Process for the production of catalysts, catalysts therefrom, and processes for the production of ethylenically unsaturated carboxylic acids or esters - Patent Application 20070122997

Abstract

The present invention relates to a method for producing a catalyst, the method comprising the steps of: a) providing an uncalcined metal-modified porous silica support, wherein the modifier metal is selected from one or more of boron, magnesium, aluminum, zirconium, hafnium, and titanium, and the modifier metal is present in a mononuclear or polynuclear modifier metal moiety; b) optionally removing the solvent or liquid carrier from the modified silica support; c) optionally drying the modified silica support; d) treating the uncalcined metal-modified silica support with a catalytic metal to result in adsorption of the catalytic metal onto the metal-modified silica support; and e) calcining the impregnated silica support of step d). The invention extends to a method for producing a catalyst by providing an uncalcined catalyst intermediate and a porous silica support having isolated silanol groups.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a modified silica catalyst, the catalyst, and a method for producing an ethylenically unsaturated carboxylic acid or ester, particularly an α,β-unsaturated carboxylic acid or ester, more particularly an acrylic acid or ester, such as (alk)acrylic acid or an alkyl (alk)acrylate, particularly (meth)acrylic acid or an alkyl (meth)acrylate, such as methacrylic acid (MAA) and methyl methacrylate (MMA), by condensing a carboxylic acid or ester with formaldehyde or a source thereof, such as dimethoxymethane, in the presence of such a catalyst, particularly by condensing propionic acid or an alkyl ester thereof, such as methyl propionate, with formaldehyde or a source thereof, in the presence of such a catalyst. Thus, the present invention is particularly directed to the production of MAA and MMA. The catalyst of the present invention incorporates a modified silica support, which has been uniquely modified with a specific modifier metal, and a catalytic metal. [Background technology]

[0002] As noted above, unsaturated acids or esters may be made by reaction of a carboxylic acid or ester, suitable carboxylic acids or esters having the formula R 3 -CH2-COOR 4 where R 3 and R 4 are each independently a suitable substituent known in the art for acrylic compounds, such as hydrogen or an alkyl group, particularly a lower alkyl group containing, for example, 1 to 4 carbon atoms. Thus, for example, MAA or its alkyl esters, particularly MMA, can be prepared by the catalytic reaction of propionic acid or the corresponding alkyl ester, such as methyl propionate, with formaldehyde as the methylene source, according to Reaction Sequence 1. order 1 R 3 -CH2-COOR 4 +HCHO------->R 3-CH(CHOH)-COOR 4 and R 3 -CH(CHOH)-COOR 4 ------>R 3 -C(:CH2)-COOR 4 +H2O An example of reaction sequence 1 is reaction sequence 2. order 2 CH3-CH2-COOR 4 +HCHO------->CH3-CH(CH2OH)-COOR 4 CH3-CH(CH2OH)-COOR 4 ------>CH3-C(:CH2)-COOR 4 +H2O

[0003] The above reaction sequence is typically carried out using an acid / base catalyst at elevated temperatures, usually in the range of 250-400°C. When the desired product is an ester, the reaction is typically carried out in the presence of the relevant alcohol to minimize the formation of the corresponding acid by hydrolysis of the ester. For convenience, it is often desirable to introduce the formaldehyde in the form of a complex of formaldehyde with methanol. Thus, for the production of MMA, the reaction mixture fed to the catalyst generally consists of methyl propionate (MEP), methanol, formaldehyde, and water.

[0004] A known method for the production of MMA is the catalytic conversion of MEP to MMA using formaldehyde. Known catalysts for this are cesium catalysts incorporating supports such as silica.

[0005] WO 99 / 52628 discloses the preparation of catalysts impregnated with modifier metals (boron, magnesium, aluminum, zirconium and hafnium) from mesoporous gel silica using modifier nitrates, oxynitrates and oxides, such as zirconium nitrate, followed by incorporation and calcination with cesium carbonate. Zirconium, or zirconium and aluminum acetate solutions are mixed with cesium acetate solution and co-adsorbed onto the silica support.

[0006] U.S. Patent No. 6,887,822 teaches the option of calcining the hydrogel silica surface after treatment with a catalytic metal. However, it does not address the issue of adsorption of the modifier metal and how to treat the surface thus modified. Instead, zirconia is introduced by co-gelation. This document omits silica xerogel bead impregnation, and only exemplified hydrogel beads, which apparently results in much stronger beads.

[0007] Unpublished international application PCT / GB2018 / 052606 discloses the adsorption of metal-organic complexes of zirconium and hafnium onto a silica support, followed by the adsorption of a catalyst metal, such as cesium. Generally, a calcination step after modifier metal adsorption, in which the modifier is added as a complex, and an optional calcination step after alkali metal adsorption are specifically taught. Summary of the Invention [Problem to be solved by the invention]

[0008] Generally, after treatment of the silica support with a modifier metal, a calcination step is expected to "fix" the metal before further processing. This is especially true when organic groups are attached to the modifier metal and need to be removed. [Means for solving the problem]

[0009] We have now discovered that catalysts produced in accordance with the present invention achieve high levels of selectivity in the condensation of a methylene source, such as formaldehyde, with a carboxylic acid or alkyl ester, such as MEP.

[0010] Furthermore, the inventors have found that when the method of catalyst production of the present invention is used, the rate of catalyst surface sintering is found to be slowed, reducing the loss of surface area on which the catalytic reaction occurs during the condensation reaction.

[0011] Thus, the catalysts of the present invention are remarkably efficient catalysts for the production of α,β ethylenically unsaturated carboxylic acids or esters by condensation of the corresponding acids or esters with a methylene source, such as formaldehyde, which provides several advantages, such as high levels of selectivity and / or reduced sintering of the catalyst surface. DETAILED DESCRIPTION OF THE INVENTION

[0012] According to a first aspect of the present invention, a) providing an uncalcined metal-modified porous silica support, wherein the modifier metal is selected from one or more of B, Mg, Al, Zr, Hf, and Ti, and the modifier metal is present in a mono- or poly-nuclear modifier metal moiety; b) optionally removing the solvent or liquid carrier from the modified silica support; c) optionally drying the modified silica support; d) treating the uncalcined metal-modified silica support with a catalytic metal to result in adsorption of the catalytic metal onto the metal-modified silica support; e) calcining the impregnated silica support of step d); The present invention provides a method for producing a catalyst, comprising:

[0013] Advantageously, by treating an uncalcined modified silica support as defined with a catalytic metal, followed by calcination, improved selectivity and increased resistance to sintering is found in the catalytic production of ethylenically unsaturated carboxylic acids or esters by condensation of the carboxylic acid or ester with formaldehyde or a source thereof.

[0014] In the present invention, it has been surprisingly found to be advantageous to control the nuclearity of the modifier metal moieties, as this controls the proximity of adjacent modifier metal moieties on the silica.

[0015] According to a second aspect of the present invention, there is provided an uncalcined catalytic intermediate comprising an uncalcined porous silica support modified with a modifier metal, wherein the modifier metal is selected from one or more of B, Mg, Al, Zr, Hf and Ti, and wherein said modifier metal is present in mono- or poly-nuclear modifier metal moieties and catalytic metal adsorbed on said uncalcined modified silica support.

[0016] The silica of the first or second aspect may be provided as a co-gel of modifier metal oxide and silica, or as a modified silica having a modifier metal adsorbed onto the silica surface.

[0017] Surprisingly, the catalysts of the present invention provide improved selectivity and increased resistance to sintering.

[0018] Surprisingly, it has been found that increasing the temperature of the calcination achieves further improved selectivity.

[0019] According to a third aspect of the present invention there is provided a catalyst obtainable by the process of the first or further aspect of the present invention.

[0020] According to a fourth aspect of the present invention there is provided a catalyst obtainable by the process of the first or further aspects of the present invention.

[0021] According to a further aspect of the present invention there is provided a method for producing a modified silica support for a catalyst according to the claims.

[0022] Modifier Metal Complex Typically, when the modifier metal is added as an adsorbate, it may be added as a mononuclear or polynuclear modifier metal compound. Typically, the compound is a complex, and the ligands in the coordination sphere of the compound are generally of sufficient size to prevent further oligomerization of the modifier metal and / or a significant increase in the nuclearity of the complex before and / or after adsorption. Generally, an increase in nuclearity to a dimer is acceptable. Typically, the modifier metal complex is an organic complex having one or more organic multidentate chelating ligands, or alternatively, a complex having sterically bulky monodentate ligands effective to stabilize nuclearity.

[0023] Typically, at least 25% of the modifier metal, before or after calcination, is present on the support in the form of mono- or poly-nuclear modifier moieties. Thus, typically, at least 25% of the modifier metal is present on the support in the form of modifier metal moieties derived from mono- or poly-nuclear metal compounds.

[0024] Typically, the mononuclear or polynuclear modifier metal is contacted with the silica support as a mononuclear or polynuclear modifier metal compound in solution, resulting in adsorption of the modifier metal onto the support.

