

[0127] Commercial processes for producing polymer-grade propylene by the metathesis of ethylene and butene feedstocks are available from CB&I / Lummus (trade name OCT TM ) and LyondellBasell.

[0128] Hydroformylation of propylene

[0129] The hydroformylation of propylene produces n-butyraldehyde, isobutyraldehyde or a mixture thereof. If desired, the aldehydes produced can be separated by fractionation.

[0130] The hydroformylation or oxo process is an important large-scale industrial process for the preparation of aldehydes from olefins, carbon monoxide and hydrogen. These aldehydes can optionally be hydrogenated with hydrogen in the same operation or subsequently in a separate hydrogenation step to produce the corresponding alcohols. Generally, hydroformylation is carried out in the presence of a catalyst that is homogeneously soluble in the reaction medium. The catalysts used are usually carbonyl complexes of metals of transition group VIII, especially Co, Rh, Ir, Pd, Pt or Ru, which may be unmodified or modified with, for example, amine- or phosphine-containing ligands. A summary description of the processes practiced on an industrial scale can be found in J. Falbe, “New Syntheses with Carbon Monoxide”, Springer Verlag 1980, pages 162 et seq., US 3,527,809; 3,917,661; 4,148,830; 4,742,178; 4,769,984; 4,885,401; 6,049,011.

[0131] Propylene is preferably hydroformylated using a ligand-modified rhodium carbonyl as the catalyst. The hydroformylation of propylene can be carried out at a temperature in the range of 50 °C to 200 °C, preferably 60 °C to 150 °C, and more preferably 70 °C to 120 °C.

[0132] In one embodiment, the hydroformylation reaction is carried out at low pressure, for example at a pressure in the range of 0.05 to 50 MPa (absolute), and preferably at a pressure in the range of about 0.1 MPa to 30 MPa, most preferably at a pressure below 5 MPa. Desirably, the partial pressure of carbon monoxide is not more than 50% of the total pressure.

[0133] The ratios of carbon monoxide, hydrogen and propylene 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 about 1 mol-% to 50 mol-%, preferably about 1 mol-% to 35 mol-%; H 2 is about 1 mol-% to 98 mol-%, preferably about 10 mol-% to 90 mol-%; and propylene is about 0.1 mol-% to 35 mol-%, preferably about 1 mol-% to 35 mol-%.

[0134] The hydroformylation reaction preferably takes place in the presence of both a liquid phase and a gas phase. The reactants are typically in the gas phase. The catalyst is typically in the liquid phase. Since 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 thoroughly mixed during the reaction. In continuous operation, the reactor feed gas can be contacted with the catalyst solution in, for example, a continuous flow stirred autoclave, where the gas is preferably introduced through a perforated inlet (e.g., a distributor) and dispersed at the bottom of the vessel. 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 support (a technique well known in the art as supported liquid phase catalysis) or by providing Rh as part of a permeable gel.

[0135] 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.

[0136] In the synthesis gas used for hydroformylation, the ratio of H 2 to CO 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 such a way that the ratio of hydrogen to CO is much higher than this. The excess hydrogen can be separated as needed and used in other reaction stages. For example, the excess hydrogen can be used to reduce n-butyraldehyde to n-butanol. In some practice modes, the synthesis gas in the practice of the present invention is anhydrous.

[0137] Hydrogenation of n-butyraldehyde

[0138] Hydrogenation of n-butyraldehyde, isobutyraldehyde, or a mixture thereof yields n-butanol, isobutanol, or a mixture thereof.

[0139] These aldehydes can optionally be hydrogenated with hydrogen in the same reaction step or subsequently in a separate hydrogenation step to produce the corresponding alcohols. The hydrogenation of n-butyraldehyde to n-butanol is a well-known reaction and can be carried out by any suitable known method.

[0140] In one embodiment, the hydrogenation is carried out with hydrogen in the liquid phase or gas phase in the presence of a hydrogenation catalyst. Homogeneous or heterogeneous catalysts can be used. Copper catalysts have proven to be the most suitable. Typically, the reaction is carried out in the liquid phase on a fixed bed catalyst at 20 °C to 200 °C and a pressure of up to 30 MPa. The hydrogenation in the gas phase is preferably carried out continuously. Further details can be obtained from Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Volume A1, 1984.

[0141] Condensation of n-butyraldehyde to produce 2-ethyl-3-hydroxyhexanal

[0142] Step c) further comprises the condensation of n-butyraldehyde to produce 2-ethyl-3-hydroxyhexanal, and optionally subjecting the 2-ethyl-3-hydroxyhexanal to a hydrogenation reaction to produce 2-ethylhexanol.

[0143] Aldol condensation is a well-known condensation reaction in which an enol or enolate ion reacts with a carbonyl compound in the presence of an acid or base catalyst to form a β-hydroxyaldehyde or β-hydroxyketone (aldol reaction), followed by dehydration to give a conjugated enone and hydrogenation to the corresponding alcohol. In the context of the present invention, n-butyraldehyde reacts in a self-aldol condensation to give 2-ethyl-3-hydroxyhexanal.

[0144] Aldol condensation can occur under a variety of conditions, under weakly acidic or strongly basic conditions and in the presence of different catalysts. The reaction can typically be carried out in the liquid phase using an aqueous basic catalyst at a temperature of about 80 °C to 140 °C. In another embodiment, the reaction can be carried out in the gas phase by contacting an aldehyde in the gas phase with a particulate catalyst comprising at least one basic alkali metal compound on an inert substrate at a temperature above 175 °C. Further details are provided in WO2000 / 031011.

[0145] The obtained 2-ethyl-3-hydroxyhexanal can be hydrogenated to 2-ethylhexanol. The hydrogenation can be carried out analogously to the hydrogenation of n-butyraldehyde and / or isobutyraldehyde described above.

