Catalyst and process for the production of ethylenically unsaturated carboxylic acids or esters

Abstract

The present invention discloses a catalyst comprising a silica support, a modifier metal, and a catalytic alkali metal. The silica support has a mesoporous pore size distribution (at least 0.1 cm) with an average pore size in the range of 2 to 50 nm. 3 / g) and a macroporous pore size distribution (at least 0.1 cm) with an average pore size of more than 50 nm. 3 The catalyst has a multimodal pore size distribution comprising a pore volume of said macropores of at least 1000 sq m / g (pore volume of said macropores). The level of catalytic alkali metal on the silica support is at least 2 mol %. The modifier metal is selected from Mg, B, Al, Ti, Zr and Hf. The present invention also discloses a method for producing the catalyst, a method for producing an ethylenically unsaturated carboxylic acid or ester in the presence of the catalyst, and a method for preparing an ethylenically unsaturated acid or ester in the presence of the catalyst.

Description

[Technical Field]

[0001] The present invention relates to a multimodal silica catalyst and a method for producing ethylenically unsaturated carboxylic acids or esters, particularly α,β-unsaturated carboxylic acids or esters, more particularly acrylic acids or esters, such as (alk)acrylic acids or alkyl (alk)acrylates, particularly (meth)acrylic acids or alkyl (meth)acrylates, 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 concerned with the production of MAA and MMA. The catalyst of the present invention incorporates a multimodal silica support 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.

[0003] order 1 R 3 -CH2-COOR 4 +HCHO------->R3 -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.

[0004] order 2 CH3-CH2-COOR 4 +HCHO------->CH3-CH(CH2OH)-COOR 4 CH3-CH(CH2OH)-COOR 4 ------>CH3-C(:CH2)-COOR 4 +H2O 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.

[0005] 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.

[0006] Patent Document 1 discloses a catalyst for use in the production of α,β-unsaturated carboxylic acids or esters by condensation of propionic acid or the corresponding alkyl esters, wherein the catalyst comprises alkali metal-doped silica impregnated with at least one modifier component, wherein the modifier component is selected from the group consisting of boron, aluminum, magnesium, zirconium and hafnium, preferably zirconium and / or aluminum and / or boron, and the alkali metal is selected from potassium, rubidium or cesium, preferably cesium.

[0007] Patent Document 2 discloses a catalyst for use in aldol condensation, including the condensation of propionic acid or propionic acid esters, olefin polymerization, dehydration, hydroxylation, and isomerization to produce α,β-unsaturated carboxylic acids, wherein the catalyst comprises a silica-metal hydrogel impregnated with a catalytic metal, wherein the metal of the hydrogel is selected from the group consisting of zirconium, titanium, aluminum, and iron, preferably zirconium, and the catalytic metal is selected from the group consisting of alkali metals and alkaline earth metals, preferably cesium.

[0008] None of these documents provide any teaching about multimodal silica supports. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 1999 / 52628 [Patent Document 2] International Publication No. 2003 / 026795 Summary of the Invention [Problem to be solved by the invention]

[0010] The inventors have now discovered that catalysts comprising certain multimodal silica supports and containing catalytic alkali metals achieve high levels of selectivity in the condensation of a methylene source, e.g., formaldehyde, with a carboxylic acid or alkyl ester, e.g., methyl propionate, and further, low formation of heavies (hydrocarbon by-products of lower relative volatility). The inventors have also discovered that catalysts comprising silica supports achieve high levels of selectivity even at higher loadings of catalytic metal.

[0011] Thus, catalysts comprising such silica supports and containing catalytic metals 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 low formation of heavies. [Means for solving the problem]

[0012] According to a first aspect of the present invention, there is provided a catalyst comprising a silica support, a modifier metal and a catalytic alkali metal, preferably cesium; Here, the silica support is a) Mesoporous pore size distribution with an average pore size in the range of 2 to 50 nm (at least 0.1 cm 3 / g of the pore volume of the mesopores); and b) Macroporous pore size distribution (at least 0.1 cm) with an average pore size of more than 50 nm 3 / g) having a multimodal pore size distribution comprising the catalytic alkali metal level on the silica support is at least 2 mol %; The modifier metal is selected from Mg, B, Al, Ti, Zr and Hf, preferably selected from Ti, Zr and Hf.

[0013] Typically, the support is at least 50% by weight silica, more typically at least 80% by weight, even more typically at least 90% by weight, most typically at least 95% by weight, and especially about 96 or 97 to 100% by weight.

[0014] Preferably, the level of catalytic alkali metal on the silica support is at least 3 mol %, more preferably at least 4 mol %, most preferably at least 5 mol %, especially at least 6 mol %.

[0015] Typically, the level of catalytic alkali metal on the silica support is up to 10 mol %, more typically up to 8 mol %, and most typically up to 6 mol %. silica The silica support is generally a silica gel or pyrogenic silica, whether modified or unmodified, typically a silica gel, more typically in the form of a xerogel, hydrogel, or aerogel. Silica gel may be formed by any of a variety of techniques known to those skilled in the art of gel formation, for example, as described herein.

[0016] 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.

[0017] Methods for preparing silica-modifier metal oxide cogels are known in the art, and some such methods are described by Bosman et al. in J Catalysis Vol. 148 (1994) page 660 and Monros et al. in J Materials Science Vol. 28, (1993), page 5832 in U.S. Pat. No. 5,069,816.

[0018] The silica of the present invention has a mesoporous content within the claimed range of the present invention. As mentioned above, silica with the appropriate mesoporosity can also be prepared by alternative preparation routes to gels, such as pyrogenic silica. The preparation methods and properties of typical pyrogenic silicas are disclosed in the scientific literature, for example, Chapter 1 "On the Silica Edge" in "The Surface Properties of Silica", edited by AP Legrand, 1998, John Wiley & Sons, ISBN 0-471-95332-6, and Chapter 5 "Silica Gels and Powder" in "The Chemistry of Silica", RKIler, 1979, John Wiley & Sons, ISBN 0-471-02404-X.

[0019] Typical average surface areas of silica supported catalysts according to any embodiment of the present invention are between 20 and 1000 m as measured by the BET multipoint method using a Micromeritics Tristar 3000 surface area and porosity analyzer. 2 / g, more preferably 30 to 800m 2 / g, most preferably 35 to 500m 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.

[0020] The silica component of the support may typically form 80 to 100% by weight of the support, more typically 90 to 99.7% by weight, and most typically 93.2 to 99.6% by weight thereof. The catalyst materials of the present invention are porous, being a multimodal combination of mesopores and macropores with an overall average pore size of 2 to 1000 nm, more preferably 3 to 500 nm, and most preferably 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 Barrett-Joyner-Halenda (BJH) analysis 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.

[0021] The average pore volume of catalyst particles can be measured by fluid uptake, such as water. Alternatively, pore volume can 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.

[0022] Multimodal Silica A multimodal distribution is a distribution having two or more modes. Thus, the term multimodal is understood to include bimodal or trimodal, etc. In the context of the present invention, which describes a multimodal pore size distribution, it should be understood that the pore size range of the material is a mixture of two or more unimodal pore size distributions. Thus, a material exhibiting a multimodal pore size distribution contains a single unimodal distribution spanning the mesoporous and microporous ranges. of in teeth Instead, it contains at least two distinct modes. It is possible that such modes may be completely independent or, alternatively, may overlap.

[0023] The average mesopore volume of the catalyst particles is 1 cm, as measured by nitrogen uptake.3 / g, but generally 0.2 to 3 cm 3 / g range, preferably 0.3 to 2.5 cm 3 / g, more preferably 0.4 to 2 cm 3 / g, most preferably 0.5 to 1.5 cm 3 / g range.

