Method for the hydroformylation of olefins comprising 2 to 8 carbon atoms

Abstract

Disclosed is a method for the hydroformylation of olefins including 2 to 8 carbon atoms, whereby (i) reacting an inflow containing olefins and an added saturated hydrocarbon comprising 2 to 8 carbon atoms, as well as carbon monoxide and hydrogen, fed into a reaction zone and reacted in the presence of a hydroformylation catalyst, (ii) separating a flow consisting partly of unreacted olefins and saturated hydrocarbons from the discharge from the reaction zone, (iii) separating said flow into an olefin-enriched fraction and an olefin-depleted fraction by means of an olefin-selective membrane, and (iv) removing the olefin-enriched fraction is at least partially redirected into the reaction zone.

Description

METHOD FOR THE HYDROFORMYLATION OF OLEFINS COMPRISING 2 TO 8 CARBON ATOMSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority from U.S. Provisional Patent Application No. 63 / 735,027, filed December 17, 2024, the disclosures of which are incorporated herein by reference.BACKGROUND OF THE INVENTIONField of the Invention

[0002] The present invention is directed to a process for the hydroformylation of olefins having 2 to 8 carbon atoms. The present invention is also directed to a gas treatment system for obtaining and recycling olefins, the use of an olefin-selective membrane, and an olefin-enriched fraction obtained by the process.Discussion of the Background

[0003] Hydroformylation or the oxo process is an important industrial process for preparing aldehydes from olefins, carbon monoxide and hydrogen. These aldehydes can, if desired, be hydrogenated by means of hydrogen in the same process step or subsequently in a separate hydrogenation step to give the corresponding alcohols. Other oxo-process related products may be formed. The hydroformylation is carried out in the presence of catalysts which are homogeneously dissolved in the reaction medium. Catalysts used are generally compounds or complexes of metals of transition group VIII, especially Co, Rh, lr, Pd, Pt or Ru compounds or complexes, which may be unmodified or modified with, for example, amine- or phosphine- containing compounds.

[0004] Since a quantitative conversion of the olefin in hydroformylation requires a high outlay in terms of apparatus, the hydroformylation of lower olefins in particular is usually carried out only to a partial conversion. The hydroformylation product is separated from the output from the reaction and the unreacted olefin is then recirculated to the hydroformylation reactor together with fresh carbon monoxide and hydrogen. However, inert components, e.g. saturated hydrocarbons, which are not accessible to thehydroformylation reaction and have been introduced with the olefin or formed by secondary reactions, are returned to the reactor with the recirculated olefin. To prevent the concentration of inert components continually increasing in the hydroformylation reactor and reaching values at which the hydroformylation reaction ceases, a substream of the recirculated stream continuously has to be discharged from the process in order to remove the inert components from the system.

[0005] However, this bleed stream consists only partly of inert components. The major part is made up of unreacted olefin and unreacted carbon monoxide and hydrogen, which are thus lost from the reaction. To keep the bleed stream small and keep the losses associated therewith low, an olefin feed of high purity is generally used. Thus, in the hydroformylation of propylene, use is generally made of a propylene feed having a purity of about 99.5% with the balance being essentially propane. This is sometimes known as “polymer grade propylene”. However, such high-purity olefin feeds are costly to obtain and therefore command significantly higher market prices than do olefins of lower purity. Thus, for example, “chemical grade propylene” which contains from about 3 to 7% by weight of propane is considerably cheaper than the abovementioned polymer grade propylene.

[0006] For the reasons mentioned, olefin feeds of lower purity, which contain, for example, more than 0.5% by weight of saturated hydrocarbons, cannot be used in industrial hydroformylation processes without specific measures being taken. To prevent the concentration of saturated hydrocarbons in the hydroformylation reactor reaching values which are so high that the hydroformylation ceases, the bleed stream would have to be so large that the associated loss of unreacted olefin would wipe out the savings achieved by using the cheaper feedstock.

[0007] EP-A 0 648 730 discloses a process for preparing an oxo product obtained from propylene, in which a gas stream comprising unreacted propylene and propane is separated off from the product stream from a propylene hydroformylation. Selective adsorption of propylene on an adsorbent and subsequent desorption give a propylene- enriched gas stream which is at least partly recirculated to the reaction zone. The alternating adsorption and desorption cycles require periodic pressure and / or temperature changes. The apparatuses required for this are complicated andsusceptible to malfunctions.

[0008] Walz et al. U.S. 6,969,777 discloses a method for the hydroformylation of olefins comprising 2 to 8 carbon atoms.

[0009] Loprete et al. WO 2018 / 209362 discloses improved membranes for separating alkenes from other compounds.

[0010] Majumdar et al. WO 2016 / 182887 A1 discloses thin film composite membranes for separation of alkenes from alkanes.

[0011] Freeman et al. WO 2023 / 023280 A1 discloses selective and hydrogen-stable facilitated transport membranes for olefin-paraffin separation.

[0012] Baker et al. U.S. Patent Publication No. US 6,271 ,319 B1 discloses membrane- augmented polypropylene manufacturing.

[0013] Dembicki et al. U.S. Patent Publication No. US 4,623,704 discloses the use of membranes for ethylene recovery in polymerization processes.

[0014] Murnen et al. 31stEthylene Producers Conference 2019, Topical Conference at the 2019 AIChE Spring Meeting and 15thGlobal Congress on Process Safety, session 121 : Ethylene Plant Technology Fundamentals Paper 121d. “Separation of Olefin- Paraffin Mixtures with OPTIPERM™ Customized Amorphous Fluoropolymer Membranes”, pp. 393-402, discloses the separation of olefins from paraffins.

[0015] Wolfgang et al. EP1294670 discloses a method for producing hydroformylation products of olefins with 2 to 8 carbon atoms.

[0016] It is an object of the present invention to provide an improved process for the hydroformylation of olefins which allows the use of olefin-containing feeds in which a proportion of saturated hydrocarbons is present.SUMMARY OF THE INVENTION

[0017] This object is achieved by a process for the hydroformylation of olefins having from 2 to 8 carbon atoms, the process comprising each of the following at least once:(i) reacting an olefin-containing feed in which a proportion of a saturated hydrocarbon having from 2 to 8 carbon atoms is present, with carbon monoxide and hydrogen fed into a reaction zone in the presence of a hydroformylation catalyst;(ii) separating a stream comprising unreacted olefin and saturatedhydrocarbon from an output from the reaction zone;(iii) separating the stream into an olefin-enriched fraction and an olefin- depleted fraction using an olefin-selective membrane; and(iv) removing at least part of the olefin-enriched fraction for recirculating to the reaction zone or reactor, and / or removing at least part of the olefin-depleted fraction.