[0146] Oxidation of propylene to produce acrolein or acrylic acid

[0147] Step c) comprises an oxidation reaction to produce an intermediate selected from acrolein and acrylic acid.

[0148] Acrylic acid is an important basic chemical. Due to its highly reactive double bond and acid functional group, it is particularly suitable as a monomer for the preparation of polymers. Of the amount of acrylic acid monomer produced, most is esterified prior to polymerization, for example to form acrylate adhesives, dispersions or coatings. Only a smaller portion of the acrylic acid monomer produced is polymerized directly, for example to form superabsorbent resins. However, generally, direct polymerization of acrylic acid requires a high purity monomer, while the acrylic acid used to be converted to an acrylate prior to polymerization does not have to be so pure.

[0149] As is well known, acrylic acid can be produced via acrolein from propylene by heterogeneously catalyzed gas-phase oxidation with molecular oxygen at a temperature between 200 °C and 400 °C over a solid catalyst in two stages (see, for example, DE-A 19 62431, DE-A 29 43 707, DE-C 1 205 502, EP-A 257 565, EP-A 253 409, DE-B 22 51 364, EPA 117 146, GB-C 1 450 986 and EP-A 293224). The catalysts used are oxidation multicomponent catalysts based on oxides of elements such as molybdenum, chromium, vanadium or tellurium. The five most commonly used catalyst systems for acrolein production are cuprous oxide, uranium antimonide oxide, tin antimonide oxide, bismuth molybdate oxide and oxides based on multicomponent bismuth molybdate. The most effective catalysts for the partial oxidation of propylene to acrolein consist of multicomponent metal oxide systems. In almost every multicomponent catalyst system, bismuth molybdate acts as the main component. The following components are most commonly used as catalyst additives in catalysts based on bismuth molybdate oxide: iron, cobalt, nickel, tungsten, potassium and phosphorus. Typical catalyst supports are inert porous solids such as SiO 2 、Al 2 O 3 、MgO、TiO 2 、ZrO 2 、aluminosilicates, zeolites, activated carbon and ceramics.

[0150] The oxidation of propylene to acrylic acid can be carried out in one or two stages. The catalysts for the heterogeneously catalyzed reaction are usually multimetal oxide materials which usually contain heavy metal molybdates as the main component and compounds of various elements as promoters. The oxidation of propylene takes place in the first step to obtain acrolein and in the second step to obtain acrylic acid. Since these two oxidation steps may be different in their kinetics, uniform process conditions and a single catalyst usually do not lead to optimal selectivity. Recently, therefore, a two-stage process with an optimal adaptation of catalyst and process variables has preferably been developed. Generally, in the first stage, propylene undergoes an exothermic reaction in the presence of molecular oxygen in a fixed-bed tubular reactor and is oxidized to acrolein. The reaction product is directly transferred to a second reactor and further oxidized to acrylic acid. The reaction gas obtained in the second stage can be condensed and acrylic acid can be separated therefrom by extraction and / or distillation.

[0151] The oxidation of propylene to acrolein and / or acrylic acid is highly exothermic. Therefore, the tubes of the fixed-bed tubular reactor filled with the heterogeneous catalyst are surrounded by a cooling medium (usually a salt melt such as a eutectic mixture of KNO 3 and NaNO 2 ). The heat of reaction is released through the wall of the catalyst-filled tube into the salt bath.

[0152] Particularly preferred polymetallic oxide materials have the formula I or II

[0153] [X 1 a X 2 b O x p [X 3 c X 4 d X 5 e X 6 f X 7 g X 2 h O y q (I)

[0154] Mo 12 Bi i X 8 k Fe l X 9 m X 10 n O z (II)

[0155] wherein

[0156] X 1 is Bi, Te, Sb, Sn, and / or Cu, preferably Bi,

[0157] X 2 is Mo and / or W,

[0158] X 3 is an alkali metal, Tl, and / or Sm, preferably K,

[0159] X 4 is an alkaline earth metal, Ni, Co, Cu, Mn, Zn, Sn, Cd, and / or Hg, preferably Ni and / or Co,

[0160] X 5 is Fe, Cr, Ce, and / or V, preferably Fe,

[0161] X 6 is P, As, B, and / or Sb,

[0162] X 7 is a rare earth metal, Ti, Zr, Nb, Ta, Re, Ru, Rh, Ag, Au, Al, Ga, In, Si, Ge, Pb, Th, and / or U, preferably Si, Al, Ti, and / or Zr, ​​

[0163] a is from 0.01 to 8,

[0164] b is from 0.1 to 30,

[0165] c is from 0 to 4,

[0166] d is from 0 to 20,

[0167] e is from 0 to 20,

[0168] f is from 0 to 6,

[0169] g is from 0 to 15,

[0170] h is from 8 to 16,

[0171] x and y are numbers determined by the valence and the number of occurrences of the elements other than oxygen in I,

[0172] p and q are numbers with a ratio p / q of from 0.1 to 10,

[0173] X 8 is cobalt and / or nickel, preferably cobalt,

[0174] X 9 is silicon and / or aluminum, preferably silicon,

[0175] X 10 is an alkali metal, preferably potassium, sodium, cesium and / or rubidium, especially potassium,

[0176] i is from 0.1 to 2,

[0177] k is from 2 to 10,

[0178] l is from 0.5 to 10,

[0179] m is from 0 to 10,

[0180] n is from 0 to 0.5,

[0181] z is a number determined by the valence and the number of occurrences of the elements other than oxygen in II.

[0182] The multimetal oxide material having the formula I is known per se from EP 0 000 835 and EP 0 575 897, and the multimetal oxide material having the formula II is known per se from DE 198 55 913.