[0024] The average macropore volume of the catalyst particles is 1 cm, as measured by mercury uptake. 3 / g, but generally 0.1 to 3 cm 3 / g range, preferably 0.15 to 2.5 cm 3 / g, more preferably 0.2 to 2 cm 3 / g, most preferably 0.2 to 1.5 cm 3 / g range.

[0025] The macropore:mesopore volume ratio of catalyst particles according to any embodiment of the present invention is in the range of 0.03-15, optionally in the range of 0.4-4, more typically in the range of 0.5-2. Micropores in the catalyst may also be present.

[0026] In the present invention, it has been surprisingly found to be advantageous to control the porosity of the claimed silica support, however, it is also beneficial to control the volume, distribution and amount of both mesopores and macropores.

[0027] Advantageously, when the multimodal silica support of the catalyst of the above aspect of the present invention comprises mesopores and macropores, high reaction selectivity and / or low heavies formation during the production of α,β ethylenically unsaturated carboxylic acids or esters has been found.

[0028] A variety of different methods known to those skilled in the art can be used to form macropores in what would otherwise be mesoporous silica. Suitable techniques include hard and soft template methodologies and binder techniques. There are many suitable techniques that can be used to create macropores in materials. The review "Hierarchically porous materials: synthesis strategies and structure design", Yang et al., Chem. Soc. Rev., 2017, 46, 481, lists many methodologies for creating porosity in materials, particularly macropores, including:

[0029] Surfactant template method Colloidal crystal template method Macroporous polymer template method Biomimetic processes ·Supercritical fluid Emulsion template method ·Lyophilization Breath figure Selective leaching ·Phase separation Zeolitization process Replica creation Sol-gel control Post-processing ·Self-formation ·coagulation In one embodiment, the macropores are created by a hard template method. In a further embodiment, the macropores are created by a soft template method. In another further embodiment, the macropores are created by a binder technique.

[0030] "Hard" templating involves the use of solid, insoluble particles of dimensions similar in size to the required macropores, which can be incorporated into a precursor liquid to form a two-phase solid / liquid slurry used to make the silica gel. The solid, insoluble particles remain as a separate phase, which can be removed from the resulting silica gel by, for example, pyrolysis or calcination in an inert or oxidizing atmosphere at high temperatures. Literature examples of this type of technique include:

[0031] "Multiphased assembly of macroporous silica particles", Journal of Non-Crystalline Solids 285 (2001) 71-78, CJ Brinker et al. disclose the use of polymer latex spheres, in particular polystyrene beads, to produce macroporous silica, which are used as a hard template to produce macroporosity; “Impact of Macroporosity on Catalytic Upgrading of Fast Pyrolysis Bio-Oil by Esterification over Silica Sulfonic Acids”, ChemSusChem. 2017, 10, 3506-3511, K. Wilson et al., details the use of a hard template derived from an emulsion polymer from styrene and divinylbenzene to produce macroporous silica with macropore diameters of approximately 200 nm; “Synthesis of three-dimensionally ordered macroporous silica spheres by evaporation-induced assembling template process”, Materials Letters 109 (2013) 257-260, Yang et al.—This technique is a variation of the above method in that a “skeleton” of polystyrene spheres is constructed, a silica precursor is injected, and then the polystyrene sphere template is removed by calcination to yield macroporous silica.

[0032] "Soft" templating involves the use of a soluble or insoluble liquid that is incorporated into a precursor liquid, e.g., silica, as a single liquid phase or a two-phase liquid / liquid emulsion and then used to make silica gel. Macropores are formed in the resulting silica gel by liquid removal, e.g., by pyrolysis or calcination in an inert or oxidizing atmosphere at high temperature. Literature examples of this type of technique include:

[0033] The soluble liquid approach—"Effects of aging and solvent exchange on pore structure of silica gels with interconnected macropores," Journal of Non-Crystalline Solids 189, 1995, pp. 66-76, Takahashi et al.—describes a technique used in the examples of our patent application in which a polymer solution is mixed into a silica sol precursor, the precursor is gelled, and in the gelling process undergoes phase separation into silica gel and polymer, in the case of this particular reference, polyacrylic acid. The resulting two-phase solid is then "heat treated" to produce macroporous silica; The soluble liquid approach - "Synthesis and Textural Characterization of Mesoporous and Meso- / Macroporous Silica Monoliths Obtained by Spinodal Decomposition", Inorganics 2016, 4, 9, Galarneau et al. - uses polyethylene oxide in a silica sol precursor, resulting in macroporous silica as the mixed single-phase solution of polymer and silica precursor phases separates; Two-phase liquid / liquid emulsions, specifically surfactant micelles within silica precursors—“Ordered nanoporous silica with periodic 30-60 nm pores as an effective support for gold nanoparticle catalysts with enhanced lifetime,” J Am Chem Soc. 2010, 132, 9596-7, Fan et al.—describe the use of specific templating polymer / surfactant mixtures to form micelles within gelled silica materials, which can then be removed by an unspecified thermal process to yield silica with a range of mesopores and macropores.

[0034] "Binder technology" involves the use of one or more binder compounds that are incorporated with at least mesoporous silica powder and optionally water, then formed into a solid body, and subsequently removed to form a silica body with a macroporous network. The initial silica powder may be mesoporous or may contain macropores. The silica powder may be formed from silica gel or pyrogenic silica. When the binder is removed from the solid silica thus obtained by a suitable technique, for example, by pyrolysis / calcination at high temperature in an oxidizing atmosphere or by solvent extraction, macropores resulting from the binder are formed. The silica powder and binder may be formed into a solid body by extrusion. The resulting pore size may be determined, for example, by the ratio of silica particles:water:binder. A second binder may or may not be used in this process.

[0035] Two examples of the use of binders or formers in the preparation of macroporous catalyst bodies with alternative support chemistries to silica can be found in the following references: US Patent No. 5,137,855 (WR Grace & Co.) discloses the use of different amounts of combustible binder to produce different titania-supported catalyst extrudates with different macroporosity levels and improved catalytic performance.

[0036] US Patent No. 10,022,702 (IFP Energies Nouvelles) discloses the use of different amounts of liquid or solid pore formers in the preparation of alumina catalyst particles prepared by powder coagulation, followed by drying and calcination.

[0037] In addition to the techniques described above, other techniques for forming binderless catalyst bodies are also available. Typical methods for forming catalyst bodies, which may or may not contain binders, can be found in "Manual of Methods and Procedures for Catalyst Characterization", Pure and Applied Chemistry, Vol. 67, 1257-1306, 1995, J. Haber, JH Block, and B. Delmon. These include spray drying of powder-based suspensions in liquids, forming beads from sols or gels introduced into hot immiscible oil ("oil droplets"), granulating a mix of different sized powders, optionally containing a binder material, molding a mix of different sized powders, optionally containing a binder material, and extruding a paste of different sized powders, optionally containing a binder material.

[0038] According to a second aspect of the present invention, (a) preparing a modified silica by modifying silica with a modifier metal selected from Mg, B, Al, Ti, Zr, and Hf; (b) treating the modified silica with an alkali metal catalyst; (c) introducing macropores into the silica before step (a), before step (b), or after step (b);

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

[0039] Preferably, the silica is a silica gel or pyrogenic silica containing at least mesopores. Preferably, macropores are introduced into the silica gel by hard templating, soft templating, binders, or other techniques as indicated herein.

