Catalysts and processes for producing ethylenically unsaturated carboxylic acids or carboxylic acid 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 multimodal pore size distribution, the multimodal pore size distribution including an average pore size in the range of 2 nm to 50 nm and a pore size of at least 0.1 cm 3 / g of the mesopore volume, and a mesopore size distribution having an average pore size greater than 50 nm and a pore size of at least 0.1 cm 3 The present invention also discloses a method for producing the catalyst, a method for producing an ethylenically unsaturated carboxylic acid or carboxylic ester in the presence of the catalyst, and a process for preparing an ethylenically unsaturated acid or ester in the presence of the catalyst.

Description

[0001] The present invention relates to a multimodal silica catalyst and a process for producing olefinically unsaturated carboxylic acids or carboxylic esters, particularly α,β unsaturated carboxylic acids or carboxylic esters, more particularly acrylic acid or acrylic acid esters, such as (alk) acrylic acid or alk) acrylic acid esters, particularly (meth) acrylic acid or alk) acrylic acid esters, such as methacrylic acid (MAA) and methyl methacrylate (MMA), by condensing carboxylic acids or carboxylic acid esters with formaldehyde or a source thereof, such as dimethoxymethane, in the presence of such a catalyst. The catalyst of the present invention incorporates a multimodal silica support modified with a specific modifier metal and a catalytic metal.

[0002] As mentioned above, the unsaturated acid or unsaturated ester can be prepared by the reaction of a carboxylic acid or a carboxylic acid ester, and suitable carboxylic acids or carboxylic acid esters are of the formula R 3 -CH2-COOR 4 Alkanoic acid (or alkyl ester), wherein R 3 and R 4 Each is independently a suitable substituent known in the art of acrylic compounds, such as hydrogen or a hydrocarbyl group, in particular a lower hydrocarbyl group containing, for example, 1 to 4 carbon atoms. Thus, for example, MAA or its hydrocarbyl ester, in particular MMA, can be prepared according to reaction sequence 1 by the catalytic reaction of propionic acid or the corresponding hydrocarbyl ester, such as methyl propionate, with formaldehyde as a methylene source.

[0003] R 3 -CH2–COOR 4 +HCHO------->R 3 -CH(CH2OH)–COOR 4

[0004] as well as

[0005] R 3 -CH(CH2OH)–COOR 4 ------>R 3 -C(:CH2)–COOR 4 +H2O

[0006] Sequence 1

[0007] An example of reaction sequence 1 is reaction sequence 2

[0008] CH3-CH2–COOR 4 +HCHO------->CH3-CH(CH2OH)–COOR 4

[0009] CH3-CH(CH2OH)–COOR 4 ------>CH3-C(:CH2)–COOR 4 +H2O

[0010] Sequence 2

[0011] The above reaction sequence is usually carried out at high temperature, usually in the range of 250°C to 400°C, using an acid / base catalyst. When the desired product is an ester, the reaction is usually carried out in the presence of the relevant alcohol in order to minimize the formation of the corresponding acid by hydrolysis of the ester. In addition, for convenience, it is usually desirable to introduce the formaldehyde in the form of a complex of formaldehyde and methanol. Therefore, for the production of MMA, the reaction mixture fed to the catalyst will usually consist of methyl propionate (MEP), methanol, formaldehyde and water.

[0012] A known method for the production of MMA is the catalytic conversion of MEP to MMA using formaldehyde. A known catalyst for this is a cesium catalyst incorporated into a support such as silica.

[0013] WO1999 / 52628 discloses a catalyst for producing α,β-unsaturated carboxylic acids or carboxylic esters by condensation of propionic acid or the corresponding hydrocarbyl esters, wherein the catalyst comprises alkali metal-doped silica impregnated with at least one modifier element, wherein the modifier element 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.

[0014] WO2003 / 026795 discloses a catalyst for aldol condensation, comprising the production of α,β-unsaturated carboxylic acids by condensation of propionic acid or a propionic acid ester, olefin polymerization, dehydration, hydroxylation and isomerization, 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.

[0015] There is no teaching of multimodal silica supports in any of these documents.

[0016] The present inventors have now discovered that catalysts comprising certain multimodal silica supports and comprising a catalytic alkali metal provide high levels of selectivity in the condensation of a methylene source such as formaldehyde with a carboxylic acid or a hydrocarbyl ester such as methyl propionate and, in addition, provide low formation of heavies (hydrocarbon by-products of lower relative volatility). The present inventors have also discovered that catalysts comprising a silica support provide high levels of selectivity even at higher loadings of catalytic metal.

[0017] Thus, catalysts comprising such a silica support and comprising a catalytic metal are very efficient catalysts for producing α,β ethylenically unsaturated carboxylic acids or carboxylic acid esters by condensation of the corresponding acid or ester with a methylene source such as formaldehyde, which catalysts offer several advantages, such as high levels of selectivity and / or low formation of heavies.

[0018] According to a first aspect of the present invention, there is provided a catalyst comprising:

[0019] a silica support, a modifier metal, and a catalytic alkali metal, preferably cesium,

[0020] The silica support has a multimodal pore size distribution, and the multimodal pore size distribution includes:

[0021] a) having an average pore size in the range of 2 nm to 50 nm and a pore size of at least 0.1 cm 3 / g of the pore volume of the mesopores; and

[0022] b) having an average pore size greater than 50 nm and at least 0.1 cm 3 / g of the macropore volume, the macropore size distribution,

[0023] wherein the level of catalytic alkali metal on the silica support is at least 2 mol%,

[0024] And wherein the modifier metal is selected from Mg, B, Al, Ti, Zr and Hf, and preferably selected from Ti, Zr and Hf.

[0025] Typically, the support is at least 50 wt% silica, more typically at least 80 wt%, even more typically at least 90 wt%, most typically at least 95 wt%, particularly about 96 wt% or 97 wt% to 100 wt%.

[0026] 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%.

[0027] Typically, the level of catalytic alkali metal on the silica support is up to 10 mol%, more typically up to 8 mol%, most typically up to 6 mol%.

[0028] Silicon dioxide

[0029] The silica support, whether modified or not, is typically in the form of silica gel or pyrogenic silica, typically in the form of silica gel, more typically in the form of xerogel, hydrogel or aerogel. The silica gel can be formed by any of a variety of techniques known to those skilled in the art of gel formation, such as those mentioned herein.

[0030] Methods for preparing silica gel are well known in the art, and some such methods are described in The Chemistry of Silica: Solubility, Polymerisation, Colloid and Surface Properties and Biochemistry of Silica, Ralph K Iler, 1979, John Wiley and Sons Inc., ISBN 0-471-02404-X and references therein.

[0031] Methods for preparing silica-modifier metal oxide cogels are known in the art and some such methods are described in US 5,069,816, Bosman et al., J Catalysis Vol. 148 (1994) p. 660, and Monros et al., J Materials Science Vol. 28, (1993), p. 5832.

[0032] The silica of the present invention has a mesoporous content within the scope of the present invention. As mentioned above, silica with appropriate mesoporosity (mesoporosity) can also be prepared by alternative preparation routes of gels such as fumed silica. Typical fumed silica preparation methods and properties are disclosed in scientific literature, for example, in "The Surface Properties Of Silica", edited by AP Legrand, 1998, John Wiley & Sons, ISBN 0-471-95332-6, Chapter 1 "On the Silica Edge", and in "The Chemistry Of Silica", RK Iler, 1979, John Wiley & Sons, ISBN 0-471-02404-X, Chapter 5 "Silica Gels And Powder".

[0033] The typical average surface area of the silica-supported catalyst according to any aspect of the present invention is in the range of 20 m 2 / g-1000m 2 / g, more preferably 30m 2 / g-800m 2 / g, and most preferably 35m 2 / g-500m 2 The range of pore volume is as measured by the BET multipoint method using a Micromeritics Tristar 3000 surface area and porosity analyzer. The reference material used to check the performance of the instrument can be a 30.6 m 2 / g(+ / -0.75m 2 / g) of carbon black powder, material number 004-16833-00.

[0034] The silica component of the support may typically form 80 wt% to 100 wt% of the support, more typically 90 wt% to 99.7 wt% of the support, and most typically 93.2 wt% to 99.6 wt% of the support.

[0035] The catalyst material of the present invention is porous and is a multimodal combination of mesopores and macropores with an overall average pore size between 2 nm and 1000 nm, more preferably between 3 nm and 500 nm, and most preferably between 5 nm and 250 nm. Macropore size (over 50 nm) can be determined by mercury intrusion porosimetry using NIST standards, while the Barrett-Joyner-Halenda (BJH) analysis method using liquid nitrogen at 77 K is used to determine the pore size of the mesopores (2 nm to 50 nm). The average pore size is the pore volume weighted average of the pore volume relative to the pore size distribution.

[0036] The average pore volume of the catalyst particles can be measured by absorption of a fluid such as water. Alternatively, the 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 the pore volume as in the case of the surface area measurement, and the same standards are employed.

[0037] Multimodal silica

[0038] A multimodal distribution is a distribution having two or more modes. Thus, it should be understood that the term multimodal includes bimodal or trimodal, etc. With respect to the present invention describing a multimodal pore size distribution, it should be understood that the range of pore sizes of a material is a mixture of two or more unimodal pore size distributions. Thus, a material exhibiting a multimodal pore size distribution not only comprises a single unimodal distribution extending within the mesopore and micropore range, but also comprises at least two different peaks. Possibly, such peaks may be completely independent or optionally overlapping.

[0039] The average mesopore volume of the catalyst particles can be less than 1 cm as measured by nitrogen absorption. 3 / g, but usually at 0.2cm 3 / g-3cm 3 / g, preferably within 0.3cm 3 / g-2.5cm 3 / g, more preferably 0.4cm 3 / g-2cm 3 / g, most preferably 0.5cm 3 / g-1.5cm 3 / g.

[0040] The average macropore volume of the catalyst particles may be less than 1 cm3 / g as measured by mercury adsorption, but is typically in the range of 0.1 cm3 / g. 3 / g-3cm 3 / g, preferably within the range of 0.15cm 3 / g-2.5cm 3 / g, more preferably 0.2cm 3 / g-2cm 3 / g, most preferably 0.2cm 3 / g-1.5cm 3 / g.

[0041] The catalyst particles according to any aspect of the present invention have a macropore:mesopore volume ratio in the range of 0.03-15, optionally in the range of 0.4-4, more typically in the range of 0.5-2.

[0042] Micropores may also be present in the catalyst.