[0025] Typically, the modifier metal compounds are mononuclear or polynuclear, more preferably mononuclear.

[0026] It has been surprisingly found that modifier metal clusters of more than two metal atoms dispersed throughout a support, such as a hydrogel support, reduce the reaction selectivity for the production of α,β ethylenically unsaturated carboxylic acids or esters by condensation of the corresponding acid or ester with a methylene source, such as formaldehyde. Such large clusters have also been surprisingly found to increase sintering of the modified silica particles compared to mononuclear or polynuclear moieties, thereby reducing the surface area, which reduces strength and catalyst life before activity becomes unacceptably low. Furthermore, selectivity is often lower due to the clustered nature of the modifier metal.

[0027] Advantageously, improved reaction selectivity and / or reduced rates of catalyst surface sintering have been found during the production of α,β ethylenically unsaturated carboxylic acids or esters when at least a proportion of the modifier metal incorporated in the modified silica of the above aspects of the invention is derived from a mononuclear or polynuclear modifier metal cation source at the initiation of modified silica formation.

[0028] Typically, the modifier metal is selected from zirconium, hafnium and titanium.

[0029] Typically, the metal compound is a complex containing two or more chelating ligands, preferably two, three, or four chelating ligands. The chelating ligands herein can be bidentate, tridentate, tetradentate, or polydentate. However, it is also possible for the compound to contain bulky monodentate ligands that are also effective in effectively spacing the modifier metal on the silica surface as demonstrated herein.

[0030] Typically, the metal complexes are tetracoordinate, pentacoordinate, hexacoordinate, heptacoordinate, or octacoordinate.

[0031] Advantageously, the size of the ligands in the coordination sphere of the metal compound, e.g., the size of chelating ligands, results in the modifier metal being more dispersed than the same modifier metal with a simple counterion, e.g., nitrate, acetate, or oxynitrate. It has been found that smaller metal salt adsorption results in clustering of the modifier metal following heat treatment or calcination, which reduces the selectivity of the catalyst and reduces the sintering resistance of the catalyst.

[0032] Generally, as used herein, the modifier metal is an adsorbate that is adsorbed onto the silica support surface of the catalyst. The adsorbate may be chemisorbed or physisorbed as its compound onto the silica support surface, and typically it is chemisorbed thereon.

[0033] Suitable chelating ligands herein may be non-labile ligands optionally selected from molecules having lone pairs of electrons containing oxygen or nitrogen atoms that can form five- or six-membered rings with the modifier metal atom. Examples include diones, diimines, diamines, diols, dicarboxylic acids or derivatives thereof, such as esters, or molecules having two different such functional groups, in each case with the respective N or O and N or O atoms separated by two or three atoms, thereby forming a five- or six-membered ring. Examples are pentane-2,4-dione, esters of 3-oxobutanoic acid with aliphatic alcohols containing 1 to 4 carbon atoms, such as ethyl 3-oxobutanoate, propyl 3-oxobutanoate, isopropyl 3-oxobutanoate, n-butyl 3-oxobutanoate, t-butyl 3-oxobutanoate, heptane-3,5-dione, 2,2,6,6-tetramethyl-3,5-heptanedione, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol. , 1,2-butanediol, 1,2-diaminoethane, ethanolamine, 1,2-diamino-1,1,2,2-tetracarboxylate, 2,3-dihydroxy-1,4-butanedioate, 2,4-dihydroxy-1,5-pentanedioate, salts of 1,2-dihydroxylbenzene-3,5-disulfonate, diethylenetriaminepentaacetic acid, nitrilotriacetic acid, N-hydroxyethylethylenediaminetriacetic acid, N-hydroxyethyliminodiacetic acid, N,N-dihydroxyethylglycine, oxalic acid and its salts. Most preferred are pentane-2,4-dione, heptane-3,5-dione, 2,2,6,6-tetramethyl-3,5-heptanedione, ethyl 3-oxobutanoate, and t-butyl 3-oxobutanoate. For example, smaller bidentate chelating ligands having less than 10 total carbon and / or heteroatoms may allow smaller complexes to be formed, which may allow higher concentrations to deposit on the surface of the silica compared to larger ligands.Thus, the mononuclear or polynuclear modifier metal cation source herein may be in the form of a complex of the modifier metal with such smaller chelating ligands, preferably at least one such ligand. Such compounds may contain labile ligands, such as solvent ligands in alcohol solvents, alkoxide ligands such as ethoxide or propoxide, and the like.

[0034] The chelating ligand is typically a non-labile ligand. By non-labile ligand is meant a ligand that is coordinated to the modifier metal and is not removed by adsorption of the modifier metal onto the silica surface. Thus, non-labile ligands are typically coordinated to the modifier metal in solution prior to treatment of the silica surface with the modifier metal. For the avoidance of doubt, non-labile ligands are typically removed by appropriate treatment of the silica surface following adsorption of the modifier metal.

[0035] The size of the chelating ligand is selected to space the modifier metal atoms on the silica surface and prevent their recombination during catalyst formation.

[0036] Alternatively, modifier metal complexes with bulky monodentate ligands (to prevent oligomerization of the metal complex) can be used. Typical ligands used in such complexes include, but are not limited to, alkoxides with suitable organic groups, such as tert-butoxide or 2,6-ditert-butylphenoxide, amides with suitable organic groups, such as dialkylamides (methyl, ethyl, and higher linear and branched alkyl groups, and bis(trimethylsilylamide) complexes), and alkyl ligands with suitable organic groups, such as 2,2-dimethylpropyl(neopentyl) ligands.

[0037] Typically, the silica support has isolated silanol groups, and by contacting the silica support with a modifier metal species, the modifier metal is adsorbed onto the surface of the silica support by reaction with the silanol groups.

[0038] Preferably, the adsorbed or co-gelled modifier metal cations are sufficiently spaced from one another by the modifier metal compound to substantially prevent their oligomerization, more preferably their dimerization, trimerization or oligomerization with adjacent modifier metal cations, during subsequent processing steps, such as impregnation with a catalyst metal, or optionally subsequent calcination.

[0039] Typically, at least 25% of the modifier metal species contacting the silica support in the contacting step are mononuclear and / or polynuclear species, more typically at least 30%, such as at least 35%, more preferably at least 40%, such as at least 45%, most suitably at least 50%, such as at least 55%, such as at least 60% or 65%, most preferably at least 70%, such as at least 75% or 80%, more typically at least 85%, most typically at least 90%, especially at least 95%.

[0040] According to a fifth aspect of the present invention, a) providing a porous silica support having isolated silanol groups; b) treating the porous silica support with a mononuclear or polynuclear modifier metal compound such that the modifier metal is adsorbed onto the surface of the silica support by reaction with the isolated silanol groups, the adsorbed modifier metal atoms being sufficiently spaced from one another to substantially prevent their oligomerization with adjacent modifier metal atoms before and / or after calcination, more preferably being sufficiently spaced from one another to substantially prevent their dimerization or trimerization with adjacent modifier metal atoms, wherein the modifier metal is selected from B, Mg, Al, Zr, Hf and Ti; c) optionally removing the solvent or liquid carrier from the modified silica support; d) optionally drying the modified silica support; e) treating the uncalcined modified silica support with a catalytic alkali metal to result in adsorption of the catalytic alkali metal onto the modified silica support; f) calcining the impregnated silica support of step e);

[0023] The present invention provides a method for producing a catalyst according to any of the aspects herein or other aspects, comprising:

[0041] Preferably, the spacing of the modifier metal atoms is provided by the size of the modifier metal compound.

[0042] Typically, the silica support is 2 Contains isolated silanol groups (—SiOH) at a level of <2.5 groups per silane.

[0043] Preferably, the modifier metal herein is a solution of a compound of said modifier metal such that the compound is in solution when contacted with the support, resulting in adsorption onto the support.

[0044] Typically, the solvent for the solution is water or other than water.

[0045] Typically, the solvent is an organic solvent, such as toluene or heptane, and the solvent may be an aliphatic or aromatic solvent. Furthermore, the solvent may be a chlorinated solvent, such as dichloromethane. More typically, the solvent is an aliphatic alcohol, typically selected from a C1-C6 alkanol, such as methanol, ethanol, propanol, isopropanol, butanol, pentanol, and hexanol, more typically methanol, ethanol, or propanol.

[0046] The concentration of isolated silanol groups on the silica support prior to modifier metal adsorption is preferably controlled by calcination or other suitable methods known to those skilled in the art. Methods for identifying silanols include, for example, LT Zhuravlev, "Colloids and Surfaces: Physicochemical and Engineering Aspects, vol. 173, pp. 1-38, 2000," which describes four different forms of silanol that can coexist on silica surfaces: isolated silanols, geminal silanols, vicinal silanols, and internal silanols. Isolated silanol groups are most preferred. These have a peak at 3730-3750 cm. -1 silanols can be identified by infrared spectroscopy as a narrow absorption peak at 3460-3715 cm, while other silanols -1 (See "The Surface Properties of Silicas," Edited by Andre P. Legrand, John Wiley and Sons, 1998 (ISBN 0-471-95332-6) pp. 147-234).

