Title of Invention	A PROCESS FOR CONTINUOUS CARBONYLATION BY SUPPORTED IONIC LIQUID-PHASE CATALYSIS
Abstract	There is disclosed a process for the continuous carbonylation of carbonylatable products with carbon monoxide in the gaseous phase in the presence of a catalyst, wherein said catalyst is a Supported Ionic Liquid-Phase (SILP) catalyst comprising a solution of a Group VIII metal selected from iron, luthenium, rhodium, indium, nickel, cobalt and palladium or any combinations thereof in an ionic liquid, such as herein described, confined on a support, such as herein described.

Title of Invention

A PROCESS FOR CONTINUOUS CARBONYLATION BY SUPPORTED IONIC LIQUID-PHASE CATALYSIS

Abstract

There is disclosed a process for the continuous carbonylation of carbonylatable products with carbon monoxide in the gaseous phase in the presence of a catalyst, wherein said catalyst is a Supported Ionic Liquid-Phase (SILP) catalyst comprising a solution of a Group VIII metal selected from iron, luthenium, rhodium, indium, nickel, cobalt and palladium or any combinations thereof in an ionic liquid, such as herein described, confined on a support, such as herein described.

Full Text	Title A process for continuous carbonylation by supported ionic liquid-phase catalysis Technical Field The present invention relates to a process for continuous carbonylation of carbonylat- able reactants with carbon monoxide in the gaseous phase in the presence of a cata- lyst, wherein said catalyst is a Supported Ionic Liquid-Phase (SILP) catalyst comprising a solution of a Group VIII metal in an ionic liquid confined on a support Background Art Carbonylation of carbonylatable reactants, especially alcohols, in particular methanol, is an industrially important homogeneous catalysed batch reaction Processes for the manufacture of acetic acid from methanol by carbonylation are operated extensively throughout the world Acetic acid is used in a variety of applications, among which are in the manufacture of (poly) vinyl acetate, cellulose acetate, acetic anhydride, and ace- tyl chloride The manufacture of acetic acid from methanol and carbon monoxide at high tempera- ture and high pressure was described by BASF as early as 1913 In 1941 BASF devel- oped an improved process using Group VIII metal carbonyls as catalysts for carbonyla- tion reactions This led to the development of a high-pressure, high-temperature proc- ess (70 MPa, 250° C) with a cobalt iodide catalyst Monsanto developed a low-pressure process for the manufacture of acetic acid in the late 1960s with a rhodium iodide promoted catalyst system that demonstrated a pro- nounced higher selectivity and activity than the cobalt-based process, US patent No 3,769,329 The Monsanto operating conditions in the reactor were milder (3-4 MPa and 180-220°C) than in the BASF process In the early 1980s Celanese Chemical Company developed a low-reaction-water rho- dium-catalysed methanol carbonylation process using inorganic iodide salts to improve catalyst stability and activity, US patent No 5,001,259 BP developed in the early 1990s a process using indium instead of rhodium in the cata- lyst system, a process known as the Cativa™ process ( Process Engineering, 1996, July, p21) Said process is claimed to improve catalyst stability, increase reaction rates, increase yields, and produce less liquid by-products Thomas Swan & Co discloses in WO 01/07388 a continuous process for carrying out carbonylation reactions with carbon monoxide using a heterogeneous catalyst with or without use of a solvent medium, wherein at least one component is under supercritical or near cntical conditions Ionic liquids have been used as solvents for organic reactions and metal-catalysed re- actions including carbonylation reactions US 2004/0059153 (Institut Francars du Petrole) discloses a process for liquid phase carbonylation of alcohols by carbon monoxide in the presence of at least one catalyst comprising at least one rhodium and/or iridium complex and a halogenated promoter in at least one non-aqueous ionic liquid The liquid product of the process must be sepa- rated by distillation after decreasing the pressure Said decrease in pressure may cause more or less pronounced deactivation of the catalyst system used US patent No 4, 366,259 discloses a high pressure batch process for prepanng acetic acid and propronic acid and their esters by contacting a mixture of carbon monoxide and hydrogen gas with a catalyst system comprising a ruthenium-containing compound and a cobalt halide dispersed in a low melting quaternary phosphonium or ammonium base or salt The liquid product must be separated by distillation The liquid phase processes discussed above require separation of the reaction prod- ucts from the catalysts by distillation from the reactor or by flashing of the reaction solu- tion at reduced pressure Catalyst decomposition and precipitation may cause prob- lems during the flashing process wherein the liquid products from the reactor are sub- jected to a pressure decrease Furthermore these separation processes are often cumbersome, require additional reaction steps, and require the use of expensive corro- sion-resistant equipment US 2003/0212295 (Charles et al.) discloses a continuous process for the preparation of carbonylatable products wherein carbon monoxide, a reactant and a halide in the gas phase are contacted with a non-volatile catalyst solution comprising an ionic liquid and a Group VIII metal to produce a carbonylation product in the gas phase The process is said to be useful for the continuous preparation of acetic acid by the carbonylation of methanol The catalytically active component is incorporated in the ionic liquid, which is positioned in the reactor on a metal filter A need still exists for an improved process for the carbonylation of carbonylatable reac- tants, which provides for use of less catalyst materials, presents few requirements for the equipment used and allows a simple process design without the need for recircula- tion of and pressure change for the catalyst system Disclosure of Invention The present invention relates to a process for continuous carbonylation of carbonylat- able reactants with carbon monoxide in the gaseous phase in the presence of a cata- lyst, wherein said catalyst is a Supported Ionic Liquid-Phase (SILP) catalyst comprising a solution of a Group VIII metal in an ionic liquid confined on a support The present invention thus describes a highly efficient carbonylation process The use of a SILP catalyst provides a very large active catalyst area ensuring a very effective use of the catalyst Since the catalyst is maintained in the carbonylation reactor the process according to the invention obviates the need for subsequent separation of any catalyst under decreased pressure with the concomitant deactivation and decomposi- tion problems expenenced with pnor art carbonylation processes The present invention furthermore relates to an apparatus for carrying out the carbon- ylation process according to the invention charactensed in that it comprises i) at least one reactor 1, ii) at least one liquid evaporator 2, iii) at least one condenser 3, iv) at least one separator 4 to separate the product stream from residual process gas which is recycled to said at least one reactor Finally the present invention relates to the use of a SILP catalyst for use in the carbon- ylation process according to the invention Brief Description of the Drawings The invention is explained in detail below with reference to the drawing(s), in which Fig 1 shows schematically the build-up of a SILP catalyst particle, and Fig 2 is a flow-sheet showing diagrammatically the process according to the invention Best Modes for Carrying out the Invention More particularly the present invention relates to a process for carbonylation of carbon- ylatable reactants, comprising i) continuously feeding to a reaction zone a carbonylatable reactant and carbon monoxide, wherein said carbonylatable reactant and carbon monoxide are in the gaseous phase, ii) continuously contacting said carbonylatable reactant and carbon monoxide with a SILP catalyst comprising a solution of a Group VIII metal in an ionic liquid con- fined on a support, and iii) continuously recovering from said reaction zone a gaseous effluent comprising a carbonylated product Although a carbonylation reaction may be performed simply as a reaction between a carbonylatable reactant and carbon monoxide it has been shown that an enhanced yield and selectivity may be obtained by the addition of a reaction promoter Conse- quently in a preferred embodiment of the continuous process according to the invention a reaction promoter is added to the liquid feed initially and