[0043] In the present invention, it has been found that controlling the porosity of the silica support as claimed is surprisingly advantageous.However, controlling the volume, distribution and amount of both mesopores and macropores is also beneficial.

[0044] Advantageously, when the multimodal silica support of the catalyst of the above aspects of the invention comprises mesopores and macropores, high reaction selectivity and / or low heavies formation during the production of α,β ethylenically unsaturated carboxylic acids or carboxylic esters has been found.

[0045] Macropores can be formed in otherwise mesoporous silica using a variety of different methods known to those skilled in the art. Suitable techniques include hard and soft template methods as well as adhesive 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" by Yang et al., Chem. Soc. Rev., 2017, 46, 481 lists many methods for creating pores in materials, especially for macropores, including the following:

[0046] Surfactant template

[0047] Colloidal crystal templates

[0048] Macroporous polymer templates

[0049] Bioinspiring process

[0050] Supercritical fluid

[0051] ·Emulsion template

[0052] Freeze drying

[0053] Breath figure

[0054] Selective leaching

[0055] Phase separation

[0056] Zeolite process

[0057] ·copy

[0058] Sol-gel control

[0059] Post-processing

[0060] Self-formation

[0061] Cohesion

[0062] In one embodiment, the macropores are generated by hard templating. In another embodiment, the macropores are generated by soft templating. In another further embodiment, the macropores are generated by adhesive technology.

[0063] "Hard" templates involve the use of solid insoluble particles of a size similar to the size of the desired macropores, which can be incorporated into a precursor liquid to form a two-phase solid / liquid slurry for preparing the silica gel. The solid insoluble particles remain as a discrete phase that can be removed from the resulting silica gel by, for example, pyrolysis or calcination at high temperature in an inert or oxidizing atmosphere. Literature examples of this type of technology include the following:

[0064] "Multiphased assembly of macroporous silica particles", Journal of Non-Crystalline Solids 285 (2001) 71-78, CJ Brinker et al. - discloses the use of polymer latex spheres to make macroporous silica, in particular polystyrene beads, which are used as hard templates to produce macroporosity

[0065] “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 hard templates derived from emulsion polymers of styrene and divinylbenzene to generate macroporous silica with macropore diameters of approximately 200 nm;

[0066] “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 assembled, infused with a silica precursor, and then the polystyrene sphere template is removed by calcination to produce macroporous silica.

[0067] "Soft" templates involve the use of a soluble or insoluble fluid that is incorporated into a precursor liquid such as silicon dioxide as a single liquid phase or a two-phase liquid / liquid emulsion, which is then used to make silica gel. Macropores are formed in the resulting silica gel by removal of the fluid, such as by pyrolysis or calcination at high temperature in an inert or oxidizing atmosphere. Literature examples of this type of technology include the following:

[0068] Soluble liquid method - "Effects of aging and solvent exchange on pore structure of silica gels with interconnected macropores", Journal of Non-Crystalline Solids 189, 1995, 66-76, Takahashi et al. - This describes the technique used in the examples of our patent application, which is to mix a polymer solution into a silica sol precursor, gel the precursor, and during the gelation process undergo phase separation into silica gel and polymer - in this particular reference, polyacrylic acid. The resulting two-phase solid is then "heat treated" - to produce macroporous silica;

[0069] Soluble liquid method - "Synthesis and Textural Characterization of Mesoporous and Meso- / Macroporous Silica Monoliths Obtained by Spinodal Decomposition", Inorganics 2016, 4, 9, Galarneau et al. This uses polyethylene oxide in the silica sol precursor to produce macroporous silica when a mixed single-phase solution of polymer and silica precursor phases separates;

[0070] 2-phase liquid / liquid emulsions, specifically micelles of surfactants 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. - This paper describes the use of a specific template polymer / surfactant mixture that forms micelles within a gelling silica material that can then be removed by an unspecified thermal process to produce silica with a range of mesopores and macropores.

[0071] "Binder technology" includes the use of one or more binder compounds, which are incorporated with at least mesoporous silica powder and optionally water, and are then formed into a solid body that is subsequently removed to form a silica body with a macroporous network. The original silica powder can be mesoporous or can contain macropores. The silica powder can be formed from silica gel or pyrogenic silica. When the binder is removed from the resulting solid silica by suitable techniques such as pyrolysis / calcination, for example, at high temperatures in an oxidizing atmosphere or by solvent extraction, macropores derived from the binder are formed. The silica powder and binder can be formed into a solid body by extrusion. The pore size produced can be determined, for example, by the ratio of silica particles: water: binder. A secondary binder may or may not be used in this process.

[0072] Two examples of the use of binders or forming agents in the preparation of macroporous catalyst bodies with alternating support chemistries of silica can be found in the following references:-

[0073] US5137855 (WR Grace & Co) discloses the use of different amounts of combustible binder to produce different titania-supported catalyst extrudates having different levels of macroporosity and improved catalyst performance.

[0074] US 10022702 (IFP Energies Nouvelles) discloses the use of liquid or solid pore formers in varying amounts in the preparation of alumina catalyst particles prepared by agglomeration of powders followed by drying and calcination.

[0075] Furthermore, in addition to the above-mentioned techniques, other techniques for forming the catalyst body that do not use a binder are also available.

[0076] Typical methods for forming catalyst bodies, which may or may not contain a binder, can be found in "Manual of Methods and Procedures for Catalyst Characterisation", 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, bead formation from sols or gels introduced into hot immiscible oils ("oil droplets"), granulation of mixtures of powders of different sizes optionally containing a binder material, tabletting of mixtures of powders of different sizes optionally containing a binder material, and extrusion of pastes of powders of different sizes optionally containing a binder material.

[0077] According to a second aspect of the present invention, there is provided a method of producing a catalyst according to any aspect herein, the method comprising:

[0078] (a) preparing modified silica by modifying silica with a modifier metal selected from the group consisting of Mg, B, Al, Ti, Zr and Hf,

[0079] (b) treating the modified silica with a catalytic alkali metal,

[0080] (c) introducing macropores into the silica before step (a), before step (b), or after step (b).

[0081] Preferably, the silica is silica gel or fumed silica, which comprises at least mesopores.

[0082] Preferably, the macropores are introduced into the silica gel by hard templating, soft templating, adhesives, or other techniques such as those presented herein.

[0083] Macropores can be introduced into silica, modified silica, or modified silica treated with a catalytic alkali metal.

[0084] It will be appreciated that the silica may have porosity in the macroporous range as well as the mesoporous range prior to the introduction of the macropores in step (c).

[0085] Typically, the silica is in powder form prior to introduction into the macropores by a suitable technique. Suitable processing of the silica powder may include: adding processing aids, liquids, and binders to the powdered silica, if necessary, to produce a multiphase particle mixture of the desired composition and rheology;

[0086] forming silica bodies or particles, including but not limited to cylinders, tablets, extrudates, and structured extrudates, by methods including but not limited to extrusion, agglomeration, granulation, and tableting;

[0087] Subsequent heat treatment of the shaped bodies or particles produces a porous support body comprising silica having appropriate amounts of mesoporosity and macroporosity as set forth herein.

[0088] Catalytic alkali metal

[0089] Typically, in this context, the catalytic alkali metal is an adsorbate adsorbed on 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, typically, the adsorbate is chemisorbed onto the surface of the modified silica support.

[0090] As will be understood, the catalytic alkali metal herein is a metal that is different from the modifier metal. Preferably, the catalytic alkali metal may be selected from one or more alkali metals. Typically, the catalytic alkali metal is selected from cesium, potassium or rubidium, more preferably cesium.

[0091] 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 level of catalytic alkali metal may be up to 10 mol / 100 (silicon + modifier metal) mol in the catalyst, more preferably up to 6 mol / 100 (silicon + modifier metal) mol or 7.5 mol / 100 (silicon + modifier metal) mol in the catalyst, most preferably up to 5 mol / 100 (silicon + modifier metal) mol in the catalyst.

[0092] Preferably, the level of catalytic alkali metal in the catalyst is in the range of from 1 mol / 100 (silicon + modifier metal) mol to 10 mol / 100 (silicon + modifier metal) mol, more preferably 2 mol / 100 (silicon + modifier metal) mol to 8 mol / 100 (silicon + modifier metal) mol, most preferably 2.5 mol / 100 (silicon + modifier metal) mol to 6 mol / 100 (silicon + modifier metal) mol in the catalyst.

[0093] Alternatively, the catalyst may have a wt% of catalytic alkali metal in the catalyst in the range of 1 wt% to 22 wt%, more preferably 4 wt% to 18 wt%, most preferably 5 wt% to 13 wt%.

[0094] Thus, the molar ratio of catalytic alkali metal:modifier metal is typically at least 1.4 or 1.5: 1, preferably it is in the range of 1.4 to 5: 1, such as 1.5 to 4.0: 1, particularly 1.5 to 3.6: 1. Typically, herein, the catalytic alkali metal exceeds the amount that would be required to neutralize the modifier metal.

[0095] Preferably, the catalytic alkali metal is present in the range of 0.5 mol / mol modifier metal to 7.0 mol / mol modifier metal (if present), more preferably 1.0 mol / mol modifier metal to 6.0 mol / mol modifier metal, most preferably 1.5 mol / mol modifier metal to 5.0 mol / mol modifier metal.

[0096] Unless indicated to the contrary, the alkali metal or amount of alkali metal in the catalyst refers to the alkali metal ion and not to the salt.

[0097] Suitably, the catalytic alkali metal may be incorporated into the silica support by any method known in the art, such as impregnation or adsorption, co-gelation or vapour deposition with the catalytic metal.

[0098] The level of catalytic metal in the catalyst, whether mol% or wt%, can be determined by taking appropriate samples and taking an average of such samples. Typically, 5-10 samples of a particular catalyst batch will be taken and the alkali metal levels determined and averaged, for example, by XRF, atomic absorption spectroscopy, neutron activation analysis, ion coupled plasma mass spectrometry (ICPMS) analysis, or ion coupled plasma atomic emission spectroscopy (ICPAES).

[0099] Modification of silica supports - modifier metals

[0100] The silica of the present invention may be provided as a co-gel of the modifier metal oxide and silica, or as a modified silica in which the modifier metal is adsorbed on the silica surface.

[0101] Typically, the modifier metal is adsorbed on the surface of the silica support. Typically, the modifier metal is present on the surface of the modified silica support in the form of a metal oxide portion. The modifier metal oxide can be distributed through the silica matrix as well as its surface.

[0102] Typically, the modified silica gel is produced by a suitable adsorption reaction. Adsorption of the relevant metal compound onto a silica gel such as silica xerogel to form the modified silica gel with the relevant modifier metal moiety is a suitable technique.