[0047] The modified silica support according to any of the embodiments herein may be 2 The modified support may contain isolated silanol groups (—SiOH) at a level of <2.5 groups per nm. 2 at levels of >0.1 and <2.5 groups per nm, more preferably at levels of 0.2 to 2.2, and most preferably at levels of 2 Contains isolated silanol groups (—SiOH) at a level of 0.4 to 2.0 groups per unit area.

[0048] Still further, the invention extends to a process, catalyst or catalytic intermediate according to any embodiment herein, wherein the support is present on a support and 2 The modifier comprises metal moieties present at a level of <2.5 moieties per metal.

[0049] Typically, the carrier is 2at levels of >0.025 and <2.5 groups per nm, more preferably at levels of 0.05 to 1.5, and most preferably at levels of 2 The modifier contains metal moieties at a level of 0.1 to 1.0 parts per 1000 carbon atoms.

[0050] Preferably, the concentration of isolated silanol groups determines the maximum number of modifier metals, and since the distribution of silanol sites is generally uniform, it can be effectively determined. The isolated silanol concentration for the production of modified silica supports according to the present invention is expressed in nm 2 less than 2.5 groups per nm, more typically 2 Fewer than 2.5 groups per nm, most typically 2 less than 1.5 groups per nm, in particular 2 The suitable range for the silanol concentration for the production of modified silica supports is 2 0.1 to 4.6 silanol groups per nm, more preferably 2 0.15 to 2.5 silanol groups per nm, most preferably 2 The number of silanol groups per atom can be 0.2 to 1.0.

[0051] The concentration of the modifier metal complex should be set at a level that prevents the formation of significant double layers on the surface of the support, which would result in modifier metal-metal interactions. Furthermore, filling gaps in the initial monolayer, which could result in weak adsorption of the modifier metal away from isolated silanol sites, should also be avoided to prevent interactions with neighboring strongly adsorbed modifier metals. Typical concentration ranges for the modifier metals of the present invention can be as shown herein.

[0052] Typically, at least 30%, such as at least 35%, more preferably at least 40%, such as at least 45%, most suitably at least 50%, such as at least 55%, such as at least 60% or 65%, most preferably at least 70%, such as at least 75% or 80%, more typically at least 85%, most typically at least 90%, especially at least 95%, of the modifier metal in the modifier metal complex is a mononuclear and / or polynuclear modifier metal compound when the complex is contacted with the support to result in adsorption of the complex onto the support.

[0053] A suitable method for treating silica to provide isolated silanol groups at the levels specified herein is by calcination. However, other techniques, such as hydrothermal treatment or chemical dehydration, are also possible. U.S. Pat. No. 5,583,085 teaches the chemical dehydration of silica with dimethyl carbonate or ethylene dicarbonate in the presence of an amine base. U.S. Pat. Nos. 4,357,451 and 4,308,172 teach chemical dehydration by chlorination with SOCl2, followed by dechlorination with H2 or ROH in a dry atmosphere, followed by oxygen. Chemical dehydration results in a minimum of 0.7 nm. 2 Up to 100% removal of silanols can be achieved by thermal treatment, whereas chemical dehydration can provide more scope for control of silanol groups in some cases.

[0054] The term isolated silanols (also known as single silanols) is well known in the art and is distinct from the group of vicinal or geminal or internal silanols. Suitable methods for determining the occurrence of isolated silanols include surface-sensitive infrared spectroscopy and 1 H NMR or 31 Includes Si NMR.

[0055] Preferably, the silica support is dried or calcined prior to treatment with the modifier metal.

[0056] silica Typically, the modified silica support is a xerogel. The gel may also be a hydrogel or an aerogel.

[0057] The gel may also be a silica-modifier metal oxide co-gel. Silica gels may be formed by any of a variety of techniques known to those skilled in the art of gel formation, such as those described herein. In this case, the modifier metal oxide may also be distributed throughout the silica matrix and its surface. Typically, however, the modified silica gel is produced by a suitable adsorption reaction. Adsorption of the relevant modifier metal compound onto a silica gel, e.g., a silica xerogel, to form a modified silica gel with relevant mono- or polynuclear modifier metal moieties is a suitable technique.

[0058] The silica may be in the form of a gel prior to treatment with the modifier metal adsorbate. The gel may be in the form of a hydrogel, xerogel, or aerogel at the start of modification. Typically, the silica support is a hydrogel or xerogel, most preferably a xerogel.

[0059] As noted, methods for preparing silica gels are well known in the art, and some such methods are described in The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface Properties and Biochemistry of Silica, by Ralph K Iler, 1979, John Wiley and Sons Inc., ISBN 0-471-02404-X and references therein.

[0060] The silica component of the modified silica support will typically form 80 to 99.9 wt % of the modified support, more typically 85 to 99.8 wt %, and most typically 90 to 99.7 wt % thereof.

[0061] Porous silica supports typically have a range of pore sizes from mesoporous to macroporous, with average pore sizes ranging from 2 to 1000 nm, more preferably from 3 to 500 nm, and most preferably from 5 to 250 nm. Macropore sizes (greater than 50 nm) can be determined by mercury intrusion porosimetry using NIST standards, while mesopore sizes (2 to 50 nm) are determined using the Barrett-Joyner-Halenda (BJH) analysis method using liquid nitrogen at 77 K. The average pore size is the pore volume-weighted average of the pore volume over the pore size distribution.

[0062] Surprisingly, it has also been found that preparing a silica support modified by cogelation of a xerogel and then carrying out steps b) to e) of the first aspect of the present invention also results in catalysts with improved selectivity and increased sintering resistance.

[0063] Still further, according to a sixth aspect of the present invention there is provided a catalyst comprising an intermediate according to the second aspect of the present invention, wherein said uncalcined intermediate has been calcined.

[0064] catalytic metals Generally, as used herein, the catalytic alkali metal is an adsorbate that is adsorbed onto the surface of the modified silica support of the catalyst. The adsorbate may be chemisorbed or physisorbed onto the surface of the modified silica support, and typically it is chemisorbed thereon.

[0065] As used herein, the catalytic metal is a metal other than the modifier metal. Preferably, the catalytic metal can be selected from one or more alkali metals. Typically, the catalytic alkali metal can be selected from cesium, potassium, or rubidium, more preferably cesium.

[0066] Suitably, the catalytic metal, for example cesium, may be present in the catalyst at a level of at least 1 mol / 100 (silicon + modifier metal) mol, more preferably at least 1.5 mol / 100 (silicon + modifier metal) mol, and most preferably at least 2 mol / 100 (silicon + modifier metal) mol. The level of catalytic metal may be up to 10 mol / 100 (silicon + modifier metal) mol in the catalyst, more preferably up to 7.5 mol / 100 (silicon + modifier metal) mol in the catalyst, and most preferably up to 5 mol / 100 (silicon + modifier metal) mol.

[0067] Preferably, the level of catalytic metal in the catalyst is in the range of 1 to 10 mol / 100 (silicon + modifier metal) mol in catalyst, more preferably 2 to 8 mol / 100 (silicon + modifier metal) mol, most preferably 2.5 to 6 mol / 100 (silicon + modifier metal) mol.

[0068] Alternatively, the catalyst may have a weight percent of catalytic metal in the catalyst ranging from 1 to 22 weight percent, more preferably 4 to 18 weight percent, and most preferably 5 to 13 weight percent. These amounts apply to all alkali metals, especially cesium.

[0069] Thus, the molar ratio of catalytic metal to modifier metal in the catalyst is typically at least 1.4 or 1.5:1, preferably in the range of 1.4 to 5:1, for example 1.5 to 4.0:1, especially 1.5 to 3.6:1, and typically in this context the catalytic metal is cesium. Generally, herein the catalytic metal exceeds that required to neutralize the modifier metal.

[0070] Preferably, the catalyst metal is present in the range of 0.5 to 7.0 mol / mol modifier metal, more preferably 1.0 to 6.0 mol / mol, and most preferably 1.5 to 5.0 mol / mol modifier metal.

[0071] Calcination Those skilled in the art will appreciate that the catalytic metals of the present invention can be added to the modified silica support by any suitable means. The catalytic metals are fixed onto the support by calcination after deposition of the catalytic metal compound onto the support. Calcination processes are well known to those skilled in the art.

[0072] In preferred calcinations of the catalyst, the temperature is at least 450° C., more preferably at least 475° C., most preferably at least 500° C., especially at least 600° C., and more especially above 700° C. Typically, the calcination temperature is in the range of 400 to 1000° C., more typically 500 to 900° C., and most typically 600 to 850° C.

[0073] The calcination atmosphere should typically contain some oxygen, suitably 1 to 30% oxygen, most suitably 2 to 20% oxygen, in an inert atmosphere or vacuum. Calcination times are typically 0.01 to 100 hours, suitably 0.5 to 40 hours, most suitably 1 to 24 hours.

[0074] General method Those skilled in the art will appreciate that the catalytic metal may be added to the modified silica by any suitable means. Typically, the modified silica is contacted with the catalytic metal to produce the modified silica catalyst.