[0018] The present invention also relates to a process for the hydroformylation of olefins having from 2 to 8 carbon atoms, the process comprising each of the following at least once:(i) reacting an olefin-containing feed in which a proportion of a saturated hydrocarbon having from 2 to 8 carbon atoms is present, with carbon monoxide and hydrogen fed into a reaction zone in the presence of a hydroformylation catalyst;(ii) separating a stream comprising unreacted olefin and saturated hydrocarbon from the reaction zone;(iii) separating the stream into an olefin-enriched fraction and an olefin- depleted fraction using an olefin-selective membrane; and(iv) removing at least part of the olefin-enriched fraction for recirculating to the reaction zone, and wherein the stream comprising unreacted olefin and saturated hydrocarbon is obtained by firstly separating off a crude hydroformylation product comprising unreacted olefin and saturated hydrocarbon in dissolved form from an output from the reaction zone, and subjecting the crude hydroformylation product to a degassing step.

[0019] The present invention also provides a gas treatment system for obtaining and recycling olefins, the system comprising: an olefin-gas selective membrane separation unit that permeates olefins at least two times faster, or at least 2 to 700 times faster, than saturated hydrocarbons with the same number of carbons, to produce an olefin-enriched permeate stream; and an outlet gas vent for an olefin-depleted retentate stream to be removed; and optionally further comprising an inlet for the olefin-enriched permeate stream to be recycled into an oxo-process reactor.

[0020] Further provided in the present invention is the use of an olefin-selective membrane to separate a mixture of an olefin-enriched fraction and an olefin-depletedfraction, wherein the mixture is obtained from hydroformylation of an olefin-containing feed comprising a saturated hydrocarbon having 2 or more carbon atoms, carbon monoxide and hydrogen.BRIEF DESCRIPTION OF THE DRAWINGS

[0021] A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

[0022] FIG. 1 shows an embodiment of a schematic representation of the inventive method using the gas recycling process.

[0023] FIG. 2 shows an embodiment of a schematic representation of the inventive method combined with a rectification column.

[0024] FIG. 3 shows an embodiment of a schematic representation of the inventive method combined with a rectification column.DETAILED DESCRIPTION OF THE INVENTION

[0025] The process of the invention permits the use of olefin-containing feeds with saturated hydrocarbons that can be separated downstream in the process, such that any unreacted olefin can be recycled or recirculated. Olefin / saturated hydrocarbon separation is traditionally performed by distillation in a rectification column, such as a “C3 splitter”, which requires large capital investment (to use hundreds or even more trays in one column), due to the low relative volatility between the two components. The required investment is so high that typically oxo plants do not have an olefin recovery section, with unreacted olefin being sent directly to the flare.

[0026] Instead, the process of the present invention targets the use of an alternative to distillation for recovering unreacted olefin, from an outlet gas of the reaction section of the oxo process. Gas permeation membranes that are selective towards olefins in olefin / paraffin separations may be used on streams associated with crackers or olefin- producing facilities. However, the present inventors have found that use of separation membranes to recover olefin when using the oxo process, i.e. , in an oxo plant,particularly allows recovery of olefin at a lower investment cost compared to traditional distillation. This enables olefins to be recycled at plants that currently do not have a rectification column, as well as debottlenecking the olefin recycling system in plants where an existing rectification column is already operating at maximum capacity.

[0027] In one embodiment, there is provided a process for the hydroformylation of olefins having 2 to 8 carbon atoms, the process comprising each of the following at least once:(i) reacting an olefin-containing feed in which a proportion of a saturated hydrocarbon having from 2 to 8 carbon atoms is present, with carbon monoxide and hydrogen fed into a reaction zone in the presence of a hydroformylation catalyst;(ii) separating a stream comprising unreacted olefin and saturated hydrocarbon from an output from the reaction zone;(iii) separating the stream into an olefin-enriched fraction and an olefin- depleted fraction using an olefin-selective membrane; and(iv) removing at least part of the olefin-enriched fraction for recirculating to the reaction zone or reactor, and / or removing at least part of the olefin-depleted fraction. In one aspect, the reaction zone comprises a reactor. In another aspect, the reaction zone contains more than one reactor. For example, two or three reactors.Olefin-containing feed

[0029] In one embodiment, in (i) of the present process, the olefin-containing feed is fed in a liquid phase or a gas phase. Olefins which can be hydroformylated by the process of the present invention contain from 2 to 8, preferably from 2 to 4 carbon atoms. They can be straight-chain, branched or cyclic olefins, as would be known to one of ordinary skill in the art. Preferred examples of suitable olefins are ethene, propene, 1 -butene and / or 2-butene. The olefin-containing feed can comprise a single olefin or a mixture of olefins. The olefin is fed into the reaction zone in the form of an olefin-containing feed containing, for example, from 0.5 to 40% by weight, preferably from 2 to 30% by weight, in particular from 3 to 10% by weight, of at least one saturated hydrocarbon, i.e. an alkane and / or cycloalkane, having from 2 to 8 carbon atoms. In general, the olefin and the saturated hydrocarbon have the same number of carbon atoms. The olefin-containing feed usually comprises olefin and saturated hydrocarbon, i.e. it preferably contains less than 0.5% by weight of components other than olefin and saturated hydrocarbon.

[0030] The term “comprising” is interchangeable with “including” and “containing” as used herein. “Consists essentially of’ refers to the specified materials or steps and those that do not materially affect the scope of the properties or characteristics of the claimed invention.

[0031] In one embodiment, the olefin is at least one selected from the group consisting of: decene, nonene, octene, heptene, hexene, pentene, butene, propene, ethene, and combinations thereof.

[0032] Suitable olefin-containing feeds are available on an industrial scale. A preferred example is a mixture of propane and propene, preferably containing from 2 to 10% by weight, in particular from 3 to 7% by weight, of propane. Such mixtures are commercially available as “chemical grade propylene”. They are obtained, for example, by conversion of naphtha or natural gas in steam crackers and subsequent work-up by distillation. A further example of a suitable olefin-containing feed is “refinery grade propylene” which has a propane content of from 20 to 40% by weight.

[0033] Carbon monoxide and hydrogen are usually used in the form of a mixture, known as synthesis gas. The composition of the synthesis gas used in the process of the present invention can vary within a wide range. The molar ratio of carbon monoxide to hydrogen is generally from 2:1 to 1 :2, in particular from about 45:55 to 50:50.