[0040] Macropores can be introduced into silica, modified silica, or modified silica treated with catalytic alkali metals. It will be appreciated that the silica may have pores in the macroporous range and in the mesoporous range prior to the introduction of macropores in step (c).

[0041] Typically, the silica is in powder form prior to the introduction of macropores by suitable techniques. Suitable processing of the silica powder may include the addition of processing aids, liquids, and binders to the powdered silica, as needed, to produce a multiphase particulate mixture of the desired composition and rheology; Formation of silica bodies or particles, including but not limited to cylinders, tablets, extrudates and structured extrudates, by methodologies including but not limited to extrusion, coagulation, granulation and molding; Subsequent thermal processing of the formed powder or particles to produce a silica-containing porous support having the appropriate amount of mesoporosity and macroporosity as indicated herein.

[0042] Alkali metal catalyst 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 is typically chemisorbed thereon.

[0043] As will be appreciated, catalytic alkali metals, as used herein, are metals other than the modifier metal. Preferably, catalytic alkali metals may be selected from one or more alkali metals. Typically, catalytic alkali metals are selected from cesium, potassium, or rubidium, more preferably cesium.

[0044] Suitably, the catalytic alkali metal may be present in the catalyst at a level of at least 1 mol / 100 (silicon + any modifier metal) mol, more preferably at least 1.5 mol / 100 (silicon + any modifier metal) mol, most preferably at least 2 mol / 100 (silicon + any modifier metal) mol, more preferably at least 3 mol / 100 (silicon + any modifier metal) mol, most preferably at least 3.5 mol / 100 (silicon + any modifier metal) mol. The catalytic alkali metal level may be up to 10 mol / 100 (silicon + modifier metal) mol in the catalyst, more preferably up to 6 mol or 7.5 mol / 100 (silicon + modifier metal) mol in the catalyst, most preferably up to 5 mol / 100 (silicon + modifier metal) mol.

[0045] Preferably, the level of catalytic alkali 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, and most preferably 2.5 to 6 mol / 100 (silicon + modifier metal) mol.

[0046] Alternatively, the catalyst may have a weight percent of catalytic alkali metal in the range of 1 to 22 wt %, more preferably 4 to 18 wt %, and most preferably 5 to 13 wt % of the catalyst. Thus, the molar ratio of catalytic alkali metal to modifier metal is typically at least 1.4 or 1.5:1, preferably in the range of 1.4 to 5:1, such as 1.5 to 4.0:1, especially 1.5 to 3.6:1. Generally, herein, catalytic alkali metal is in excess of that required to neutralize the modifier metal.

[0047] Preferably, the catalytic alkali metal is present in the range of 0.5 to 7.0 mol / mol of modifier metal (if present), more preferably 1.0 to 6.0 mol / mol, and most preferably 1.5 to 5.0 mol / mol of modifier metal.

[0048] Unless specifically stated to the contrary, the amount of alkali metal or alkali metals in the catalyst refers to the alkali metal ion and not the salt. Suitably, the catalytic alkali metal may be incorporated into the silica support by any method known in the art, for example by impregnation or adsorption, co-gelling or vapor deposition with the catalytic metal.

[0049] The level of catalytic metal in the catalyst, whether mol% or wt%, can 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) or ion-coupled plasma atomic emission spectroscopy (ICPAES).

[0050] Modification of Silica Support - Modifier Metals The silica of the present invention may be provided as a co-gel of modifier metal oxide and silica, or as a modified silica having a modifier metal adsorbed on the silica surface.

[0051] Typically, the modifier metal is adsorbed onto the surface of the silica gel support. Typically, the modifier metal is present on the surface of the modified silica gel support in the form of metal oxide moieties. The modifier metal oxide may be distributed throughout the silica matrix and its surface.

[0052] Typically, the modified silica gel is produced by a suitable adsorption reaction. Adsorption of the relevant metal compound onto a silica gel, e.g., a silica xerogel, to form a modified silica gel having the relevant modifier metal moiety is a suitable technique.

[0053] Typically, when the modifier metal is added as an adsorbate, it may be added as a mononuclear or binuclear modifier metal compound. Controlling the nuclearity of the modifier metal moiety has surprisingly been found to be advantageous because it helps control the proximity of adjacent modifier metal moieties on the silica.

[0054] Typically, the modifier metal compound is a complex, and the ligands in the coordination sphere of the compound are usually 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.

[0055] Typically, before or after calcination, at least 25% of the modifier metal is present on the support in the form of mononuclear or binuclear 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 mononuclear or binuclear metal compounds.

[0056] Typically, the mononuclear or dinuclear modifier metal is contacted with the silica support as a mononuclear or dinuclear modifier metal compound in solution, resulting in adsorption of the modifier metal onto the support. Typically, the modifier metal compound is mononuclear or binuclear, for example mononuclear.

[0057] Advantageously, when a modifier metal is incorporated into the multimodal silica of the above-described embodiment of the present invention, it has been found that the rate of sintering of the catalyst surface during the production of α,β ethylenically unsaturated carboxylic acids or esters is reduced. The addition of the modifier metal prevents sintering and the loss of mesopore surface area. The combination of the modifier metal preventing mesopore sintering and the presence of a macropore network allows for the preservation of an open pore structure, which allows for the diffusion of raw materials throughout the catalyst pellet and the leaching of products and by-products from the catalyst surface within the catalyst pellet, thereby reducing the formation of "heavy" by-products formed by undesired coupling reactions. This advantageous combination results in improved reaction selectivity to products. Typically, the modifier metal is selected from zirconium, hafnium, and / or titanium.

[0058] 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, which are also effective in effectively spacing the modifier metal on the silica surface as shown herein.

[0059] Typically, the metal complexes are tetracoordinate, pentacoordinate, hexacoordinate, heptacoordinate, or octacoordinate. Advantageously, the size of the ligands in the coordination sphere of the modifier metal compound, e.g., the size of the 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. Smaller metal salt adsorption results in clustering of the modifier metal following heat treatment or calcination, which has been found to reduce the selectivity of the catalyst and reduce the sintering resistance of the catalyst.

[0060] In some embodiments of the present invention, 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 is typically chemisorbed thereon.

[0061] 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 mono- or binuclear 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.

[0062] 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, the non-labile ligand is typically coordinated to the modifier metal in solution prior to treatment of the silica surface with the modifier metal. For the avoidance of doubt, the non-labile ligand is typically removed by appropriate treatment of the silica surface following adsorption of the modifier metal.

[0063] The size of the chelating ligand is selected to space the modifier metal atoms on the silica surface, preventing their recombination during catalyst formation. Alternatively, modifier metal complexes can be used that have bulky monodentate ligands that prevent the oligomerization of the metal complex. Typical ligands used in the 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.

[0064] 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.

[0065] 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 of the catalyst metal, or optionally subsequent calcination.

[0066] Typically, the carrier is 2 At levels of >0.025 per nm, more preferably at levels from 0.05 per nm, most preferably 2 The modifier comprises metal moieties at levels of from 0.1 parts per 1000 mol.

[0067] Typically, at least 30%, e.g., at least 35%, more preferably at least 40%, e.g., at least 45%, and most suitably at least 50%, e.g., at least 55%, e.g., at least 60% or 65%, most preferably at least 70%, e.g., at least 75% or 80%, more typically at least 85%, and most typically at least 90%, and particularly at least 95%, of the modifier metal in the modifier metal complex is a mononuclear and / or binuclear modifier metal compound when the complex is contacted with the support to result in adsorption of the complex onto the support. Accordingly, the level of mononuclear and / or binuclear modifier metal on the silica surface can be at such a level.