[0183] Briefly, the process for preparing acrylic acid typically comprises the following steps:

[0184] (a) catalytic gas-phase oxidation of propene and / or acrolein to acrylic acid to obtain a gaseous reaction product comprising acrylic acid;

[0185] (b) solvent absorption of the reaction product

[0186] (c) Distill the solvent loaded with the reaction product in a column to obtain crude acrylic acid and the solvent.

[0187] (d) Purify the crude acrylic acid by crystallization.

[0188] Step (a) provides not pure acrylic acid but a gaseous mixture which may essentially contain, in addition to acrylic acid, unreacted acrolein and / or propene, water vapor, carbon monoxide, carbon dioxide, nitrogen, oxygen, acetic acid, propionic acid, formaldehyde, additional aldehydes, and maleic anhydride.

[0189] The remaining, unabsorbed reaction gas from step (a) is further cooled so that the condensable portion of its low-boiling co-components, in particular water, formaldehyde, and acetic acid, can be separated by condensation. This condensate is called acid water. The remaining gas stream (hereinafter referred to as the recycle gas) mainly consists of nitrogen, carbon oxides, and unreacted starting materials. Preferably, the recycle gas is partially recycled as a diluent gas to the reaction stage.

[0190] The oxidation of propene to acrolein and the oxidation of acrolein to acrylic acid proceed with a selectivity of less than 100%, and are accompanied by the combustion of propene or acrolein on the catalyst, which produces carbon monoxide and carbon dioxide, collectively referred to herein as CO x . It should be understood that since the starting propene is carbon-neutral, the emission of the carbon dioxide by-product does not affect the carbon footprint of the process.

[0191] CO from the oxidation reaction x hydrogenation

[0192] In an embodiment in this regard, the propene oxidation reaction proceeds with the formation of CO x as a by-product, and the process further comprises subjecting said CO x to hydrogenation to produce at least one of syngas, methanol, formaldehyde, and formic acid. Although carbon monoxide and / or carbon dioxide can be sequestered, for example, by underground storage, it may be beneficial to subject said CO x to hydrogenation to produce at least one of syngas, methanol, formaldehyde, and formic acid.

[0193] The resulting syngas, methanol, formaldehyde, and / or formic acid can then be shown to be carbon-negative and can at least partially displace their fossil-based counterparts and reduce the carbon footprint of chemical conversion processes that utilize syngas, methanol, formaldehyde, and / or formic acid.

[0194] Esterification of acrylic acid to produce acrylate

[0195] Step c) further comprises the esterification reaction of acrylic acid to produce an acrylate, in particular an acrylate selected from n-butyl acrylate and 2-ethylhexyl acrylate.

[0196] Acrylates are generally known and are important, for example, as reactive monoethylenically unsaturated monomers for the preparation of aqueous polymer dispersions by free radical aqueous emulsion polymerization processes, which dispersions are used, for example, as adhesives.

[0197] Acrylic acid can be esterified in a conventional manner using the corresponding alkanol, such as methanol, ethanol, n-propanol, isopropanol, n-butanol or 2-ethylhexanol, to produce the desired acrylate.

[0198] The process for preparing alkyl acrylates by reacting acrylic acid with an alkanol in a homogeneous liquid phase at elevated temperature and in the presence of a catalyst is an equilibrium reaction, where the conversion of acrylic acid and the alkanol to the corresponding ester is limited by the equilibrium constant. Therefore, for an economic procedure, the unreacted starting materials must be separated from the resulting ester and recycled to the reaction zone.

[0199] Conveniently, the reaction zone can consist of a cascade of reaction zones connected in series, and the effluent stream of one reaction zone forms the feed stream of the subsequent reaction zone, and the concentration of the esterification catalyst increases along the reaction cascade. Acrylic acid, alkanol and catalyst are continuously fed to the reaction zone. The azeotropic mixture comprising the alkyl acrylate, water and optionally the starting alkanol is separated by distillation via the top of a distillation zone installed on the reaction zone. The azeotropic mixture is separated into an organic phase containing the alkyl acrylate and an aqueous phase, where a portion of the organic phase is recycled to the reaction zone. The alkyl acrylate is separated from the excess organic phase. The latter is usually carried out by a separation step involving distillation (see, for example, DE 19536178).

[0200] The temperature in the reaction zone depends on the type of alcohol used and is suitably in the range of 70 °C to 160 °C, preferably 100 °C to 140 °C. The total residence time of the reactants in the reaction zone is usually 0.25 - 15 h, often 1 - 7 h or 2 - 5 h.

[0201] Suitable acidic esterification catalysts include acidic ion exchange resins and strong mineral acids (such as sulfuric acid), or organic sulfonic acids (such as methanesulfonic acid, benzenesulfonic acid, dodecanesulfonic acid or p-toluenesulfonic acid), or mixtures of some or all of the above acids. Sulfuric acid is particularly suitable for carrying out this novel process. This is especially applicable to the preparation of n-butyl acrylate.

[0202] The content of the acidic esterification catalyst in the reaction zone is suitably 0.1 wt.-% to 20 wt.-%, often 0.5 wt.-% to 5 wt.-%, based on the reaction mixture contained therein.

[0203] To prevent the formation of unwanted polymers initiated by free radicals, polymerization inhibitors are typically used during esterification. Examples of suitable polymerization inhibitors are hydroquinone, 4-methoxyphenol, and phenothiazine, which can be used alone or in mixtures with each other. Typically, about 0.01 wt.-% to 0.1 wt.-% of the polymerization inhibitor is added to the esterification mixture and the mixture containing methacrylate.

[0204] Additional embodiments

[0205] The present invention also relates to a method for manufacturing a chemical of interest, which is selected from propylene-derived chemicals according to the following examples.