[0075] Typically, to produce the catalyst, the modified silica support is contacted with a 100% aqueous solution of the catalytic metal, or an acidic, neutral, or alkaline aqueous solution containing the catalytic metal, e.g., cesium, in the form of a salt of the catalytic metal and a base. Alternatively, the support can be contacted with a water-miscible solution of the catalytic metal salt in an organic solvent. Preferred solvents are alcohols, e.g., methanol, ethanol, propanol, and isopropanol, preferably methanol. The most preferred solvent is methanol. Most preferably, the catalytic metal is added as a salt solution in methanol. A low level of water, typically up to 20% by volume, can be included in the solution.

[0076] Typically, the conditions of temperature, contact time and pH during this stage of the catalyst production process are those that allow impregnation of the modified silica support with, for example, the catalytic metal to form a modified silica-supported catalyst.

[0077] Typical conditions for temperature for this step are 5 to 95° C., more typically 10 to 80° C., and most typically 20 to 70° C. The temperature for this step can be at least 5° C., more typically at least 10° C., and most typically at least 20° C.

[0078] Typical contact times between the modified support and the catalytic metal-containing solution for this step can be from 0.05 to 48 hours, more typically from 0.1 to 24 hours, and most typically from 0.5 to 18 hours. The contact time can be at least 0.05 hours, more typically at least 0.1 hours, and most typically at least 0.5 hours.

[0079] The concentration of the catalytic metal salt solution for this step depends on a number of factors, including the solubility limit of the catalytic metal compound, the porosity of the modified silica support, the desired loading of the catalytic metal on the support, and the method of addition, including the amount of liquid used to impregnate the support, the pH and choice of catalytic metal compound. The concentration in solution is best determined by experimentation.

[0080] Suitable salts of catalytic metals for incorporation can generally be selected from one or more of the group consisting of formates, acetates, propionates, bicarbonates, chlorides, nitrates, hydroxides, and carbonates, more typically hydroxides, acetates, or carbonates, and most typically hydroxides and / or carbonates. pH can be controlled during impregnation by adding ammonia with the metal compound, or in all cases by using a suitable catalytic metal compound, such as a formate, carbonate, acetate, or hydroxide, more preferably a hydroxide or carbonate, alone, in combination, or with a suitable carboxylic acid. Control of pH within the preferred range is most important at the end of impregnation to result in satisfactory adsorption. Most typically, these salts can be incorporated using an alkaline solution of the salt. If the salt is not itself alkaline, a suitable base, such as ammonium hydroxide, can be added. Because hydroxide salts are basic in nature, mixtures of one or more of the above salts with a particular catalytic metal, such as a hydroxide salt of cesium, can be conveniently prepared.

[0081] The addition of the catalytically active metal can be carried out by the methods described above, or by any other conventional method used to impregnate a catalyst support, such as a xerogel support, using, for example, water or a solvent other than water, such as an alcohol, suitably methanol, ethanol, propanol, or isopropanol, or simply using the incipient wetness method of adding enough solution to the xerogel support to fill the pores of the xerogel support. In this case, the concentration of the catalytically active metal can be calculated to introduce a target amount of catalytically active metal into the xerogel support material, rather than providing an excess solution of a lower concentration. The addition of the catalytically active metal can utilize any suitable methodology known in the art.

[0082] Drying of the modified silica prior to calcination can occur at temperatures ranging from 20 to 200°C, more typically from 30 to 180°C, and most typically from 40 to 150°C. Drying of the modified silica prior to calcination can occur at atmospheric or subatmospheric pressures ranging from 0.001 to 1.01 bar. Drying of the modified silica can also be effected under a flow of inert gas in a fixed or fluidized bed. Drying times can range from 0.1 to 24 hours, more typically from 0.5 to 12 hours, and most typically from 1 to 6 hours.

[0083] Vacuum drying at lower temperatures or fluidized bed drying with an inert gas are suitable techniques.

[0084] General characteristics The modifier metal and catalytic metal adsorbate in the final catalyst are generally metal oxide moieties.

[0085] Modifier Metal Typically, the modifier metal is present in the modified silica support in an effective amount to reduce sintering and improve catalyst selectivity. Typically, at least 30%, such as at least 35%, more preferably at least 40%, such as at least 45%, most suitably at least 50%, such as at least 55%, such as at least 60% or 65%, most preferably at least 70%, such as at least 75% or 80%, more typically at least 85%, most typically at least 90%, particularly at least 95% of the modifier metal in the modified silica support is in a mononuclear or polynuclear metal moiety or is derived from a mononuclear or polynuclear modifier metal complex having one or more chelating ligands at the start of the formation of the silica modified at such levels.

[0086] Typically, the modifier metal is uniformly distributed over the surface of the support.

[0087] Preferably, the level of modifier metal present in the modified silica or catalyst is 7.6×10 -2 mol / mol silica, more preferably up to 5.9 x 10 -2mol / mol silica, most preferably up to 3.5 x 10 -2 mol / mol silica. Typically, the level of such metals is 0.067×10 -2 ~7.3×10 -2 mol / mol silica, more preferably 0.13 x 10 -2 ~5.7×10 -2 mol / mol silica, most preferably 0.2 x 10 -2 ~3.5×10 -2 mol / mol silica. Typically, the level of modifier metal present is at least 0.1×10 -2 mol / mol silica, more preferably at least 0.15×10 -2 mol / mol silica, most preferably at least 0.25×10 -2 mol / mol silica.

[0088] Preferably, the % w / w level of the modifier metal will depend on the metal, but can be up to 20% w / w, more preferably up to 16% w / w, and most preferably up to 11% w / w of the modified silica support. Typically, the level of the modifier metal will be 0.02-20% w / w, more preferably 0.1-15% w / w, and most preferably 0.15-10% w / w of the modified silica support. Typically, the level of the modifier metal will be at least 0.02% w / w, such as 0.25% w / w, for example 0.4% w / w, more typically at least 0.5% w / w, and most typically at least 0.75% w / w of the modified silica support.

[0089] catalyst Typically, the catalyst of the present invention can be in any suitable form. A typical embodiment is in the form of discrete particles. Typically, in use, the catalyst is in the form of a fixed bed of catalyst. Alternatively, the catalyst can be in the form of a fluidized bed of catalyst. A further alternative is a monolithic reactor.

[0090] When the catalyst is used in a fixed-bed configuration, the supported catalyst is typically formed into granules, agglomerates, or shaped units, such as spheres, cylinders, rings, saddles, stars, or polylobes prepared by pelleting or extrusion, with maximum and minimum dimensions in the range of 1 to 10 mm, more preferably with an average dimension greater than 2 mm, e.g., 2.5 mm or 3 mm. The catalyst is also effective in other forms, such as powders or small beads of the same dimensions as indicated. When the catalyst is used in a fluidized-bed configuration, the catalyst particles desirably have maximum and minimum dimensions in the range of 10 to 500 μm, preferably 20 to 200 μm, and most preferably 20 to 100 μm.

[0091] The average pore volume of the catalyst particles is 0.1 cm 3 / g, but generally between 0.1 and 5 cm as measured by fluid, e.g., water, uptake. 3 / g. However, microporous catalysts with very low porosity are least preferred as they can inhibit the transport of reagents across the catalyst, and a more preferred average pore volume is between 0.2 and 2.0 cm. 3 / g. Pore volume can alternatively be measured by a combination of nitrogen adsorption and mercury porosimetry at 77 K. A Micromeritics TriStar surface area and porosity analyzer is used to determine pore volume as for surface area measurements, and the same standards are used.

[0092] Catalytic Process According to a seventh aspect of the present invention, there is provided a process for producing an ethylenically unsaturated carboxylic acid or ester, typically an α,β ethylenically unsaturated carboxylic acid or ester, comprising the step of contacting formaldehyde, or a suitable source thereof, with the carboxylic acid or ester in the presence of a catalyst, and optionally in the presence of an alcohol, wherein the catalyst is according to any of the other aspects of the invention defined herein.

[0093] Advantageously, catalysts comprising modified silica as defined herein and containing catalytic metals have also been found to be remarkably efficient catalysts for the production of α,β ethylenically unsaturated carboxylic acids or esters by condensation of the corresponding acids or esters with a methylene source, such as formaldehyde, with reduced sintering of the catalyst surface, improved selectivity, and high catalyst surface area. Particularly enhanced properties are found when the modified silica support is not calcined prior to treatment with the catalytic metal. Furthermore, the use of certain metal complexes that incorporate the modifier metal onto the support by adsorption achieves a more dispersed distribution of the mono- or binuclear modifier metal moieties.

[0094] The term "suitable source thereof," as used herein with respect to formaldehyde, means that free formaldehyde can be formed in situ from the source under the reaction conditions, or the source can act as an equivalent of free formaldehyde under the reaction conditions, e.g., the source can form the same reactive intermediate as formaldehyde, such that an equivalent reaction occurs.