[0068] Preferably, the silica support is dried and / or calcined prior to treatment with the modifier metal. Thus, the modifier metal may be incorporated onto the support as a cation source, more preferably as 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.

[0069] Typically, the solvent for the solution is water or other than water. 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.

[0070] Examples of suitable metal cation sources are referred to herein as inorganic and organic complexes, such as zirconium(pentane-2,4-dione)4, zirconium(ethyl 3-oxobutanoate)4, zirconium(heptane-3,5-dione)4, zirconium(2,2,6,6-tetramethylheptane-3,5-dione)4, zirconium(propoxide)(pentane-2,3-dione)3, zirconium(propoxide)3(2,2,6,6-tetramethyl-3,5-heptanedione)4, and the like. ) (including zirconium(Ot-butyl)3(t-butyl 3-oxobutanoate), zirconium(Ot-butyl)2(t-butyl 3-oxobutanoate)2 and metal salts such as zirconium(IV) chloride, zirconium(IV) carbonate, zirconium(IV) perchlorate, zirconium(IV) nitrate, zirconium(IV) oxynitrate, zirconium(IV) oxysulfate, zirconium(IV) lactate, zirconium(IV) tetraacetate, and zirconium(IV) oxychloride.

[0071] Examples of suitable metal cation sources herein include organic complexes such as titanium tetrakis(methoxide), titanium tetrakis(ethoxide), titanium tetrakis(n-propoxide), titanium tetrakis(i-propoxide), titanium tetrakis(n-butoxide), titanium tetrakis(t-butoxide), titanium tetrakis(2-ethylhexyloxide), titanium oxide bis(acetylacetonate), titanium oxide bis(2,2,6,6-tetramethyl-3,5-heptanedionate), titanium(triethanolaminato)isopropoxy titanium(IV) bis(ammonium lactate) dihydroxide, titanium bis(triethanolamine) di-isopropoxide, titanium tetrakis(diethylamide), titanium tetrakis(ethylmethylamide), titanium tetrakis(dimethylamide), titanium tetrakis(neopentyl), titanium(IV) bis(ammonium lactate) dihydroxide, and metal salts such as titanium(IV) oxysulfate, titanium(IV) oxynitrate, titanium(IV) oxychloride, titanium(IV) chloride, titanium(IV) carbonate, titanium(IV) perchlorate, titanium(IV) nitrate, titanium(IV) lactate, and titanium(IV) tetraacetate.

[0072] The source of metal cations may be provided as an organic complex. In one embodiment, the metal cation source is provided as a solution of one or more of zirconium(IV) acetylacetonate (zirconium, tetrakis(2,4-pentanedionato-O,O')) zirconium(heptane-3,5-dione)4, zirconium(2,2,6,6-tetramethyl-3,5-heptanedione)4, zirconium(IV) ethyl 3-oxobutanoate, zirconium(IV) t-butyl 3-oxobutanoate, or zirconium(IV) i-propyl 3-oxobutanoate in one of methanol, ethanol, isopropanol, propanol, butanol, isobutanol, or 2-butanol.

[0073] Preferably, after adsorption of the modifier metal onto the silica support, the solvent is removed by evaporation. Optionally, the modified silica support is calcined to remove ligands or other organics from the modified support.

[0074] When the modifier metal is present in the support in the form of a co-gel, the modified silica support is a silica-modifier metal oxide co-gel. In such embodiments, the modifier metal is typically incorporated in a uniform distribution throughout the silica-modifier metal oxide structure.

[0075] Typically, the modifier metal, whether adsorbate or co-gel, is present in a mononuclear or binuclear oxide moiety. Typically, when the modifier metal is added as an adsorbate, it may be added as a mononuclear or binuclear modifier metal compound.

[0076] Typically, the modifier metal, when present, is uniformly dispersed throughout the surface of the silica support or throughout the silica modifier metal oxide structure. For the avoidance of doubt, reference to modifier metals on the silica support of catalysts according to the present invention relates to modifier metals such as magnesium, boron, aluminium, titanium, zirconium and hafnium and not to silica.

[0077] Preferably, the level of modifier metal present in the modified silica or catalyst is 7.6×10 -2 mol / mol of silica, more preferably up to 5.9 x 10 -2 mol / mol of silica, most preferably 3.5 x 10 -2 mol / mol of silica. Typically, the level of such metals is 0.067×10 -2 ~7.3×10 -2 mol / mol of 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 of silica, more preferably at least 0.15×10 -2mol / mol of silica, most preferably at least 0.25×10 -2 mol / mol silica.

[0078] Preferably, the wt% level of the modifier metal will depend on the metal, but can be up to 20 wt% of the modified silica support, more preferably up to 16 wt% and most preferably up to 11 wt%. Typically, the level of the modifier metal will be 0.02 to 20 wt% of the modified silica support, more preferably 0.1 to 15 wt% and most preferably 0.15 to 10 wt%. Typically, the level of the modifier metal will be at least 0.02 wt% of the modified silica support, such as 0.25 wt% of the modified silica support, for example 0.4 wt%. More typically, at least 0.5 wt% and most typically at least 0.75 wt%.

[0079] The level of a particular type of metal oxide in the catalyst / support is determined by XRF, atomic absorption spectroscopy, neutron activation analysis, ion-coupled plasma mass spectrometry (ICPMS) or ion-coupled plasma atomic emission spectroscopy (ICPAES).

[0080] 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 monolith reactor.

[0081] 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, having maximum and minimum dimensions in the range of 1 to 10 mm, more preferably with an average dimension greater than 2 mm, e.g., greater than 2.5 mm or greater than 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, it is desirable for the catalyst particles to 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.

[0082] Amount of catalyst metal and modifier metal The total metal content of the catalyst is at least 80 wt.% of the alkali metal, catalyst as defined herein, and modifier metals. Typically, the total metal content of the catalyst is at least 85 wt.% of the alkali metal, catalyst as defined herein, and modifier metals, more typically at least 90 wt.%, even more typically at least 95 wt.%, and most typically at least 99 wt.%, particularly at least 99.5 wt.%, for example at least 99.9 wt.%.

[0083] Exclusion of tungsten / antimony / vanadium / bismuth The catalyst according to the present invention may be substantially free, essentially free, or completely free of tungsten and / or antimony and / or vanadium and / or bismuth and / or Group 3 metals and / or Group 8, 9, or 10 metals and / or Group 13 metals and / or Group 14 metals, as indicated hereinabove. Tungsten and / or antimony and / or vanadium and / or bismuth and / or Group 3 metals and / or Group 8, 9, or 10 metals and / or Group 13 metals and / or Group 14 metals may be present in trace amounts due to unavoidable contamination from the environment. By "substantially free," we mean catalysts and supports containing less than 1000 parts per million (ppm) of tungsten and / or antimony and / or vanadium and / or bismuth and / or Group 3 metals and / or Group 8, 9, or 10 metals and / or Group 13 metals and / or Group 14 metals. By "essentially free", we mean that the catalyst and support contain less than about 100 ppm of tungsten and / or antimony and / or vanadium and / or bismuth and / or Group 3 metals and / or Group 8, 9 or 10 metals and / or Group 13 metals and / or Group 14 metals, and by "completely free", we mean that the catalyst contains less than 200 ppb (parts per billion) of tungsten and / or antimony and / or vanadium and / or bismuth and / or Group 3 metals and / or Group 8, 9 or 10 metals and / or Group 13 metals and / or Group 14 metals.