[0206] 1. A method for manufacturing a chemical of interest selected from propylene-derived chemicals, the method comprising the following steps:

[0207] a) Subjecting a feedstock containing ethanol from a renewable source to dehydration to produce a stream of ethylene from a renewable source;

[0208] b) Subjecting the stream of ethylene from a renewable source to olefin metathesis to obtain propylene from a renewable source; the olefin metathesis includes (i) and (ii):

[0209] (i) Dimerizing ethylene to obtain n-butene;

[0210] (ii) A metathesis reaction between the n-butene obtained according to (i) and ethylene to obtain propylene; and

[0211] c) Subjecting the propylene from a renewable source to one chemical transformation or a series of chemical transformations to obtain the chemical of interest.

[0212] 2. The method according to embodiment 1, wherein step c) includes an oxidation reaction to produce an intermediate selected from acrolein and acrylic acid.

[0213] 3. The method according to embodiment 2, wherein step c) further includes an esterification reaction of the acrylic acid to produce an acrylate.

[0214] 4. The method according to embodiment 2, wherein step c) further includes polymerizing the acrylic acid, optionally together with one or more comonomers, to produce a water-absorbing resin.

[0215] 5. The method according to embodiment 2, wherein step c) further includes reacting the acrylic acid with isobutene to produce tert-butyl acrylate.

[0216] 6. The method according to embodiment 1, wherein step c) includes hydroformylation of the propylene from a renewable source to produce n-butyraldehyde, isobutyraldehyde, or a mixture thereof.

[0217] 7. The method according to embodiment 6, wherein step c) further comprises a hydrogenation reaction of the n-butyraldehyde, isobutyraldehyde or a mixture thereof to produce n-butanol, isobutanol or a mixture thereof.

[0218] 8. The method according to embodiment 6, wherein step c) further comprises a condensation of the n-butyraldehyde to produce 2-ethyl-3-hydroxyhexanal, and optionally subjecting the 2-ethyl-3-hydroxyhexanal to a hydrogenation reaction to produce 2-ethylhexanol.

[0219] 9. The method according to embodiment 7 or 8, wherein step c) further comprises an esterification of the n-butanol, the isobutanol and / or the 2-ethylhexanol with (meth)acrylic acid to produce a (meth)acrylate.

[0220] 10. The method according to embodiment 6, wherein step c) further comprises a condensation reaction of isobutyraldehyde with formaldehyde to produce hydroxypivalaldehyde, and optionally subjecting the hydroxypivalaldehyde to a hydrogenation reaction to produce neopentyl glycol.

[0221] 11. The method according to embodiment 1, wherein step c) comprises an epoxidation reaction to produce propylene oxide, and

[0222] - optionally, a hydrolysis reaction of the propylene oxide to produce propylene glycol, or

[0223] - optionally, a ring-opening polymerization of the propylene oxide to produce polypropylene glycol.

[0224] Polymerization of acrylic acid

[0225] In an embodiment, step c) further comprises polymerizing acrylic acid optionally together with one or more comonomers to produce a water-absorbing resin.

[0226] The water-absorbing resin is used for the production of diapers, tampons, sanitary napkins and other hygiene products, and is also used as a water retention agent in market gardening. The water-absorbing resin is also known as a superabsorbent. The production of the water-absorbing resin is described in the monograph "Modern Superabsorbent Polymer Technology", F.L. Buchholz and A.T. Graham, Wiley-VCH, 1998, pages 71 to 103.

[0227] Typical methods for producing a water-absorbing resin include polymerizing a monomer solution or suspension comprising:

[0228] a) acrylic acid, which may be at least partially neutralized,

[0229] b) at least one crosslinking agent,

[0230] c) at least one initiator,

[0231] d) an ethylenically unsaturated monomer which is optionally copolymerizable with acrylic acid, and

[0232] e) optionally one or more water-soluble polymers,

[0233] The resulting polymer gel is dried, the dried polymer gel is ground, fractionated and subjected to post-crosslinking on the hot surface.

[0234] Suitable crosslinking agents b) are compounds having at least two groups suitable for crosslinking. The crosslinking agent b) is preferably a compound having at least two polymerizable groups which can be polymerized into the polymer network by free radicals. Suitable crosslinking agents b) are, for example, ethylene glycol dimethacrylate, diethylene glycol diacrylate, polyethylene glycol diacrylate, allyl methacrylate, trimethylolpropane triacrylate, triallylamine, tetraallylammonium chloride, tetraallyloxyethane, as described in EP 0530 438 A1; diacrylates and triacrylates, as described in EP 0 547 847 A1, EP 0 559 476 A1, EP0 632 068 A1, WO 93 / 21237A1, WO 03 / 104299A1, WO 03 / 104300A1, WO 03 / 104301A1 and DE103 31 450A1; mixed acrylates containing additional ethylenically unsaturated groups in addition to the acrylate groups, as described in DE 103 31 456A1 and DE 103 55 401A1; or crosslinking agent mixtures, as described in, for example, DE 195 43368A1, DE 196 46 484A1, WO 90 / 15830A1 and WO 02 / 032962A2. The amount of the crosslinking agent b) is preferably 0.25 wt.-% to 1.5 wt.-%, more preferably 0.3 wt.-% to 1.2 wt.-%, and most preferably 0.4 wt.-% to 0.8 wt.-% based on the unneutralized acrylic acid. With increasing crosslinking agent content, the centrifuge retention capacity decreases and the absorption under pressure reaches a maximum.

[0235] The initiator c) used can be all compounds which generate free radicals under the polymerization conditions, such as thermal initiators, redox initiators or photoinitiators. Suitable redox initiators are sodium persulfate / ascorbic acid, hydrogen peroxide / ascorbic acid, sodium persulfate / sodium bisulfite and hydrogen peroxide / sodium bisulfite.