[0095] A suitable source of formaldehyde is a compound of formula (I): [ka] wherein R 5 and R 6 is C1~C 12 independently selected from hydrocarbon or H; X is O; n is an integer from 1 to 100; and m is 1.

[0096] Typically, R 5 and R 6 are C1 to C as defined herein. 12 Alkyl, alkenyl or aryl, or H, more suitably C1-C 10 alkyl, or H, most suitably C1-C6 alkyl or H, especially methyl or H. Typically n is an integer from 1 to 10, more suitably 1 to 5, especially 1 to 3.

[0097] However, other sources of formaldehyde may be used, including trioxane.

[0098] Therefore, suitable sources of formaldehyde also include any equilibrium composition that can provide a source of formaldehyde. Examples of such compositions include, but are not limited to, dimethoxymethane, trioxane, polyoxymethylene R 1 -O-(CH2-O) i -R 2 (In the formula, R 1 and / or R 2 is an alkyl group or hydrogen, and i=1 to 100), paraformaldehyde, formalin (formaldehyde, methanol, water), and other equilibrium compositions, such as a mixture of formaldehyde, methanol, and methyl propionate.

[0099] Polyoxymethylene is a higher formal or hemiformal of formaldehyde and methanol, CH3-O-(CH2-O) i -CH3 ("formal-i") or CH3-O-(CH2-O) i —H (“hemiformal-i”), where i=1 to 100, suitably 1 to 5, especially 1 to 3, or other polyoxymethylenes having at least one non-methyl end group. Thus, the source of formaldehyde may also be a compound of the formula R 31 -O-(CH2-O-) i R 32 wherein R 31 and R 32 may be the same or different groups, at least one of which is C1 to C 10 alkyl groups, such as R 31 = isobutyl, R 32 = methyl.

[0100] Generally, suitable sources of formaldehyde are the lower hemiformals CH3-O-(CH2-O) of dimethoxymethane, formaldehyde, and methanol. i-H (wherein i=1 to 3), formalin, or a mixture containing formaldehyde, methanol, and methyl propionate.

[0101] Typically, the term formalin refers to a mixture of formaldehyde:methanol:water in the ratios of 25-65%:0.01-25%:25-70% by weight. More typically, the term formalin refers to a mixture of formaldehyde:methanol:water in the ratios of 30-60%:0.03-20%:35-60% by weight. Most typically, the term formalin refers to a mixture of formaldehyde:methanol:water in the ratios of 35-55%:0.05-18%:42-53% by weight.

[0102] Typically, the mixture containing formaldehyde, methanol, and methyl propionate contains less than 5% by weight of water. More suitably, the mixture containing formaldehyde, methanol, and methyl propionate contains less than 1% by weight of water. Most suitably, the mixture containing formaldehyde, methanol, and methyl propionate contains 0.1 to 0.5% by weight of water.

[0103] According to an eighth aspect of the present invention, a compound of formula R is prepared by reacting a compound of formula R in the presence of a catalyst according to any aspect of the present invention, and optionally in the presence of an alkanol. 1 -CH2-COOR 3 and formaldehyde or a suitable source of formaldehyde of formula (I) as defined below. [ka] wherein R5 is methyl and R6 is H; X is O; m is 1; wherein n is any value from 1 to 20, or any mixture thereof; wherein R1 is hydrogen or an alkyl group having 1 to 12, more suitably 1 to 8, most suitably 1 to 4 carbon atoms, and R3 may also independently be hydrogen or an alkyl group having 1 to 12, more suitably 1 to 8, most suitably 1 to 4 carbon atoms.

[0104] Thus, the present inventors have discovered that producing a catalyst according to the present invention allows for a surprising improvement in selectivity for the condensation of a methylene source, such as formaldehyde, with a carboxylic acid or alkyl ester, such as methyl propionate, to form an ethylenically unsaturated carboxylic acid. Furthermore, the rate of sintering of the catalyst surface during the condensation reaction is significantly and surprisingly reduced.

[0105] Thus, one particular process for which the catalysts of the present invention have been found to be particularly advantageous is the condensation of formaldehyde with methyl propionate in the presence of methanol to produce MMA.

[0106] For the production of MMA, the catalyst is typically contacted with a mixture containing formaldehyde, methanol, and methyl propionate.

[0107] The process of the seventh or eighth aspect of the present invention is particularly suitable for the production of acrylic acid and alkacrylic acid and their alkyl esters, and also methylene-substituted lactones. Suitable methylene-substituted lactones include 2-methylenevalerolactone and 2-methylenebutyrolactone from valerolactone and butyrolactone, respectively. Suitable (alk)acrylic acids and their esters are typically produced from the reaction of the corresponding alkanoic acid or ester with a methylene source, such as formaldehyde, in the presence of a catalyst, suitably to produce methacrylic acid, acrylic acid, methyl methacrylate, ethyl acrylate, or butyl acrylate, more suitably from the production of methacrylic acid or, in particular, methyl methacrylate (MMA) from propanoic acid or methyl propionate, respectively (C 0~8 Alk)acrylic acid or alkyl (C 0~8Therefore, in the production of methyl methacrylate or methacrylic acid, 1 -CH2-COOR 3 The preferred ester or acid of is methyl propionate or propionic acid, respectively, and the preferred alkanol is therefore methanol. However, it will be understood that in the production of other ethylenically unsaturated acids or esters, the preferred alkanol or acid will be different.

[0108] The reaction of the present invention can be a batch reaction, a semi-batch reaction or a continuous reaction.

[0109] Typical conditions of temperature and gauge pressure in the process of the seventh or eighth aspect of the present invention are 100°C to 400°C, more preferably 200°C to 375°C, most preferably 275°C to 360°C; and / or 0.001 MPa to 1 MPa, more preferably 0.03 MPa to 0.5 MPa, most preferably 0.03 MPa to 0.3 MPa. Typical residence times for the reactants in the presence of the catalyst are 0.1 to 300 seconds, more preferably 1 to 100 seconds, most preferably 2 to 50 seconds, and in particular 3 to 30 seconds.

[0110] The amount of catalyst used in the process for producing the products of the present invention is not necessarily critical and is determined by the practicality of the process in which the catalyst is used. However, the amount of catalyst is generally selected to provide optimal selectivity and yield of the product and an acceptable temperature for operation. Nevertheless, those skilled in the art will recognize that the minimum amount of catalyst should be sufficient to provide efficient catalytic surface contact of the reactants. Furthermore, those skilled in the art will recognize that there is practically no upper limit to the amount of catalyst relative to the reactants, although in practice this may also be governed by the required contact time and / or economic considerations.

[0111] The relative amounts of reagents in the process of the seventh or eighth aspect of the invention can vary within wide limits, but generally the molar ratio of formaldehyde or a suitable source thereof to carboxylic acid or ester will be in the range of 20:1 to 1:20, more suitably 5:1 to 1:15. The most preferred ratio will depend on the form of formaldehyde and the ability of the catalyst to liberate formaldehyde from the formaldehyde species. Thus, highly reactive formaldehyde materials (where R 31 O-(CH2-O) i R 32 R in 31 and R 32 where one or both of R is H) requires a relatively low ratio, typically in this case the molar ratio of formaldehyde or a suitable source thereof to carboxylic acid or ester is in the range of 1:1 to 1:9. 31 and R 32 When neither of the groups is H, as in, for example, CH3O-CH2-OCH3, or trioxane, a higher ratio, typically 6:1 to 1:3, is most preferred.

[0112] As mentioned above, depending on the source of formaldehyde, water may also be present in the reaction mixture. Depending on the source of formaldehyde, it may be necessary to remove some or all of the water therefrom prior to catalysis. Maintaining a lower level of water than that in the formaldehyde source may be advantageous for catalyst efficiency and / or subsequent product purification. Less than 10 mol% water in the reactor is preferred, more preferably less than 5 mol%, and most preferably less than 2 mol%.

[0113] The molar ratio of alcohol to acid or ester is typically in the range of 20:1 to 1:20, preferably 10:1 to 1:10, and most preferably 5:1 to 1:5, e.g., 1:1.5. However, the most preferred ratio will depend on the amount of water provided to the catalyst in the reaction and the amount produced by the reaction; therefore, the preferred overall molar ratio of alcohol to water in the reaction is at least 1:1, more preferably at least 2:1.

[0114] The reagents of the seventh or eighth aspects may be fed to the reactor independently or after prior mixing, and the reaction process may be continuous or batch, although typically a continuous process is used.

[0115] Typically, the process of the seventh or eighth aspect of the invention is carried out when the reactants are in the gas phase.

[0116] In a still further aspect, the invention extends to a method of producing an ethylenically unsaturated carboxylic acid or ester according to any of the relevant aspects herein, comprising first producing a catalyst according to any of the relevant aspects herein.

[0117] definition By uncalcined modified silica support is meant that the silica support has not been calcined (e.g., by treatment above 275°C or 325°C or 375°C or 425°C) after the modification step and prior to treatment with the catalytic metal, and does not necessarily mean that the initial silica support was not calcined prior to modification with the modifier metal. Similarly, by uncalcined catalytic intermediate is meant that the modified silica support has not been calcined since its modification, and does not necessarily mean that the initial unmodified silica support was not calcined prior to modification with the modifier metal.