[0084] By the term "Group 3 metals," we include the metals Sc, Y, and the former set of lanthanides and actinides. Preferably, the metal is selected from La or Ce. For the avoidance of doubt, references to Group 3 metals herein refer to the latest IUPAC nomenclature. Group 3 should therefore be taken to include the transition metal group IIIB as well as the lanthanide and actinide blocks according to the older nomenclature scheme.

[0085] By the term "Group 8, 9 or 10 metal," we include metals such as Ni, Pd, Pt and Ds. Preferably, the metal is Pt. For the avoidance of doubt, references to Group 8, 9 or 10 metals herein refer to the latest IUPAC nomenclature. Thus, Group 8, 9 or 10 should be taken to include transition metal group VIII according to the older nomenclature scheme.

[0086] By the term "Group 13 metals," we include metals such as B, Al, Ga, In, and Tl. Preferably, the metal is Al. For the avoidance of doubt, references to Group 13 metals herein refer to the latest IUPAC nomenclature. Group 13 should therefore be taken to include main group elements III, 3, or IIIA according to the older nomenclature scheme.

[0087] By the term "Group 14 metals," we include metals such as Ge, Sn, and Pb. Preferably, the metal is Sn. For the avoidance of doubt, references to Group 14 metals herein refer to the latest IUPAC nomenclature. Thus, Group 14 should be taken to include main group elements IV, 4, or IVA according to the older nomenclature schemes.

[0088] silanol The concentration of silanol groups on the silica support may be reduced prior to treatment with the modifier metal compound by calcination, chemical dehydration, or other suitable methods.

[0089] A suitable method for treating silica to provide the required level of isolated silanol groups 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 chlorination with SOCl2, followed by dechlorination with H2 or ROH, followed by chemical dehydration with oxygen in a dry atmosphere. Chemical dehydration can be reduced to a minimum of 0.7 nm by thermal treatment. 2 Thus, in some cases, chemical dehydration can provide more scope for silanol group control.

[0090] The term isolated silanols (also known as single silanols) is well known in the art and is distinct from groups of vicinal, 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.

[0091] As noted, the silica support may be dried or calcined prior to treatment with the modifier metal cation source. The formed modified silica, whether previously dried or calcined, may be dried or calcined prior to addition of the catalytic metal.

[0092] The silica may be in the form of a multimodal gel prior to treatment with the modifier metal. The gel may be in the form of a hydrogel, xerogel or aerogel at the start of the modification. The multimodal silica support can be a xerogel, a hydrogel, or an aerogel. In one embodiment, the silica support is a xerogel.

[0093] Overall Process Those skilled in the art will appreciate that the catalytic alkali metal may be added to the modified silica by any suitable means. Typically, silica is contacted with the catalytic alkali metal to produce the modified silica catalyst.

[0094] Typically, to produce the catalyst, the silica support is contacted with an acidic, neutral, or alkaline aqueous solution containing a catalytic alkali metal, such as cesium; more typically, the catalytic alkali metal is in the form of a catalytic alkali metal salt; most typically, the silica support is contacted with an alkaline aqueous solution containing the catalytic alkali metal, such as cesium, in the form of a catalytic alkali metal and a base salt. Alternatively, the support can be contacted with a water-miscible solution of the catalytic alkali metal salt in an organic solvent. Preferred solvents are alcohols, such as methanol, ethanol, propanol, and isopropanol, preferably methanol. The most preferred solvent is methanol. Most preferably, the catalytic alkali metal is added as a salt solution in methanol. A low level of water, typically up to 20% by volume, can be contained in the solution.

[0095] Typically, the conditions of temperature, contact time and pH during this stage of the catalyst production process are those that allow impregnation of the multimodal silica support with, for example, the catalytic alkali metal to form a multimodal silica supported catalyst.

[0096] 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.

[0097] Typical contact times between the 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.

[0098] 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 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.

[0099] Suitable salts of catalytic alkali metals for the incorporation of catalytic metals can typically 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. The 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. Controlling the pH within the preferred range is most important at the end of impregnation to ensure 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.

[0100] Those skilled in the art will appreciate that the catalytic alkali metal or modifier metal of the present invention may be added to the silica support by any suitable means. The catalytic metal and / or modifier metal may typically be fixed onto the support by calcination after deposition of the metal on the support.

[0101] Drying of the silica support is typically accomplished by any suitable method known to those skilled in the art, for example, in a drying unit or oven. Typically, the catalyst contains 0.01 to 25 w / w% water, more typically 0.1 to 15 w / w% water, and most typically 0.5% to 5.0 w / w% water.

[0102] Optionally, the silica supported catalyst containing catalytic metals may be dried or calcined, the process of calcination being well known to those skilled in the art. In some cases, it may be necessary to calcinate the support formed from the modification step at 200 to 1000°C, more typically 300 to 800°C, and most typically 350 to 600°C, prior to addition of the catalytic metal. In a preferred calcination of the support formed from the modification step, the temperature is at least 375°C, e.g., 400°C. The calcination atmosphere should typically contain some oxygen, suitably 1 to 30% oxygen, most suitably 2 to 20% oxygen, to result in removal of organic residues as carbon dioxide and water. Calcination times may typically be 0.01 to 100 hours, suitably 0.5 to 40 hours, and most suitably 1 to 24 hours. In a preferred calcination of the catalyst, the temperature is at least 450°C, more preferably at least 475°C, most preferably at least 500°C, particularly at least 600°C, and more particularly above 700°C. Typically, the calcination temperature ranges from 400 to 1000° C., more typically from 500 to 900° C., and most typically from 600 to 850° C. The calcined support, e.g., xerogel material, should be cooled to a suitable temperature for impregnation.

[0103] 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.

[0104] Drying of the modified silica prior to calcination may be carried out 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 may be carried out at atmospheric or subatmospheric pressures ranging from 0.001 to 1.01 bar. Drying of the modified silica may also be effected under a flow of inert gas in a fixed or fluidized bed. Drying times may range from 0.1 to 24 hours, more typically from 0.5 to 12 hours, and most typically from 1 to 6 hours.

[0105] Vacuum drying at lower temperatures or fluidized bed drying with an inert gas are suitable techniques. overall characteristics The modifier metal and catalytic alkali metal adsorbate in the final catalyst are usually metal oxide moieties.

[0106] According to a third 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 a 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 first or other aspects of the invention as defined herein.

[0107] Advantageously, catalysts comprising silica as defined herein and containing a catalytic alkali metal 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 acid or ester with a methylene source, such as formaldehyde.

[0108] The term "suitable source thereof", in relation to formaldehyde in the third aspect of the invention, 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.

[0109] A suitable source of formaldehyde is a compound of formula (I):

[0110] [ka]

[0111] 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. 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.

[0112] However, other sources of formaldehyde may be used, including trioxane. 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] According to a fourth 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

[0118] [ka]

[0119] 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.

[0120] Thus, the present inventors have discovered that the 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 production of heavies during the condensation reaction is quite surprisingly reduced.

[0121] 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.

[0122] For the production of MMA, the catalyst is typically contacted with a mixture containing formaldehyde, methanol, and methyl propionate. The process of the third or fourth aspect of the present invention is particularly suitable for the production of acrylic acid and alkacrylic acid and their alkyl esters, particularly alkacrylic acid and its 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 by reacting the corresponding alkanoic acid or ester with a methylene source, such as formaldehyde, in the presence of a catalyst to produce, suitably, methacrylic acid, acrylic acid, methyl methacrylate, ethyl acrylate, or butyl acrylate, more suitably, 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.