[0236] Suitable ethylenically unsaturated monomers d) copolymerizable with acrylic acid include acrylamide, methacrylamide, hydroxyethyl acrylate, hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminopropyl acrylate, diethylaminopropyl acrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate.

[0237] Suitable water-soluble polymers e) include polyvinyl alcohol, polyvinylpyrrolidone, starch, starch derivatives, modified celluloses (such as methylcellulose or hydroxyethylcellulose), gelatin, polyglycols, or polyacrylic acid, preferably starch, starch derivatives, and modified celluloses.

[0238] Conveniently, the polymerization is carried out in a polymerization reactor or kneader having at least two axes rotating in an axially parallel manner. Typically, an aqueous monomer solution is used. The water content of the monomer solution is preferably 40 wt.-% to 75 wt.-%, more preferably 45 wt.-% to 70 wt.-%, and most preferably 50 wt.-% to 65 wt.-%.

[0239] Then, the polymer gel is preferably dried, for example, with a belt dryer until the residual moisture content is preferably 0.5 wt.-% to 15 wt.-%, more preferably 1 wt.-% to 10 wt.-%, and most preferably 2 wt.-% to 8 wt.-%. Thereafter, the dried polymer gel is ground and classified. The equipment used for grinding can typically be a single-stage or multi-stage roll mill, preferably a two-stage or three-stage roll mill, a needle mill, a hammer mill, or a vibration mill.

[0240] The average particle size of the polymer particles removed as the product fraction is preferably at least 200 μm, more preferably 250 to 600 μm, and most preferably 300 to 500 μm.

[0241] To further improve the properties, the polymer particles can be surface post-crosslinked. Suitable surface post-crosslinking agents are compounds containing groups that can form covalent bonds with at least two carboxylic acid groups of the polymer particles. Suitable compounds are, for example, polyfunctional amines, polyfunctional amidoamines, polyfunctional epoxides as described in EP 0 083 022 A2, EP 0 543 303 A1, and EP 0 937 736 A2; difunctional or polyfunctional alcohols as described in DE 33 14 019 A1, DE 35 23 617 A1, and EP 0 450 922 A2; or β-hydroxyalkylamides as described in DE 102 04 938 A1 and U.S. Patent No. 6,239,230. Preferred surface post-crosslinking agents are ethylene carbonate, ethylene glycol diglycidyl ether, the reaction product of polyamide and epichlorohydrin, and a mixture of propylene glycol and 1,4-butanediol.

[0242] Reaction of acrylic acid with isobutene to produce tert-butyl acrylate

[0243] In the examples, step c) further comprises reacting acrylic acid with isobutene to produce tert-butyl acrylate.

[0244] Tert-butyl acrylate is an important starting material for the preparation of polymers which are used, inter alia, as constituents of paints, adhesives or coating resins. Tert-butyl esters of this kind are generally prepared by the acid-catalyzed addition of carboxylic acids to isobutene (Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry], Volume 8, 1952, page 534; US 3,031,495 and US 3,082,246). The catalysts used are acids which are soluble in the reaction mixture, such as mineral acids or alkylsulfonic or arylsulfonic acids (DE-A-12 49 857, US 3,087,962, US 3,088,969), or insoluble catalysts such as acidic ion-exchange resins (US 3,037,052, US 3,031,495, DE-A-31 05 399, EP-A-268 999).

[0245] The reaction of acrylic acid with isobutene is generally carried out in the absence of solvents and in the liquid phase. The catalysts used are therefore those which are at least partially soluble in the reaction mixture. Suitable catalysts are strong inorganic or organic acids. Strong inorganic acids are, for example, mineral acids such as sulfuric acid, phosphoric acid and polyphosphoric acid, preferably sulfuric acid. Strong organic acids are, for example, sulfonic acids such as p-toluenesulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid and methanesulfonic acid, preferably p-toluenesulfonic acid and methanesulfonic acid. In particular, inorganic catalysts are only partially soluble in the reaction mixture at the start of the reaction. During the reaction, the solubility of the catalyst is improved (mainly due to the formation of partial esters of the catalyst, such as sulfuric acid monoesters). Thus, at least in the last section, it is generally present in solution in the reaction mixture.

[0246] The concentration of the catalyst in the reaction mixture is generally about 0.1% to 10% by weight, preferably 0.5% to 5% by weight, based on the total amount of the reaction mixture.

[0247] The reaction of acrylic acid with isobutene in the presence of an acidic catalyst is preferably carried out in a conventional reaction vessel or in a column (DE-A-1128 428). Suitable reactors are described by way of example in WO 02 / 10109A1. Preferably, the reaction is carried out in a reactor, in particular a cylindrical reactor. The reactor is divided into a plurality of, preferably 3, 4 or 5, separate sections. The volumes of the reactor sections can be the same or different. Preferably, the volume of the first reactor section is greater than the volumes of the remaining sections.

[0248] The resulting reaction mixture is withdrawn at the upper end of the reactor and sent for further work-up. Unconverted gaseous isobutene accumulates in the upper region of the reactor. Preferably, condensable organic compounds, such as unconverted acrylic acid, are condensed out of the isobutene-containing gas stream withdrawn at the upper end of the reactor and are thus free of gases inert to the reaction, such as air and butane. Unconverted isobutene is partially soluble in the condensed components. The condensed organic compounds can then be fed back into the reaction in liquid form.

[0249] The reaction temperature is typically in the range of about 10 °C to 40 °C. It is preferably controlled in such a way that it is highest in the first reactor section. Preferably, the reaction temperature in the first reactor section is in the range of about 30 °C to 40 °C. The temperature in the second section is lower, preferably about 5 °C to 15 °C. The temperature in the sections downstream of the second section can be the same or different. It is generally not higher than the temperature in the second section, preferably lower, in particular about 3 °C to 10 °C. The temperature in the fourth section is generally as high as in the third section or about 1 °C to 5 °C lower. The temperature in the last reactor section is preferably in the range of about 10 °C to 25 °C.