[0034] In another embodiment, there is provided a process for the hydroformylation of olefins having from 2 to 8 carbon atoms, the process comprising each of the following at least once:(i) reacting an olefin-containing feed in which a proportion of a saturated hydrocarbon having from 2 to 8 carbon atoms is present, with carbon monoxide and hydrogen fed into a reaction zone and reacted in the presence of a hydroformylation catalyst;(ii) separating a stream comprising unreacted olefin and saturated hydrocarbon from the reaction zone;(iii) separating the stream into an olefin-enriched fraction and an olefin-depleted fraction using an olefin-selective membrane; and(iv) removing at least part of the olefin-enriched fraction for recirculating to the reaction zone, and wherein the stream comprising unreacted olefin and saturated hydrocarbon is obtained by firstly separating off a crude hydroformylation product comprising unreacted olefin and saturated hydrocarbon in dissolved form from an output from the reaction zone, and subjecting the crude hydroformylation product to a degassing step.

[0035] In one embodiment, the output from the reaction zone is essentially gaseous, and the crude hydroformylation product is separated off by condensation from the gaseous output. In one aspect, the output from the reaction zone is essentially liquid, the liquid output is depressurized so that it is separated into a liquid phase which comprises high-boiling by-products, a homogeneously dissolved hydroformylation catalyst and small amounts of hydroformylation product, small amounts of unreacted olefin and small amounts of saturated hydrocarbon, and a gas phase comprising hydroformylation product, unreacted olefin and saturated hydrocarbon and also unreacted carbon monoxide and hydrogen, and the crude hydroformylation product is obtained by at least partial condensation of the gas phase.

[0036] In one embodiment, the olefin and the saturated hydrocarbon have the same number of carbon atoms. In one aspect, in (i) the olefin-containing feed comprises a mixture selected from the group consisting of: butene and butane, iso-butene and isobutane, propene and propane, and ethene and ethane, and combinations thereof. In a further aspect, the mixture contains from 0.5 to 10 % by weight of propane or ethane.Reaction conditions

[0037] In one embodiment, the mole fraction ratio of olefin: saturated hydrocarbon in a permeate side of the olefin-selective membrane is approximately 4:1 or greater.

[0038] The temperature in the hydroformylation reaction is generally in a range from about 50 to 200° C, preferably from about 60 to 190° C, in particular from about 90 to 190° C. The reaction is preferably carried out at a pressure in the range from about 10 to 700 bar, preferably from 15 to 200 bar, in particular from 15 to 60 bar. The reaction pressure can be varied as a function of the activity of the hydroformylation catalystused.

[0039] Suitable pressure-rated reaction apparatuses for hydroformylation are known to those skilled in the art. They include the generally customary reactors for gas-liquid reactions, e.g. gas circulation reactors, bubble columns, etc., which may optionally be divided by internals.

[0040] Suitable hydroformylation catalysts are the customary transition metal compounds and complexes known to those skilled in the art, which can be used either with or without cocatalysts. The transition metal is preferably a metal of transition group VIII of the Periodic Table, in particular Co, Ru, Rh, Pd, Pt, Os or Ir, especially Rh, Co, lr or Ru. In one embodiment, the hydroformylation catalyst used is a phosphorus- containing rhodium catalyst.

[0041] Suitable complexes are, for example, the carbonyl compounds of the abovementioned metals and also complexes whose ligands are selected from among amines, arylphosphines, alkylphosphines, arylalkylphosphines, olefines, dienes, etc., and mixtures thereof.

[0042] Examples of suitable catalysts are rhodium complexes of the formula RhXmL1L2(L3)n, where:X is halide, preferably chloride or bromide, alkylcarboxylate or arylcarboxylate, acetylacetonate, arylsulfonate or alkylsulfonate, in particular phenylsulfonate and toluenesulfonate, hydride or the diphenyltriazine anion,L1, L2, L3are, independently of one another, CO, olefins, cycloolefins, preferably cyclooctadiene (COD), dibenzophosphole, benzonitrile, PR3 or R2P-A-PR2, m is 1 or 3, and n is 0, 1 or 2.

[0043] Radicals R (which may be identical or different) are alkyl, cycloalkyl and aryl radicals, preferably phenyl, p-tolyl, m-tolyl, p-ethylphenyl, p-cumyl, p-t-butylphenyl, p-C1- C4-alkoxyphenyl, preferably p-anisyl, xylyl, mesityl, p-hydroxyphenyl, which may also be ethoxylated, sulfophenyl, isopropyl, C1-C4-alkoxy, cyclopentyl or cyclohexyl. A is 1 ,2- ethylene or 1 ,3-propylene.

[0044] L1, L2and L3 are each preferably, independently of one another, CO, COD, P(phenyl)3, P(i-propyl)3, P(anisyl)3, P(OC2H5)3, P(cyclohexyl)3, dibenzophosphole orbenzonitrile.

[0045] X is preferably hydride, chloride, bromide, acetate, tosylate, acetylacetonate or the diphenyltriazine anion, in particular hydride, chloride or acetate.

[0046] Preferred hydroformylation catalysts are phosphorus-containing rhodium catalysts as are formed, for example, in situ under hydroformylation conditions from a rhodium source and a triarylphosphine such as triphenylphosphine, for example RhH(CO)2(PPh3)2 or RhH(CO)(PPh3)3.

[0047] Suitable hydroformylation catalysts are described, for example, in Beller et al., Journal of Molecular Catalysis A, 104 (1995), pp. 17-85, which is hereby fully incorporated by reference.

[0048] In one embodiment, the process further comprises flash evaporation, cooling, rectification, distillation, compression, and / or condensation. In one aspect, the process further comprises rectification or distillation before or after using the olefin-selective membrane. In another aspect, the olefin-selective membrane treats a sidedraw stream from a rectification column. A sidedraw stream permits a stream to be drawn from the side of the column.Conversion

[0049] A partial conversion, based on the olefin fed in, takes place per pass through the reaction zone. The conversion is generally from about 10 to about 90%, based on the olefin fed in. In one aspect, the hydroformylation conversion is greater than about 50 %, about 60 %, about 70 %, and / or about 80 %.Separation

[0050] The output from the reaction zone is subjected to a single-stage or multistage separation operation to give at least a stream comprising a major part of the hydroformylation product and a stream comprising unreacted olefin and saturated hydrocarbon. Depending on the output method, further streams, e.g. waste gases comprising synthesis gas and streams comprising high-boiling by-products of the hydroformylation and / or hydroformylation catalyst, may be obtained and are, if appropriate after work-up, wholly or partly recirculated to the reaction zone ordischarged from the process. For example, the hydroformylation product and any components having higher boiling points than the hydroformylation product can firstly be separated off from the output from the reaction zone. Subsequently, a mixture of unreacted olefin and saturated hydrocarbon can be condensed out. In one aspect, the stream of the process is purged. The stream may be purged with an inert gas such as nitrogen, argon, helium and / or hydrogen.