re-circulated by the residual process gas A reaction promoter may act as a (co)-catalyst and is not consumed once steady-state conditions have been reached The Group VIII metal of the SILP catalyst used in the process according to the inven- tion may be any Group VIII metal which will react with carbon monoxide in the reaction medium to produce a metal-carbonyl complex Preferred Group VIII metals are se- lected from iron, ruthenium, rhodium, indium, nickel, cobalt, palladium or any combina- tions thereof Any source of catalyst precursor which will liberate the Group VIII metal by dissolution in an ionic liquid may be used as Group VIII metal catalyst precursor Examples of catalyst precursors include, without limitation, Rh(CO)2(acac), Rh(COD)(acac), [Rh(COD)CI]2, [Rh(CO)zCI]2, [Rh(CO)2l]2, [Rh(OAc)2]2, RhCI3 xH20, [lr(COD)CI]2, lr(CO)2(acac), lrCI3 x H20, Pd(OAc)2, Pd(acac)2, Co(acac)2 x H20, [Ru(COD)Cl2]x, wherein acac = acetylacetonate, OAc = acetate, and COD = 1,5-cyclooctadiene Ionic liquids are liquids composed solely of ions Ionic liquids are characterised by hav- ing a melting point below about 100 °C distinguishing ionic liquids from traditional mol- ten salts An advantage by using ionic liquids is their negligible vapour pressure below their point of decomposition This allows the separation of mixtures of ionic liquid and volatile substances, which makes them suitable as solvents for organic reactions Fur- thermore said fact means that ionic liquids are not lost by evaporation like common or- ganic solvents The physical and chemical properties of ionic liquids may be adjusted by selection of the ions of the ion pair, which again allows the designing of an ionic liquid having the properties desired Thus, the cation of an ionic liquid dictates to a large degree the melting point of said ionic liquid Generally the bigger the cation the lower the melting point Furthermore the degree of cation substitution influences the iipophilicity of an ionic liquid and thus the miscibility with an organic solvent Preferred cations of the ionic liquids used in the SILP catalysts employed in the process according to the inven- tion are quaternary nitrogen- and/or quaternary phosphorous-containing cations Particularly preferred cations of the ionic liquids are selected from the group consisting of 0 wherein R1, R2, R3, and R4 are independently selected from optionally substituted, lin- ear or branched-chamed C1-C20 alkyl, optionally substituted cyclic C3-C20 alkyl, and op- tionally substituted C6_C2Q aryl, and Y is N or P, li) wherein R5 and R7 are independently selected from optionally substituted, linear or branched-chained C1-C2o alkyl, optionally substituted cyclic C3-C20 alky], and optionally substituted C6-C20 aryl, and R6, R8 and R9 are independently selected from hydrogen, optionally substituted, linear or branched-chained C1-C20 alkyl, optionally substituted cyclic C3-C20 alkyl, and option- ally substituted C6-C2oaryl, in) wherein R10 is independently selected from optionally substituted, linear or branched- chained C1-C20 alkyl, optionally substituted cyclic C3-C20 alkyl, and optionally substi- tuted C6-C2o aryl; and R11 and R12 are independently selected from hydrogen, optionally substituted, linear or branched-chained C1-C20 alkyl, optionally substituted cyclic C3-C20 alkyl, and optionally substituted C6-C2oaryl, and IV) wherein R13 and R14 are independently selected from optionally substituted, linear or branched-chamed C1-C20 alkyl, optionally substituted cyclic C3-C2o alkyl, and optionally substituted C6-C2o aryl, X is C, N, O, or S, n and in are each integers from 0 to 6 with the proviso that the sum 1 ^m+n Non-limiting examples of alkyl moreties of the substituents mentioned above include methyl, ethyl, n-propyl, iso-propyl,cyclo-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n- pentyl, n-hexyl, cyclo-hexyl.n-octyl, and iso-octyl Non-limiting examples of aryl groups include phenyl, benzyl, and ethyl-phenyl As examples of substituents of the above al- kyl and aryl groups may be mentioned, without limitation, halogen, such as fluoro, chloro, bromo or lodo, hydroxy, C1-C6 alkyl, and GrC6 alkoxy The anion of an ionic liquid is generally considered to be the ion having the most pro- found influence on the water-solubility thereof Thus a hydrophobic anion results in a poor water-solubility Likewise water is poorly soluble in an ionic liquid comprising a hydrophobic anion The viscosity of an ionic liquid depends largely on the anion, since the charge density on the anion may contribute to hydrogen bonds between the cation and the anion, the strength of hydrogen bonds being one of the significant causes of higher viscosity Preferred anions of the ionic liquids are selected from the group con- sisting of halides, nitrates, sulfates, sulfonates, sulfonyl amides, phosphates, borates, antimonates, and acetates or optionally halogen substituted hydrocarbyl derivatives thereof Examples of preferred ionic liquids for employment in the SILP catalysts for use in the process according to the invention are selected from tetrabutylphosphonium tetra- fluoroborate, N-butylpyridimum hexafluorophosphate, N-ethylpyndinium tetrafluorobo- rate, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide, 1-butyl-3-methyl- imidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1- butyI-3-methyIimidazoIium tnfluoromethylsulfonate, 1 -butyl-3-methylimidazolium bis(tnfluoromethyIsulfonyl)amide, 1 -ethyI-3~methylimidazolium bis(tnfluoromethylsulfonyl)am[de, 1-butyl-3-methyIimidazoIium acetate, 1 -butyl-3- methylimidazolium iodide, 1-ethyI-3-methylimidazoIium hydrogensulfate, 1-butyl-3- methylimidazolium methylsulfate, 1-ethyl-3-methylimidazolium ethylsulfate, 1-butyl-3- methylimidazolium octylsulfate, 1,3-dimethylimidazolium octylsulfate, 1-butyl-3~ ethylimidazolium p-toluenesulfonate, 1-ethyI-3-methylimidazoIium methanesulfonate, 1,3-dimethyIimidazolium dimethylphosphate, l-ethyl-3-methylimidazolium thiocyanate, and 1-butyl-3-methylimidazolium dicyanamide, alone or as a mixture Particularly pre- ferred ionic liquids are 1-butyl-3-methylimidazolium bis(tnfluoromethylsulfonyl)amide, 1- butyl-3-methylimidazohum iodide, and 1-butyl -3-methylimidazolium octylsulfate Supported Ionic Liquid-Phase (SILP) catalysts comprise an ionic liquid as disclosed above having the catalytically active complex dispersed on an inert support material having a large surface area Said design allows the preparation of operationally solid catalysts which may be placed in the reactor bed while ensuring easy accessibility of the reactants to the active components of the catalyst in the ionic liquid In the present context a SILP catalyst refers to a catalyst wherein the catalytically active component is dissolved/ incorporated in the ionic liquid Ideally a SILP catalyst utilizes the advan- tages of both homogeneous and heterogeneous catalysis Thus the distance of diffu- sion is minimised since the ionic liquid is dispersed as a very thin film on a large sur- face area Fig 1 shows diagrammatically the exemplary design of a SILP catalyst particle, wherein an immobilised catalytic ionic liquid phase consisting of ionic liquid A+B" and a Group VIII metal represented as M+X"is dispersed at low liquid loading on a porous high-area support (By the term "low liquid loading" is meant the pore filling degree of an ionic liquid in the porous support Typically the desired liquid loading is below 0 5 )Gaseous reactants diffuse into the porous structure of the SILP catalyst and reacts in the inter-phase of the thin ionic liquid catalyst film, where-after the product leaves the SILP particles again Suitable support materials are selected from the group consisting of silicas, polymers, zeolites, clays, alumina, titania, zirconia and combinations thereof A preferred support material is silica, since it is mechanically robust, possesses a large surface area and is easy to process to the desired particle sizes The process according to the invention may be used for the carbonylation of any car- bonylatable reactant The term "carbonylatable reactant" as used in the present context is intended to mean any organic reactant which is capable of reacting with carbon monoxide, under carbonylation conditions of temperature and pressure, to obtain a re- action product resulting from the insertion of carbon monoxide into one or more chemi- cal bonds Examples of carbonylatable compounds include alcohols, ethers, and car- boxylic acid esters having up to about 20 carbon atoms More particularly said carbon- ylatable reactants are selected from the group consisting of saturated or mono- or d1- unsaturated, linear or branched aliphatic C1-Cao reactants and saturated or mono- or d1- unsaturated aromatic reactants