[0250] The reaction can be carried out under reduced pressure, ambient pressure or slightly elevated pressure (100 to 300 mbar absolute) or preferably under elevated pressure (for example 0.5 to 3 bar).

[0251] Esterification of n-butanol, isobutanol and / or 2-ethylhexanol

[0252] In the examples, step c) further comprises the esterification of n-butanol, isobutanol and / or 2-ethylhexanol with a carboxylic acid. Suitable carboxylic acids include saturated and unsaturated C 1 -C 16 -carboxylic acids, in particular (meth)acrylic acid, as described above for the esterification of acrylic acid to produce acrylate esters. When the carboxylic acid is a saturated carboxylic acid, no polymerization inhibitor is required.

[0253] C 4 -C 10Esters of carboxylic acids (such as phthalic acid and adipic acid) with n-butyl alcohol and / or 2-ethylhexanol are widely used as plasticizers in plastics (e.g., cellulose acetate, polyurethane, PVC, polyacrylates, etc.). They can be prepared by reacting an acid component or its anhydride with an alcohol component in the presence of an esterification catalyst. The reaction is an equilibrium reaction. The equilibrium can be shifted to the product side (i.e., the ester side) by continuously removing water produced as a by-product from the reaction. 2-ethylhexanol has a region in which it is immiscible with water; therefore, a mixture of water of reaction and 2-ethylhexanol can be continuously distilled off from the reaction mixture, and after phase separation, the organic phase is returned to the esterification while removing the aqueous phase from the system.

[0254] Condensation of isobutylaldehyde and formaldehyde

[0255] In an embodiment, step c) further comprises a condensation reaction of isobutyraldehyde with formaldehyde (ie, a cross-aldol condensation) to produce hydroxypivaldehyde.

[0256] The aldol condensation is a well-known condensation reaction in which an enolate or enolate ion reacts with a carbonyl compound in the presence of an acid or base catalyst to form a β-hydroxyaldehyde or β-hydroxyketone (aldol reaction), which is subsequently dehydrated to give a conjugated ketone and hydrogenated to the corresponding alcohol. In the present case, isobutyraldehyde is reacted with formaldehyde in a cross-aldol condensation to obtain hydroxypivalaldehyde.

[0257] The aldol condensation can take place under a variety of conditions, under weakly acidic or strongly basic conditions and in the presence of different catalysts. In the present case, preference is given to using a catalyst comprising a secondary amine (preferably di-C 1 -C 6 The catalyst system of the present invention is a catalyst system of a 4-, 5- or 6-membered cyclic monoamine or diamine and an organic acid (preferably a monocarboxylic acid or a dicarboxylic acid) having up to 10 carbon atoms. Examples of amines are dimethylamine, diethylamine, methylethylamine, ethylbutylamine, di-n-butylamine, di-2-ethylhexylamine, diisooctylamine, diphenylamine, dicyclohexylamine, piperidine, piperazine or morpholine or a combination thereof. Examples of organic acids are formic acid, acetic acid, propionic acid, malic acid, malonic acid, glutaric acid, tartaric acid, adipic acid, succinic acid, hydroxysuccinic acid, maleic acid, 2-ethylhexanoic acid or salicylic acid or a combination thereof.

[0258] The molar ratio of formaldehyde to isobutyraldehyde is preferably in the range of 1:1 to 1.5:1. The secondary amine is preferably used in a molar ratio to propionaldehyde of 0.005:1 to 0.1:1. The organic acid may be used in a molar ratio to propionaldehyde of 0.002:1 to 0.05:1.

[0259] The reaction temperature may be in the range of 70 to 120°C, preferably 80 to 100°C, and the pressure may be 100 to 300 kPa, preferably 150 to 250 kPa.

[0260] The produced hydroxypivaldehyde can be subjected to a hydrogenation reaction to produce neopentyl glycol. The hydrogenation can be carried out similarly to the hydrogenation of n-butyraldehyde and / or isobutyraldehyde described above.

[0261] Epoxidation of propylene

[0262] In another aspect of the invention, the renewable source of C 3-4 - the olefin is propylene and step c) comprises an epoxidation reaction to produce propylene oxide, and

[0263] - Optionally, the hydrolysis reaction of propylene oxide to produce propylene glycol, or

[0264] - Optionally, ring-opening polymerization of propylene oxide to produce polypropylene glycol.

[0265] The oxidation of propylene is typically carried out with an organic peroxide. The following hydroperoxides are commonly used:

[0266] 1) tert-Butyl hydroperoxide derived from the oxygenation of isobutane (Halcon process).

[0267] 2) Ethylbenzene hydroperoxide derived from the oxygenation of ethylbenzene.

[0268] 3) Oxygenated cumene hydroperoxide derived from cumene (isopropylbenzene).

[0269] 4) Hydrogen peroxide or a source of hydrogen peroxide catalyzed by titanium-doped silicalite (HPPO process).

[0270] Preferably, the oxidation of propylene is carried out using hydrogen peroxide or a source of hydrogen peroxide. An advantage of using hydrogen peroxide or a source of hydrogen peroxide is that water is obtained as a by-product instead of alcohol.

[0271] In one embodiment, the oxidation of propylene comprises

[0272] 1) introducing a feed stream comprising propylene, hydrogen peroxide or a source of hydrogen peroxide and an organic solvent into a reactor containing a catalyst;

[0273] 2) subjecting the feed stream to epoxidation conditions in the presence of a catalyst so as to obtain a reaction mixture comprising propylene oxide and an organic solvent;

[0274] 3) Removing a product stream comprising propylene oxide and organic solvent from the reactor.