[0118] The term "impregnated," as used herein, includes the addition of a catalytic metal dissolved in a solvent to create a solution that is added to a xerogel or aerogel such that the solution is incorporated into voids within said xerogel or aerogel. The term also covers replacing the hydrogel liquid with a suitable solvent and adding the catalytic metal as a solution in the solvent, resulting in mass transfer into the hydrogel by diffusion.

[0119] The silica support may be treated with mononuclear and / or polynuclear modifier metals by any of a variety of techniques known to those skilled in the art of support formation. The silica support may be contacted with the mononuclear or polynuclear modifier metal in a manner to distribute the modifier metal throughout the silica support. Typically, the modifier metal may be uniformly distributed throughout the surface of the silica support. Preferably, the modifier metal is dispersed throughout the silica support by adsorption.

[0120] The term "adsorption," as used herein with respect to a modifier metal or catalyst metal, refers to its incorporation onto the surface of the silica support by its interaction with the silica support, optionally by physical adsorption, but typically by chemical adsorption. Typically, the addition of the modifier to the silica support involves adsorbing a source of metal cations onto the silica support, forming a metal complex residue, drying the support, and converting the metal complex to a metal oxide moiety. Typically, therefore, there is a random distribution of the modifier metal throughout the contacted silica support.

[0121] For the avoidance of doubt, modifier metal moieties having a total of one metal atom are considered to be mononuclear. It will be appreciated that in a silica network, the modifier metal moieties are associated with the silica network, and therefore the terms mononuclear or polynuclear moieties refer to the modifier metal and its immediately surrounding atoms, and not to the silicon atoms of the network, or other modifier metal atoms that are associated with the network but nevertheless form part of separate, generally unassociated, moieties.

[0122] The modifier metal and modifier metal oxide portions in the modified silica support according to the present invention refer to the modifier metal and not to the silicon or silica. Similarly, the modifier metal herein is not the same metal as the catalyst metal.

[0123] Unless specifically stated to the contrary, references to modifier or catalytic metal or the amount of modifier or catalytic metal in a catalyst refer to the modifier or catalytic metal ion and not to the surrounding atoms.

[0124] The level of catalytic metal in the catalyst, whether molar, weight percent, or otherwise, may be determined by appropriate sampling and averaging of such samples. Typically, 5-10 samples of a particular catalyst batch are taken and the alkali metal level is determined and averaged, for example, by XRF, atomic absorption spectroscopy, neutron activation analysis, ion-coupled plasma mass spectrometry (ICPMS) analysis, or ion-coupled plasma atomic emission spectroscopy (ICPAES).

[0125] The level of a particular type of metal oxide in the catalyst / support is determined by XRF, atomic absorption spectroscopy, neutron activation analysis or ion-coupled plasma mass spectrometry (ICPMS) analysis.

[0126] Typical average surface areas of modified silica supported catalysts according to any embodiment of the present invention are between 20 and 600 m as measured by the BET multipoint method using a Micromeritics Tristar 3000 surface area and porosity analyzer. 2 / g, more preferably 30 to 450 m 2 / g, most preferably 35 to 350 m 2 The reference material used to check the performance of the instrument is 30.6 m 2 / g(+ / -0.75m 2 The carbon black powder may be carbon black powder supplied by Micromeritics having a surface area of ​​1 / g, part number 004-16833-00.

[0127] The term "alkyl," as used herein, unless otherwise specified, refers to a C1-C 12 "alkyl" means methyl, ethyl, ethenyl, propyl, propenyl, butyl, butenyl, pentyl, pentenyl, hexyl, hexenyl, and heptyl groups, and typically the alkyl group is selected from methyl, ethyl, propyl, butyl, pentyl, and hexyl, more typically, methyl. Unless otherwise specified, the alkyl group, when there are a sufficient number of carbon atoms, may be straight or branched, cyclic, acyclic, or part cyclic / acyclic, and may be unsubstituted or include any of the following radicals: halo, cyano, nitro, -OR19 , -OC(O)R 20 , -C(O)R 21 , -C(O)OR 22 , -NR 23 R 24 , -C(O)NR 25 R 26 , -SR 29 , -C(O)SR 30 , -C(S)NR 27 R 28 , unsubstituted or substituted aryl, or unsubstituted or substituted Het, wherein R 19 ~R 30 each independently represent, here and generally herein, hydrogen, halo, unsubstituted or substituted aryl, or unsubstituted or substituted alkyl, or R 21 represents halo, nitro, cyano, and amino, and / or is interrupted by one or more (typically less than four) oxygen, sulfur, silicon atoms, or by silano or dialkylsilcon groups, or mixtures thereof. Typically, an alkyl group is unsubstituted, typically linear, and typically saturated.

[0128] The term "alkenyl" should be understood as "alkyl" above, except that at least one carbon-carbon bond therein is unsaturated, and thus the term refers to an alkyl group having C2 to C6 12 With respect to alkenyl groups.

[0129] The terms "alk" and the like, in the absence of information to the contrary, should be considered to follow the above definition of "alkyl," except that "COalk" means unsubstituted with alkyl.

[0130] The term "aryl" as used herein includes 5- to 10-membered, typically 5- to 8-membered, carbocyclic aromatic or pseudoaromatic groups such as phenyl, cyclopentadienyl, and indenyl and naphthyl, which groups may be unsubstituted or may include unsubstituted or substituted aryl, alkyl (which may itself be unsubstituted, substituted or terminated as defined herein), Het (which may itself be unsubstituted, substituted or terminated as defined herein), halo, cyano, nitro, OR 19 ,OC(O)R 20 , C(O)R 21 , C(O)OR 22 , N.R. 23 R 24 , C(O)NR 25 R 26 , S.R. 29 , C(O)SR 30 or C(S)NR 27 R 28 (In the formula, R 19 ~R 30 each independently represent hydrogen, unsubstituted or substituted aryl or alkyl (which alkyl group may itself be unsubstituted, or substituted or terminated as defined herein), or R 21 may be substituted with one or more substituents selected from halo, nitro, cyano or amino).

[0131] The term "halo" as used herein means a chloro, bromo, iodo or fluoro group, typically chloro or fluoro.

[0132] The term "Het" as used herein includes 4- to 12-membered, typically 4- to 10-membered, ring systems, which rings contain one or more heteroatoms selected from nitrogen, oxygen, sulfur, and mixtures thereof, and which rings may contain zero double bonds, one or more double bonds, or may be non-aromatic, partially aromatic, or fully aromatic in nature. The ring systems may be monocyclic, bicyclic, or fused. Each "Het" group identified herein is unsubstituted or may be selected from the group consisting of halo, cyano, nitro, oxo, alkyl (which alkyl groups may themselves be unsubstituted, substituted, or terminated, as defined herein), -OR, -O, -O- ... 19 , -OC(O)R 20 , -C(O)R 21 , -C(O)OR 22 , -N(R 23 )R 24 , -C(O)N(R 25 )R 26 , -SR 29 , -C(O)SR 30 or -C(S)N(R 27 )R 28 (In the formula, R 19 ~R 30 each independently represent hydrogen, unsubstituted or substituted aryl or alkyl (which alkyl group may itself be unsubstituted, or substituted or terminated as defined herein), or R 21 represents halo, nitro, amino or cyano). Thus, the term "Het" includes groups such as optionally substituted azetidinyl, pyrrolidinyl, imidazolyl, indolyl, furanyl, oxazolyl, isoxazolyl, oxadiazolyl, thiazolyl, thiadiazolyl, triazolyl, oxatriazolyl, thiatriazolyl, pyridazinyl, morpholinyl, pyrimidinyl, pyrazinyl, quinolinyl, isoquinolinyl, piperidinyl, pyrazolyl and piperazinyl. Substitution on Het may be at a carbon atom of the Het ring or, where appropriate, at one or more of the heteroatoms.

[0133] The "Het" groups may also be in the form of N-oxides.

[0134] Suitable optional alcohols for use in the catalytic reactions of the seventh and eighth aspects of the present invention include alkyl, aryl, Het, halo, cyano, nitro, OR, as defined herein. 19 ,OC(O)R 20 , C(O)R 21 , C(O)OR 22 , N.R. 23 R 24 , C(O)NR 25 R 26 , C(S)NR 27 R 28 , S.R. 29 or C(O)SR 30 C1-C, including aryl alcohols, which may be optionally substituted with one or more substituents selected from 30 The alkanol may be selected from alkanols. Highly preferred alkanols are C1-C8 alkanols, such as methanol, ethanol, propanol, isopropanol, isobutanol, t-butyl alcohol, phenol, n-butanol, and chlorocapryl alcohol, especially methanol. Monoalkanols are most preferred, but polyalkanols, typically selected from dioctaols, e.g., diols, triols, tetraols, and sugars, can also be utilized. Typically, such polyalkanols are selected from 1,2-ethanediol, 1,3-propanediol, glycerol, 1,2,4 butanetriol, 2-(hydroxymethyl)-1,3-propanediol, 1,2,6 trihydroxyhexane, pentaerythritol, 1,1,1 tri(hydroxymethyl)ethane, nannose, sorbace, galactose, and other sugars. Preferred sugars include sucrose, fructose, and glucose. Particularly preferred alkanols are methanol and ethanol. The most preferred alkanol is methanol. The amount of alcohol is not critical; generally, an amount in excess of the amount of substrate to be esterified is used. Thus, the alcohol can also serve as the reaction solvent, although a separate or additional solvent can also be used, if desired.