having from 7 to 20 carbon atoms If the desired product of the carbonylation process is an acid or a derivative thereof, such as an ester or ether thereof, preferred carbonylatable reactants are alcohols, in particular lower alcohols The most preferred alcohol is methanol, which is reacted with carbon monoxide to produce the industrially important chemical acetic acid In a preferred embodiment of the process according to the invention a reaction pro- moter is used Suitable reaction promoters are selected from the group consisting of halides, hydrogen halides, or alkyl or aryl halides having up to about 10 carbon atoms Preferred halides are selected from chlorine, bromine and iodine compounds, most preferably iodine compounds, that are gaseous under vapour phase carbonylation conditions Suitable halides include hydrogen halides such as hydrogen iodide and gaseous hydroiodic acid, alkyl and aryl halides having up to about 10 carbon atoms such as methyl iodide, ethyl iodide, methyl bromide, ethyl bromide, benzyl iodide and any mixtures thereof The halide may also be molecular halogen such as l2, Br2 or Cl2 In the embodiment of the process according to the invention in which carbon monoxide is reacted with methanol to produce acetic acid, the most preferred reaction promoter is methyl iodide Scheme 1 below shows the essential steps of the catalytic cycle for the Monsanto car- bonylation process of methanol for the preparation of acetic acid Without wishing to be bound by any specific theory it is thought that the process according to the invention may be performed analogously for any carbonylatable reactant The reaction mechanism of the Monsanto process as it is believed to take place is thus as follows Methanol is first reacted with an iodide source (HI) to form methyl iodide Methyl iodide reacts with the rhodium complex by oxidative addition of methyl and io- dide to the rhodium complex under formation of an alkyl complex Said addition is fol- lowed by a migratory insertion of CO between the methyl group and the rhodium atom under formation of an unsaturated acyl complex having a free coordination site Said "free" coordination site is occupied by a new CO molecule and subsequently acetic acid iodide is separated by reductive elimination of the acyl group and one of the iodide ligands Acetic acid iodide is converted to acetic acid by reaction with water to reform the iodide source Said iodide source is by re-reaction with methanol converted to the reaction promoter methyl iodide The carbonylation reaction according to the invention may be carried out at a tempera- ture in the range from ambient to the temperature of decomposition of the ionic liquid at a pressure in the range 1-100 bar However, since the carbonylation reaction is to take place in the gaseous phase the temperature must be kept above the dew point of the carbonylation reaction mixture Typically the process according to the invention is carried out at a temperature in the range 100 -300° C, more preferably in the range 150-230° C A wide range of pressures is available under which the carbonylation process accord- ing to the invention may be earned out provided maintenance of a gaseous state of all reactants is ensured Typically the process according to the invention is carried out at a pressure in the range 5-50 bar, more preferably in the range 10 - 30 bar The process according to the invention may be carried out in an apparatus shown dia- grammatically in Fig 2, wherein said apparatus comprises i) at least one reactor 1 , u) at least one liquid evaporator 2, in) at least one condenser 3, iv) at least one separator 4 to separate the product stream from residual process gas which is recycled to said at least one reactor Through an evaporator inlet line 5 liquid carbonylatable reactant enters the evaporator 2 In a preferred embodiment of the invention a liquid mixture of carbonylatable reac- tant and reaction promoter, at any desired ratio, such as about 20 1-1 1, preferably about 9 1-21, enters the evaporator 2 The process gas is evaporated by the evapora- tor and combined with re-circulated process gas from line 7 The reactant gas mixture enters the reactor 1 through a reactor inlet line 6 either at the bottom as shown on fig 2 or at the top, if so desired The reactor 1 to be used in the process according to the in- vention may be any conventional fixed-bed or fluidised-bed reactor, wherein the SILP catalyst is present As an alternative to the above mentioned fixed-bed or fluidised-bed reactor a tube reactor may be employed A single reactor may be used, however, the use of more than one reactor, in series or parallel, is also contemplated in the present invention The reaction mixture is forced to pass the SILP catalyst, wherein the presence of the very thin film of ionic liquid containing the catalyst dispersed on a robust, inert, porous high-area support material 8 offers a highly efficient use of the ionic liquid catalyst phase The SILP catalyst thus requires smaller amounts of expensive metal catalyst and ionic liquid than any pnor art catalyst systems Due to the increased efficiency of the catalyst also a smaller reactor size may be used compared to prior art reaction de- signs in order to obtain similar catalyst efficiency The heat of the exothermic reaction may be removed by inter-stage cooling of a multi-bed reactor, through the fluidised bed design or as an alternative using a tube reactor with external cooling The product stream from the reactor 1 is fed to a condenser 3 through a condenser inlet line 9 either at the top as shown on fig 2 or at the bottom thereof, if so desired In the condenser 3 the gaseous reactants are evaporated from the top of the condenser 3 and re-circulated via line 7 to the reactor 1 whereas the liquified reaction products are transferred to a separator 4 through a liquid reaction product line 10 In the separator 4 a further separation of gaseous carbon monoxide and any other process gasses, if present, from the punfied liquid product stream is obtained The product stream from the separator 4 is processed further in a manner known per se employing e g frac- tional distillations and/or drying operations The separator 4 may be any separator known in the art, such as a common distillation unit, a flash distillation unit etc In each of the above described process steps a single unit operation device will nor- mally be used However, the invention also contemplates the use of more than one unit operation device, such as e g more than one distillation unit, if required A major advantage by the use of the above simple process design is the omission of any catalyst recirculation since the catalyst is maintained in the reactor Separation of the liquid phase currently employed in industrial plants often results in catalyst deacti- vation since carefully controlled conditions are required in order to avoid cntical low pressures in connection with flash distillation operations This also adds to a reduced demand for expensive catalyst material by the process according to the invention Fur- thermore the simplified process design provides economical benefits as a result of lower operating and running costs Existing plants may easily be adapted to the appa- ratus according to the invention or may be implemented at reduced plant investments EXAMPLES The following examples illustrate the invention without limiting its scope or content S1LP CATALYST PREPARATION The l-bufyl-3-methylimidazolium iodide/dicarbonylduodorhodium(l) SILP catalyst em- ployed in the examples was prepared by initial stirring of a dry methanol solution (8 ml) containing 16 5 mg tetracarbonyldnododirhodium(l) (0 029 mmol) metal precursor and 302 5 mg ionic liquid 1-butyl-3-methylimidazolium iodide (1 137 mmol) under argon at- mosphere for 24 hours Subsequently, 0 600 g thermally pretreated (500 °C, 15 h, in air) silica support (silica gel 100, Merck, BET surface area 304 m2g"1> pore volume 1 01 cm3g"1. mean pore diameter (monomodal) 13 2 nm) was added, where after the suspension was left with slow stirring for additionally 4 hours before the volatile solvent was removed at reduced pressure at room temperature The residue consisting of fine red-brown SILP catalyst particles was then dried in a vacuum oven overnight (0 1 mbar, 60 °C) and further kept in vacuo over phosphor pentaoxide prior to use CATALYTIC TEST SYSTEM Continuous, gas-phase carbonylations of methanol with carbon monoxide and methyl iodide as reaction promoter were performed in an all-heated stainless steel (AISI 316Ti) catalyst test system with the SILP catalyst positioned as a fixed-bed in a tubular reactor, placed in a temperature controlled aluminum block oven The test system al- lowed the reactant feed