[0103] Typically, when the modifier metal is added as an adsorbate, it can be added as a mononuclear modifier metal compound or a binuclear modifier metal compound. It has been found that controlling the nucleation properties of the modifier metal moiety is surprisingly advantageous because it helps control the proximity of adjacent modifier metal moieties on the silica.

[0104] Typically, the modifier metal compound is a complex, and before and / or after adsorption, the ligand in the coordination sphere of the compound has enough sizes usually, to prevent the further oligomerization of the modifier metal and / or to prevent the significant increase of the nucleation of the complex. Usually, the increase to the nucleation of dimer can be acceptable. Typically, the modifier metal complex is an organic complex with one or more organic multidentate chelate ligands, or alternatively is a complex with a monodentate ligand that is large in volume in the space of the effectively stabilizing nucleation.

[0105] Typically, at least 25% of the modifier metal is present on the support before or after calcination as a mononuclear modifier moiety or a binuclear modifier moiety. Thus, typically, at least 25% of the modifier metal is present on the support as a modifier metal moiety derived from a mononuclear metal compound or a binuclear metal compound.

[0106] Typically, the mononuclear modifier metal or binuclear modifier metal is contacted with the silica support as a mononuclear modifier metal compound or binuclear modifier metal compound in solution to effect adsorption of the modifier metal onto the support.

[0107] Typically, the modifier metal compound is mononuclear or dinuclear, eg, mononuclear.

[0108] Advantageously, when a modifier metal is incorporated into the multimodal silica of the above-described aspects of the invention, a reduced sintering rate of the catalyst surface during the production of α,β olefinically unsaturated carboxylic acids or carboxylates has been found. Adding the modifier metal prevents sintering and loss of mesoporous surface area. The combination of the modifier metal that prevents mesoporous sintering and the presence of a macroporous network allows for the maintenance of an open pore structure that allows diffusion of the raw materials throughout the catalyst pellets and seepage of products and by-products within the catalyst pellets from the catalyst surface, which reduces the formation of "heavy" by-products formed by unwanted coupling reactions. This advantageous combination results in improved reaction selectivity to the product. Typically, the modifier metal is selected from zirconium, hafnium and / or titanium.

[0109] Typically, the metal compound is a complex comprising two or more chelating ligands, preferably 2, 3 or 4 chelating ligands. The chelating ligands herein may be bidentate, tridentate, quadridentate or multidentate. However, the compound may also comprise bulky monodentate ligands which are also effective for effectively isolating the modifier metal on the silica surface as described herein.

[0110] Typically, the metal complex is tetra-, penta-, hexa-, hepta- or octa-coordinated.

[0111] Advantageously, the size of the ligands in the coordination sphere of the modifier metal compound, such as the size of the chelating ligands, results in a more dispersed modifier metal than the same modifier metal with a simple counterion such as a nitrate, acetate, or oxynitrate. It has been found that adsorption of smaller metal salts results in clustering of the modifier metal after heat treatment or calcination, which in turn reduces the selectivity of the catalyst and reduces the sintering resistance of the catalyst.

[0112] In some embodiments of the present invention, the modifier metal is an adsorbate adsorbed on the surface of the silica support of the catalyst. The adsorbate can be chemically adsorbed or physically adsorbed onto the surface of the silica support as its compound. Typically, the adsorbate is chemically adsorbed on the surface of the silica support.

[0113] Suitable chelating ligands herein may be non-labile ligands, optionally selected from molecules having a lone pair of electrons, comprising an oxygen atom or nitrogen atom capable of forming a 5-membered ring or a 6-membered ring with the modifier metal atom. Examples include diketones, diimines, diamines, diols, dicarboxylic acids or derivatives thereof such as esters, or molecules having two different such functional groups, and in either case, the corresponding N or O and N or O atoms are separated by 2 or 3 atoms to form a 5-membered ring or a 6-membered ring. Examples include pentane-2,4-dione, esters of 3-oxobutyric acid with aliphatic alcohols containing 1 to 4 carbon atoms such as ethyl 3-oxobutyrate, propyl 3-oxobutyrate, isopropyl 3-oxobutyrate, n-butyl 3-oxobutyrate, tert-butyl 3-oxobutyrate, heptane-3,5-dione, 2,2,6,6-tetramethyl-3,5-heptanedione, 1,2-ethanediol, 1,2-propylene glycol, 1,3-propylene glycol, Alcohols, 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-dihydroxybenzene-3-5-disulfonate, diethylenetriaminepentaacetic acid, nitrotriacetic acid, N-hydroxyethylethylenediaminetriacetic acid, N-hydroxyethyliminodiacetic acid, N,N-dihydroxyethylglycine, oxalic acid and its salts. Pentane-2,4-dione, heptane-3,5-dione, 2,2,6,6-tetramethyl-3,5-heptanedione, ethyl 3-oxobutanoate and tert-butyl 3-oxobutanoate are most preferred. In one embodiment, the present invention provides the compound of the present invention.Have for example amount to and be less than 10 carbon and / or heteroatomic less bidentate chelate ligand and make it possible to form little complex compound, compared with bigger part, described little complex compound can allow higher concentration to be deposited on the surface of silicon-dioxide.Therefore, mononuclear or binuclear modifier metal cation source herein can be modifier metal and such less chelate ligand, preferably, with the form of the complex compound of at least a such part.Such compound can comprise variable part, such as the solvent ligand in alcoholic solvent, alkoxide part, such as ethanolate or propoxide etc.

[0114] Chelating ligands are typically non-labile ligands. A non-labile ligand is a ligand that coordinates to the modifier metal and is not removed by adsorption of the modifier metal onto the silica surface. Thus, prior to treating the silica surface with the modifier metal, the non-labile ligand is typically coordinated to the modifier metal in solution. 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.

[0115] The size of the chelating ligand is selected so as to space the modifier metal atoms on the silica surface to prevent their binding during catalyst production.

[0116] Alternatively, a modifier metal complex with a bulky monodentate ligand can be used to prevent oligomerization of the metal complex. Typical ligands used in the complex include, but are not limited to, alkoxides with a suitable organic group such as tert-butyl alcohol or 2,6-di-tert-butylphenol, amides with a suitable organic group such as dialkylamides (methyl, ethyl and higher linear and branched alkyl groups) and bis(trimethylsilylamido) complexes, and alkyl ligands with a suitable organic group such as 2,2-dimethylpropyl (neopentyl) ligands.

[0117] Typically, the silica support has isolated silanol groups, and by contacting the silica support with the modifier metal species, the modifier metal is adsorbed onto the surface of the silica support via reaction with the silanol groups.

[0118] Preferably, the adsorbed or co-gelled modifier metal cations are sufficiently separated from each other by the modifier metal compound to substantially prevent their oligomerization, more preferably, dimerization, trimerization or oligomerization with adjacent modifier metal cations during subsequent processing steps, such as impregnation of the catalytic metal, or optionally, subsequent calcination.

[0119] Typically, the support contains >0.025 moieties per nm 2 level, more preferably from 0.05 parts per nm 2 levels, most preferably from 0.1 parts per nm 2 The level of the modifier metal portion.

[0120] Typically, when the modifier metal complex is contacted with the support to achieve adsorption of the complex onto the support, at least 30%, such as at least 35%, more preferably at least 40%, such as at least 45%, most suitably at least 50%, such as at least 55%, for example at least 60% or 65%, and most preferably at least 70%, such as at least 75% or 80%, more typically at least 85%, most typically at least 90%, especially at least 95%, of the modifier metal in the modifier metal complex is a mononuclear modifier metal compound and / or a binuclear modifier metal compound. Accordingly, the level of mononuclear modifier metal and / or binuclear modifier metal on the silica surface may be at such a level.

[0121] Preferably, the silica support is dried and / or calcined prior to treatment with the modifier metal.

[0122] Thus, the modifier metal may be incorporated onto the support as a source of cations, more preferably as a solution of a compound of said modifier metal, such that the compound is in solution when contacted with the support to effect adsorption onto the support.

[0123] Typically, the solvent used in the solution is water or other than water.

[0124] Typically, the solvent is an organic solvent such as toluene or heptane. In addition, the solvent can be an aliphatic solvent or an aromatic solvent. Still additionally, the solvent can be a chlorinated solvent such as dichloromethane. More typically, the solvent is an aliphatic alcohol, which is typically selected from C1-C6 alkanols such as methanol, ethanol, propanol, isopropanol, butanol, pentanol and hexanol, more typically methanol, ethanol or propanol.

[0125] Examples of suitable metal cation sources herein include 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 (propanol) (pentane-2-3-dione) 3, zirconium (propanol) 3 (2,2,6,6-tetramethyl-3,5-heptanedione), zirconium (Ot-butyl) 3 (tert-butyl 3-oxobutanoate), zirconium (Ot-butyl) 2 (tert-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.

[0126] Examples of suitable metal cation sources herein include organic complexes such as titanium tetrakis(methanol), titanium tetrakis(ethoxide), titanium tetrakis(n-propoxide), titanium tetrakis(isopropoxide), titanium tetrakis(n-butoxide), titanium tetrakis(tert-butoxide), titanium tetrakis(2-ethylhexyl)oxide, titanium bis(acetylacetonate) oxide, titanium bis(2,2,6,6-tetramethyl-3,5-heptanedioate) oxide, titanium (triethanolamine)isopropoxide, titanium bis(triethanolamine)diisopropoxide, titanium tetrakis(diethylamide), titanium tetrakis(ethylmethylamide), titanium tetrakis(dimethylamide), titanium tetrakis(neopentyl), titanium bis(ammonium lactate)dihydroxytitanium(IV); 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.

[0127] The source of metal cations may be provided as an organic complex.

[0128] 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 (pentane-3,5-dione)4, zirconium (2,2,6,6-tetramethyl-3,5-heptanedione)4, zirconium (IV) ethyl 3-oxobutyrate, zirconium (IV) tert-butyl 3-oxobutyrate, or zirconium (IV) isopropyl 3-oxobutyrate in one of methanol, ethanol, isopropanol, propanol, butanol, isobutanol, or 2-butanol.

[0129] Preferably, after adsorption of the modifier metal onto the silica support, the solvent is removed by evaporation.

[0130] Optionally, the modified silica support is calcined to remove any ligands or other organics from the modified support.

[0131] When the modifier metal is present in the support in the form of a cogel, the modified silica support is a silica-modifier metal oxide cogel. In such an embodiment, the modifier metal is typically incorporated as a uniform dispersion throughout the silica-modifier metal oxide structure.