[0135] The term "gel," as used herein and known to those skilled in the art, may, in case of doubt, be considered as a solid network in which a fluid is dispersed. Generally, a gel is a polymer network in which a fluid is dispersed. Cogel is a term used to indicate that multiple initial compounds / moieties are incorporated into a polymer network, usually silica and a metal oxide or salt. Thus, cogelation, as used herein, refers to the formation of a cogel.

[0136] Thus, a gel is a solidifying sol. A hydrogel is thus a gel as defined herein in which the fluid is water. A xerogel is a gel that has been dried to remove the fluid. An aerogel is a gel in which the fluid has been replaced by a gas and therefore does not tend to shrink in the same way as a xerogel.

[0137] The term initiation is used herein to mean the beginning of the formation of the modified silica.

[0138] The term "moiety," as used herein with respect to the modifier metal, is used to refer to the form of the modifier metal on the modified support. The adsorbed modifier metal generally forms part of the network, but the modifier metal is in the form of a separate residue on the silica substrate, whether as a metal complex or oxide, and in the latter case, before or after calcination. The term mononuclear means having a single metal center, and in the case of moieties on silica, means having the form of a mononuclear residue. Polynuclear should be interpreted accordingly.

[0139] The % of modifier metal is unitless herein, as it refers to the number of metal atoms per total number of such atoms. It is recognized that the moieties may take the form of non-mononuclear or polynuclear clusters, but these clusters are also composed of modifier metal atoms.

[0140] The term "surface", as used herein in reference to a silica support, includes, unless otherwise specified, the surface of the silica within the pores of the silica, more particularly within its macropores and mesopores.

[0141] Embodiments of the present invention will now be defined by reference to the accompanying examples. [Example]

[0142] experiment Silica Support Description Example 1 (preparative) Fuji Silysia CARiACT Q10 silica was dried in a laboratory oven at 160°C for 16 hours, after which it was removed from the oven and allowed to cool to room temperature in a sealed flask stored in a desiccator. The silica had a solubility of 333 m as determined by nitrogen adsorption / desorption isotherm analysis (Micromeritics Tristar II). 2 The silica had a surface area of ​​1.0 ml / g, a pore volume of 1.0 ml / g, and an average pore diameter of 10 nm. The silica was composed primarily of spherical silica beads with diameters ranging from 2.0 to 4.0 mm.

[0143] Zr modification of silica support Example 2 (2.7 wt% Zr, comparative example) 1.671 g of Zr(acac)4 (97%, Sigma Aldrich) was dissolved in 20 ml of MeOH (99%, Sigma Aldrich). 10 g of silica from Example 1 was weighed into a separate flask. The weighed silica was then added to the Zr(acac)4 solution with stirring. Stirring was continued until the pore volume of the silica was completely occupied by the solvent, effectively forming a slurry. Once pore filling was complete, the Zr-modified silica was allowed to stand in the sealed flask with periodic stirring for 16 hours. After this time, the extraporous solution was removed by filtration. This was followed by a drying step in which the intraporous organic solvent was removed by passing a stream of nitrogen gas over the wet Zr-modified silica at room temperature. Alternatively, the intraporous solvent was removed under reduced pressure on a rotary evaporator. Once all of the solvent was removed, the Zr-modified silica support was calcined in a furnace at 500°C under flowing air with a heating ramp rate of 5°C / min and a final hold of 5 hours. Upon cooling, this produced a Zr-grafted silica support with a Zr utilization efficiency of 89%. The Zr loading (wt%) on the Zr-modified support was determined by powder energy-dispersive X-ray fluorescence analysis (Oxford Instruments X-Supreme8000).

[0144] Example 3 (2.7 wt% Zr) After the drying step was completed, the support modification was carried out as described in Example 2, except that an additional 16-hour drying step in a laboratory oven set at 110-120°C was performed. Additionally, the high-temperature calcination step at 500°C was not performed. This resulted in a Zr-grafted silica support with a Zr utilization efficiency of 89%. (Note: Zr loading was determined after oxidative calcination at 500°C of a sample of the Zr-grafted material.)

[0145] Cs modification of modified supports Example 4 (11.3 wt% Cs, 2.4 wt% Zr, Comparative Example) 1.80 g of CsOH·HO (99.5%, Sigma Aldrich) was weighed out in a glovebox and dissolved in 20 ml of a 9:1 v / v MeOH:HO solvent mixture. 10 g of the modified silica from Example 2 was added to the CsOH solution with stirring. Stirring was continued for an additional 15 minutes, after which the sample was left in a sealed flask for 16 hours with periodic stirring. After this time, the extraporous solution was removed by filtration. This was followed by a drying step in which the intraporous solvent was removed by passing a stream of nitrogen gas over the wet Cs / Zr-modified silica at room temperature. Alternatively, the intraporous solvent was removed under reduced pressure on a rotary evaporator. Following this, the catalyst beads were placed in a drying oven at 110-120 °C and dried for 16 hours. Upon cooling, this yielded a Cs / Zr / SiO catalyst with a Cs utilization efficiency of 90%. The Cs loading (wt%) on the catalyst was determined by powder energy dispersive X-ray fluorescence analysis (Oxford Instruments X-Supreme8000).

[0146] Example 5 (11.0 wt% Cs, 2.4 wt% Zr, Comparative Example) The catalyst was prepared as described in Example 4, except that 1.75 g of CsOH·HO was used. After a drying step at 120 °C, the catalyst was calcined at 700 °C in a furnace under flowing air with a heating ramp rate of 5 °C / min and a final hold of 5 h. Upon cooling, this yielded the Cs / Zr / SiO catalyst.

[0147] Example 6 (11.3 wt% Cs, 2.4 wt% Zr) The catalyst was prepared as described in Example 4, except that 10.5 g of silica from Example 3 was used. After a further drying step at 120° C., the catalyst was calcined at 700° C. in a furnace under flowing air with a heating ramp rate of 5° C. / min and a final hold of 5 hours. Upon cooling, this yielded the Cs / Zr / SiO catalyst.

[0148] Example 7 (10.6 wt% Cs, 2.4 wt% Zr) The catalyst was prepared as described in Example 4, except that 10.5 g of silica from Example 3 was used and water was used as the solvent instead of 9:1 v / v MeOH:HO. After a drying step at 120°C, the catalyst was calcined at 400°C in a furnace under flowing air with a heating ramp rate of 5°C / min and a final hold of 5 hours. Upon cooling, this yielded the Cs / Zr / SiO2 catalyst.

[0149] Example 8 (10.6 wt% Cs, 2.4 wt% Zr) The catalyst was prepared as described in Example 7, except that the final calcination was carried out at 600°C.

[0150] Example 9 (10.6 wt% Cs, 2.4 wt% Zr) The catalyst was prepared as described in Example 7, except that the final calcination was carried out at 700°C.

[0151] Example 10 (catalytic performance test) The catalysts from Examples 4 to 9 were tested for the reaction of methyl propionate and formaldehyde in a laboratory-scale microreactor. For this purpose, 3 g of catalyst was loaded into a fixed-bed reactor with a 10 mm inner diameter tube. The reactor was heated to 330°C and preconditioned by feeding a vaporized stream consisting of 70 wt% methyl propionate, 20 wt% methanol, 6 wt% water, and 4 wt% formaldehyde from a vaporizer fed by a Gilson pump at 0.032 ml / min. This preconditioning was continued overnight. After preconditioning, a feed stream consisting of 75.6 wt% methyl propionate, 18.1 wt% methanol, 5.7 wt% formaldehyde, and 0.6 wt% water was pumped by a Gilson pump into the vaporizer set at 330°C and then fed into the heated reactor containing the catalyst, set at 330°C. The reactor outlet vapor was cooled and condensed, with samples collected at five different liquid feed rates (0.64–0.032 ml / min) to obtain conversions at varying vapor / catalyst contact times. The liquid feed and condensed pre-reactor liquid product were analyzed using a Shimadzu 2010 gas chromatograph with a DB1701 column. Sample compositions were determined from their respective chromatograms, and yields and selectivities at varying contact times were determined. Activity was defined as the reciprocal of the contact time (in seconds) required to obtain a 12% MMA+MAA yield on the methyl propionate feed and was determined by interpolation of the contact time versus MMA+MAA yield graph. This interpolated contact time was then used to obtain the MMA+MAA selectivity at 12% MMA+MAA yield.