composition to be controlled by gas- and liquid mass-flow con- trollers integrated with an evaporator and mixing unit and the reaction pressure to be controlled by a regulator valve equipped with a pneumatic actuator via connection to an electronic controller and pressure transducer Gas-phase reactants and products were analyzed continuously by an integrated on-line FID-GC using auto gas sampling Example 1 1 00 g of SILP catalyst (containing 0 0437 mmol Rh metal), prepared as above, was positioned in a fixed catalyst bed in the tubular reactor where after the system was pressurized with carbon monoxide gas at a constant flow (FCo) of 50 ncm3min"1 to a constant reaction pressure (Pr) of 20 bara Meanwhile the reactor was heated to a con- stant reaction temperature (7r) of 180 °C and the rest of the test system to 160 °C When the preset reaction pressure and temperatures were reached the carbon monox- ide gas was bypassed the reactor, and a liquid mixture containing 75 25 w/w % of methanol methyl iodide was introduced into the bypassed reactant gas, after evapora- tion of the liquid mixture, with a constant flow (fiiq) of 0 69 gh"1 When the reactant gas mixture composition became constant, as determined by the FID-GC analysis, the methanol carbonylation reaction was started by allowing the reactant gas stream to flow through the SILP catalyst bed The carbonylation reaction was afterwards followed for 1 5 hour while determining the gas composition regularly by FID-GC analysis, allow- ing determination of methanol conversion and catalyst activity (as tum-over-frequency in mo! product formed per mol rhodium per hour) and selectivity for formation of the ob- served products acetic acid (AcOH), acetic acid methyl ester (AcOMe) and d1- methylether (MeOMe), respectively Example 2 The results illustrated in this example are consecutive steady-state results obtained af- ter continuation of the methanol carbonylation reaction described in Example 1 at 180 °C, using the 1-butyl-3-methylimidazo!ium lodide/dicarbonyldnodorhodium (I) SILP catalyst, at different reaction pressure and reactant flows, respectively WE CLAIM 1 A process for the continuous carbonylation of carbonylatable products with carbon monoxide in the gaseous phase in the presence of a catalyst wherein said catalyst is a Supported Ionic Liquid- Phase (SILP) catalyst comprising a solution of a Group VIII metal selected from iron, ruthenium, thodmm, iridium, nickel, cobalt and palladium or any combinations thereof in an ionic liquid, such as herein described, confined on a support, such as herein described 2 The process as claimed in claim 1, comprising i) continuously feeding to a reaction zone a carbonylatable reactant and carbon monoxide, wherein said carbomlatable reactant and carbon monoxide are in the gas phase, ii) continuously contacting said carbonylatable reactant and carbon monoxide with a SILP catalyst comprising a solution of a Group VIII metal in an ionic liquid confined on a support, and in) continuously lecovenng from said reaction zone a gaseous effluent comprising a carbonylated product 3 The process as claimed in claim 2 optionally composing initial addition to the reaction zone in step l) of a reaction promoter, such as herein described 4 The process as claimed in claim 1, wherein said ionic liquid is of the formula A'B" wherein A lepresents a quaternary nitrogen- and/or a quaternary phosphoious- containing cation 5 The process as claimed in claim 4, wherein the cation A is selected from the group consisting of i) wherein R1 R2, R3, and R4 are independently selected fiom optionally substituted, linear or branched-chamed C1-C20 alkyl. optionally substituted cyclic C3-C20 alkyl, and optionally substituted C6-C20 aryl. and Y is N or P, II) wherein R5 and R7 are independently selected from optionally substituted, linear or branched- chamed C1-C20 alky], optionally substituted cyclic G-C20 alkyl, and optional!) substituted C6-C20 aryl and R6. R8 and R9 are independently selected from hydiogen optionally substituted, linear or branched-chamed C1-C20 alkyl optionally substituted cyclic C3-C20 alkyl, and optionally substituted C„-C2o aiyl, 111) wherein R10 is independently selected from optionally substituted, linear or branched- chained G- C20 alkyl, optionally substituted cyclic C3-C20 alkyl, and optionally substituted C„-C20 aryl. and R1 and R12 are independently selected from hydrogen, optional!} substituted, linear or branched- chamed C1-C20 alkyl, optionally substituted cyclic C3-C20 alkyl, and optionally substituted C0-C2o ary 1. and n) wherein R13 and R14 are independently selected from optionally substituted, linear or branched- chained C1-C20 alkyl, optional!} substituted cyclic C1-C20 alky], and optionally substituted C6-C20 aryl, X is C, N, O, or S, n and in are each integers from O to 6 with the proviso that the sum 1 less than or equal to m+n less than or equal to 6 6 The process as claimed in claim 4, wherein the anion B" is selected from the gioup consisting of hahdes, nitrates, sulfates, sulfonates, sulfonyl amides phosphates, borates, antimonates, and acetates or optionally halogen, hydroxy 1, or C1-C6 alkoxy- substituted hydrocarbyl derivatives thereof 7 The process as claimed in any of the preceding claims, wherein the ionic liquid A+B" is selected from tetrabutylphosphonium tetrafluoroborate, N-butylpyridimum hexafluorophosphate, N- ethylpyndinmm tetrafluoroboi ate 1 -butyl-1 -methylpy n ohdimum bis(tnfluoiomethylsulfon\l)amide l-butyl-3-methyhmidazohum tetrafluoroborate, 1- butyl-3- methyliinidazohum hexafiuorophosphate, l-butyl-3-methylimidazohum tnfluoro- methylsulfonate, l-butyl-3-methylimidazolmm bis(trifluorometh\lsulfonyl)amide. 1-ethyl- 3-methyhmidazolium bis(tnfluoromethylsulfonyl)amide. l-butyl-3-methyhmidazolium acetate. 1-but} 1-3- methylimidazohurn iodide, l-ethyl-3-methylimidazohum rrvdrogensul- fate, l-butyl-3- methyhmidazohum methylsulfate, l-ethyl-3-meth}limidazolium ethylsul- fate, l~butyl-3- methyhmidazohum octylsulfate, 1,3-dimethylimidazohum octylsulfate, 1- butyl-3- ethyhmidazolium p-toluenesulfonate. l-ethyl-3-methyhmidazohum methanesul- fonate. 1,3- dimethylimidazohum dimethylphosphate, l-ethyl-3-methylnnidazohum thio-cyanate, and 1-buryl- 3-methyhmidazolium dicyanamide, in paiticulai l-butyl-3- methylimidazolium bis(tnfluoromethylsulfonyl)amide, l-butyl-3-methyhmidazohum iodide, and l-butyl-3- methyhmidazolium octylsulfate. alone or as a mixture 8 The process as claimed in any of the preceding claims, u herein the suppoit of said S1LP catalyst is selected from the gioup consisting of silicas, polymers, zeolites, clays, alumina titania, zircoma and combinations thereof, preferably silica 9 The process as claimed in claim 1, wherein said carbonylatable reactants are selected from the group consisting of alcohols etheis, and carboxyhc acid esters having up to 20 carbon atoms 10 The process as claimed in claim 9, wherein said carbon}latable reactants are selected from the group consisting of saturated or mono- or d1-unsaturaled, linear or blanched aliphatic C1-C20 leactants and saturated 01 mono- or d1-unsaturated aromatic leactants having from 7 to 20 carbon atoms 11 The process as claimed in any of claims 9 or 10, for the carbony lation of alcohols 12 The process as claimed in claim 11, for the carbonylation of methanol 13 The process as claimed in claim 3 wherein said leaction promoter is selected from the gioup consisting of halides. hydiogen halides, or alkyl or aryl hahdes having up to 10 carbon atoms 14 The process as claimed 111 claim 13. wherein said reaction promoter is methyl iodide 15 The process as claimed in claim 1, wherein the carbon\ lation reaction is carried out at a temperature in the range from ambient to the temperature of decomposition of the ionic liquid at a pressure in the range 1-100 bar 16 The process as claimed in claim 15, wherein the carbonylation leaction is carred out at a temperatuie in the range 100 -300 degrees C. more preferably in the lange 150-230 degrees centigrade 17 The process as claimed in claim 1, wherein the carbonylation reaction is carried out at a pressure in the range 5-50 bar, more preferably in the lange 10-30 bar ABSTRACT A PROCESS FOR CONTINUOUS CARBONYLATION BY SUPPORTED IONIC LIQUID-PHASE CATALYSIS There is disclosed a process for the continuous carbonylation of carbonylatable products with carbon monoxide in the gaseous phase in the presence of a catalyst, wherein said catalyst is a Supported Ionic Liquid-Phase (SILP) catalyst comprising a solution of a Group VIII metal selected from iron, luthenium, rhodium, indium, nickel, cobalt and palladium or any combinations thereof in an ionic liquid, such as herein described, confined on a support, such as herein described.