[0051] In one embodiment, the stream in the discharge outlet in the process from the reaction zone is gaseous or liquid. In one embodiment, the stream from the reaction zone is liquid; and / or a liquid discharge stream is obtained that is expandable; and / or a crude hydroformylation product is separated into a liquid phase comprising high-boiling by-products, highly-solubilized hydroformylation catalyst, low amounts of hydroformylation product, small amounts of unreacted olefin, and small amounts of saturated hydrocarbon, and a gas phase comprising a crude hydroformylation product, unreacted olefin, saturated hydrocarbon, unreacted carbon monoxide, hydrogen, wherein the crude hydroformylation product is obtained by at least partial condensation of the gas phase.

[0052] However, the stream comprising unreacted olefin and saturated hydrocarbon is advantageously obtained by firstly separating off a crude hydroformylation product comprising unreacted olefin and saturated hydrocarbon in dissolved form from the output from the reaction zone and then subjecting the crude liquid hydroformylation product to a degassing step, giving a stream which consists essentially of unreacted olefin and saturated hydrocarbon. The remainder of the reaction mixture from which the crude hydroformylation product has been separated is generally wholly or partly recirculated to the reaction zone. The crude hydroformylation product can be degassed by depressurizing it, heating it and / or treating it with a stripping gas such as synthesis gas or nitrogen. The degassing is advantageously carried out in a column where the crude hydroformylation product is fed in in the region of the middle of the column, the degassed hydroformylation product is taken off at the bottom of the column and passed to further work-up, and a liquid or gaseous stream comprising unreacted olefin and saturated hydrocarbon is taken off the top of the column.

[0053] The separation of the crude hydroformylation product from the output from the reaction zone can be carried out in various ways. One way is to use the liquid output process, in which the essentially — apart from the synthesis gas used in excess for the hydroformylation — liquid output from the reaction zone is depressurized so that it is, as a result of the pressure reduction, separated into a liquid phase which consists essentially of high-boiling by-products, the homogeneously dissolved hydroformylation catalyst and small amounts of hydroformylation product, unreacted olefin and saturated hydrocarbon, and a gas phase which consists essentially of hydroformylation product, unreacted olefin and saturated hydrocarbon together with unreacted synthesis gas. The liquid phase can be recirculated to the reactor as recycle stream. The crude hydroformylation product is obtained by at least partial condensation of the gas phase. The gas phase remaining after the condensation is wholly or partly recirculated to the reaction zone.

[0054] The gas and liquid phase obtained initially in the depressurization step can advantageously be worked up by the process described in WO 97 / 07086. For this purpose, the liquid phase is heated and introduced into the upper region of a column, while the gas phase is introduced into the bottom of the column. Liquid phase and gas phase are thus conveyed in countercurrent. To increase mutual contact of the phases, the column is preferably provided with packing. As a result of the intimate contact of the gas phase with the liquid phase, the residual amounts of hydroformylation product, unreacted olefin and saturated hydrocarbon present in the liquid phase are transferred to the gas phase, so that the gas stream leaving the top of the column is enriched in hydroformylation product, unreacted olefin and saturated hydrocarbon compared to the gas stream introduced at the lower end of the column. The further work-up of the gas stream leaving the column and of the liquid phase leaving the column is carried out in a customary manner, for example as described above.

[0055] Alternatively, it is possible to employ, particularly with the use of C2-C4-olefins, the gas recycle process, in which a gas stream is taken off from the gas space of the hydroformylation reactor. This gas stream comprises synthesis gas, unreacted olefin and saturated hydrocarbon together with an amount, determined by the vapor pressure in the hydroformylation reactor, of the hydroformylation product formed in thehydroformylation reaction. The hydroformylation product present in the gas stream is separated off from the gas stream, e.g. condensed out by cooling, and the gas stream which has been freed of the liquid component is recirculated to the hydroformylation reactor.

[0056] The stream comprises unreacted olefin and saturated hydrocarbon comprises, for example, from about 50 to about 95% by weight, preferably from about 60 to about 80% by weight, of olefin and from about 5 to about 50% by weight, preferably from about 20 to about 40% by weight, of saturated hydrocarbon.

[0057] The stream comprising unreacted olefin and saturated hydrocarbon is separated into an olefin-enriched fraction and an olefin-depleted fraction using an olefin-selective membrane. The olefin-selective membrane is as described herein.Olefin-selective membranes

[0058] Suitable membranes for practicing applicant’s invention are described in WO 2023 / 023280 A1 , WO 2016 / 182887 A1 , WO 2018 / 209362, and U.S. Patent Publication Numbers US 6,271 ,319 B1 , US 4,623,704.

[0059] In one embodiment, the olefin-selective membrane comprises at least one membrane selected from the group consisting of: a porous support, a nonporous layer optionally including a silver ionomer of a fluorinated polymer, a thin film composite (TFC), a polymeric membrane, an inorganic membrane, a solid polymer electrolyte membrane, and combinations thereof.

[0060] In a further aspect, the polymeric membrane comprises a membrane selected from the group consisting of: a polyimide selective layer, a poly(phenylene oxide) selective layer, a selective layer comprising perfluorinated dioxole, a selective layer comprising perfluorinated dioxolane, a selective layer comprising perfluorinated cyclic ether, and combinations thereof.

[0061] In another embodiment, the process comprises a polymeric membrane, wherein the polymeric membrane comprises a polymer selected from the group consisting of: polyamides, polyimides, polyetherimide, polypyrrolones, polyesters, polyethers, poly (vinyl methyl ketone), poly (ether ether ketone), polymethylene oxides, polyethylene oxides, poly(trimethylene oxides), poly(tetramethylene oxides), polypropylene oxides),polyethylene glycols, polyethylene imine), polyalkylene sulfides, sulfone-based polymers, nitrile-based polymers, polymeric organosilicones, fluorinated polymers, polydimethylsiloxane, polydiethylsiloxane, polydi-iso- propylsiloxane, polydiphenylsiloxane, polyethersulfone, polyphenylsulfone, polysulfone, polyacrylonitrile, polyvinylidene fluoride, polyphenylene oxide, polybenzimidazole, polyvinylpyrrolidone, poly(2-oxazoline), poly(ethyl methacrylate), poly(methyl methacrylate), poly(acrylic acid), polyacrylamide, poly(vinyl alcohol), poly(e- caprolactone), poly(styrene-b- butadiene-b-styrene), chitosan, cellulose acetate, copolymers thereof, and combinations thereof.