[0152] [Table 1]

[0153] Example 11 (Determination of catalyst stability) The initial catalyst stability was assessed by measuring the surface area (nitrogen adsorption / desorption isotherm analysis, Micromeritics Tristar II) after calcination treatment at 700°C according to Example 5. This provided a means of assessing the surface stabilization provided to the catalyst.

[0154] [Table 2]

[0155] Example 12 (Accelerated Aging Test) The catalyst sintering resistance was assessed in an accelerated aging test. For this, 1 g of catalyst was loaded into a U-tube stainless steel reactor and placed in an oven. The oven was heated to 385°C, and a nitrogen flow (10 ml / min) was passed through a saturated vaporizer containing water heated to 92°C. This ensured that the feed stream with a water pressure of 0.75 bar passed over the catalyst heated to 385°C. Periodically, the surface area of ​​the catalyst samples was determined ex situ using nitrogen adsorption / desorption isotherm analysis (Micromeritics Tristar II).

[0156] [Table 3]

[0157] Attention is directed to all articles and documents related to this specification, filed contemporaneously or previously hereto, and open for public inspection herewith, and the contents of all such articles and documents are incorporated herein by reference.

[0158] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations in which at least some of such features and / or steps are mutually exclusive.

[0159] Each feature disclosed in this specification (including any accompanying claims, abstract, and drawings), unless expressly stated to the contrary, may be replaced by alternative features serving the same, equivalent, or similar purpose. Thus, unless expressly stated to the contrary, each feature disclosed is merely an example of a generic series of equivalent or similar features.

[0160] The invention is not limited to the details of the above embodiments, and extends to any novel or any novel combination of preferred, exemplary or optional inventive features disclosed herein (including any accompanying claims, abstract and drawings), or to any novel or any novel combination of preferred, exemplary or optional inventive steps of any method or process so disclosed.

Claims

1. 1. An uncalcined catalytic intermediate for the production of an ethylenically unsaturated carboxylic acid or ester thereof, comprising an uncalcined porous silica support modified with a modifier metal, wherein said modifier metal is selected from zirconium, hafnium or titanium, and wherein said modifier metal is present in mono- or polynuclear modifier metal moieties and a catalytic metal adsorbed on said uncalcined modified silica support, said catalytic metal being an alkali metal.

2. 10. The uncalcined catalyst intermediate of claim 1, comprising a porous modifier metal oxide-silica cogel support.

3. 3. A catalyst based on the intermediate of claim 1 or 2, wherein the uncalcined intermediate has undergone calcination.

4. 3. The catalytic intermediate of claim 1 or 2, wherein the silica support is a hydrogel or a xerogel.

5. 5. The catalytic intermediate of claim 1, 2 or 4, wherein the modifier metal is an adsorbate that is adsorbed onto the surface of the silica support.

6. 6. The catalytic intermediate of claim 5, wherein the modifier metal is chemisorbed or physisorbed onto the surface of the silica support.

7. 7. The catalytic intermediate of any one of claims 1, 2, 4-6, wherein the catalytic metal is selected from cesium, potassium, or rubidium.

8. 8. The catalytic intermediate of any one of claims 1, 2, 4-7, wherein the adsorbed or co-gelled modifier metal cations are sufficiently spaced from one another to substantially prevent oligomerization thereof during subsequent processing steps.

9. 9. The catalytic intermediate of any one of claims 1, 2, 4-8, wherein the silica component of the modified silica support may form 80 to 99.9% by weight of the modified support.

10. 10. The catalytic intermediate of any one of claims 1, 2, 4-9, wherein the silica support has an average pore size of 2 to 1000 nm.

11. 11. The catalytic intermediate of any one of claims 1, 2, 4-10, wherein the catalytic metal is an adsorbate adsorbed onto the surface of the modified silica support of the catalyst.

12. 12. The catalytic intermediate of claim 11, wherein the catalytic metal is chemisorbed or physisorbed onto the surface of the modified silica support.

13. 13. The catalytic intermediate of any one of claims 1, 2, 4-12, wherein the catalytic metal is present in the catalyst at a level of at least 1 mol / 100 (silicon+modifier metal) mol in the catalyst.

14. 14. The catalytic intermediate of any one of claims 1, 2, 4-13, wherein the molar ratio of catalytic metal to modifier metal in the catalyst is at least 1.4 or 1.5:

1.

15. 15. The catalytic intermediate of any one of claims 1, 2, 4-14, wherein the catalytic metal is present in the range of 0.5 to 7.0 mol / mol modifier metal.

16. 16. The catalyst intermediate of any one of claims 1, 2, 4-15, wherein the level of catalytic metal in the catalyst is in the range of 1 to 10 mol / 100 (silicon + modifier metal) mol in the catalyst.

17. The level of the modifier metal is 0.067 x 10 －２ ~7.3 x 10 －２ 17. The catalytic intermediate of any one of claims 1, 2, 4-16, which is mol / mol silica.

18. 4. The catalyst of claim 3, wherein the calcination step is carried out at a temperature of at least 450°C.

19. 20. The catalyst of claim 3 or 18, wherein the silica support is a hydrogel or a xerogel.

20. 20. The catalyst of any one of claims 3, 18 and 19, wherein the modifier metal is an adsorbate that is adsorbed onto the surface of the silica support.

21. 21. The catalyst of claim 20, wherein the modifier metal is chemisorbed or physisorbed onto the surface of the silica support.

22. 22. The catalyst of any one of claims 3, 18-21, wherein the modifier metal is selected from zirconium, hafnium or titanium.

23. 23. The catalyst of any one of claims 3, 18-22, wherein the catalytic metal is selected from cesium, potassium or rubidium.

24. 24. The catalyst of any one of claims 3, 18-23, wherein the adsorbed or co-gelled modifier metal cations are sufficiently spaced from one another to substantially prevent their oligomerization during subsequent processing steps.

25. 25. The catalyst of any one of claims 3, 18-24, wherein the silica component of the modified silica support may form 80 to 99.9% by weight of the modified support.

26. Catalyst according to any one of claims 3, 18-25, wherein the silica support has an average pore size of 2 to 1000 nm.

27. 27. The catalyst of any one of claims 3, 18-26, wherein the catalytic metal is an adsorbate adsorbed onto the surface of the modified silica support of the catalyst.

28. 28. The catalyst of claim 27, wherein the catalytic metal is chemisorbed or physisorbed onto the surface of the modified silica support.

29. 29. The catalyst of any one of claims 3, 18-28, wherein the catalytic metal is present in the catalyst at a level of at least 1 mol / 100 (silicon+modifier metal) mol in the catalyst.

30. 30. The catalyst of any one of claims 3, 18-29, wherein the molar ratio of catalytic metal to modifier metal in the catalyst is at least 1.4 or 1.5:

1.

31. 31. The catalyst of any one of claims 3, 18-30, wherein the catalytic metal is present in the range of 0.5 to 7.0 mol / mol modifier metal.

32. 32. The catalyst of any one of claims 3, 18-31, wherein the level of catalytic metal in the catalyst is in the range of 1 to 10 mol / 100 (silicon+modifier metal) mol in the catalyst.

33. The level of the modifier metal is 0.067 x 10 －２ ~7.3 x 10 －２ Catalyst according to any one of claims 3, 18-32, which is mol / mol silica.

34. 34. A method for producing an ethylenically unsaturated carboxylic acid or ester, comprising contacting formaldehyde or a suitable source thereof with a carboxylic acid or ester in the presence of a catalyst, and optionally in the presence of an alcohol, wherein the catalyst is as defined in any one of claims 3, 18-33.

35. 35. The method of claim 34, wherein the ethylenically unsaturated carboxylic acid or ester is an alpha, beta ethylenically unsaturated carboxylic acid or ester.

36. 36. The method of claim 34 or 35, wherein the ethylenically unsaturated carboxylic acid or ester is methyl propionate or propionic acid.

37. 10. A process for preparing an ethylenically unsaturated acid or ester, comprising reacting an ethylenically unsaturated acid or ester of formula R in the presence of a catalyst as defined in any one of claims 3, 18-33, and optionally in the presence of an alkanol. １ -CH ２ -COOR ３ and formaldehyde or a suitable source of formaldehyde of formula (I) as defined below. 【Chemical 1】 (In the formula, R ５ is methyl, and R ６ is H; X is O; m is 1; n is any value from 1 to 20), or any mixture thereof; １ is hydrogen or an alkyl group having 1 to 12 carbon atoms, and R ３ is also independently hydrogen or an alkyl group having 1 to 12 carbon atoms.

38. Formula R １ -CH ２ -COOR ３ 38. The method of claim 37, wherein the alkanoic acid or ester of is methyl propionate or propionic acid.

39. 39. The method of claim 37 or 38, wherein the optional alkanol is methanol and the ethylenically unsaturated carboxylic acid or ester is methyl methacrylate or methacrylic acid.

40. 18. The catalytic intermediate of any one of claims 1, 2, 4-17, wherein said moieties are uniformly distributed over the surface of said silica support.

41. 34. The catalyst of any one of claims 3, 18-33, wherein the moieties are uniformly distributed over the surface of the silica support.

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