[0123] The reaction of the present invention can be a batch reaction or a continuous reaction. Typical conditions of temperature and gauge pressure in the process of the third or fourth 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.

[0124] 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 usually selected to provide optimal selectivity and yield of the product and an acceptable temperature of 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.

[0125] The relative amounts of reagents in the process of the third or fourth aspect of the present invention can vary within wide limits, but typically 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.

[0126] 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%.

[0127] 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.

[0128] The reagents of the third or fourth aspect 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. Typically, the process of the third or fourth aspect of the invention is carried out when the reactants are in the gas phase.

[0129] 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.

[0130] definition 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, -OR 19 , -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 here, and throughout this specification, represents hydrogen, halo, unsubstituted or substituted aryl, or unsubstituted or substituted alkyl; or R21 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.

[0131] 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.

[0132] 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.

[0133] 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 30each 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).

[0134] The term "halo" as used herein means a chloro, bromo, iodo or fluoro group, typically chloro or fluoro. 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 21represents 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.

[0135] The "Het" groups may also be in the form of N-oxides. Suitable optional alcohols for use in the catalytic reactions of the third and fourth 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 30The 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; typically, 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.

[0136] The term "aging" is described, for example, in patent application WO 2009 / 003722. The general principles of aging 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, pages 358-364. If this step is performed, the hydrogel is washed again to remove materials used in the aging process and the solution is brought to the correct pH for the addition of catalytically active metals, which depends on the choice of salt for the catalytically active metals.

[0137] The term "impregnated," as used herein, includes the addition of a catalytic alkali 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 extends to exchanging the hydrogel liquid with a suitable solvent and adding the catalytic alkali metal as a solution in the solvent, resulting in mass transfer into the hydrogel by diffusion.

[0138] The silica support may be treated with mononuclear and / or binuclear 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 binuclear modifier metal in a manner such that the modifier metal is dispersed throughout the silica support. Typically, the modifier metal may be uniformly distributed over the surface of the silica support. Preferably, the modifier metal is dispersed throughout the silica support by adsorption.

[0139] The term "adsorption" or the like, as used herein with respect to a modifier metal or catalytic alkali metal, refers to the incorporation of the metal onto the silica support surface by interaction of a metal cation source with the silica support, by chemisorption or physisorption, typically by chemisorption. Typically, the addition of the modifier to the silica support involves the adsorption of the metal cation source onto the silica support to form an organometallic complex, and drying or calcining the complex to convert the organometallic complex to metal oxide moieties. Typically, therefore, there is a random distribution of the modifier or catalytic alkali metal throughout the silica support.

[0140] 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, as used herein, is not the same metal as the catalytic alkali metal.

[0141] Unless specifically stated to the contrary, references to modifier or catalytic alkali metal in a catalyst or the amount of modifier or catalytic alkali metal refer to the modifier or catalytic alkali metal ion and not to the surrounding atoms.

[0142] 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. Typically, 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, typically silica and a metal oxide or salt, such as zirconia. Thus, cogelation, as used herein, refers to the formation of a cogel.

[0143] 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.

[0144] The term initiation is used herein to mean the beginning of the formation of the modified silica. The term "moiety," as used herein with respect to metals, is used to refer to the form of the modifier metal on the modified support. The modifier metal usually forms part of the network, whereas the modifier metal is in the form of a separate residue on the silica substrate. 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, and binuclear should be interpreted accordingly.

[0145] 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 binuclear moieties refer to the modifier metal and its immediately surrounding atoms, and not to silicon atoms of the network, or other modifier metal atoms that are associated with the network but nevertheless form part of separate, usually unassociated, moieties.

[0146] The % of modifier metal is unitless herein, as it refers to the number of metal atoms per total number of such atoms. It will be understood that the moieties may take the form of non-mononuclear or binuclear clusters, but these clusters are also composed of modifier metal atoms.

[0147] 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.

[0148] Embodiments of the present invention are defined by reference to the accompanying examples and drawings. [Brief explanation of the drawings]

[0149] [Figure 1] Mercury porosimetry results are shown for selected examples. [Figure 2] N2 adsorption results are shown for selected examples. [Figure 3] Mercury porosimetry results are shown for selected examples. [Figure 4] N2 adsorption results are shown for selected examples. DETAILED DESCRIPTION OF THE INVENTION

[0150] experiment N2 adsorption The catalysts from Examples 1 to 4 were measured for their mesopore size distribution in the mesopore range of 5 to 50 nm by N adsorption on a MICROMERITICS INSTRUMENT CORPORATION TriStar II 3020. 0.1 to 0.2 g of sample was loaded into a dedicated sample cell. The cell was heated to 380 °C under airflow, and this preconditioning was carried out for at least 2 hours. After preconditioning, the sample was weighed, and the equipment was set up for surface area determination. N adsorption of the sample was carried out at -196 °C to obtain adsorption-desorption isotherms. The BET surface area and BJH mesopore size distribution were calculated from these isotherms.

[0151] Mercury Porosimetry The catalysts from Examples 1 to 4 were measured for their macropore size distribution in the macropore range above 50 nm by mercury porosimetry using a MICROMERITICS INSTRUMENT CORPORATION Autopore IV9500 instrument. 0.3 to 1 g of dried sample was loaded into a dedicated sample cell. The cell was loaded into the setup. Mercury (Hg) was inserted into the catalyst pores in the sample by varying the pressure, and the macropore size distribution was obtained.

[0152] Silica Support Description Example 1 (Preparation) (Silica without Macropores) Silica gel samples were prepared using commercially available water glass, a sodium silicate solution containing 25.5–28.5 wt % SiO2 and 7.5–8.5 wt % Na2O as the silica source (EMD Millipore Corporation).

[0153] 69 g of distilled water and 53 g of nitric acid (65% HNO3, Sigma-Aldrich) were placed in a plastic flask to form solution 1. 80 g of water glass and 73 g of distilled water were placed in a separate flask to form solution 2. These two solutions were then mixed under stirring. The mixed solution was kept at room temperature for 10 to 60 minutes. The solution underwent gelation and transformed into a silica hydrogel. The silica hydrogel was washed several times with distilled water. The silica hydrogel was then aged by contacting it with a basic solution (0.1 M NH3 solution) in a temperature-controlled oil bath at 50 °C for 24 hours. After the aging process, the silica hydrogel was dried at 50 °C and then calcined in a tubular furnace at 600 °C under air flow (1 L / min) for 3 hours. After the calcination process, the silica support was sieved into a 1-4 mm fraction. After sieving, a macropore-free silica support was obtained.

[0154] Example 2 (Preparation) (Silica with a Macropore Diameter of 0.13 μm) Silica was prepared as described in Example 1, except that 10 g of polyacrylic acid (polyacrylic acid from Wako Pure Chemical Industries, Ltd., Mw=25000) was added to Solution 1 and 66 g of 65% nitric acid was used. The macropore diameter in the thus obtained processed silica was obtained by Hg porosimetry.

[0155] Example 3 (Preparation) (Silica with a Macropore Diameter of 0.20 μm) Silica was prepared as described in Example 1, except that 10 g of polyacrylic acid was added to solution 1 and 65 g of 65% nitric acid was used. The macropore diameter in the processed silica thus obtained was obtained by Hg porosimetry.

[0156] Example 4 (Preparation) (Silica with a Macropore Diameter of 0.88 μm) Silica was prepared as described in Example 1, except that 9.5 g of polyacrylic acid was added to solution 1 and 59 g of 65% nitric acid was used. The macropore diameter in the processed silica thus obtained was obtained by Hg porosimetry.