[0132] Typically, whether an adsorbate or a cogel, the modifier metal is present in the mononuclear oxide portion or the binuclear oxide portion. Typically, when the modifier metal is added as an adsorbate, it may be added as a mononuclear modifier metal compound or a binuclear modifier metal compound.

[0133] Typically, when present, the modifier metal is uniformly dispersed throughout the surface of the silica support or uniformly dispersed throughout the silica modifier metal oxide structure.

[0134] For the avoidance of doubt, the modifier metal on the silica support of the catalyst according to the present invention relates to modifier metals such as magnesium, boron, aluminium, titanium, zirconium and hafnium and not to silica.

[0135] Preferably, the level of modifier metal present in the modified silica or catalyst may be as high as 7.6×10 -2 mol / mol silica, more preferably up to 5.9×10 -2 mol / mol silica, most preferably up to 3.5×10 -2 mol / mol silica. Typically, the level of such metals is 0.067×10 -2 mol / mol silica and 7.3×10 -2mol / mol silica, more preferably between 0.13×10 -2 mol / mol silica and 5.7×10 -2 mol / mol silica, and most preferably between 0.2×10 -2 mol / mol silica and 3.5×10 -2 Typically, the level of modifier metal present is at least 0.1×10 -2 mol / mol silica, more preferably at least 0.15×10 -2 mol / mol silica, and most preferably at least 0.25×10 -2 mol / mol silica.

[0136] Preferably, the % w / w level of the modifier metal will depend on the metal, but can be up to 20% w / w, more preferably up to 16% w / w, most preferably up to 11% w / w of the modified silica support. Typically, the level of the modifier metal is between 0.02% and 20% w / w of the modified silica support, more preferably between 0.1% and 15% w / w, and most preferably between 0.15% and 10% w / w. Typically, the level of the modifier metal is at least 0.02% w / w of the modified silica support, such as 0.25% w / w, for example 0.4% w / w, more typically, at least 0.5% w / w, most typically, at least 0.75% w / w.

[0137] 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) analysis, or ion coupled plasma atomic emission spectroscopy (ICPAES).

[0138] catalyst

[0139] Typically, the catalyst of the present invention can be in any suitable form. Typical embodiments are 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. Another alternative is a monolithic reactor.

[0140] In the case where the catalyst is used in the form of a fixed bed, it is desirable that the supported catalyst is formed into particles, aggregates or shaped units, such as spheres, cylinders, rings, saddles, stars, poly-lobes prepared by pelletizing or extrusion, typically having a maximum dimension and a minimum dimension in the range of 1 mm to 10 mm, more preferably having an average dimension greater than 2 mm, such as greater than 2.5 mm or 3 mm. The catalyst is also effective in other forms, for example, powders or beads of the same size as indicated. In the case where the catalyst is used in the form of a fluidized bed, it is desirable that the catalyst particles have a maximum dimension and a minimum dimension in the range of 10 μm to 500 μm, preferably 20 μm to 200 μm, most preferably 20 μm to 100 μm.

[0141] Amount of catalytic metal and modifier metal

[0142] The total metal content of the catalyst is at least 80 wt% of catalytic base metal and modifier metal as defined herein. Typically, the total metal content of the catalyst is at least 85 wt% of catalytic base metal and modifier metal as defined herein, more typically at least 90 wt%, even more typically at least 95 wt%, most typically at least 99 wt%, in particular at least 99.5 wt%, such as at least 99.9 wt%.

[0143] Tungsten / antimony / vanadium / bismuth exclusion

[0144] As set forth above, the catalyst according to the present invention may be substantially free, substantially free, or completely free of tungsten and / or antimony and / or vanadium and / or bismuth and / or a metal from Group 3 and / or a metal from Group 8, Group 9, or Group 10 and / or a metal from Group 13 and / or a metal from Group 14. Tungsten and / or antimony and / or vanadium and / or bismuth and / or a metal from Group 3 and / or a metal from Group 8, Group 9, or Group 10 and / or a metal from Group 13 and / or a metal from Group 14 may be present in trace amounts due to unavoidable contamination from the environment. By "substantially free," we intend to refer to catalysts and supports that contain less than 1000 parts per million (ppm) of tungsten and / or antimony and / or vanadium and / or bismuth and / or a metal from Group 3 and / or a metal from Group 8, Group 9, or Group 10 and / or a metal from Group 13 and / or a metal from Group 14. By "substantially free" we intend to refer to catalysts and supports comprising 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, Group 9 or Group 10 metals and / or Group 13 metals and / or Group 14 metals, and by "completely free" we intend to refer to catalysts comprising less than 200 parts per billion (ppb) of tungsten and / or antimony and / or vanadium and / or bismuth and / or Group 3 metals and / or Group 8, Group 9 or Group 10 metals and / or Group 13 metals and / or Group 14 metals.

[0145] By the term "Group 3 metals", we include the metals Sc, Y, and the entire set of lanthanides and actinides. Preferably, the metal is selected from La or Ce. For the avoidance of doubt, references herein to Group 3 metals refer to the modern IUPAC nomenclature. Thus, Group 3 should be considered to include the transition metal Group IIIB according to the older nomenclature scheme, as well as the lanthanide and actinide regions.

[0146] By the term "metal of Group 8, Group 9 or Group 10", we include metals such as Ni, Pd, Pt and Ds. Preferably, the metal is Pt. For the avoidance of doubt, references herein to metals of Group 8, Group 9, Group 10 refer to the modern IUPAC nomenclature. Thus, Groups 8, 9, and 10 should be considered to include the transition metal Group VIII according to the older nomenclature.

[0147] By the term "metal of Group 13", we include metals such as B, Al, Ga, In and Tl. Preferably, the metal is Al. For the avoidance of doubt, references herein to metals of Group 13 refer to the modern IUPAC nomenclature. Thus, Group 13 should be considered to include Group III, Group 3 or Group IIIA according to the older nomenclature.

[0148] By the term "metal of Group 14", we include metals such as Ge, Sn and Pb. Preferably, the metal is Sn. For the avoidance of doubt, references herein to metals of Group 14 refer to the modern IUPAC nomenclature. Thus, Group 14 should be considered to include Group IV, Group 4 or Group IVA according to the older nomenclature.

[0149] silanol

[0150] Prior to treatment with the modifier metal compound, the concentration of silanol groups on the silica support may be reduced by calcination, chemical dehydration, or other suitable methods.

[0151] A suitable method for treating silica to provide isolated silanol groups at the desired level is by calcination. However, other techniques such as hydrothermal treatment or chemical dehydration are also possible. US5583085 teaches chemical dehydration of silica with dimethyl carbonate or ethylene dicarbonate in the presence of an amine base. US4357451 and US4308172 teach chemical dehydration by chlorination with SOCl2, followed by dechlorination with H2 or ROH, and then dechlorination with oxygen in a dry atmosphere. Chemical dehydration can provide up to 100% silanol removal, compared to 0.7 / nm by thermal treatment. 2 Therefore, in some cases, chemical dehydration can provide more space for silanol group control.

[0152] The term isolated silanol (also known as single silanol) is well known in the art and distinguishes this group from vicinal or geminal silanols or internal silanols. Suitable methods for determining the incidence of isolated silanols include surface sensitive infrared spectroscopy and 1 H NMR or 31 Si NMR.

[0153] As mentioned, the silica support may be dried or calcined prior to treatment with the modifier metal cation source.The formed modified silica may be dried or calcined prior to addition of the catalytic metal, regardless of whether it has been previously dried or calcined.

[0154] Prior to treatment with the modifier metal, the silica may be in the form of a multimodal gel. At the start of modification, the gel may be in the form of a hydrogel, xerogel or aerogel.

[0155] The multimodal silica support may be a xerogel, a hydrogel or an aerogel. In one embodiment, the silica support is a xerogel.

[0156] General process

[0157] The skilled person will appreciate that the catalytic alkali metal may be added to the modified silica by any suitable means.Typically, to produce the modified silica catalyst, the silica is contacted with the catalytic alkali metal.

[0158] 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 in the form of a salt of the catalytic alkali metal, and most typically, the silica support is contacted with an alkaline aqueous solution containing a catalytic alkali metal such as cesium in the form of a salt of the catalytic alkali metal and a base. 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. Low levels of water, typically up to 20 vol%, may be included in the solution.

[0159] Typically, during this stage of the catalyst production process, the conditions of temperature, contact time and pH are such as to allow impregnation of the multimodal silica support with the catalytic alkali metal to form the multimodal silica-supported catalyst.

[0160] Typical temperature conditions for this step are between 5° C. and 95° C., more typically between 10° C. and 80° C., and most typically between 20° C. and 70° C. The temperature for this step may be at least 5° C., more typically at least 10° C., and most typically at least 20° C.

[0161] For this step, the typical contact time between the support and the solution containing the catalytic metal can be between 0.05 hours and 48 hours, more typically between 0.1 hours and 24 hours, and most typically between 0.5 hours and 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.

[0162] The concentration of the catalytic metal salt solution used in this step depends on many 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 the choice of catalytic metal compound. The concentration in solution is best determined experimentally.

[0163] Suitable catalytic alkali metal salts for incorporating the catalytic metal can generally be selected from one or more of the group consisting of formates, acetates, propionates, bicarbonates, chlorides, nitrates, hydroxides and carbonates, more typically hydroxides, acetates or carbonates, and most typically hydroxides and / or carbonates. During the impregnation, the pH can be controlled by adding ammonia and a metal compound, or by using a suitable catalytic metal compound such as formates, carbonates, acetates or hydroxides, more preferably hydroxides or carbonates, in each case, alone, in combination or with a suitable carboxylic acid. At the end of the impregnation, it is most important to control the pH within a preferred range in order to achieve satisfactory adsorption. Most typically, these salts can be incorporated using an alkaline solution of the salt. If the salt itself is not alkaline, a suitable base such as ammonium hydroxide can be added. Since hydroxide salts are alkaline in nature, a mixture of one or more of the above salts with a specific catalytic metal such as a hydroxide salt of cesium can be conveniently prepared.

[0164] The skilled artisan 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. After the catalytic metal and / or modifier metal is deposited on the support, the metal may be fixed to the support, typically by calcination.

[0165] Typically, drying of the silica support is achieved by suitable methods known to the skilled person, such as in a drying unit or an oven.

[0166] Typically, the catalyst comprises between 0.01% w / w-25% w / w water, more typically between 0.1% w / w-15% w / w water, and most typically between 0.5% w / w-5.0% w / w water.