[0062] In another embodiment, the olefin-selective membrane comprises metal ions including metal ions selected from the group consisting of: transition metal ions, silver ions, copper ions, gold ions, nickel ions, iron ions, manganese ions, zinc ions, and combinations thereof; and / or comprises at least about 15 % polymers relative to metal ions.

[0063] In one embodiment, the process comprises a membrane unit which contains a membrane that exhibits a substantially higher permeability for propylene than for propane. In one embodiment, the olefin-enriched fraction is transported through the olefin-selective membrane in the process by facilitated transport. These membranes contain a liquid that itself contains, for example, free silver ions that reacts selectively and reversibly with unsaturated hydrocarbons, to selectively carry propylene across the membrane.

[0064] Other membranes include those that make use of free carrier ions dissolved in a solid polymer solution, rather than an aqueous solution. The membranes remain mechanically stable up to feed pressures of at least 500 psig and can work with dry feed gases.

[0065] Yet other membranes with olefin / paraffin separating properties are very finely porous inorganic membranes, such as carbon membranes, that act as very fine sieves that separate on the basis of difference in molecular size. Inorganic membranes are characterized by good temperature and chemical resistance. Such membranes are available commercially for propylene / propane separation, Such as from Carbon Membranes Ltd., of Arava, Israel, and are reported to provide propylene / propaneselectivity of up to 12-15 and propylene permeance of 180 GPU under favorable conditions.

[0066] In another aspect for example, water-wet cellulose ester membranes are available in both hollow fiber and spiral devices, which can be dried before use.

[0067] Suitable membranes for use in the invention are polymeric membranes. The permeability of a gas or vapor through a polymer film is a product of the diffusion coefficient, D, and the Henry's law sorption coefficient, kD is a measure of the permeant's mobility in the polymer; k is a measure of the permeant's Sorption into the polymer. The diffusion coefficient tends to decrease as the molecular size of the permeant increases, because large molecules interact with more segments of the polymer chains and are thus less mobile. The sorption coefficient depends, amongst other factors, on the condensability of the gas.

[0068] In one aspect, the membrane is an inorganic membrane. In another aspect the membrane is a solid polymer electrolyte membrane.

[0069] Several membranes can be employed in series to improve separation performance. The optimum number of membrane stages depends upon the feed composition, nature of the membrane, the process pressure, the permeate pressure, feed temperature and other factors. Not all the membrane stages need operate with liquids present in the fluid feed. The most advantageous number of stages can be determined empirically.

[0070] In one aspect, for example the stream may be passed over a cellulose triacetate membrane that is selective for ethylene over ethane. The separation is such that the permeate containing an olefin-rich fraction is sufficiently free from impurities, and the olefin-rich fraction can return to the reactor. For example, the permeate contains less than or equal to 5 % impurities relative to the entire permeate.

[0071] In one embodiment, the process further comprises a step of dehydrogenating the stream prior to feeding it to the olefin-selective membrane, wherein the dehydrogenating forms the olefin from the saturated hydrocarbon and generates hydrogen gas.

[0072] In one embodiment, in (iii) of the process of the present invention the stream comprising unreacted olefin and saturated hydrocarbon is obtained by: removing a crude hydroformylation product containing the unreacted olefin and the saturatedhydrocarbon in solution from a discharge outlet, and subjecting the crude hydroformylation product to degassing. In one aspect, the stream in the discharge outlet in the process from the reaction zone is gaseous, and / or the crude hydroformylation product is separated from the gaseous stream by condensation.

[0073] In yet another embodiment, the permeate stream comprises an olefin concentration of less than 95 %. In one embodiment, the process comprises long chain olefins in the gaseous phase, and the olefin-selective membrane is configured to sustain high pressure optionally using a compressor that is not upstream of the olefinselective membrane. The upstream side is the feed side or the retentate side.

[0074] In one embodiment, the olefin-rich fraction is rich in propene or ethene and / or the olefin- depleted fraction is rich in propane and / or ethane.

[0075] In one embodiment, the olefin-selective membrane comprises at least two layers in which: one of the at least two layers contains metal ions and includes a silver ionomer of polymeric sulfonic acid; and / or a second layer comprises a high diffusion rate layer of one or more fluorinated polymers having a permeance to the olefin of at least about 250 GPU, and optionally the second layer is about 0.05 to about 1.0 pm in thickness.

[0076] In one embodiment, the olefin-selective membrane comprises: a three-layer membrane in which at least two layers are laminated to each other, and / or a porous layer is laminated to a second layer.

[0077] In a further embodiment, the process has a driving force for (iv) separating the stream of olefins from non-olefins in a gaseous state, is obtained by selecting from the group consisting of: a partial pressure of the olefin on a feed side of the olefin-selective membrane being higher than a partial pressure of olefin on a permeate side, sweeping a permeate side with an inert gas, reducing pressure of a permeate side using a vacuum pump to lower the partial pressure of olefin, and combinations thereof.

[0078] In one embodiment, the olefin-selective membrane is about 0.05 pm to about 1.0 pm in thickness, and / or at least about 80% selective for the olefin over the saturated hydrocarbon. In another embodiment, the process further comprises:

[0079] collecting and removing the olefin-enriched fraction from a permeate stream obtained from a permeate side of the olefin-selective membrane, and / or

[0080] collecting and removing the olefin-depleted fraction from a feed side of the olefin-selective membrane, and / or

[0081] recycling or reusing the olefin-selective membrane in a continuous process.

[0082] In one embodiment, there is provided a use of an olefin-selective membrane to separate a mixture of an olefin-enriched fraction and an olefin-depleted fraction, wherein the mixture is obtained from hydroformylation of an olefin-containing feed comprising a saturated hydrocarbon having 2 or more carbon atoms, carbon monoxide and hydrogen.Gas treatment system

[0083] The present invention further relates to the use of olefin / unsaturated hydrocarbon gas separation membranes as part of the gas treatment system for olefin to be recycled to the reactor, in the oxo process. The actual location of the membrane separation unit in the process is likely to vary from one oxo plant to the other, depending on whether an olefin recycle system is already available or not at the plant. In all cases, an olefin / unsaturated hydrocarbon mixture is fed to a membrane unit, which is provided with an olefin-selective membrane. This membrane unit then produces an olefin- enriched stream as the permeate, which can then be further processed (in the case of debottlenecking an existing rectification column, for instance), or recycled back to the reactor directly (if the plant is currently flaring unreacted olefin), depending on the selectivity of the membrane.