[0157] Zr modification of silica support Example 5 (Preparative) (2.2 wt% Zr, no macropores) 1.57 g of Zr(acac)4 (97% zirconium acetylacetonate, Sigma Aldrich) was dissolved in 25 ml of methanol (99.9% anhydrous, Sigma Aldrich). 11.3 g of silica from Example 1 was weighed in a separate flask. The weighed silica was then added to the Zr-complex solution. The Zr-modified silica was allowed to stand in the sealed flask for 24 hours. This was followed by a drying step at room temperature. Once all of the solvent was removed, the Zr-modified silica support was calcined at 500 °C under air flow (1 L / min) in a tube furnace with a heating ramp rate of 5 °C / min and a final hold time of 5 hours. The Zr loading (wt%) on the Zr-modified support was determined by ion-coupled plasma mass spectrometry (ICPMS) or ion-coupled plasma atomic emission spectroscopy (ICPAES) analysis.

[0158] Example 6 (Preparation) (2.2 wt% Zr, 0.13 μm macropore diameter) Support modification was carried out as described in Example 5, except that silica from Example 2 was used. In addition, 50 ml of methanol was used instead of 25 ml.

[0159] Example 7 (Preparation) (2.2 wt% Zr, 0.20 μm macropore diameter) Support modification was carried out as described in Example 5, except that silica from Example 3 was used. In addition, 50 ml of methanol was used instead of 25 ml.

[0160] Example 8 (Preparative) (2.2 wt% Zr, 0.88 μm macropore diameter) Support modification was carried out as described in Example 5, except that the silica from Example 4 was used. In addition, 50 ml of methanol was used instead of 25 ml.

[0161] Cs modification of modified supports Example 9 (Comparative) (7.7 wt% Cs, 2.2 wt% Zr, no macropores) 0.329 g of CsOH·HO (99.5%, Sigma Aldrich) was weighed out in a glove box and dissolved in 20 ml of MeOH (99.9% anhydrous MeOH from Sigma Aldrich) solvent. 3.1 g of the modified silica from Example 5 was added to the CsOH solution. The sample was left in a sealed flask for 24 hours. This was followed by a drying step at room temperature. Following this step, the catalyst granules were placed in a drying oven at 110-120 °C and dried for 16 hours.

[0162] Example 10 (Comparative) (9.6 wt% Cs, 2.2 wt% Zr, no macropores) The catalyst was prepared as described in Example 9, except that 0.419 g of CsOH·H 2 O was used.

[0163] Example 11 (Comparative) (11.4 wt% Cs, 2.2 wt% Zr, no macropores) The catalyst was prepared as described in Example 9, except that 0.509 g of CsOH·H 2 O was used.

[0164] Example 12 (7.7 wt. % Cs, 2.2 wt. % Zr, macropore diameter of 0.13 μm) The catalyst was prepared as described in Example 9, except that the modified silica from Example 6 was used.

[0165] Example 13 (9.6 wt. % Cs, 2.2 wt. % Zr, 0.13 μm macropore diameter) The catalyst was prepared as described in Example 9, except that 0.419 g of CsOH·H O was used and the modified silica from Example 6 was used.

[0166] Example 14 (having 11.4 wt. % Cs, 2.2 wt. % Zr, and a macropore diameter of 0.13 μm) The catalyst was prepared as described in Example 9, except that 0.509 g of CsOH·H 2 O was used and the modified silica from Example 6 was used.

[0167] Example 15 (7.7 wt. % Cs, 2.2 wt. % Zr, 0.20 μm macropore diameter) The catalyst was prepared as described in Example 9, except that the modified silica from Example 7 was used.

[0168] Example 16 (9.6 wt. % Cs, 2.2 wt. % Zr, 0.20 μm macropore diameter) The catalyst was prepared as described in Example 9, except that 0.419 g of CsOH·H O was used and the modified silica from Example 7 was used.

[0169] Example 17 (having 11.4 wt. % Cs, 2.2 wt. % Zr, and a macropore diameter of 0.20 μm) The catalyst was prepared as described in Example 9, except that 0.509 g of CsOH·H O was used and the modified silica from Example 7 was used.

[0170] Example 18 (7.7 wt. % Cs, 2.2 wt. % Zr, macropore diameter of 0.88 μm) The catalyst was prepared as described in Example 9, except that the modified silica from Example 8 was used.

[0171] Example 19 (9.6 wt. % Cs, 2.2 wt. % Zr, 0.88 μm macropore diameter) The catalyst was prepared as described in Example 9, except that 0.419 g of CsOH·H O was used and the modified silica from Example 8 was used.

[0172] Example 20 (having 11.4 wt. % Cs, 2.2 wt. % Zr, and a macropore diameter of 0.88 μm) The catalyst was prepared as described in Example 9, except that 0.509 g of CsOH·H O was used and the modified silica from Example 8 was used.

[0173] Silica-zirconia support (co-gel) description Example 21 (Preparation) (Silica-Zirconia without Macropores) 2.16 g of zirconium oxynitrate hydrate (Sigma Aldrich) was dissolved in 69 g of distilled water and 59 g of nitric acid (65% HNO3, Sigma Aldrich) in a plastic flask to form solution 1. 80 g of water glass and 73 g of distilled water were mixed in a separate flask to form solution 2. These two solutions were then mixed under stirring. The mixed solution was kept at room temperature for 10 to 60 minutes. The solution underwent gelation and transformed into a silica-zirconia hydrogel (co-gel). The silica hydrogel was washed several times with distilled water. The silica-zirconia hydrogel was then aged by contacting it with a basic solution (1 M NH3 solution) at 70 °C in a temperature-controlled oil bath. After the aging process, the silica-zirconia hydrogel was dried at 50 °C and calcined at 600 °C for 3 hours under air flow (1 L / min) in a tubular furnace. After the calcination process, the silica-zirconia support was sieved to 1-4 mm. After sieving, a silica-zirconia support without macropores was obtained.

[0174] Example 22 (Preparation) (Silica-Zirconia with Macropore Diameter of 0.42 μm) Silica-zirconia was prepared as described in Example 21, except that 10 g of polyacrylic acid (polyacrylic acid Mw=25000, Wako Pure Chemical Industries, Ltd.) was added to solution 1 and 64 g of 65% nitric acid was used. Macropore diameters were obtained by Hg porosimetry.

[0175] Example 23 (Preparation) (Silica-Zirconia with Macropore Diameter of 0.61 μm) Silica-zirconia was prepared as described in Example 21, except that 9.5 g of polyacrylic acid (polyacrylic acid Mw=25000, Wako Pure Chemical Industries, Ltd.) was added to solution 1 and 53 g of 65% nitric acid was used. Macropore diameters were obtained by Hg porosimetry.

[0176] Cs modification of silica-zirconia support Example 24 (Comparative) (8.0 wt% Cs, 2.4 wt% Zr, no macropores) 0.341 g of CsOH·HO (99.5%, Sigma Aldrich) was weighed out in a glove box and dissolved in 20 ml of MeOH (99.9% anhydrous MeOH from Sigma Aldrich) solvent. 3.1 g of the silica-zirconia support from Example 21 was added to the CsOH solution. The sample was left to stand in a sealed flask for 24 hours. This was followed by a drying step at room temperature. Following this step, the catalyst granules were placed in a drying oven at 110-120 °C and dried for 16 hours.

[0177] Example 25 (Comparative) (9.5 wt% Cs, 2.4 wt% Zr, no macropores) The catalyst was prepared as described in Example 24, except that 0.411 g of CsOH·H 2 O was used.