[0167] Optionally, the silica-supported catalyst comprising the catalytic metal may be dried or calcined, the process of calcination being well known to those skilled in the art.

[0168] In some cases, it may be necessary to calcine the support formed from the modification stage at 200°C to 1000°C, more typically 300°C to 800°C, and most typically 350°C to 600°C, before adding the catalytic metal. In the preferred calcination of the support formed from the modification stage, the temperature is at least 375°C, such as 400°C. The calcination atmosphere should typically contain some oxygen, suitably 1% to 30% oxygen, and most suitably 2% to 20% oxygen, to achieve removal of organic residues as carbon dioxide and water. The calcination time may typically be between 0.01 hours and 100 hours, suitably 0.5 hours to 40 hours, and most suitably 1 hour to 24 hours. In the 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 is in the range of 400-1000° C., more typically 500-900° C., most typically 600-850° C. The calcined support, such as a xerogel material, should be cooled to a suitable temperature for impregnation.

[0169] The addition of the catalytically active metal may be carried out by the methods described above, or may be by any other standard method for impregnating a catalyst support such as a xerogel support, such as using water or a solvent other than water such as an alcohol, suitably methanol, ethanol, propanol or isopropanol, or using an incipient wetness method, wherein only enough solution is added to the xerogel support to fill the pores of the xerogel support. In this case, the concentration of the catalytically active metal may be calculated so as to introduce a target amount of the catalytically active metal into the xerogel support material, rather than providing an excess of a less concentrated solution. The addition of the catalytically active metal may utilize any preferred method known in the art.

[0170] The drying of the modified silica prior to calcination can be carried out at a temperature in the range of 20°C to 200°C, more typically 30°C to 180°C, and most typically 40°C to 150°C. The drying of the modified silica prior to calcination can be carried out at atmospheric or subatmospheric pressure in the range of 0.001 bar to 1.01 bar. The drying of the modified silica can also be achieved in a fixed bed or fluidized bed under an inert gas flow. The drying time can be in the range of 0.1 hour to 24 hours, more typically 0.5 hour to 12 hours, and most typically 1 hour to 6 hours.

[0171] Drying under reduced pressure at relatively low temperatures or fluidized bed drying with an inert gas are suitable techniques.

[0172] General properties

[0173] The modifier metal and catalytic alkali metal adsorbates in the final catalyst are typically metal oxide moieties.

[0174] According to a third aspect of the present invention there is provided a process for producing an ethylenically unsaturated carboxylic acid or carboxylic ester, typically an α,β ethylenically unsaturated carboxylic acid or carboxylic ester, the process comprising the step of contacting formaldehyde or a suitable source thereof with the carboxylic acid or carboxylic ester in the presence of a catalyst and optionally in the presence of an alcohol, wherein the catalyst is according to the first aspect or any other aspect of the invention as defined herein.

[0175] Advantageously, it has also been found that catalysts comprising silica as defined herein and comprising a catalytic alkali metal are very effective catalysts for producing α,β ethylenically unsaturated carboxylic acids or carboxylic acid esters by condensation of the corresponding acid or ester with a methylene source such as formaldehyde.

[0176] The term "a 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 that the source can act as an equivalent to free formaldehyde under the reaction conditions, for example the source can form the same reaction intermediate as formaldehyde, allowing an equivalent reaction to occur.

[0177] Suitable formaldehyde sources may be compounds of formula (I):

[0178]

[0179] where R 5 and R 6 Independently selected from C1-C 12 hydrocarbon or H, X is O, n is an integer from 1 to 100, and m is 1.

[0180] Typically, R 5 and R 6 independently selected from C1-C 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 1-3.

[0181] However, other formaldehyde sources, including trioxane, may also be used.

[0182] Therefore, suitable formaldehyde sources also include any equilibrium composition that can provide a formaldehyde source. Examples include, but are not limited to, dimethoxymethane; trioxane; polyoxymethylene R 1 -O-(CH2-O) i -R2 , where R 1 and / or R 2 is a hydrocarbyl group or hydrogen, i = 1 to 100; paraformaldehyde; formalin (formaldehyde, methanol, water); and other equilibrium compositions such as mixtures of formaldehyde, methanol, and methyl propionate.

[0183] Polyoxymethylene is a higher formals or hemiformals of formaldehyde and methanol, CH3-O-(CH2-O) i -CH3("formal-i") or CH3-O-(CH2-O) i -H ("hemialfond-i"), wherein i = 1 to 100, suitably 1-5, in particular 1-3, or other polyoxymethylenes having at least one non-methyl terminal group. Thus, the formaldehyde source may also be of the formula R 31 -O-(CH2-O-) i R 32 Polyoxymethylene, where R 31 and R 32 can be the same group or different groups, and at least one is selected from C1-C 10 Hydrocarbyl groups, such as R 31 =isobutyl and R 32 = methyl.

[0184] Typically, suitable formaldehyde sources are selected from dimethoxymethane; the lower hemiformals of formaldehyde and methanol, CH3-O-(CH2-O) i -H, wherein i=1-3; formalin; or a mixture comprising formaldehyde, methanol and methyl propionate.

[0185] Typically, the term formalin means a mixture of formaldehyde:methanol:water in a ratio of 25% to 65% by weight:0.01% to 25%:25% to 70% by weight. More typically, the term formalin means a mixture of formaldehyde:methanol:water in a ratio of 30% to 60% by weight:0.03% to 20%:35% to 60% by weight. Most typically, the term formalin means a mixture of formaldehyde:methanol:water in a ratio of 35% to 55% by weight:0.05% to 18%:42% to 53% by weight.

[0186] Typically, the mixture comprising formaldehyde, methanol and methyl propionate comprises less than 5% by weight of water. More suitably, the mixture comprising formaldehyde, methanol and methyl propionate comprises less than 1% by weight of water. Most suitably, the mixture comprising formaldehyde, methanol and methyl propionate comprises from 0.1% to 0.5% by weight of water.

[0187] According to a fourth aspect of the present invention, there is provided a process for preparing an ethylenically unsaturated acid or ester, the process comprising 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 The alkanoic acid or alkanoic acid ester is contacted with formaldehyde or a suitable formaldehyde source according to formula (I) as defined below:

[0188]

[0189] where R 5 is methyl and R 6 It is H;

[0190] X is O;

[0191] m is 1;

[0192] and n is any value between 1 and 20 or any mixture of these values;

[0193] where R 1 is hydrogen or a hydrocarbyl group having 1 to 12, more suitably 1 to 8, most suitably 1 to 4 carbon atoms, and R 3 It may also independently be hydrogen or a hydrocarbyl group having 1 to 12, more suitably 1 to 8, most suitably 1 to 4 carbon atoms.

[0194] Thus, the inventors have found that the catalyst according to the present invention is able to surprisingly improve the selectivity for the condensation of a methylene source such as formaldehyde with a carboxylic acid or a hydrocarbyl ester such as methyl propionate to form an olefinically unsaturated carboxylic acid. In addition, the production of heavies during the condensation reaction is significantly and surprisingly reduced.

[0195] Thus, one particular process in 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.

[0196] In the case of the production of MMA, the catalyst is typically contacted with a mixture comprising formaldehyde, methanol, and methyl propionate.

[0197] The process of the third or fourth aspect of the invention is particularly suitable for producing acrylic acid and hydrocarbyl acrylic acid and their hydrocarbyl esters, in particular hydrocarbyl acrylic acid and their hydrocarbyl esters, and also methylene-substituted lactones. Suitable methylene-substituted lactones include 2-methylene valerolactone and 2-methylene butyrolactone, which are derived from valerolactone and butyrolactone, respectively. Suitable (hydrocarbyl) acrylic acid and its esters are (C 0-8 Hydrocarbon) acrylic acid or (C 0-8alkyl) acrylate, which is typically derived from the reaction of the corresponding alkanoic acid or its ester with a methylene source such as formaldehyde in the presence of a catalyst, suitably from propionic acid or methyl propionate to produce methacrylic acid, acrylic acid, methyl methacrylate, ethyl acrylate or butyl acrylate, more suitably methacrylic acid or especially methyl methacrylate (MMA). Thus, in the production of methyl methacrylate or methacrylic acid, the formula R 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.

[0198] The reaction of the present invention may be a batch reaction or a continuous reaction.

[0199] In the process of the third aspect or the fourth aspect of the invention, typical conditions of temperature and gauge pressure are between 100° C. and 400° C., more preferably between 200° C. and 375° C., most preferably between 275° C. and 360° C.; and / or between 0.001 MPa and 1 MPa, more preferably between 0.03 MPa and 0.5 MPa, most preferably between 0.03 MPa and 0.3 MPa. Typical residence time of the reactants in the presence of the catalyst is between 0.1 seconds and 300 seconds, more preferably between 1 second and 100 seconds, most preferably between 2 seconds and 50 seconds, and especially between 3 seconds and 30 seconds.

[0200] The amount of the catalyst used in the process producing the product in the present invention is not necessarily critical, and will be determined by the practice of the process using it. However, usually the amount of the catalyst will be selected to achieve optimal selectivity and the yield of product and an acceptable operating temperature. However, the technician will understand that the minimum amount of catalyst should be enough to cause the effective catalyst surface contact of reactant. In addition, the technician will understand that, relative to reactant, there is actually no upper limit to the amount of the catalyst, but in practice, this can be determined again by required contact time and / or economic considerations.

[0201] In the process of the third or fourth aspect of the invention, the relative amounts of the reagents may vary within wide limits, but typically the molar ratio of formaldehyde or a suitable source thereof to the carboxylic acid or carboxylic acid ester is 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 formaldehydic species. Thus, in R 31 O-(CH2-O) i R 32 R in 31 and R 32In the case where one or both of the R is H, relatively low ratios are required for highly reactive formaldehyde species, typically in this case the molar ratio of formaldehyde or a suitable source thereof to the carboxylic acid or carboxylic acid ester is in the range of 1:1 to 1:9. 31 and R 32 Where neither is H, as for example in CH3O-CH2-OCH3, or in trioxane, higher ratios are most preferred, typically 6:1 to 1:3.

[0202] As mentioned above, water may also be present in the reaction mixture due to the formaldehyde source. Depending on the formaldehyde source, it may be necessary to remove some or all of the water from the reaction mixture prior to catalysis. Maintaining a lower level of water than that in the formaldehyde source can benefit catalytic efficiency and / or subsequent purification of the product. Less than 10 mol % water in the reactor is preferred, more preferably less than 5 mol %, and most preferably less than 2 mol %.