[0275] In case hydrogen peroxide is employed, it is preferred that the hydrogen peroxide is an aqueous hydrogen peroxide solution, wherein the solution preferably comprises 30 wt.-% to 50 wt.-% hydrogen peroxide relative to the total amount of water.

[0276] It is also possible to form hydrogen peroxide in situ from hydrogen and oxygen in the reaction mixture in the presence of a suitable catalyst or catalyst system, for example in the presence of a titanium-containing zeolite which additionally contains one or more noble metals, or a titanium-containing zeolite and a further catalyst containing one or more noble metals, for example supported on a suitable support such as charcoal or a suitable inorganic oxide or mixture of inorganic oxides.

[0277] Suitable organic solvents include alcohols, nitriles and mixtures thereof, optionally with water. Preferably, the organic solvent is selected from methanol and acetonitrile. Most preferably, the organic solvent is acetonitrile.

[0278] Typically, the feed stream is not limited by the molar ratio of propylene to hydrogen peroxide or one equivalent of hydrogen peroxide produced by the source of hydrogen peroxide. Preferably, propylene is present in the feed stream in a molar excess relative to hydrogen peroxide or one equivalent of hydrogen peroxide produced by the source of hydrogen peroxide. Preferably, the molar ratio of propylene to hydrogen peroxide or one equivalent of hydrogen peroxide produced by the source of hydrogen peroxide in the feed stream is from 1 to 1.6, more preferably from 1.1 to 1.55, more preferably from 1.2 to 1.5, more preferably from 1.40 to 1.45.

[0279] Typically, the catalyst is a titanium-containing zeolite. The zeolite catalyst preferably has an MWW-type framework structure. Therefore, the catalyst is preferably a "titanium zeolite with framework structure type MWW", also referred to as "TiMWW", these terms relate to zeolites with framework structure MWW containing titanium as an isomorphous substitution element in the zeolite framework. Preferably, the zeolite framework is substantially free of aluminum and is substantially composed of silicon, titanium and oxygen.

[0280] The titanium-containing zeolite preferably comprises one or more of Al, B, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Zn, Ga, Ge, In, Sn, Pb, Pd, Pt, Au, Cd, preferably one or more of B, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Zn, Ga, Ge, In, Sn, Pb, Pd, Pt, Au, Cd, more preferably Zn.

[0281] Preferably, the titanium zeolite of framework structure type MWW contained in the catalyst contains titanium in an amount in the range of 0.1 wt-% to 5 wt-%, more preferably 0.2 wt-% to 4 wt-%, more preferably 0.5 wt-% to 3 wt-%, more preferably 1 wt-% to 2 wt-%, based on the total weight of the titanium zeolite of framework structure type MWW, calculated as elemental titanium.

[0282] The feed stream is subjected to epoxidation conditions in the presence of a catalyst in a reactor and a reaction mixture comprising propylene oxide and an organic solvent is obtained. The reactor may be operated isothermally or adiabatically, wherein it is preferred that the reactor is an isothermally operated reactor. Preferably, the reaction is carried out in a tubular reactor or in a tube bundle reactor.

[0283] Preferably, the reaction temperature is in the range of 20° to 100°C, more preferably 25° to 80°C, more preferably 25° to 60°C, more preferably 30° to 60°C.

[0284] Preferably, the reaction pressure is in the range of 5 to 100 bar, more preferably 10 to 32 bar, more preferably 15 to 25 bar, wherein the epoxidation reaction pressure is defined as the pressure at the outlet of the isothermal reactor.

[0285] A product stream comprising propylene oxide and an organic solvent is removed from the reactor. The product stream is typically subjected to at least one post-treatment step to separate propylene oxide from the product stream. In addition, the organic solvent (which typically comprises a by-product of the epoxidation reaction) is preferably subjected to one or more post-treatment steps to allow the organic solvent (preferably acetonitrile) to be recycled to step 1), preferably after one or more purification steps.

[0286] Hydrolysis of propylene oxide to produce propylene glycol

[0287] In one embodiment of this aspect, propylene oxide is subjected to a hydrolysis reaction to produce propylene glycol.

[0288] The reaction is carried out without a catalyst and produces monopropylene glycol as the main product as well as dipropylene glycol, tripropylene glycol and polyglycols. Further details are given in Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, volume A22, 239-252, 1993.

[0289] Ring-opening polymerization of propylene oxide to produce polypropylene glycol

[0290] In another embodiment of this aspect, propylene oxide is subjected to ring-opening polymerization to produce polypropylene glycol.

[0291] The ring-opening polymerization of propylene oxide typically proceeds via anionic polymerization. Anionic polymerization is based on nucleophiles as initiators. The widely used standard method for the technical synthesis of low molecular weight propylene glycol is the controlled addition of propylene oxide to water or an alcohol as an initiator in the presence of a basic catalyst. In most cases, for this purpose, alkali metal compounds with high nucleophilicity are employed. For higher molecular weights, alkali metal hydrides, alkyls, aryls, hydroxides, alkoxides, and amides are used for the living anionic polymerization of propylene oxide in an inert solvent.

[0292] The counterion should exhibit low Lewis acidity and preferably have little or no interaction with the chain ends. The solvent for the anionic polymerization of epoxides must be polar and aprotic; thus, tetrahydrofuran (THF), dioxane, dimethyl sulfoxide (DMSO), and hexamethylphosphoramide (HMPA) are commonly used. Alkoxides with sodium, potassium, or cesium counterions in an ether (most often THF) or other polar aprotic solvent represent the most commonly used initiator systems. The addition of a complexing agent (such as a crown ether suitable for the corresponding cation) can strongly accelerate the epoxide polymerization.

