Catalysts and processes for producing ethylenically unsaturated carboxylic acids or esters

Abstract

To provide a modified silica support used as a catalyst for producing ethylenically unsaturated carboxylic acids or esters, and to provide a method for producing the same.SOLUTION: In a modified silica support for a catalyst comprising a silica support and a modifier metal wherein the modifier metal is selected from at least one of zirconium and hafnium, at least a proportion of the modifier metal is present as monomeric and / or dimeric metal oxide residues or is derived from a monomeric and / or dimeric modifier metal cation source at the commencement of the modification. At least 25% of the modifier metal is present as monomeric and / or dimeric metal oxide residues or is derived from a monomeric and / or dimeric modifier metal cation source at the commencement of the modification.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a modified silica catalyst support, a catalyst incorporating the modified silica support, and a process for producing ethylenically unsaturated carboxylic acids or esters, specifically α,β-unsaturated carboxylic acids or esters, more specifically acrylic acids or esters, such as (alk)acrylic acid or (alk)alkyl acrylate, particularly (meth)acrylic acid or (meth)alkyl acrylate, such as methacrylic acid (MA) and methyl methacrylate (MMA), by condensing a carboxylic acid or ester with formaldehyde or a source thereof, such as dimethoxymethane, in the presence of such a catalyst, and especially by condensing propionic acid or its alkyl ester, such as methyl propionate, with formaldehyde or a source thereof, in the presence of such a modified silica-supported catalyst metal catalyst. Accordingly, the present invention relates particularly to the production of methacrylic acid (MAA) and methyl methacrylate (MMA). [Background technology]

[0002] As mentioned above, such unsaturated acids or esters can be produced by the reaction of carboxylic acids or esters, and suitable carboxylic acids or esters are given by formula R 3 -CH2-COOR 4 It is an alkanoic acid (or ester) of which, where R 3 and R 4 Each of these is independently a suitable substituent known in the art of acrylic compounds, such as hydrogen or an alkyl group, particularly a lower alkyl group containing, for example, 1 to 4 carbon atoms. Therefore, for example, methacrylic acid or its alkyl ester, particularly methyl methacrylate, can be produced by catalytically reacting propionic acid or its corresponding alkyl ester, such as methyl propionate, with formaldehyde as a methylene-derived substance according to reaction sequence 1. R 3 -CH2-COOR 4 +HCHO→R 3 -CH(CH2OH)-COOR4 and R 3 -CH(CH2OH)-COOR 4 →R 3 -C(:CH2)-COOR 4 +H2O (Sequence 1) An example of Reaction Sequence 1 is Reaction Sequence 2. CH3-CH2-COOR 4 +HCHO → CH3-CH(CH2OH)-COOR 4 CH3-CH(CH2OH)-COOR 4 → CH3-C(:CH2)-COOR 4 +H2O (Sequence 2) The above reaction sequences are typically carried out using an acid / base catalyst at high temperature, usually in the range of 250 - 400 °C. When the desired reaction product is an ester, the reaction is typically carried out in the presence of the corresponding alcohol to minimize the formation of the corresponding acid by hydrolysis of the ester. Further, for convenience, it is often desirable to introduce formaldehyde in the form of a complex of formaldehyde and methanol. Thus, for the production of methyl methacrylate, the reaction mixture fed to the catalyst generally consists of methyl propionate, methanol, formaldehyde and water.

[0003] A known production method for MMA is the catalytic conversion reaction of methyl propionate (MEP) to MMA using formaldehyde. Known catalysts for this are cesium catalysts incorporating a support, such as silica.

[0004] Patent Document 1 discloses a catalyst for use in the production of α,β-unsaturated carboxylic acids or esters by condensing propionic acid or a corresponding alkyl ester, wherein the catalyst comprises silica impregnated with at least one modifying element doped with an alkali metal, where the modifying 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.