Full Text

Title A process for continuous carbonylation by supported ionic liquid-phase catalysis
Technical Field
The present invention relates to a process for continuous carbonylation of carbonylat-
able reactants with carbon monoxide in the gaseous phase in the presence of a cata-
lyst, wherein said catalyst is a Supported Ionic Liquid-Phase (SILP) catalyst comprising
a solution of a Group VIII metal in an ionic liquid confined on a support
Background Art
Carbonylation of carbonylatable reactants, especially alcohols, in particular methanol,
is an industrially important homogeneous catalysed batch reaction Processes for the
manufacture of acetic acid from methanol by carbonylation are operated extensively
throughout the world Acetic acid is used in a variety of applications, among which are
in the manufacture of (poly) vinyl acetate, cellulose acetate, acetic anhydride, and ace-
tyl chloride
The manufacture of acetic acid from methanol and carbon monoxide at high tempera-
ture and high pressure was described by BASF as early as 1913 In 1941 BASF devel-
oped an improved process using Group VIII metal carbonyls as catalysts for carbonyla-
tion reactions This led to the development of a high-pressure, high-temperature proc-
ess (70 MPa, 250° C) with a cobalt iodide catalyst
Monsanto developed a low-pressure process for the manufacture of acetic acid in the
late 1960s with a rhodium iodide promoted catalyst system that demonstrated a pro-
nounced higher selectivity and activity than the cobalt-based process, US patent No
3,769,329 The Monsanto operating conditions in the reactor were milder (3-4 MPa and
180-220°C) than in the BASF process
In the early 1980s Celanese Chemical Company developed a low-reaction-water rho-
dium-catalysed methanol carbonylation process using inorganic iodide salts to improve
catalyst stability and activity, US patent No 5,001,259
BP developed in the early 1990s a process using indium instead of rhodium in the cata-
lyst system, a process known as the Cativa™ process ( Process Engineering, 1996,

July, p21) Said process is claimed to improve catalyst stability, increase reaction
rates, increase yields, and produce less liquid by-products
Thomas Swan & Co discloses in WO 01/07388 a continuous process for carrying out
carbonylation reactions with carbon monoxide using a heterogeneous catalyst with or
without use of a solvent medium, wherein at least one component is under supercritical
or near cntical conditions
Ionic liquids have been used as solvents for organic reactions and metal-catalysed re-
actions including carbonylation reactions
US 2004/0059153 (Institut Francars du Petrole) discloses a process for liquid phase
carbonylation of alcohols by carbon monoxide in the presence of at least one catalyst
comprising at least one rhodium and/or iridium complex and a halogenated promoter in
at least one non-aqueous ionic liquid The liquid product of the process must be sepa-
rated by distillation after decreasing the pressure Said decrease in pressure may
cause more or less pronounced deactivation of the catalyst system used
US patent No 4, 366,259 discloses a high pressure batch process for prepanng acetic
acid and propronic acid and their esters by contacting a mixture of carbon monoxide
and hydrogen gas with a catalyst system comprising a ruthenium-containing compound
and a cobalt halide dispersed in a low melting quaternary phosphonium or ammonium
base or salt The liquid product must be separated by distillation
The liquid phase processes discussed above require separation of the reaction prod-
ucts from the catalysts by distillation from the reactor or by flashing of the reaction solu-
tion at reduced pressure Catalyst decomposition and precipitation may cause prob-
lems during the flashing process wherein the liquid products from the reactor are sub-
jected to a pressure decrease Furthermore these separation processes are often
cumbersome, require additional reaction steps, and require the use of expensive corro-
sion-resistant equipment
US 2003/0212295 (Charles et al.) discloses a continuous process for the preparation of
carbonylatable products wherein carbon monoxide, a reactant and a halide in the gas
phase are contacted with a non-volatile catalyst solution comprising an ionic liquid and
a Group VIII metal to produce a carbonylation product in the gas phase The process is

said to be useful for the continuous preparation of acetic acid by the carbonylation of
methanol The catalytically active component is incorporated in the ionic liquid, which is
positioned in the reactor on a metal filter
A need still exists for an improved process for the carbonylation of carbonylatable reac-
tants, which provides for use of less catalyst materials, presents few requirements for
the equipment used and allows a simple process design without the need for recircula-
tion of and pressure change for the catalyst system
Disclosure of Invention
The present invention relates to a process for continuous carbonylation of carbonylat-
able reactants with carbon monoxide in the gaseous phase in the presence of a cata-
lyst, wherein said catalyst is a Supported Ionic Liquid-Phase (SILP) catalyst comprising
a solution of a Group VIII metal in an ionic liquid confined on a support
The present invention thus describes a highly efficient carbonylation process The use
of a SILP catalyst provides a very large active catalyst area ensuring a very effective
use of the catalyst Since the catalyst is maintained in the carbonylation reactor the
process according to the invention obviates the need for subsequent separation of any
catalyst under decreased pressure with the concomitant deactivation and decomposi-
tion problems expenenced with pnor art carbonylation processes
The present invention furthermore relates to an apparatus for carrying out the carbon-
ylation process according to the invention charactensed in that it comprises
i) at least one reactor 1,
ii) at least one liquid evaporator 2,
iii) at least one condenser 3,
iv) at least one separator 4 to separate the product stream from residual process gas
which is recycled to said at least one reactor
Finally the present invention relates to the use of a SILP catalyst for use in the carbon-
ylation process according to the invention

Brief Description of the Drawings
The invention is explained in detail below with reference to the drawing(s), in which
Fig 1 shows schematically the build-up of a SILP catalyst particle, and
Fig 2 is a flow-sheet showing diagrammatically the process according to the invention
Best Modes for Carrying out the Invention
More particularly the present invention relates to a process for carbonylation of carbon-
ylatable reactants, comprising
i) continuously feeding to a reaction zone a carbonylatable reactant and carbon
monoxide, wherein said carbonylatable reactant and carbon monoxide are in the
gaseous phase,
ii) continuously contacting said carbonylatable reactant and carbon monoxide with a
SILP catalyst comprising a solution of a Group VIII metal in an ionic liquid con-
fined on a support, and
iii) continuously recovering from said reaction zone a gaseous effluent comprising a
carbonylated product
Although a carbonylation reaction may be performed simply as a reaction between a
carbonylatable reactant and carbon monoxide it has been shown that an enhanced
yield and selectivity may be obtained by the addition of a reaction promoter Conse-
quently in a preferred embodiment of the continuous process according to the invention
a reaction promoter is added to the liquid feed initially and re-circulated by the residual
process gas A reaction promoter may act as a (co)-catalyst and is not consumed once
steady-state conditions have been reached
The Group VIII metal of the SILP catalyst used in the process according to the inven-
tion may be any Group VIII metal which will react with carbon monoxide in the reaction
medium to produce a metal-carbonyl complex Preferred Group VIII metals are se-
lected from iron, ruthenium, rhodium, indium, nickel, cobalt, palladium or any combina-
tions thereof