[0084] In one embodiment, there is provided a gas treatment system for obtaining and recycling olefin, the system comprising:

[0085] an olefin-gas selective membrane separation unit that permeates olefin at least two times faster, or at least 2 to 700 times faster than saturated hydrocarbons with the same number of carbons, to produce an olefin-enriched permeate stream; and

[0086] an outlet gas vent for an olefin-depleted retentate stream to be removed; and

[0087] optionally further comprising an inlet for the olefin-enriched permeate stream to be recycled into an oxo-process reactor.Rectification

[0088] In one embodiment, the process described herein further comprises separating the stream into an olefin-enriched fraction and an olefin-depleted fraction by rectification(distillation). The rectification is usually carried out at low temperature and / or superatmospheric pressure, with the precise temperature and / or pressure conditions depending on factors such as the number of carbon atoms in the olefin / saturated hydrocarbon to be separated, etc. The rectification is generally carried out in a column which is provided with a sufficiently large number of rectification trays. Columns for such separation tasks are known per se and are used, for example, for the separation of olefins and saturated hydrocarbons present in the cracker gas from a steam cracker. The stream to be fractionated can be introduced into the column either in gaseous form or in liquid form, preferably in the region of the middle of the column. The olefin- enriched fraction can advantageously be taken off at the top or in the upper region of the column, and the olefin-depleted fraction can advantageously be taken off at the bottom or in the lower region of the column.

[0089] In one embodiment, there is provided an olefin-enriched fraction obtained by the process of the present invention.Olefin-depleted fraction

[0090] In one embodiment, the olefin-depleted fraction comprises at least one saturated hydrocarbon selected from the group consisting of: butane, isobutane, propane, ethane, and combinations thereof. In general, efforts are made to obtain an olefin-depleted fraction consisting of substantially pure saturated hydrocarbon, so that it can be discharged from the process without resulting in a relatively large loss of olefin. In contrast, pure olefin is generally not sought in the case of the olefin-enriched fraction, but instead a certain content of saturated hydrocarbons is permitted so as to reduce the cost of the separation. For the purposes of the present invention, it is sufficient for the olefin-enriched fraction to be enriched in olefin compared to the output from the reaction zone, i.e. the ratio of olefin to saturated hydrocarbon in it is greater than in the output from the reaction zone.

[0091] The olefin-depleted fraction preferably comprises less than about 50% by weight, in particular less than about 30% by weight, of olefin. The olefin-enriched fraction usually comprises more than about 70% by weight, e.g. from about 75 to about 95% by weight, of olefin.

[0092] In a particularly preferred embodiment of the process of the present invention, a propylene-containing feed in which a proportion of propane is present is used. A mixture of propylene and propane is therefore obtained as stream to be separated. The separation of this stream into a propylene-enriched fraction and a propylene-depleted fraction is carried out in a suitable distillation column operated under positive gauge pressure, namely a C3 splitter. The column is preferably operated so that a propylene- enriched fraction which can be recirculated directly to the reaction zone is obtained at the top, and largely pure propane which can be removed from the system without loss of propylene can be taken off at the bottom. Typical operating conditions for the C3 splitter are: pressure at the top = 20 to 25 bar, temperature at the bottom = 60 to 70° C, from 100 to 150 theoretical plates.

[0093] The olefin-depleted fraction is discharged from the system. It can, for example, be burnt. It can also be used as feedstock for chemical reactions, e.g. in a steam cracker. In one aspect, the olefin-depleted fraction is fed to a steam cracker. In a particularly advantageous embodiment, the olefin-depleted fraction is fed to a steam cracker from whose cracker gas the olefin-containing feed for the process of the present invention is obtained. After attainment of steady-state operation of the process of the present invention, an amount of saturated hydrocarbon which corresponds essentially to the sum of the amount of saturated hydrocarbon introduced with the olefin-containing feed and the amount formed in the hydroformylation is discharged together with the olefin-depleted fraction.

[0094] The process of the present invention starts from olefin-containing feeds in which a proportion of a saturated hydrocarbon is present. Such mixtures are obtained on an industrial scale and isolation of them is considerably less costly than that of the corresponding highly purified olefin feeds. Although a point downstream of the hydroformylation is required for separation of olefin and saturated hydrocarbon in the process of the invention, the fractionation of an olefin / saturated hydrocarbon stream separated from the hydroformylation product is significantly simpler and less costly than the fractionation of the entire olefin-containing feed, since the stream obtained after the hydroformylation is reduced by the proportion of olefin which has been converted into aldehyde and / or alcohol in the hydroformylation reaction. The amounts of mixture to befractionated are considerably lower in the stage downstream of the reaction zone than in the entire feed. Thus, the separation plant can be made smaller, which is associated with lower capital costs. A further advantage is that the olefin content of the olefin- enriched fraction has to be increased only to a sufficient extent for the weight ratio of olefin to saturated hydrocarbon in the olefin-enriched fraction to be greater than that in the output from the reaction zone. An olefin-containing feed in conventional hydroformylation processes generally has significantly higher olefin contents, e.g. about 99.5%.

[0095] For example, when propylene is used as raw material in the oxo process for production of butyraldehyde, it is converted to butanol and / or other oxo-related products such as 2-ethyl hexanol. During the reaction, propane is generated as a by-product, which undergoes a propylene / propane separation using an olefin-selective membrane. The unreacted propylene is recycled in the process.

[0096] An advantageous embodiment of the process of the present invention is shown in FIG. 1 and is explained below.

[0097] FIG. 1 shows a schematic flow diagram of the process of the present invention carried out by the gas recycle method. Self-evident plant details which are not necessary to illustrate the process of the present invention have been omitted in the interest of clarity. Other suitable components may be present.