[0005] Patent Document 2 discloses a catalyst for use in aldol condensation, polymerization, dehydration, hydroxylation, and isomerization of olefins, including the production of α,β-unsaturated carboxylic acids by condensation of propionic acid or propionic acid esters, wherein the catalyst comprises a silica-metal hydrogel impregnated with a catalyst metal, the metal of the hydrogel being selected from the group consisting of zirconium, titanium, aluminum, and iron, preferably zirconium, and the catalyst metal being selected from the group consisting of alkali metals and alkaline earth metals, preferably cesium. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 1999 / 52628 Pamphlet [Patent Document 2] International Publication No. 2003 / 026795 Pamphlet [Overview of the project] [Means for solving the problem]

[0007] The inventors hereby discovered that a catalyst comprising a silica support modified with a certain metal, and comprising a catalytic metal, provides a high level of selectivity in the condensation of a methylene source, such as formaldehyde, with a carboxylic acid or alkyl ester, such as methyl propionate, when at least a portion of the modifying metal is incorporated into or present in the support in the form of a metal species having a total of up to two zirconium atoms and / or hafnium atoms.

[0008] From Yung-Jin Hu et al., J.Am.Chem.Soc., Volume 135, 2013, p.14240, it is known that zirconium can form large clusters in solution. Zr-18 clusters are typical examples.

[0009] However, surprisingly, the inventors have found that when a modified silica support contains monomeric and / or dimeric modified metal cation sources, such as zirconium oxide and / or hafnium oxide residues derived from their compounds, rather than large clusters, at the start of modification, the binding of the catalytic metal to the modified support is improved, resulting in higher selectivity in the production of unsaturated carboxylic acids or esters by condensation of the corresponding acid or ester with a methylene source, such as formaldehyde. Furthermore, the inventors have found that the modified silica support that yields these high selectivity contains monomeric or dimeric modified metal atoms after precipitation / adsorption onto the silica surface.

[0010] The inventors have further discovered that using such a modified silica support suppresses the sintering rate of the catalyst surface, thereby reducing the loss of surface area on which the catalytic reaction occurs during the condensation reaction.

[0011] Therefore, catalysts containing such modified silica supports and catalytic metals are remarkably high-performance catalysts for producing α,β-ethylenically unsaturated carboxylic acids or esters by condensation of the corresponding acid or ester with a methylene source, such as formaldehyde, offering several advantages, such as high selectivity and / or suppression of catalyst surface sintering.

[0012] Therefore, in the first aspect of the present invention, Modified silica support, Modified silica support containing a modified metal, and The catalyst metal on the modified silica support A catalyst is provided, comprising a catalyst in which the modifying metal is selected from one or more of zirconium and / or hafnium, characterized in that at least a portion, typically at least 25%, of the modifying metal exists in the form of modified metal residues having a total of up to two modified metal atoms.

[0013] In a further aspect of the present invention, Modified silica support, Modified silica support containing a modified metal, and The catalyst metal on the modified silica support A catalyst is provided, comprising a modified metal selected from one or more of zirconium and / or hafnium, wherein at least a portion, typically at least 25%, of the modified metal exists in the form of modified metal residues derived from monomeric and / or dimeric modified metal cation sources.

[0014] At least one of the monomers and dimers of the modified metal comes into contact with a silica support as a cation source for at least one zirconium or hafnium-modified metal monomer or dimer in solution, for example, as a compound thereof, to adsorb the modified metal onto the support and thereby form a modified metal residue. A suitable source may be a complex of the modified metal in solution, more typically a ligand complex.

[0015] In a second aspect of the present invention, Silica NT, and modified metal A modified silica support for a catalyst containing a modified metal is provided, wherein the modifying metal is selected from one or more of zirconium and / or hafnium, and the modified silica support is characterized in that at least a portion, typically at least 25%, of the modifying metal is present in the form of modified metal residues having a total of up to two modified metal atoms.

[0016] In a third aspect of the present invention, Silica NT, and modified metal A modified silica support for a catalyst containing a modified metal is provided, wherein the modifying metal is selected from one or more of zirconium and / or hafnium, characterized in that at least a portion, typically at least 25%, of the modifying metal is present at the start of modification in the form of modified metal residues derived from monomeric and / or dimeric modified metal cation sources.