Any source of catalyst precursor which will liberate the Group VIII metal by dissolution
in an ionic liquid may be used as Group VIII metal catalyst precursor Examples of
catalyst precursors include, without limitation, Rh(CO)2(acac), Rh(COD)(acac),
[Rh(COD)CI]2, [Rh(CO)zCI]2, [Rh(CO)2l]2, [Rh(OAc)2]2, RhCI3 xH20, [lr(COD)CI]2,
lr(CO)2(acac), lrCI3 x H20, Pd(OAc)2, Pd(acac)2, Co(acac)2 x H20, [Ru(COD)Cl2]x,
wherein acac = acetylacetonate, OAc = acetate, and COD = 1,5-cyclooctadiene
Ionic liquids are liquids composed solely of ions Ionic liquids are characterised by hav-
ing a melting point below about 100 °C distinguishing ionic liquids from traditional mol-
ten salts An advantage by using ionic liquids is their negligible vapour pressure below
their point of decomposition This allows the separation of mixtures of ionic liquid and
volatile substances, which makes them suitable as solvents for organic reactions Fur-
thermore said fact means that ionic liquids are not lost by evaporation like common or-
ganic solvents
The physical and chemical properties of ionic liquids may be adjusted by selection of
the ions of the ion pair, which again allows the designing of an ionic liquid having the
properties desired Thus, the cation of an ionic liquid dictates to a large degree the
melting point of said ionic liquid Generally the bigger the cation the lower the melting
point Furthermore the degree of cation substitution influences the iipophilicity of an
ionic liquid and thus the miscibility with an organic solvent Preferred cations of the
ionic liquids used in the SILP catalysts employed in the process according to the inven-
tion are quaternary nitrogen- and/or quaternary phosphorous-containing cations
Particularly preferred cations of the ionic liquids are selected from the group consisting
of
0

wherein R1, R2, R3, and R4 are independently selected from optionally substituted, lin-
ear or branched-chamed C1-C20 alkyl, optionally substituted cyclic C3-C20 alkyl, and op-
tionally substituted C6_C2Q aryl, and Y is N or P,

li)
wherein R5 and R7 are independently selected from optionally substituted, linear or
branched-chained C1-C2o alkyl, optionally substituted cyclic C3-C20 alky], and optionally
substituted C6-C20 aryl, and
R6, R8 and R9 are independently selected from hydrogen, optionally substituted, linear
or branched-chained C1-C20 alkyl, optionally substituted cyclic C3-C20 alkyl, and option-
ally substituted C6-C2oaryl,
in)

wherein R10 is independently selected from optionally substituted, linear or branched-
chained C1-C20 alkyl, optionally substituted cyclic C3-C20 alkyl, and optionally substi-
tuted C6-C2o aryl; and
R11 and R12 are independently selected from hydrogen, optionally substituted, linear or
branched-chained C1-C20 alkyl, optionally substituted cyclic C3-C20 alkyl, and optionally
substituted C6-C2oaryl, and

IV)

wherein R13 and R14 are independently selected from optionally substituted, linear or
branched-chamed C1-C20 alkyl, optionally substituted cyclic C3-C2o alkyl, and optionally
substituted C6-C2o aryl, X is C, N, O, or S, n and in are each integers from 0 to 6 with
the proviso that the sum 1 ^m+n Non-limiting examples of alkyl moreties of the substituents mentioned above include
methyl, ethyl, n-propyl, iso-propyl,cyclo-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n-
pentyl, n-hexyl, cyclo-hexyl.n-octyl, and iso-octyl Non-limiting examples of aryl groups
include phenyl, benzyl, and ethyl-phenyl As examples of substituents of the above al-
kyl and aryl groups may be mentioned, without limitation, halogen, such as fluoro,
chloro, bromo or lodo, hydroxy, C1-C6 alkyl, and GrC6 alkoxy
The anion of an ionic liquid is generally considered to be the ion having the most pro-
found influence on the water-solubility thereof Thus a hydrophobic anion results in a
poor water-solubility Likewise water is poorly soluble in an ionic liquid comprising a
hydrophobic anion The viscosity of an ionic liquid depends largely on the anion, since
the charge density on the anion may contribute to hydrogen bonds between the cation
and the anion, the strength of hydrogen bonds being one of the significant causes of
higher viscosity Preferred anions of the ionic liquids are selected from the group con-
sisting of halides, nitrates, sulfates, sulfonates, sulfonyl amides, phosphates, borates,
antimonates, and acetates or optionally halogen substituted hydrocarbyl derivatives
thereof
Examples of preferred ionic liquids for employment in the SILP catalysts for use in the
process according to the invention are selected from tetrabutylphosphonium tetra-

fluoroborate, N-butylpyridimum hexafluorophosphate, N-ethylpyndinium tetrafluorobo-
rate, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide, 1-butyl-3-methyl-
imidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-
butyI-3-methyIimidazoIium tnfluoromethylsulfonate, 1 -butyl-3-methylimidazolium
bis(tnfluoromethyIsulfonyl)amide, 1 -ethyI-3~methylimidazolium
bis(tnfluoromethylsulfonyl)am[de, 1-butyl-3-methyIimidazoIium acetate, 1 -butyl-3-
methylimidazolium iodide, 1-ethyI-3-methylimidazoIium hydrogensulfate, 1-butyl-3-
methylimidazolium methylsulfate, 1-ethyl-3-methylimidazolium ethylsulfate, 1-butyl-3-
methylimidazolium octylsulfate, 1,3-dimethylimidazolium octylsulfate, 1-butyl-3~
ethylimidazolium p-toluenesulfonate, 1-ethyI-3-methylimidazoIium methanesulfonate,
1,3-dimethyIimidazolium dimethylphosphate, l-ethyl-3-methylimidazolium thiocyanate,
and 1-butyl-3-methylimidazolium dicyanamide, alone or as a mixture Particularly pre-
ferred ionic liquids are 1-butyl-3-methylimidazolium bis(tnfluoromethylsulfonyl)amide, 1-
butyl-3-methylimidazohum iodide, and 1-butyl -3-methylimidazolium octylsulfate
Supported Ionic Liquid-Phase (SILP) catalysts comprise an ionic liquid as disclosed
above having the catalytically active complex dispersed on an inert support material
having a large surface area Said design allows the preparation of operationally solid
catalysts which may be placed in the reactor bed while ensuring easy accessibility of
the reactants to the active components of the catalyst in the ionic liquid In the present
context a SILP catalyst refers to a catalyst wherein the catalytically active component is
dissolved/ incorporated in the ionic liquid Ideally a SILP catalyst utilizes the advan-
tages of both homogeneous and heterogeneous catalysis Thus the distance of diffu-
sion is minimised since the ionic liquid is dispersed as a very thin film on a large sur-
face area
Fig 1 shows diagrammatically the exemplary design of a SILP catalyst particle,
wherein an immobilised catalytic ionic liquid phase consisting of ionic liquid A+B" and a
Group VIII metal represented as M+X"is dispersed at low liquid loading on a porous
high-area support (By the term "low liquid loading" is meant the pore filling degree of
an ionic liquid in the porous support Typically the desired liquid loading is below
0 5 )Gaseous reactants diffuse into the porous structure of the SILP catalyst and reacts
in the inter-phase of the thin ionic liquid catalyst film, where-after the product leaves the
SILP particles again

Suitable support materials are selected from the group consisting of silicas, polymers,
zeolites, clays, alumina, titania, zirconia and combinations thereof A preferred support
material is silica, since it is mechanically robust, possesses a large surface area and is
easy to process to the desired particle sizes
The process according to the invention may be used for the carbonylation of any car-
bonylatable reactant The term "carbonylatable reactant" as used in the present context
is intended to mean any organic reactant which is capable of reacting with carbon
monoxide, under carbonylation conditions of temperature and pressure, to obtain a re-
action product resulting from the insertion of carbon monoxide into one or more chemi-
cal bonds Examples of carbonylatable compounds include alcohols, ethers, and car-
boxylic acid esters having up to about 20 carbon atoms More particularly said carbon-
ylatable reactants are selected from the group consisting of saturated or mono- or d1-
unsaturated, linear or branched aliphatic C1-Cao reactants and saturated or mono- or d1-
unsaturated aromatic reactants having from 7 to 20 carbon atoms
If the desired product of the carbonylation process is an acid or a derivative thereof,
such as an ester or ether thereof, preferred carbonylatable reactants are alcohols, in
particular lower alcohols The most preferred alcohol is methanol, which is reacted with
carbon monoxide to produce the industrially important chemical acetic acid
In a preferred embodiment of the process according to the invention a reaction pro-
moter is used Suitable reaction promoters are selected from the group consisting of
halides, hydrogen halides, or alkyl or aryl halides having up to about 10 carbon atoms
Preferred halides are selected from chlorine, bromine and iodine compounds, most
preferably iodine compounds, that are gaseous under vapour phase carbonylation
conditions Suitable halides include hydrogen halides such as hydrogen iodide and
gaseous hydroiodic acid, alkyl and aryl halides having up to about 10 carbon atoms
such as methyl iodide, ethyl iodide, methyl bromide, ethyl bromide, benzyl iodide and
any mixtures thereof The halide may also be molecular halogen such as l2, Br2 or Cl2
In the embodiment of the process according to the invention in which carbon monoxide
is reacted with methanol to produce acetic acid, the most preferred reaction promoter is
methyl iodide
Scheme 1 below shows the essential steps of the catalytic cycle for the Monsanto car-
bonylation process of methanol for the preparation of acetic acid Without wishing to be

bound by any specific theory it is thought that the process according to the invention
may be performed analogously for any carbonylatable reactant