[0098] In FIG. 1, an olefin-containing feed (9) comprising the olefin to be hydroformylated and a saturated hydrocarbon, and an olefin-containing stream recirculated via line (8) together with synthesis gas (10), i.e. a mixture of carbon monoxide and hydrogen, are fed into the reactor (1) and hydroformylated there to partial conversion. A gaseous stream comprising unreacted olefin, saturated hydrocarbon, unreacted synthesis gas and a hydroformylation product is taken from the gas space of the reactor. The stream is cooled in the heat exchanger (2) and passed to a phase separation vessel (3). The gaseous part is recirculated via the compressor (4) to the reactor (1). The liquid obtained in the separation vessel (3), which consists essentially of crude hydroformylation product together with olefin and saturated hydrocarbon dissolved therein, is fed to the degassing column (5) at the top of which a mixture of olefin and saturated hydrocarbon is obtained. At the bottom of the degassing column(5), the crude hydroformylation product (7) is taken off and is subsequently processed further. The mixture of olefin and saturated hydrocarbon is fed to the gas permeation unit (6) containing the olefin-selective membrane (11), which is shown in one embodiment to be positioned in or configured to be connected to the reaction zone or reactor 1. At the gas permeation unit, an olefin stream having a reduced proportion of saturated hydrocarbon is obtained on the permeate side of the olefin-selective membrane, and it is recirculated via line (8) to the hydroformylation reactor (1). At the retentate side of the olefin- selective membrane, a mixture with a lower olefin-to-paraffin ratio compared to the stream at the top of the degassing column is obtained. This stream is removed from the system via line (12).

[0099] FIG. 2 shows a schematic flow diagram of the process of the present invention combining a gas permeation unit and a rectification column for olefin recovery. Self- evident plant details which are not necessary to illustrate the process of the present invention have been omitted in the interest of clarity. Other suitable components may be present.

[0100] In FIG. 2, the gas permeation unit (6) containing the olefin-selective membrane (11) is fed by the mixture of olefin and saturated hydrocarbon coming from the degassing column (5). The olefin-rich stream (13) from the permeate side of the membrane and the retentate stream enriched in the saturated hydrocarbon (14) are fed to the rectification column (15) at different positions. The top product of the rectification column is an olefin stream with a small amount of saturated hydrocarbon, which is recycled to the reactor via line (16). The bottom production of the rectification column, in turn, comprises the saturated hydrocarbon with a small amount of olefin, which is purged from the system via line (17).

[0101] Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified.EXAMPLEExample 1 : A system or plant as shown in FIG. 2 is used.

[0102] A feed stream of 10 t / h of chemical grade propylene (95% propylene, 5% propane), synthesis gas, and a recycle stream (16) of 3.2 t / h from the olefin recovery system including a gas permeation unit (6) and a rectification column (15), are fed to a reactor (1). A liquid phase comprising high boilers and an Rh / triphenylphosphine catalyst homogeneously dissolved therein are present in the reactor. The hydroformylation is carried out at 105° C and 20 bar. The product to be formed, namely a mixture of n-butyraldehyde and isobutyraldehyde, is discharged from the reactor, together with unreacted propylene and the propane introduced and to be formed, by means of a circulating gas stream. The condensable components are condensed in the downstream cooler (2) and collected in the subsequent separator (3). The condensate contains 78.3% of butyraldehyde, 14.3% of propylene and 7.4% of propane. It is fed (20.3 t / h) to the degassing column (5) where a C3 -free hydroformylation product (15.9 t / h) is obtained at the bottom, and a mixture of 66% of propylene and 34% of propane (4.4 t / h) are obtained at the top. The latter mixture is run through an olefin-selective membrane (11) in a gas permeation unit (6), and fractionated in the subsequent column (15), to give a virtually propylene-free propane stream at the bottom (1.2 t / h), and a mixture of 90% of propylene and 10% of propane at the top (3.2 t / h). The latter stream is recirculated to the propylene feed to the synthesis reactor (1). The rectification column (15) is operated at a pressure at the top of from 20 to 21 bar, and a temperature at the bottom of from 60 to 70° C and has 130 theoretical plates.Example 2: A system or plant as shown in FIG. 3 is used.

[0103] A feed stream of 10.25 t / h of polymer grade propylene (99.5% propylene, 0.5% propane), synthesis gas, and a recycle stream (14) of 549.1 kg / h from the gas permeation unit (6) are fed to a reactor (1). A liquid phase comprising high boilers and an Rh / triphenylphosphine catalyst homogeneously dissolved therein are present in the reactor. The hydroformylation is carried out at 105° C and 20 bar. The product to be formed, namely a mixture of n-butyraldehyde and isobutyraldehyde, is discharged from the reactor, together with unreacted propylene and the propane introduced and to be formed, by means of a circulating gas stream. The condensable components are condensed in the downstream cooler (2) and collected in the subsequent separator (3).The condensate contains 81.4% of butyraldehyde, 2.5% of propylene and 2.2% of propane, together with isobutyraldehyde, light gases, and high boilers. It is fed (17.2 t / h) to the degassing column (5) where a C3 -free hydroformylation product (16.4 t / h) is obtained at the bottom, and a mixture (744.3 kg / h) containing 52.8% of propylene and 45.1 % of propane is obtained at the top. The latter mixture is run through an olefinselective membrane (11) in a gas permeation unit (6) to give a permeate stream (8) with a propylene concentration of 65.9 %, and a retentate stream (12), whose propylene concentration is 16.1 % and whose propane concentration is 82.7%. The olefin-selective membrane has a propylene permeance of 34 GPU and propylene I propane selectivity of 4.9. The gas permeation unit (6) operates at 35°C, with a feed inlet pressure equal to 6.8 bar and a permeate outlet pressure equal to 1.7 bar. The installed membrane area of 1551 m2. The permeate stream (8) is fed to a compressor (13) and then recycled to a reactor (1). The retentate stream (12), with a flow rate of 195.2 kg / h, is flared. Overall, the gas permeation unit (6) allows a recovery of 92% of the propylene in its feed stream.

[0104] While the invention has been described in detail, modifications within the spirit and scope of the invention will be readily apparent to those of ordinary skill in the art in view of the foregoing disclosure, relevant knowledge in the art, and references discussed above in connection with the Background and Detailed Description. In addition, embodiments of the invention and portions of various aspects and various features recited and / or in the appended claims may be combined or interchanged either in whole or in part. In the foregoing descriptions of the various embodiments, those embodiments which refer to another embodiment may be appropriately combined with other embodiments as will be appreciated by one of ordinary skill in the art.Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention.