[0293] The anionic polymerization of propylene oxide produces low molecular weight PPO with unsaturated allyl end groups. Due to this reaction, the molecular weight of PPO prepared by anionic polymerization is limited to 6000 g / mol.

[0294] Further details regarding the anionic polymerization of propylene oxide can be obtained from Chem. Rev. [Chemical Reviews] 2016, 116, 2170 to 2243.

[0295] CO from the epoxidation of propylene x hydrogenation

[0296] In one embodiment in this regard, the epoxidation reaction is carried out with the formation of CO x as a by-product, and the method further comprises subjecting the CO x to hydrogenation to produce at least one of syngas, methanol, formaldehyde, and formic acid, as described above for the oxidation of propylene to acrylic acid.

Claims

1. A process for manufacturing an acrylate selected from n-butyl acrylate and 2-ethylhexyl acrylate, the process comprising the following steps: a) subjecting a feedstock comprising ethanol from renewable sources to dehydration to produce an ethylene stream from renewable sources; b) subjecting the ethylene stream from renewable sources to olefin metathesis to obtain propylene from renewable sources; the olefin metathesis comprises (i) and (ii): (i) dimerizing ethylene to obtain n-butene; and (ii) a metathesis reaction between the n-butene obtained according to (i) and ethylene to obtain propylene; and c) subjecting the propylene from renewable sources to a series of chemical transformations to obtain an acrylate selected from n-butyl acrylate and 2-ethylhexyl acrylate, the series of chemical transformations comprising α), β), δ) and ε) or α), γ), δ) and ε): α) hydroformylating the propylene to produce n-butyraldehyde; β) hydrogenating the n-butyraldehyde obtained in α) to produce n-butanol; γ) condensing the n-butyraldehyde obtained in α) to produce 2-ethyl-3-hydroxyhexanal, and subjecting the 2-ethyl-3-hydroxyhexanal to a hydrogenation reaction to produce 2-ethylhexanol; δ) oxidizing the propylene to produce acrylic acid; ε) esterifying the acrylic acid with one of the n-butanol obtained in β) or the 2-ethylhexanol obtained in γ) to produce an acrylate.

2. The process according to claim 1, which comprises blending the ethylene from renewable sources with supplementary ethylene before step b), the supplementary ethylene not being obtained from ethanol from renewable sources according to step a); and / or blending the propylene from renewable sources with supplementary propylene before step c), the supplementary propylene not being obtained from ethanol from renewable sources according to steps a) and b); and / or blending the n-butene from renewable sources with supplementary n-butene before step b)-(ii), the supplementary n-butene not being obtained from ethanol from renewable sources according to steps a) and b)-(i).

3. The process according to claim 1 or 2, wherein, step b)-(i) comprises: - contacting the ethylene stream from renewable sources with a dimerization catalyst in a dimerization zone; - operating the dimerization zone under conditions effective to produce an effluent consisting essentially of: n-butene, a stream consisting essentially of heavier olefins, and optionally an unreacted ethylene stream; - fractionating the effluent to recover a stream consisting essentially of n-butene, a stream consisting essentially of heavier olefins, and an optional ethylene stream; and - optionally subjecting the stream consisting essentially of heavier olefins to hydrogenation to obtain naphtha from renewable sources.

4. The process according to claim 1, 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 stream rich in 2-butene, and subjecting the stream rich in 2-butene to the metathesis reaction.

5. The process according to claim 1, wherein, the n-butene is a mixed stream comprising 1-butene and 2-butene, and wherein b)-(ii) comprises b)-(iia) Subject the mixed stream to the metathesis reaction to obtain propylene and unreacted 1-butene; b)-(iib) Subject the unreacted 1-butene to double bond isomerization to obtain 2-butene; and b)-(iic) Recycle the 2-butene obtained in step b)-(iib) to step b)-(iia).

6. The method according to any one of claims 1 to 3, wherein, the n-butene is a mixed stream comprising 1-butene and 2-butene, and wherein b)-(ii) comprises passing the mixed stream through a metathesis / isomerization zone comprising both a metathesis catalyst and an isomerization catalyst.

7. The method according to any one of the preceding claims, wherein, The propylene oxidation reaction is carried out in the presence of CO as a by-product, and the method further comprises subjecting the CO to hydrogenation to produce at least one of syngas, methanol, formaldehyde, and formic acid. x x ​ 8. A method for enhancing the environmental sustainability of an acrylate selected from n-butyl acrylate and 2-ethylhexyl acrylate by blending or replacing fossil-derived propylene with propylene from renewable sources to obtain sustainability-enhanced propylene, and subjecting the sustainability-enhanced propylene to a series of chemical transformations to obtain the acrylate, wherein the propylene from renewable sources is obtained by: a) Subjecting a feedstock comprising ethanol from renewable sources to dehydration to produce a stream of ethylene from renewable sources; and b) Subjecting the stream of ethylene from renewable sources to olefin metathesis to obtain the propylene from renewable sources; the olefin metathesis comprises (i) and (ii): (i) Ethylene dimerization to obtain n-butene; and (ii) A metathesis reaction between the n-butene obtained according to (i) and ethylene to obtain propylene; the series of chemical transformations comprises α), β), δ) and ε) or α), γ), δ) and ε): α) Hydroformylation of the propylene to produce n-butyraldehyde; β) Hydrogenation of the n-butyraldehyde obtained in α) to produce n-butanol; γ) Condensation of the n-butyraldehyde obtained in α) to produce 2-ethyl-3-hydroxyhexanal, and subjecting the 2-ethyl-3-hydroxyhexanal to a hydrogenation reaction to produce 2-ethylhexanol; δ) Oxidation of the propylene to produce acrylic acid; ε) Esterification of the acrylic acid with one of the n-butanol obtained in β) or the 2-ethylhexanol obtained in γ) to produce the acrylate.