[0178] Example 26 (Comparative) (11 wt% Cs, 2.4 wt% Zr, no macropores) The catalyst was prepared as described in Example 24, except that 0.484 g of CsOH·H 2 O was used.

[0179] Example 27 (8.0 wt. % Cs, 2.4 wt. % Zr, 0.42 μm macropore diameter) The catalyst was prepared as described in Example 24, except that the silica-zirconia from Example 22 was used.

[0180] Example 28 (9.5 wt. % Cs, 2.4 wt. % Zr, 0.42 μm macropore diameter) The catalyst was prepared as described in Example 24, except that 0.411 g of CsOH·H O was used and the silica-zirconia from Example 22 was used.

[0181] Example 29 (having 11 wt% Cs, 2.4 wt% Zr, and a macropore diameter of 0.42 μm) The catalyst was prepared as described in Example 24, except that 0.484 g of CsOH·H O was used and the silica-zirconia from Example 22 was used.

[0182] Example 30 (8.0 wt. % Cs, 2.4 wt. % Zr, macropore diameter of 0.61 μm) The catalyst was prepared as described in Example 24, except that the silica-zirconia from Example 23 was used.

[0183] Example 31 (9.5 wt. % Cs, 2.4 wt. % Zr, macropore diameter of 0.61 μm) The catalyst was prepared as described in Example 24, except that 0.411 g of CsOH·H O was used and the silica-zirconia from Example 23 was used.

[0184] Example 32 (having 11 wt% Cs, 2.4 wt% Zr, and a macropore diameter of 0.61 μm) The catalyst was prepared as described in Example 24, except that 0.484 g of CsOH·H O was used and the silica-zirconia from Example 23 was used.

[0185] Example 33 (catalytic performance test) The catalysts from Examples 9-20 and Examples 24-32 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 an 18 mm inner diameter tube. The reactor was heated to 350°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 350°C and then fed into the heated reactor containing the catalyst, set at 350°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 10% 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 10% MMA+MAA yield.

[0186] The catalyst performance data for the above examples, along with composition and porosity data, are summarized in Tables 1 and 2 below. Pore ​​size distribution data for macroporous silica (Examples 1-4) and macroporous silica-zirconia supports (Examples 21-23) are shown in Figures 1-4. Figures 1 and 3 are macropore size distributions obtained by mercury porosimetry, and Figures 2 and 4 are mesopore size distributions obtained by N2 adsorption BJH analysis.

[0187] [Table 1]

[0188] [Table 2]

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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. A catalyst for the production of methacrylic acid (MAA) or methyl methacrylate (MMA), the catalyst comprising a silica support, a modifier metal, and a catalytic alkali metal; The silica support is a) an average pore size in the range of 2 to 50 nm and at least 0.1 cm ３ / g mesopore volume; and b) an average pore size of more than 50 nm and at least 0.1 cm ３ / g macropore volume of macropores having a multimodal pore size distribution comprising the level of catalytic alkali metal on the silica support is at least 2 mol %; the alkali metal catalyst is one or more alkali metals selected from potassium, rubidium, and cesium; A catalyst wherein the modifier metal is selected from Ti, Zr and Hf.

2. 10. The catalyst of claim 1, wherein the level of catalytic alkali metal on the silica support is at least 3 mol%.

3. 3. The catalyst of claim 1, wherein the amount of silica in the support is at least 50% by weight.

4. The average mesopore volume of the catalyst particles is less than 1 cm as measured by nitrogen uptake. ３ The catalyst according to any one of claims 1 to 3, wherein the Cr content is less than 1 / g.

5. The average macropore volume of the catalyst particles is less than 1 cm as measured by mercury uptake. ３ The catalyst according to any one of claims 1 to 4, wherein the Cr content is less than 1 / g.

6. 6. The catalyst according to any one of claims 1 to 5, wherein the catalyst particles have a macropore:mesopore volume ratio in the range of 0.03 to 15.

7. 7. The catalyst according to any one of claims 1 to 6, wherein the catalyst contains less than 1000 ppm of tungsten and / or antimony and / or vanadium and / or bismuth and / or Group 3 metals and / or Group 10 metals and / or Group 13 metals and / or Group 14 metals.

8. 8. The catalyst according to claim 1, wherein the catalyst contains less than 1000 ppm of tungsten and / or antimony and / or vanadium and / or bismuth and / or lanthanum and / or cerium and / or platinum and / or tin.

9. 9. The catalyst of any one of claims 1 to 8, wherein the modifier metal is an adsorbate that is adsorbed onto the surface of the silica support.

10. Catalyst according to any one of claims 1 to 9, wherein the modifier metal is present as a modifier metal oxide moiety.

11. Catalyst according to any one of claims 1 to 10, wherein the silica support is in the form of silica gel.

12. Catalyst according to any one of claims 1 to 11, wherein the modifier metal is present in the support in the form of a co-gel.

13. The level of modifier metal present is 7.6 x 10 －２ Catalyst according to any one of claims 1 to 12, wherein the total amount of the catalyst is up to 1000 mol / mol silica.

14. The level of the modifier metal is 0.067 x 10 －２ ~7.3 x 10 －２ Catalyst according to any one of claims 1 to 13, which is mol / mol silica.

15. The level of modifier metal present is at least 0.1 x 10 －２ Catalyst according to any one of claims 1 to 14, which is mol / mol silica.

16. Catalyst according to any one of claims 1 to 15, wherein the silica support is a calcined silica support.

17. The catalyst according to any one of claims 1 to 16, wherein the alkali metal catalyst is one or more alkali metals selected from rubidium and cesium.

18. 18. The catalyst of any one of claims 1 to 17, wherein the catalytic alkali metal is present in the range of 0.5 to 7.0 mol / mol modifier metal.

19. Catalyst according to any one of claims 1 to 18, wherein the catalytic alkali metal:modifier metal molar ratio is at least 1.4 or 1.5:

1.

20. The silica carrier has an average surface area of ​​20 to 1000 m ２ The catalyst according to any one of claims 1 to 19, wherein the Cr content is in the range of 1 / g.

21. 21. The catalyst of any one of claims 1 to 20, wherein the total metal content of the catalyst is at least 80% by weight of catalyst, alkali metal, and modifier metal.

22. A method for producing a catalyst according to any one of claims 1 to 21, comprising the steps of: (a) preparing a modified silica for a silica support having a modifier metal selected from Ti, Zr, and Hf; (b) treating the modified silica support with a catalytic alkali metal to provide a catalyst; (c) introducing macropores into said silica support before step (a), before step (b), or after step (b); Including, The method, wherein the catalytic alkali metal is one or more alkali metals selected from potassium, rubidium, and cesium.

23. 23. The method of producing a catalyst according to claim 22, wherein the modified silica is a silica gel or pyrogenic silica containing mesopores.

24. 24. A method of producing a catalyst according to claim 22 or 23, wherein the macropores are introduced by hard templating, soft templating, binder techniques or other techniques.

25. A method for producing methacrylic acid (MAA) or methyl methacrylate (MMA), comprising contacting formaldehyde or a suitable source thereof with propionic acid or methyl propionate in the presence of a catalyst, wherein the catalyst is a catalyst described in any one of claims 1 to 21.

26. A process for preparing methacrylic acid (MAA) or methyl methacrylate (MMA), comprising reacting propionic acid or methyl propionate with formaldehyde or a suitable source of formaldehyde of formula (I) as defined below in the presence of a catalyst as defined in any one of claims 1 to 21. 【Chemical 1】 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.

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