[0105] Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

Claims

CLAIMSWhat is claimed is:1 . A process for the hydroformylation of olefins having 2 to 8 carbon atoms, the process comprising each of the following at least once:(i) reacting an olefin-containing feed in which a proportion of a saturated hydrocarbon having from 2 to 8 carbon atoms is present, with carbon monoxide and hydrogen fed into a reaction zone in the presence of a hydroformylation catalyst;(ii) separating a stream comprising unreacted olefin and saturated hydrocarbon from an output from the reaction zone;(iii) separating the stream into an olefin-enriched fraction and an olefin- depleted fraction using an olefin-selective membrane; and(iv) removing at least part of the olefin-enriched fraction for recirculating to the reaction zone, and / or removing at least part of the olefin-depleted fraction.

2. The process according to claim 1 , wherein the olefin-selective membrane comprises at least one membrane selected from the group consisting of: a porous support, a nonporous layer optionally including a silver ionomer of a fluorinated polymer, a thin film composite (TFC), a polymeric membrane, an inorganic membrane, a solid polymer electrolyte membrane, and combinations thereof.

3. The process according to claim 1 , wherein the olefin-selective membrane is a polymeric membrane selected from the group consisting of: a polyimide selective layer, a poly(phenylene oxide) selective layer, a selective layer comprising perfluorinated dioxole, a selective layer comprising perfluorinated dioxolane, a selective layer comprising perfluorinated cyclic ether, and combinations thereof.

4. A process for the hydroformylation of olefins having from 2 to 8 carbon atoms, the process comprising each of the following at least once:(i) reacting an olefin-containing feed in which a proportion of a saturated hydrocarbon having from 2 to 8 carbon atoms is present, with carbon monoxide andhydrogen fed into a reaction zone in the presence of a hydroformylation catalyst;(ii) separating a stream comprising unreacted olefin and saturated hydrocarbon from the reaction zone;(iii) separating the stream into an olefin-enriched fraction and an olefin- depleted fraction using an olefin-selective membrane; and(iv) removing at least part of the olefin-enriched fraction for recirculating to the reaction zone, and wherein the stream comprising unreacted olefin and saturated hydrocarbon is obtained by firstly separating off a crude hydroformylation product comprising unreacted olefin and saturated hydrocarbon in dissolved form from an output from the reaction zone, and subjecting the crude hydroformylation product to a degassing step.

5. The process according to claim 4, wherein the output from the reaction zone is essentially gaseous, and the crude hydroformylation product is separated off by condensation from the gaseous output.

6. The process according to claim 4, wherein the output from the reaction zone is essentially liquid, the liquid output is depressurized so that it is separated into a liquid phase which comprises high-boiling by-products, a homogeneously dissolved hydroformylation catalyst and small amounts of hydroformylation product, small amounts of unreacted olefin and small amounts of saturated hydrocarbon, and a gas phase comprising hydroformylation product, unreacted olefin and saturated hydrocarbon and also unreacted carbon monoxide and hydrogen, and the crude hydroformylation product is obtained by at least partial condensation of the gas phase.

7. The process according to any preceding claim, wherein the hydroformylation catalyst used is a phosphorus-containing rhodium catalyst.

8. The process according to any preceding claim, wherein the olefin and the saturated hydrocarbon have the same number of carbon atoms.

9. The process according to any preceding claim, wherein in (i) the olefin-containing feed comprises a mixture selected from the group consisting of: butene and butane, isobutene and isobutane, propene and propane, and ethene and ethane, and combinations thereof.

10. The process according to claim 9, wherein the mixture contains from 0.5 to 10 % by weight of propane or ethane.11 . The process according to any preceding claim, wherein the olefin-depleted fraction is fed to a steam cracker.

12. The process according to any preceding claim, wherein the process further comprises flash evaporation, cooling, rectification, distillation, compression, and / or condensation.

13. The process according to any preceding claim, wherein the process further comprises rectification or distillation before or after using the olefin-selective membrane.

14. The process according to claim 13, wherein the olefin-selective membrane treats a sidedraw stream from a rectification column.

15. The process according to any preceding claim, further comprising a step of dehydrogenating the stream prior to feeding it to the olefin-selective membrane, wherein the dehydrogenating forms the olefin from the saturated hydrocarbon and generates hydrogen gas.

16. The process according to any preceding claim, further comprising: collecting and removing the olefin-enriched fraction from a permeate stream obtained from a permeate side of the olefin-selective membrane, and / or collecting and removing the olefin-depleted fraction from a feed side of the olefinselective membrane, and / orrecycling or reusing the olefin-selective membrane in a continuous process.

17. The process according to any preceding claim, wherein in (i) the olefin-containing feed is fed in a liquid phase or a gas phase.

18. The process according to any preceding claim, wherein the olefin-selective membrane comprises metal ions including metal ions selected from the group consisting of: transition metal ions, silver ions, copper ions, gold ions, nickel ions, iron ions, manganese ions, zinc ions, and combinations thereof; and / or comprises at least about 15 % polymers relative to metal ions.

19. The process according to any preceding claim, wherein the olefin-selective membrane comprises at least two layers in which: one of the at least two layers contains metal ions and includes a silver ionomer of polymeric sulfonic acid; and / or a second layer comprises a high diffusion rate layer of one or more fluorinated polymers having a permeance to the olefin of at least about 250 GPU, and optionally the second layer is about 0.05 to about 1 .0 pm in thickness.

20. The process according to any preceding claim, wherein the olefin is at least one selected from the group consisting of: decene, nonene, octene, heptene, hexene, pentene, butene, propene, ethene, and combinations thereof.21 . The process according to any preceding claim, wherein the olefin-depleted fraction comprises at least one saturated hydrocarbon selected from the group consisting of: butane, isobutane, propane, ethane, and combinations thereof.

22. The process according to any preceding claim, wherein the mole fraction of olefin: saturated hydrocarbon in a permeate side of the olefin-selective membrane is approximately 4:1 or greater.

23. A gas treatment system for obtaining and recycling olefin, the system comprising: an olefin-selective membrane gas separation unit that permeates olefin 2 - 700 times faster than saturated hydrocarbons with the same number of carbons, to produce an olefin- enriched permeate stream; and an outlet gas vent for an olefin-depleted retentate stream to be removed; and optionally further comprising an inlet for the olefin-enriched permeate stream to be recycled into an oxo-process reactor.

24. Use of an olefin-selective membrane to separate a mixture into an olefin- enriched fraction and an olefin-depleted fraction, wherein the mixture is obtained from hydroformylation of an olefin-containing feed comprising a saturated hydrocarbon having 2 or more carbon atoms, carbon monoxide and hydrogen.

25. An olefin-enriched fraction obtained by the process according to any one of claims 1-22.

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