[0017] In this specification, a modified silica support is modified with a modified metal. Typically, the modified metal is an adsorbate adsorbed on the surface of the silica support. The adsorbate may be chemisorbed or physicoadsorbed on the surface of the silica support, and is typically chemisorbed thereon. The modified metal residue is generally a residue of a modified metal oxide.

[0018] Silica carriers are generally in the form of silica gel, more typically xerogel or hydrogel. Typically, the modified metal is adsorbed onto the surface of the silica gel carrier. Therefore, typically, the modified metal exists on the surface of the modified silica gel carrier in the form of metal oxide residues.

[0019] Alternatively, the modified metal may exist on the support in the form of a co-gel. In such cases, the modified silica support is a silica-metal oxide gel, typically containing zirconium oxide and / or hafnium oxide residues.

[0020] Typically, the modified metal is present in the modified silica support in an amount effective in reducing sintering and improving catalyst selectivity. Typically, at least 30%, e.g., at least 35%, more preferably at least 40%, e.g., at least 45%, most preferably at least 50%, e.g., at least 55%, e.g., at least 60% or 65%, and most preferably at least 70%, e.g., at least 75% or 80%, more typically at least 85%, most typically at least 90%, particularly at least 95%, of the modified metal in the modified silica support is present in residues having a total of one and / or two metal atoms, particularly in residues having a total of one metal atom, or is derived from monomeric and / or dimeric metal compounds at such levels at the initiation of the formation of the modified silica.

[0021] To avoid any ambiguity, modified metal residues having a total of one metal atom are called monomers, and those having a total of two metal atoms are called dimers. In particularly preferred embodiments, for example, at least 35%, more preferably at least 40%, for example at least 45%, most preferably at least 50%, for example at least 55%, for example at least 60% or 65%, and most preferably at least 70%, for example at least 75% or 80%, more typically at least 85%, most typically at least 90%, and especially at least 95% of the modified metal is present in the monomeric metal residues, or in any case, typically derived from zirconium and / or hafnium compounds having such levels of modified metal as monomeric compounds at the initiation of modification. Generally, modified metal residues on silica are residues of modified metal oxides.

[0022] Clusters of three or more zirconium and / or hafnium metal atoms dispersed throughout a support, such as a hydrogel support, have surprisingly been found to reduce the reaction selectivity for producing α,β-ethylenically unsaturated carboxylic acids or esters by condensing the corresponding acid or ester with a methylene source, such as formaldehyde. Such large clusters have also surprisingly been found to increase the sinterability of modified silica particles compared to clusters of modified metals with two or one metal atom, thereby reducing the surface area, which in turn reduces strength and decreases the catalyst lifetime before activity becomes unacceptably low. Furthermore, in many cases, the selectivity also decreases depending on the properties of the modified metal clusters.

[0023] Typically, the modified metal is dispersed in a practically homogeneous manner throughout the carrier. Typically, the modified silica support is a xerogel. This gel may be a hydrogel or an aerogel.

[0024] The gel may be a silica-zirconia and / or silica-hafnia cogel. These silica gels can be prepared by various gel-making methods known to those skilled in the art, such as those described herein. Typically, modified silica gels are prepared by appropriate adsorption reactions. One suitable technique is to adsorb relevant metal compounds, such as zirconium and / or hafnium compounds, onto silica gel, such as silica xerogel, to form modified silica gel containing relevant modified metal residues.

[0025] Methods for preparing silica gel are known in the art, and some of such methods are described in the following publication: *The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface Properties and Biochemistry of Silica*, by Ralph K Iler, 1979, John Wiley and Sons Inc. (ISBN 0-471-02404-X) and the references therein.

[0026] Methods for preparing silica-zirconia cogels are also known in the art, and some of such methods are described in the following publications: U.S. Patent No. 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.