The reaction mechanism of the Monsanto process as it is believed to take place is thus
as follows Methanol is first reacted with an iodide source (HI) to form methyl iodide
Methyl iodide reacts with the rhodium complex by oxidative addition of methyl and io-
dide to the rhodium complex under formation of an alkyl complex Said addition is fol-
lowed by a migratory insertion of CO between the methyl group and the rhodium atom
under formation of an unsaturated acyl complex having a free coordination site Said
"free" coordination site is occupied by a new CO molecule and subsequently acetic
acid iodide is separated by reductive elimination of the acyl group and one of the iodide
ligands Acetic acid iodide is converted to acetic acid by reaction with water to reform
the iodide source Said iodide source is by re-reaction with methanol converted to the
reaction promoter methyl iodide
The carbonylation reaction according to the invention may be carried out at a tempera-
ture in the range from ambient to the temperature of decomposition of the ionic liquid at
a pressure in the range 1-100 bar However, since the carbonylation reaction is to
take place in the gaseous phase the temperature must be kept above the dew point of

the carbonylation reaction mixture Typically the process according to the invention is
carried out at a temperature in the range 100 -300° C, more preferably in the range
150-230° C
A wide range of pressures is available under which the carbonylation process accord-
ing to the invention may be earned out provided maintenance of a gaseous state of all
reactants is ensured Typically the process according to the invention is carried out at a
pressure in the range 5-50 bar, more preferably in the range 10 - 30 bar
The process according to the invention may be carried out in an apparatus shown dia-
grammatically in Fig 2, wherein said apparatus comprises
i) at least one reactor 1 ,
u) at least one liquid evaporator 2,
in) at least one condenser 3,
iv) at least one separator 4 to separate the product stream from residual process gas
which is recycled to said at least one reactor
Through an evaporator inlet line 5 liquid carbonylatable reactant enters the evaporator
2 In a preferred embodiment of the invention a liquid mixture of carbonylatable reac-
tant and reaction promoter, at any desired ratio, such as about 20 1-1 1, preferably
about 9 1-21, enters the evaporator 2 The process gas is evaporated by the evapora-
tor and combined with re-circulated process gas from line 7 The reactant gas mixture
enters the reactor 1 through a reactor inlet line 6 either at the bottom as shown on fig 2
or at the top, if so desired The reactor 1 to be used in the process according to the in-
vention may be any conventional fixed-bed or fluidised-bed reactor, wherein the SILP
catalyst is present As an alternative to the above mentioned fixed-bed or fluidised-bed
reactor a tube reactor may be employed A single reactor may be used, however, the
use of more than one reactor, in series or parallel, is also contemplated in the present
invention
The reaction mixture is forced to pass the SILP catalyst, wherein the presence of the
very thin film of ionic liquid containing the catalyst dispersed on a robust, inert, porous

high-area support material 8 offers a highly efficient use of the ionic liquid catalyst
phase The SILP catalyst thus requires smaller amounts of expensive metal catalyst
and ionic liquid than any pnor art catalyst systems Due to the increased efficiency of
the catalyst also a smaller reactor size may be used compared to prior art reaction de-
signs in order to obtain similar catalyst efficiency The heat of the exothermic reaction
may be removed by inter-stage cooling of a multi-bed reactor, through the fluidised bed
design or as an alternative using a tube reactor with external cooling
The product stream from the reactor 1 is fed to a condenser 3 through a condenser
inlet line 9 either at the top as shown on fig 2 or at the bottom thereof, if so desired In
the condenser 3 the gaseous reactants are evaporated from the top of the condenser 3
and re-circulated via line 7 to the reactor 1 whereas the liquified reaction products are
transferred to a separator 4 through a liquid reaction product line 10 In the separator 4
a further separation of gaseous carbon monoxide and any other process gasses, if
present, from the punfied liquid product stream is obtained The product stream from
the separator 4 is processed further in a manner known per se employing e g frac-
tional distillations and/or drying operations The separator 4 may be any separator
known in the art, such as a common distillation unit, a flash distillation unit etc
In each of the above described process steps a single unit operation device will nor-
mally be used However, the invention also contemplates the use of more than one unit
operation device, such as e g more than one distillation unit, if required
A major advantage by the use of the above simple process design is the omission of
any catalyst recirculation since the catalyst is maintained in the reactor Separation of
the liquid phase currently employed in industrial plants often results in catalyst deacti-
vation since carefully controlled conditions are required in order to avoid cntical low
pressures in connection with flash distillation operations This also adds to a reduced
demand for expensive catalyst material by the process according to the invention Fur-
thermore the simplified process design provides economical benefits as a result of
lower operating and running costs Existing plants may easily be adapted to the appa-
ratus according to the invention or may be implemented at reduced plant investments
EXAMPLES
The following examples illustrate the invention without limiting its scope or content

S1LP CATALYST PREPARATION
The l-bufyl-3-methylimidazolium iodide/dicarbonylduodorhodium(l) SILP catalyst em-
ployed in the examples was prepared by initial stirring of a dry methanol solution (8 ml)
containing 16 5 mg tetracarbonyldnododirhodium(l) (0 029 mmol) metal precursor and
302 5 mg ionic liquid 1-butyl-3-methylimidazolium iodide (1 137 mmol) under argon at-
mosphere for 24 hours Subsequently, 0 600 g thermally pretreated (500 °C, 15 h, in
air) silica support (silica gel 100, Merck, BET surface area 304 m2g"1> pore volume
1 01 cm3g"1. mean pore diameter (monomodal) 13 2 nm) was added, where after the
suspension was left with slow stirring for additionally 4 hours before the volatile solvent
was removed at reduced pressure at room temperature The residue consisting of fine
red-brown SILP catalyst particles was then dried in a vacuum oven overnight (0 1
mbar, 60 °C) and further kept in vacuo over phosphor pentaoxide prior to use
CATALYTIC TEST SYSTEM
Continuous, gas-phase carbonylations of methanol with carbon monoxide and methyl
iodide as reaction promoter were performed in an all-heated stainless steel (AISI
316Ti) catalyst test system with the SILP catalyst positioned as a fixed-bed in a tubular
reactor, placed in a temperature controlled aluminum block oven The test system al-
lowed the reactant feed composition to be controlled by gas- and liquid mass-flow con-
trollers integrated with an evaporator and mixing unit and the reaction pressure to be
controlled by a regulator valve equipped with a pneumatic actuator via connection to an
electronic controller and pressure transducer Gas-phase reactants and products were
analyzed continuously by an integrated on-line FID-GC using auto gas sampling
Example 1
1 00 g of SILP catalyst (containing 0 0437 mmol Rh metal), prepared as above, was
positioned in a fixed catalyst bed in the tubular reactor where after the system was
pressurized with carbon monoxide gas at a constant flow (FCo) of 50 ncm3min"1 to a
constant reaction pressure (Pr) of 20 bara Meanwhile the reactor was heated to a con-
stant reaction temperature (7r) of 180 °C and the rest of the test system to 160 °C
When the preset reaction pressure and temperatures were reached the carbon monox-
ide gas was bypassed the reactor, and a liquid mixture containing 75 25 w/w % of

methanol methyl iodide was introduced into the bypassed reactant gas, after evapora-
tion of the liquid mixture, with a constant flow (fiiq) of 0 69 gh"1 When the reactant gas
mixture composition became constant, as determined by the FID-GC analysis, the
methanol carbonylation reaction was started by allowing the reactant gas stream to
flow through the SILP catalyst bed The carbonylation reaction was afterwards followed
for 1 5 hour while determining the gas composition regularly by FID-GC analysis, allow-
ing determination of methanol conversion and catalyst activity (as tum-over-frequency
in mo! product formed per mol rhodium per hour) and selectivity for formation of the ob-
served products acetic acid (AcOH), acetic acid methyl ester (AcOMe) and d1-
methylether (MeOMe), respectively