[0203] 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, most preferably 5:1 to 1:5, for example 1:1.5. However, the most preferred ratio will depend on the amount of water in the reactants fed to the catalyst plus the amount produced by the reaction, such that the preferred molar ratio of alcohol to total water in the reaction will be at least 1:1, and more preferably at least 2:1.

[0204] The reagents of the third aspect or the fourth aspect can be fed to the reactor independently or after premixing, and the process of the reaction can be continuous or batch. However, typically, a continuous process is used.

[0205] Typically, the process of the third or fourth aspect of the invention is carried out when the reactants are in the gas phase.

[0206] In a further aspect, the invention extends to a process for producing an ethylenically unsaturated carboxylic acid or carboxylic acid ester according to any relevant aspect herein, the process comprising the step of first producing a catalyst according to any relevant aspect herein.

[0207] definition

[0208] Unless otherwise indicated, the term "alkyl" when used herein means a C1 to C 12Hydrocarbyl, and includes methyl, ethyl, vinyl, propyl, propenyl, butyl, butenyl, pentyl, pentenyl, hexyl, hexenyl and heptyl groups, typically, the hydrocarbyl group is selected from methyl, ethyl, propyl, butyl, pentyl and hexyl, more typically methyl. Unless otherwise indicated, when there are a sufficient number of carbon atoms, the hydrocarbyl group may be straight or branched, cyclic, acyclic or partially cyclic / acyclic, unsubstituted, substituted or terminated with one or more substituents selected from halogen, 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 here and generally herein R 19 to R 30 Each independently represents hydrogen, halogen, unsubstituted or substituted aryl or unsubstituted or substituted hydrocarbon, or in R 21 In the case of halogen, nitro, cyano and amino groups and / or by one or more (typically less than 4) oxygen atoms, sulfur atoms, silicon atoms or by silanol groups or dihydrocarbyl silicon groups or mixtures thereof. Typically, the hydrocarbyl group is unsubstituted, typically linear, and typically saturated.

[0209] The term "alkenyl" is to be understood as "hydrocarbyl" above, except that at least one carbon-carbon bond is unsaturated, and thus the term relates to C2 to C 12 Alkenyl group.

[0210] In the absence of information to the contrary, the term "alk" or similar terms should be considered to conform to the above definition of "alkyl", except that "C0 alk" means unsubstituted by alkyl.

[0211] The term "aryl" as used herein includes five- to ten-membered, typically five- to eight-membered, carbocyclic aromatic or pseudo aromatic groups such as phenyl, cyclopentadienyl and indenyl anions and naphthyl, which groups may be unsubstituted or substituted with one or more substituents selected from unsubstituted or substituted aryl, hydrocarbyl (which group may itself be unsubstituted or substituted or terminated as defined herein), Het (which group may itself be unsubstituted or substituted or terminated as defined herein), halogen, 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 or C(S)NR 27 R 28 , where R 19 to R 30 Each independently represents hydrogen, unsubstituted or substituted aryl or hydrocarbyl (the hydrocarbyl group itself may be unsubstituted or substituted or terminated as defined herein), or, in R 21 In the case of halogen, nitro, cyano or amino.

[0212] The term "halogen" when used herein means a chloro, bromo, iodo or fluoro group, typically chloro or fluoro.

[0213] The term "Het" as used herein includes 4- to 12-membered, typically 4- to 10-membered ring systems containing one or more heteroatoms selected from nitrogen, oxygen, sulfur, and mixtures thereof, and which do not contain one or more double bonds, contain 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 may be unsubstituted or substituted with one or more substituents selected from halogen, cyano, nitro, oxo, hydrocarbyl (which hydrocarbyl group may itself be unsubstituted or substituted or end-capped as defined herein), -OR 19 、-OC(O)R 20 、-C(O)R 21 、-C(O)OR 22 、-N(R 23 )R 24 、-C(O)N(R 25 )R26 、-SR 29 、-C(O)SR 30 or -C(S)N(R 27 )R 28 , where R 19 to R 30 Each independently represents hydrogen, unsubstituted or substituted aryl or hydrocarbyl (the hydrocarbyl group itself may be unsubstituted or substituted or terminated as defined herein), or in R 21 In the case of halogen, nitro, amino or cyano. Thus, the term "Het" includes groups such as optionally substituted azetidinyl, pyrrolidinyl, imidazolyl, indolyl, furyl, oxazolyl, isoxazolyl, oxadiazolyl, thiazolyl, thiadiazolyl, triazolyl, oxatriazolyl, thiatriazolyl, pyridazinyl, morpholinyl, pyrimidinyl, pyrazinyl, quinolyl, isoquinolyl, piperidinyl, pyrazolyl and piperazinyl. Substitution on Het may be on a carbon atom of the Het ring or, where appropriate, on one or more heteroatoms.

[0214] A "Het" group may also be in the form of an N-oxide.

[0215] Suitable optional alcohols for the catalytic reactions of the third and fourth aspects of the present invention may be selected from: C1-C 30 Alkanols, including aryl alcohols, may be optionally substituted with one or more substituents selected from the group consisting of hydrocarbyl, aryl, Het, halogen, 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 、C(S)NR 27 R 28 SR 29 or C(O)SR 30, as defined herein. Highly preferred alkanols are C1-C8 alkanols, such as methanol, ethanol, propanol, isopropanol, isobutanol, tert-butanol, phenol, n-butanol and chlorooctanol, in particular, methanol. Although monoalkanols are most preferred, polyalkanols (poly-alkanols) can also be used, and the polyalkanols are typically selected from diols-octaols such as diols, triols, tetraols and sugars. Typically, such polyalkanols are selected from 1,2-ethylene glycol, 1,3-propylene glycol, glycerol, 1,2,4-butanetriol, 2-(hydroxymethyl)-1,3-propanediol, 1,2,6-trihydroxyhexane, pentaerythritol, 1,1,1-tris(hydroxymethyl)ethane, mannose, sorbose, 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, the amount used exceeds the amount of substrate to be esterified. Therefore, alcohol can also be used as the reaction solvent, although a separate solvent or additional solvent can also be used if desired.

[0216] 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, Polymerisation, Colloid and Surface Properties and Biochemistry of Silica: Ralph K Iler, 1979, John Wiley and Sons Inc., ISBN 0-471-02404-X, pages 358-364. If this stage is carried out, the hydrogel is washed again to remove any materials used in the aging process and to bring the solution to the correct pH for the addition of the catalytically active metal, which depends on the choice of the catalytically active metal salt.

[0217] As used herein, the term "impregnation" includes adding a catalytic alkali metal dissolved in a solvent to form a solution, adding the solution to the xerogel or aerogel so that the solution is absorbed into the voids within the xerogel or aerogel. The term also extends to replacing the hydrogel liquid with a suitable solvent and adding the catalytic alkali metal as a solution in the solvent to achieve mass transfer into the hydrogel by diffusion.

[0218] The silica support can be treated with a mononuclear modifier metal and / or a binuclear modifier metal by any of a variety of techniques known to those skilled in the art of support formation. The silica support can be contacted with a mononuclear modifier metal or a binuclear modifier metal in such a way that the modifier metal is dispersed throughout the silica support. Typically, the modifier metal can be evenly distributed on the surface of the entire silica support. Preferably, the modifier metal is dispersed in the silica support by adsorption.

[0219] As used herein, the term "adsorption" or similar terms in relation to a modifier metal or catalytic alkali metal refers to the incorporation of the metal onto the surface of the silica support by interaction of the metal cation source with the silica support, either by chemical adsorption or physical adsorption, typically by chemical adsorption. Typically, the addition of the modifier to the silica support comprises the steps of adsorbing the metal cation source onto the silica support to form an organometallic complex, and drying or calcining the complex to convert the organometallic complex into a metal oxide moiety. Thus, there is typically a random distribution of the modifier metal or catalytic alkali metal throughout the silica support.

[0220] The modifier metal portion and the modifier metal oxide portion in the modified silica support according to the present invention relate to the modifier metal and not to silicon or silica.Similarly, the modifier metal herein is not the same metal as the catalytic alkali metal.

[0221] Unless indicated to the contrary, the modifier or catalytic alkali metal or the amount of modifier or catalytic alkali metal in the catalyst refers to the modifier or catalytic alkali metal ion and not to the surrounding atoms.

[0222] The term "gel," as used herein, is also known to those skilled in the art, but in case of doubt, it can be considered a solid network with a fluid dispersed therein. Typically, a gel is a polymer network with a fluid dispersed therein. Cogel is a term used to indicate that more than one of the original compounds / moieties, typically silica and a metal oxide or salt, such as zirconium oxide, is incorporated into the polymer network. Therefore, cogelation herein refers to the formation of a cogel.

[0223] Thus, a gel is a sol that has solidified. Thus, a hydrogel is 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 undergo the same shrinkage as a xerogel.

[0224] The term onset in this context means the start of the formation of the modified silica.

[0225] As used herein, the term "part" in relation to a metal is used to refer to the form of the modifier metal on the modified support. While the modifier metal typically forms part of a network, the modifier metal will be in the form of discrete residues on the silica substrate. The term mononuclear means having a single metal center, and in the case of a part on silica, means having the form of a mononuclear residue, and dinuclear should be interpreted accordingly.

[0226] It will be understood that in the silica network, the modifier metal moiety is associated with the silica network, and therefore the term mononuclear moiety or dinuclear moiety refers to the modifier metal and its immediately surrounding atoms, and not to the silicon atoms of the network or other modifier metal atoms that are associated with the network but still form part of a separate, substantially unassociated moiety.

[0227] The % of modifier metal is unitless herein as it refers to the number of metal atoms per the total number of such atoms. It will be understood that moieties may take the form of non-mononuclear or dinuclear clusters, but these clusters are still composed of modifier metal atoms.

[0228] Unless otherwise indicated, the term "surface" as used herein in relation to a silica support includes the surface of the silica within the pores of the silica, more particularly within the macropores and mesopores of the silica.

[0229] Embodiments of the invention will now be defined by reference to the accompanying examples and figures, in which:

[0230] FIG1 shows the results of mercury porosimetry for selected examples;

[0231] FIG2 shows the results of N2 adsorption for selected examples;

[0232] FIG3 shows the results of mercury porosimetry for selected examples; and

[0233] FIG4 shows the results of N2 adsorption for selected examples.