[0027] In preferred embodiments, the modified silica support is not formed by a co-gelation method, i.e., silica-zirconia, silica-hafnia, or silica-zirconia / hafnia is not formed by a co-gelation method involving mixing a sodium silicate solution with a modified metal complex in a sulfuric acid solution. In such embodiments, zirconium and / or hafnium are typically incorporated as adsorbates on the surface of the silica support.

[0028] Preferably, modified silica-supported catalysts and modified silica supports according to any aspect of the present invention may be substantially, essentially, or completely fluoride-free. Trace amounts of fluoride may be present due to unavoidable contamination from the environment. The phrase "substantially free" means catalysts and supports containing less than 1,000 parts per million (ppm) of fluoride. The phrase "essentially free" means catalysts and supports containing less than approximately 100 ppm of fluoride, and the phrase "completely free" means catalysts containing less than 200 parts per billion (ppb) of fluoride.

[0029] It is advantageous that at least a portion of the modified metals incorporated into the modified silica in the above-described aspects of the present invention are derived from monomeric and / or dimeric modified metal cation sources at the initiation of the formation of the modified silica, and that these improve the reaction selectivity and / or reduce the sintering rate of the catalyst surface during the production of α,β-ethylenically unsaturated carboxylic acids or esters.

[0030] The metal and metal oxide residues in the modified silica support in this invention relate to zirconium and / or hafnium and zirconia and / or hafnia, and not to silica.

[0031] The level of the modified metal present in the modified silica or catalyst is preferably 7.6 × 10⁻⁶ of the silica. -2 Up to mol / mol, more preferably 5.9 × 10⁻⁶ silica -2 Up to mol / mol, most preferably 3.5 × 10⁻⁶ silica -2 It is up to mol / mol. The level of such metals is typically 0.067 × 10⁻⁶ for silica. -2 ~7.3×10 -2 mol / mol, more preferably 0.13 × 10⁻⁶ silica -2 ~5.7×10 -2 mol / mol, most preferably 0.2 × 10⁻⁶ silica -2 ~3.5×10 -2 The concentration is mol / mol. The level of the modified metal present is typically at least 0.1 × 10⁻⁶ of silica. -2 mol / mol, more preferably at least 0.15 × 10⁻⁶ silica -2 mol / mol, most preferably at least 0.25 × 10⁻⁶ silica -2 It is mol / mol.

[0032] When zirconium is a modifying metal, the level of zirconium metal may be preferably up to 10% (w / w), more preferably up to 8% (w / w), and most preferably up to 5.5% (w / w) of the modified silica support. The level of zirconium metal is typically 0.1–10% (w / w), more preferably 0.2–8% (w / w), and most preferably 0.3–5% (w / w) of the modified silica support. The level of zirconium metal is typically at least 0.5% (w / w), e.g., 0.8% (w / w), more typically at least 1.0% (w / w), and most typically at least 1.5% (w / w) of the modified silica support.

[0033] The level of hafnium metal may be preferably up to 20% (w / w), more preferably up to 16% (w / w), and most preferably up to 10% (w / w) of the modified silica support. The level of hafnium metal is typically 0.2–20% (w / w), more preferably 0.4–16% (w / w), and most preferably 0.6–10% (w / w) of the modified silica support. The level of hafnium metal is typically at least 1.0% (w / w), more typically 2.0% (w / w), and most typically at least 3.0% (w / w) of the modified silica support.

[0034] The silica component of silica-zirconium oxide supports typically accounts for 86.5–99.9% by weight, more typically 89.2–99.7% by weight, and most typically 93.2–99.6% by weight of the modified support.

[0035] The silica component of silica-hafnium oxide supports typically accounts for 76.4–99.8% by weight, more typically 81.1–99.5% by weight, and most typically 88.2–99.3% by weight of the modified support.

[0036] As used herein, terms such as “up to two metal atoms” mean one and / or two metal atoms. Modified silica supports and catalysts in any aspect of the present invention include metal residues, typically metal oxide residues having up to two metal atoms, most preferably one metal atom. It will be understood that such residues are monomeric or dimeric metal residues.