Example 2
The results illustrated in this example are consecutive steady-state results obtained af-
ter continuation of the methanol carbonylation reaction described in Example 1 at 180
°C, using the 1-butyl-3-methylimidazo!ium lodide/dicarbonyldnodorhodium (I) SILP
catalyst, at different reaction pressure and reactant flows, respectively

WE CLAIM
1 A process for the continuous carbonylation of carbonylatable products with carbon monoxide in
the gaseous phase in the presence of a catalyst wherein said catalyst is a Supported Ionic Liquid-
Phase (SILP) catalyst comprising a solution of a Group VIII metal selected from iron, ruthenium,
thodmm, iridium, nickel, cobalt and palladium or any combinations thereof in an ionic liquid, such
as herein described, confined on a support, such as herein described
2 The process as claimed in claim 1, comprising
i) continuously feeding to a reaction zone a carbonylatable reactant and carbon monoxide, wherein
said carbomlatable reactant and carbon monoxide are in the gas phase,
ii) continuously contacting said carbonylatable reactant and carbon monoxide with a SILP catalyst
comprising a solution of a Group VIII metal in an ionic liquid confined on a support, and
in) continuously lecovenng from said reaction zone a gaseous effluent comprising a carbonylated
product
3 The process as claimed in claim 2 optionally composing initial addition to the reaction zone in
step l) of a reaction promoter, such as herein described
4 The process as claimed in claim 1, wherein said ionic liquid is of the formula A'B" wherein A
lepresents a quaternary nitrogen- and/or a quaternary phosphoious- containing cation
5 The process as claimed in claim 4, wherein the cation A is selected from the group consisting of
i)

wherein R1 R2, R3, and R4 are independently selected fiom optionally substituted, linear or
branched-chamed C1-C20 alkyl. optionally substituted cyclic C3-C20 alkyl, and optionally
substituted C6-C20 aryl. and Y is N or P,

II)

wherein R5 and R7 are independently selected from optionally substituted, linear or branched-
chamed C1-C20 alky], optionally substituted cyclic G-C20 alkyl, and optional!) substituted C6-C20
aryl and R6. R8 and R9 are independently selected from hydiogen optionally substituted, linear or
branched-chamed C1-C20 alkyl optionally substituted cyclic C3-C20 alkyl, and optionally
substituted C„-C2o aiyl,
111)
wherein R10 is independently selected from optionally substituted, linear or branched- chained G-
C20 alkyl, optionally substituted cyclic C3-C20 alkyl, and optionally substituted C„-C20 aryl. and R1
and R12 are independently selected from hydrogen, optional!} substituted, linear or branched-
chamed C1-C20 alkyl, optionally substituted cyclic C3-C20 alkyl, and optionally substituted C0-C2o
ary 1. and
n)

wherein R13 and R14 are independently selected from optionally substituted, linear or branched-
chained C1-C20 alkyl, optional!} substituted cyclic C1-C20 alky], and optionally substituted C6-C20
aryl, X is C, N, O, or S, n and in are each integers from O to 6 with the proviso that the sum 1 less
than or equal to m+n less than or equal to 6
6 The process as claimed in claim 4, wherein the anion B" is selected from the gioup consisting of
hahdes, nitrates, sulfates, sulfonates, sulfonyl amides phosphates, borates, antimonates, and
acetates or optionally halogen, hydroxy 1, or C1-C6 alkoxy- substituted hydrocarbyl derivatives
thereof
7 The process as claimed in any of the preceding claims, wherein the ionic liquid A+B" is selected
from tetrabutylphosphonium tetrafluoroborate, N-butylpyridimum hexafluorophosphate, N-
ethylpyndinmm tetrafluoroboi ate 1 -butyl-1 -methylpy n ohdimum
bis(tnfluoiomethylsulfon\l)amide l-butyl-3-methyhmidazohum tetrafluoroborate, 1- butyl-3-
methyliinidazohum hexafiuorophosphate, l-butyl-3-methylimidazohum tnfluoro- methylsulfonate,
l-butyl-3-methylimidazolmm bis(trifluorometh\lsulfonyl)amide. 1-ethyl- 3-methyhmidazolium
bis(tnfluoromethylsulfonyl)amide. l-butyl-3-methyhmidazolium acetate. 1-but} 1-3-
methylimidazohurn iodide, l-ethyl-3-methylimidazohum rrvdrogensul- fate, l-butyl-3-
methyhmidazohum methylsulfate, l-ethyl-3-meth}limidazolium ethylsul- fate, l~butyl-3-
methyhmidazohum octylsulfate, 1,3-dimethylimidazohum octylsulfate, 1- butyl-3-
ethyhmidazolium p-toluenesulfonate. l-ethyl-3-methyhmidazohum methanesul- fonate. 1,3-
dimethylimidazohum dimethylphosphate, l-ethyl-3-methylnnidazohum thio-cyanate, and 1-buryl-
3-methyhmidazolium dicyanamide, in paiticulai l-butyl-3- methylimidazolium
bis(tnfluoromethylsulfonyl)amide, l-butyl-3-methyhmidazohum iodide, and l-butyl-3-
methyhmidazolium octylsulfate. alone or as a mixture
8 The process as claimed in any of the preceding claims, u herein the suppoit of said S1LP catalyst is
selected from the gioup consisting of silicas, polymers, zeolites, clays, alumina titania, zircoma
and combinations thereof, preferably silica
9 The process as claimed in claim 1, wherein said carbonylatable reactants are selected from the
group consisting of alcohols etheis, and carboxyhc acid esters having up to 20 carbon atoms

10 The process as claimed in claim 9, wherein said carbon}latable reactants are selected from the
group consisting of saturated or mono- or d1-unsaturaled, linear or blanched aliphatic C1-C20
leactants and saturated 01 mono- or d1-unsaturated aromatic leactants having from 7 to 20 carbon
atoms
11 The process as claimed in any of claims 9 or 10, for the carbony lation of alcohols
12 The process as claimed in claim 11, for the carbonylation of methanol
13 The process as claimed in claim 3 wherein said leaction promoter is selected from the gioup
consisting of halides. hydiogen halides, or alkyl or aryl hahdes having up to 10 carbon atoms
14 The process as claimed 111 claim 13. wherein said reaction promoter is methyl iodide
15 The process as claimed in claim 1, wherein the carbon\ lation reaction is carried out at a
temperature in the range from ambient to the temperature of decomposition of the ionic liquid at a
pressure in the range 1-100 bar
16 The process as claimed in claim 15, wherein the carbonylation leaction is carred out at a
temperatuie in the range 100 -300 degrees C. more preferably in the lange 150-230 degrees
centigrade
17 The process as claimed in claim 1, wherein the carbonylation reaction is carried out at a pressure in
the range 5-50 bar, more preferably in the lange 10-30 bar

ABSTRACT

A PROCESS FOR CONTINUOUS CARBONYLATION BY SUPPORTED
IONIC LIQUID-PHASE CATALYSIS
There is disclosed a process for the continuous carbonylation of carbonylatable products with
carbon monoxide in the gaseous phase in the presence of a catalyst, wherein said catalyst is a
Supported Ionic Liquid-Phase (SILP) catalyst comprising a solution of a Group VIII metal selected
from iron, luthenium, rhodium, indium, nickel, cobalt and palladium or any combinations thereof
in an ionic liquid, such as herein described, confined on a support, such as herein described.

A PROCESS FOR CONTINUOUS CARBONYLATION BY SUPPORTED IONIC LIQUID-PHASE CATALYSIS

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