[0234] experiment

[0235] N2 adsorption

[0236] The mesopore size distribution of the catalysts from Examples 1 to 4 in the mesopore range of 5 nm to 50 nm was measured by N2 adsorption on a MICROMERITICS INSTRUMENT CORPORATION TriStar II 3020. 0.1 g to 0.2 g of sample was loaded into a dedicated sample cell. The cell was heated to 380°C under air flow and the preconditioning was continued for at least two hours. After preconditioning, the sample was weighed and the equipment was set up for surface area determination. N2 adsorption of the sample was performed at -196°C to obtain adsorption-desorption isotherms. The BET surface area and BJH mesopore size distribution were calculated from their isotherms.

[0237] Mercury porosimetry

[0238] The catalysts from Examples 1 to 4 were measured for their macropore size distribution in the macropore range exceeding 50 nm by mercury porosimetry using a MICROMERITICS INSTRUMENT CORPORATION Autopore IV 9500 instrument. 0.3-1 g of dried sample was loaded into a dedicated sample cell. The cell was loaded into the instrument. Mercury (Hg) was inserted into the catalyst pores in the sample by varying the pressure to obtain the macropore size distribution.

[0239] Silica Support Description

[0240] Example 1 (Preparation) (Silica without macropores)

[0241] Silica gel samples were prepared using commercially available water glass, sodium silicate solution EMD Millipore Corporation, containing 25.5 wt% to 28.5 wt% SiO2 and 7.5 wt% to 8.5 wt% Na2O as the silica source.

[0242] 69g of distilled water and 53g of nitric acid (65% HNO3, Sigma Aldrich) were placed in a plastic flask to form solution 1. 80g of water glass and 73g of distilled water were placed in a separate flask to form solution 2. The two solutions were then mixed under stirring. The mixed solution was kept at room temperature for 10 to 60 minutes. The solution was gelled and turned into a silica hydrogel. The silica hydrogel was washed several times with distilled water. The silica hydrogel was then aged by contacting it with an alkaline solution (0.1M 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 an air flow (1l / min) for 3 hours. After the calcination process, the silica support was sieved to a fraction of 1mm to 4mm. After sieving, a silica support without macropores was obtained.

[0243] Example 2 (Preparation) (Silica with a macropore diameter of 0.13 μm)

[0244] Silica was prepared as described in Example 1 except that 10 g of polyacrylic acid (Mw=25000 from Wako Pure Chemicals Corporation) was added to Solution 1 and 66 g of 65% nitric acid was used. The macropore diameter in the resulting processed silica was obtained by Hg porosimetry.

[0245] Example 3 (Preparation) (Silica with a macropore diameter of 0.20 μm)

[0246] 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 diameters in the resulting processed silica were obtained by Hg porosimetry.

[0247] Example 4 (Preparation) (Silica with a macropore diameter of 0.88 μm)

[0248] 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 diameters in the resulting processed silica were obtained by Hg porosimetry.

[0249] Zr modification of silica supports

[0250] Example 5 (Preparation) (2.2 wt% Zr, no macropores)

[0251] 1.57g of Zr(acac)4 (97% zirconium acetylacetonate, Sigma Aldrich) was dissolved in 25ml of methanol (99.9% anhydrous, Sigma Aldrich). In a separate flask, 11.3g of silica from Example 1 was weighed. The weighed silica was then added to the Zr-complex solution. The Zr-modified silica was left in a sealed flask for 24 hours. This was followed by a drying step at room temperature. Once all solvent had been removed, the Zr-modified silica support was calcined in a tube furnace at 500°C under an air flow (1 l / min) with a heating ramp rate of 5°C / min and a final hold 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).

[0252] Example 6 (Preparation) (2.2 wt% Zr, with 0.13 μm macropore diameter)

[0253] The support modification was carried out as described in Example 5, except that the silica from Example 2 was used. In addition, 50 ml of methanol were used instead of 25 ml.

[0254] Example 7 (Preparation) (2.2 wt% Zr, with 0.20 μm macropore diameter)

[0255] The support modification was carried out as described in Example 5, except that the silica from Example 3 was used. In addition, 50 ml of methanol were used instead of 25 ml.

[0256] Example 8 (Preparation) (2.2 wt% Zr, with 0.88 μm macropore diameter)

[0257] The 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 were used instead of 25 ml.

[0258] Cs modification of modified supports

[0259] Example 9 (Comparative) (7.7 wt% Cs, 2.2 wt% Zr, no macropores)

[0260] 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). 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. After this step, the catalyst particles were placed in a drying oven at 110-120°C and left to dry for 16 hours.

[0261] Example 10 (Comparative) (9.6 wt% Cs, 2.2 wt% Zr, no macropores)

[0262] The catalyst was prepared as described in Example 9, except that 0.419 g of CsOH.H2O was used.

[0263] Example 11 (Comparative) (11.4 wt% Cs, 2.2 wt% Zr, no macropores)

[0264] The catalyst was prepared as described in Example 9, except that 0.509 g of CsOH.H2O was used.

[0265] Example 12 (7.7 wt% Cs, 2.2 wt% Zr, with 0.13 μm macropore diameter)

[0266] The catalyst was prepared as described in Example 9, except that the modified silica from Example 6 was used.

[0267] Example 13 (9.6 wt% Cs, 2.2 wt% Zr, with 0.13 μm macropore diameter)

[0268] The catalyst was prepared as described in Example 9, except that 0.419 g of CsOH.H2O was used and the modified silica from Example 6 was used.

[0269] Example 14 (11.4 wt% Cs, 2.2 wt% Zr, with 0.13 μm macropore diameter)

[0270] The catalyst was prepared as described in Example 9, except that 0.509 g of CsOH.H2O was used and the modified silica from Example 6 was used.

[0271] Example 15 (7.7 wt% Cs, 2.2 wt% Zr, with 0.20 μm macropore diameter)

[0272] The catalyst was prepared as described in Example 9, except that the modified silica from Example 7 was used.

[0273] Example 16 (9.6 wt% Cs, 2.2 wt% Zr, with 0.20 μm macropore diameter)

[0274] The catalyst was prepared as described in Example 9, except that 0.419 g of CsOH.H2O was used and the modified silica from Example 7 was used.

[0275] Example 17 (11.4 wt% Cs, 2.2 wt% Zr, with 0.20 μm macropore diameter)

[0276] The catalyst was prepared as described in Example 9, except that 0.509 g of CsOH.H2O was used and the modified silica from Example 7 was used.

[0277] Example 18 (7.7 wt% Cs, 2.2 wt% Zr, with a macropore diameter of 0.88 μm)

[0278] The catalyst was prepared as described in Example 9, except that the modified silica from Example 8 was used.

[0279] Example 19 (9.6 wt% Cs, 2.2 wt% Zr, with a macropore diameter of 0.88 μm)

[0280] The catalyst was prepared as described in Example 9, except that 0.419 g of CsOH.H2O was used and the modified silica from Example 8 was used.

[0281] Example 20 (11.4 wt% Cs, 2.2 wt% Zr, with a macropore diameter of 0.88 μm)

[0282] The catalyst was prepared as described in Example 9, except that 0.509 g of CsOH.H2O was used and the modified silica from Example 8 was used.

[0283] Silica-Zirconia Support Description (Cogel)

[0284] Example 21 (Preparation) (Silica-zirconia without macropores)

[0285] 2.16g of zirconium oxynitrate hydrate (Sigma Aldrich) was dissolved in 69g of distilled water and 59g of nitric acid (65% HNO3 Sigma Aldrich) in a plastic flask to form solution 1. 80g of water glass and 73g of distilled water were mixed in a separate flask to form solution 2. The two solutions were then mixed under stirring. The mixed solution was kept at room temperature for 10 to 60 minutes. The solution undergoes gelation and becomes 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 an alkaline solution (1M NH3 solution) in a temperature-controlled oil bath at 70°C. After the aging process, the silica-zirconia hydrogel was dried at 50°C and calcined in a tube furnace at 600°C under an air flow (1l / min) for 3 hours. After the calcination process, the silica-zirconia support was sieved to 1mm to 4mm. After sieving, a silica-zirconia support free of macropores was obtained.

[0286] Example 22 (Preparation) (Silica-Zirconia with a Macropore Diameter of 0.42 μm)

[0287] Silica-zirconia was prepared as described in Example 21, except that 10 g of polyacrylic acid (polyacrylic acid Mw = 25000, Wako Pure Chemicals Corporation) was added to Solution 1 and 64 g of 65% nitric acid was used. Macropore diameters were obtained by Hg porosimetry.

[0288] Example 23 (Preparation) (Silica-Zirconia with a Macropore Diameter of 0.61 μm)

[0289] Silica-zirconia was prepared as described in Example 21, except that 9.5 g of polyacrylic acid (polyacrylic acid Mw = 25000, Wako Pure Chemicals Corporation) was added to Solution 1 and 53 g of 65% nitric acid was used. Macropore diameters were obtained by Hg porosimetry.

[0290] Cs modification of silica-zirconia supports

[0291] Example 24 (Comparative) (8.0 wt% Cs, 2.4 wt% Zr, no macropores)

[0292] 0.341 g of CsOH.H2O (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). 3.1 g of the silica-zirconia support from Example 21 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. After this step, the catalyst particles were placed in a drying oven at 110-120°C and left to dry for 16 hours.

[0293] Example 25 (Comparative) (9.5 wt% Cs, 2.4 wt% Zr, no macropores)

[0294] The catalyst was prepared as described in Example 24, except that 0.411 g of CsOH.H2O was used.

[0295] Example 26 (Comparative) (11 wt% Cs, 2.4 wt% Zr, no macropores)

[0296] The catalyst was prepared as described in Example 24, except that 0.484 g of CsOH.H2O was used.

[0297] Example 27 (8.0 wt% Cs, 2.4 wt% Zr, with a macropore diameter of 0.42 μm)

[0298] The catalyst was prepared as described in Example 24, except that the silica-zirconia from Example 22 was used.

[0299] Example 28 (9.5 wt% Cs, 2.4 wt% Zr, with 0.42 μm macropore diameter)

[0300] The catalyst was prepared as described in Example 24, except that 0.411 g of CsOH.H2O was used and the silica-zirconia from Example 22 was used.

[0301] Example 29 (11 wt% Cs, 2.4 wt% Zr, with a macropore diameter of 0.42 μm)

[0302] The catalyst was prepared as described in Example 24, except that 0.484 g of CsOH.H2O was used and the silica-zirconia from Example 22 was used.

[0303] Example 30 (8.0 wt% Cs, 2.4 wt% Zr, with a macropore diameter of 0.61 μm)

[0304] The catalyst was prepared as described in Example 24, except that the silica-zirconia from Example 23 was used.

[0305] Example 31 (9.5 wt% Cs, 2.4 wt% Zr, with a macropore diameter of 0.61 μm)

[0306] The catalyst was prepared as described in Example 24, except that 0.411 g of CsOH.H2O was used and the silica-zirconia from Example 23 was used.

[0307] Example 32 (11 wt% Cs, 2.4 wt% Zr, with 0.61 μm macropore diameter)

[0308] The catalyst was prepared as described in Example 24, except that 0.484 g of CsOH.H2O was used and the silica-zirconia from Example 23 was used.

[0309] Example 33 (Catalytic Performance Test)

[0310] The catalysts from Examples 9 to 20 and 24 to 32 were tested in a laboratory-scale microreactor for the reaction of methyl propionate and formaldehyde. To this end, 3 g of catalyst were loaded into a fixed-bed reactor with an inner tube diameter of 18 mm. The reactor was heated to 350° C. and pretreated by feeding an evaporated stream containing 70 wt % methyl propionate, 20 wt % methanol, 6 wt % water, and 4 wt % formaldehyde from an evaporator fed at 0.032 ml / min by a Gilson pump. This pretreatment lasted overnight. After the pretreatment, a feed stream containing 75.6 wt % methyl propionate, 18.1 wt % methanol, 5.7 wt % formaldehyde, and 0.6 wt % water was pumped to the evaporator set at 350° C. by a Gilson pump and then fed to the heated reactor set at 350° C. containing the catalyst. The reactor outlet vapor was cooled and condensed, and samples were collected at five different liquid feed rates (between 0.64 ml / min and 0.032 ml / min) to obtain conversion at different vapor / catalyst contact times. The liquid feed and the condensed liquid product outside the reactor were analyzed by a Shimadzu 2010 gas chromatograph with a DB1701 column. The composition of the samples was determined from the corresponding chromatograms, and the yield and selectivity at different 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 on a contact time versus MMA+MAA yield graph. This interpolated contact time was then used to obtain the MMA+MAA selectivity at a 10% MMA+MAA yield.

[0311] The catalytic performance data for the above examples are summarized in Tables 1 and 2 below, along with composition and porosity data.

[0312] The pore size distribution data for the macroporous silica (Examples 1 to 4) and the macroporous silica-zirconia supports (Examples 21 to 23) are shown in Figures 1 to 4. Figures 1 and 3 are macropore size distributions obtained by mercury porosimetry, and Figures 2 and 4 are mesopore size distributions obtained by N adsorption BJH analysis.

[0313] Table 1: Composition, porosity, MMA+MAA and heavies selectivity data for catalysts derived from mesoporous silica supports and meso-macroporous silica supports.

[0314]

[0315]

[0316] Table 2: Composition, porosity, MMA+MAA and heavies selectivity data for catalysts derived from mesoporous silica-zirconia supports (cogels) and meso-macroporous silica-zirconia supports (cogels).

[0317]

[0318]

[0319] Attention is directed to all papers and documents which are filed concurrently with or before this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0320] All features disclosed in this specification (including any accompanying claims, abstract and drawings) and / or all steps of any method or process so disclosed may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive.

[0321] Unless expressly stated otherwise, each feature disclosed in this specification (including any accompanying claims, abstracts and drawings) may be used as an alternative feature serving the same, equivalent or similar purpose. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0322] The invention is not limited to the details of the foregoing embodiments. The invention extends to any novel inventive feature or any novel combination of inventive features disclosed in this specification (including any accompanying claims, abstract or drawings), or to any novel inventive step or any novel combination of inventive steps of any method or process disclosed as such.

Claims

1. A catalyst comprising: silica support, modifier metal and catalytic alkali metal, The silica support has a multimodal pore size distribution, and the multimodal pore size distribution comprises: a) having an average pore size in the range of 2 nm to 50 nm and a pore size of at least 0.1 cm 3 Mesopore size distribution of the pore volume of mesopores in g / g; and b) have an average pore size greater than 50 nm and at least 0.1 cm 3 The macropore size distribution of the macropore volume / g, wherein the level of catalytic alkali metal on the silica support is at least 2 mol % And wherein the modifier metal is selected from Mg, B, Al, Ti, Zr and Hf.

2. The catalyst of claim 1, wherein the modifier metal is selected from the group consisting of Ti, Zr and Hf.

3. A catalyst according to claim 1 or 2, wherein the level of catalytic alkali metal on the silica support is at least 3 mol%.

4. The catalyst of claim 1 or 2, wherein the level of catalytic alkali metal on the silica support is less than or equal to 10 mol%.

5. The catalyst according to claim 1 or 2, wherein the amount of silica in the support is at least 50 wt%.

6. The catalyst according to claim 1 or 2, wherein the average mesopore volume of the catalyst particles as measured by nitrogen absorption is less than 1 cm 3 / g.

7. The catalyst according to claim 1 or 2, wherein the average mesopore volume of the catalyst particles is measured by nitrogen absorption at 0.3 cm 3 / g-2.5 cm 3 / g range.

8. The catalyst according to claim 1 or 2, wherein the average macropore volume of the catalyst particles, measured as mercury absorption, is less than 1 cm 3 / g.

9. The catalyst according to claim 1 or 2, wherein the average macropore volume of the catalyst particles is measured as mercury absorption 0.1 cm 3 / g-3 cm 3 / g range.

10. The catalyst according to claim 1 or 2, wherein the catalyst particles have a macropore:mesopore volume ratio in the range of 0.03-15.

11. The catalyst of claim 1 or 2, wherein the catalyst comprises less than 1000 parts per million of tungsten and / or antimony and / or vanadium and / or bismuth and / or a metal of Group 3 and / or a metal of Group 10 and / or a metal of Group 13 and / or a metal of Group 14.

12. The catalyst of claim 1 or 2, wherein the catalyst comprises less than 1000 parts per million of tungsten and / or antimony and / or vanadium and / or bismuth and / or lanthanum and / or cerium and / or platinum and / or tin.

13. The catalyst of claim 1 or 2, wherein the modifier metal is an adsorbate adsorbed on the surface of the silica support.

14. The catalyst of claim 1 or 2, wherein the modifier metal is an adsorbate chemisorbed on the surface of the silica support.

15. The catalyst of claim 1 or 2, wherein the modifier metal is present as a modifier metal oxide portion.

16. The catalyst of claim 1 or 2, wherein the silica support is in the form of silica gel.

17. The catalyst according to claim 1 or 2, wherein the silica support is in the form of a xerogel, an aerosol or a hydrogel.

18. The catalyst of claim 1 or 2, wherein the modifier metal is present in the support in the form of a co-gel.

19. The catalyst of claim 1 or 2, wherein the modifier metal is present at a level of less than or equal to 7.6 x 10 -2 mol / mol silica.

20. The catalyst of claim 1 or 2, wherein the level of modifier metal is between 0.067×10 -2 mol / mol silica and 7.3×10 -2 mol / mol silica.

21. The catalyst of claim 1 or 2, wherein the modifier metal is present at a level of at least 0.1 x 10 -2 mol / mol silica.

22. The catalyst of claim 1 or 2, wherein the silica support is a calcined silica support.

23. The catalyst of claim 1 or 2, wherein the catalytic alkali metal is one or more alkali metals selected from potassium, rubidium, and cesium.

24. The catalyst of claim 1 or 2, wherein the catalytic alkali metal is one or more alkali metals selected from rubidium and cesium.

25. The catalyst of claim 1 or 2, wherein the catalytic alkali metal is cesium.

26. The catalyst of claim 1 or 2, wherein the catalytic alkali metal is present in the range of 0.5 mol / mol modifier metal to 7.0 mol / mol modifier metal.

27. The catalyst of claim 1 or 2, wherein the molar ratio of catalytic base metal:modifier metal is at least 1.4:

1.

28. The catalyst of claim 1 or 2, wherein the molar ratio of catalytic base metal:modifier metal is at least 1.5:

1.

29. The catalyst of claim 1 or 2, wherein the molar ratio of catalytic alkali metal:modifier metal is in the range of 1.4 to 5:

1.

30. The catalyst according to claim 1 or 2, wherein the average surface area is 20 m 2 / g-1000 m 2 / g range.

31. The catalyst of claim 1 or 2, wherein the total metal content of the catalyst is at least 80 wt% of the catalytic base metal and the modifier metal.

32. A method of producing a catalyst according to any one of claims 1 to 31, comprising: (a) preparing modified silica for a silica support with a modifier metal selected from the group consisting of Mg, B, Al, Ti, Zr and Hf, (b) treating the modified silica support with a catalytic alkali metal to provide a catalyst, (c) introducing macropores into the silica support before step (a), before step (b), or after step (b).

33. The method for producing a catalyst according to claim 32, wherein the modified silica is silica gel or fumed silica containing mesopores.

34. A method of producing a catalyst according to claim 32 or 33, wherein the macropores are introduced by hard templates, soft templates, binder technology or other techniques.

35. A process for producing an ethylenically unsaturated carboxylic acid or carboxylic ester, the process comprising the step of contacting formaldehyde or a suitable source thereof with a carboxylic acid or carboxylic ester in the presence of a catalyst and optionally in the presence of an alcohol, wherein the catalyst is according to any one of claims 1 to 31.

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

37. A process for preparing an ethylenically unsaturated acid or ester, said process comprising reacting a compound of formula R in the presence of a catalyst according to any one of claims 1 to 31 and optionally in the presence of an alkanol. 1 -CH2-COOR 3 The alkanoic acid or alkanoic acid ester is contacted with formaldehyde or a suitable formaldehyde source according to formula (I) as defined below: (I) where R 5 is methyl and R 6 It is H; X is O; m is 1; and n is any value between 1 and 20 or any mixture of these values; where R 1 is hydrogen or a hydrocarbon group having 1 to 12 carbon atoms, and R 3 is independently hydrogen or a hydrocarbyl group having 1 to 12 carbon atoms.

38. The process of claim 37, wherein the ethylenically unsaturated acid or ester is an alpha, beta ethylenically unsaturated carboxylic acid or carboxylic acid ester.

39. The method of claim 36 or the process of claim 38 wherein the α,β ethylenically unsaturated carboxylic acid or carboxylic acid ester is acrylic acid or an acrylic acid ester.

40. The process of claim 39, wherein the ethylenically unsaturated acid or ester is a (hydrocarbyl) acrylic acid or a hydrocarbyl (hydrocarbyl) acrylate.

41. The process of claim 39, wherein the ethylenically unsaturated acid or ester is (meth)acrylic acid or a hydrocarbyl (meth)acrylate.

42. The process of claim 39, wherein the ethylenically unsaturated acids or esters are methacrylic acid and methyl methacrylate.

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