[0037] Preferably, the catalytic metal may be one or more alkali metals. The catalytic metal is a metal other than zirconium or hafnium. Suitable alkali metals can be selected from potassium, rubidium, and cesium, preferably rubidium and cesium. Cesium is the most preferred catalytic metal.

[0038] The catalytic metal, such as cesium, may preferably be present in the catalyst at a level of at least 1 mol / 100 (silicon + metal (zirconium and / or hafnium)) mol, more preferably at least 1.5 mol / 100 (silicon + metal) mol, and most preferably at least 2 mol / 100 (silicon + metal) mol. The level of catalytic metal in the catalyst may be up to 10 mol / 100 (silicon + metal) mol, more preferably up to 7.5 mol / 100 (silicon + metal) mol, and most preferably up to 5 mol / 100 (silicon + metal) mol in the catalyst.

[0039] The level of catalytic metal in the catalyst is preferably 1 to 10 mol / 100 (silicon + metal) mol, more preferably 2 to 8 mol / 100 (silicon + metal) mol, and most preferably 2.5 to 6 mol / 100 (silicon + metal) mol.

[0040] Unless otherwise specified, the amount of alkali metal or alkali metal in the catalyst relates to alkali metal ions and not to salts. Alternatively, the catalyst may contain a catalyst metal weight percentage in the range of 1 to 22% by weight, more preferably 4 to 18% by weight, and most preferably 5 to 13% by weight. This amount would apply to all alkali metals, particularly cesium.

[0041] The catalyst may contain alkali metals of the catalyst to zirconium and / or hafnium metals in any suitable weight ratio. However, typically, the weight ratio is in the range of 2:1 to 10:1, more preferably 2.5:1 to 9:1, and most preferably 3:1 to 8:1 in the catalyst for cesium:zirconium; 1:1 to 5:1, more preferably 1.25:1 to 4.5:1, and most preferably 1.5:1 to 4:1 in the catalyst for cesium:hafnium; 1.2:1 to 8:1, more preferably 1.5:1 to 6:1, and most preferably 2:1 to 5:1 in the catalyst for rubidium:zirconium; and 0.6:1 to 4:1, more preferably 0.75:1 to 3:1, and most preferably 1:1 to 2.5:1 in the catalyst for rubidium:hafnium. Accordingly, the molar ratio of catalyst metal to modified metal in the catalyst is typically at least 1.4 or 1.5:1, preferably in the range of 1.4 to 2.7:1, for example 1.5 to 2.1:1, and particularly 1.5 to 2.0:1, in which case the modified metal is typically zirconium and the catalyst metal is cesium. Generally, as used herein, the catalyst metal is present in excess of the amount that would be necessary to neutralize the modified metal.

[0042] Preferably, the catalyst metal is present in a range of 0.5 to 7.0 mol / mol (modified metal), more preferably 1.0 to 6.0 mol / mol, and most preferably 1.5 to 5.0 mol / mol (modified metal).

[0043] Preferably, the catalyst metal can be incorporated into the modified silica support by any method known to those skilled in the art, such as impregnation, co-gelation, or deposition using the catalyst metal.

[0044] The term "impregnated," as used herein, includes the process of adding a catalyst metal and dissolving it in a solvent to prepare a solution, and then adding this solution to a xerogel or aerogel, thereby incorporating the solution into the voids within the xerogel or aerogel.

[0045] Typically, the catalyst of the present invention can be in any suitable form. A typical embodiment is in the form of loose particles. Typically, when used, the catalyst is in the form of a fixed bed of catalysts. Alternatively, the catalyst may be in the form of a fluidized bed of catalysts. A further alternative is a monolithic reactor.

[0046] When the catalyst is used in a fixed bed, the supported catalyst is in the form of granules, aggregates, or molded units prepared by pelletizing or extrusion, such as spheres, cylinders, rings, saddles, stars, or polylobes, typically with maximum and minimum dimensions in the range of 1 to 10 mm, and more preferably with an average dimension greater than 2 mm, for example, greater than 2.5 or 3 mm. The catalyst is also useful in other forms, such as powders or small beads of the same dimensions as described above. When the catalyst is used in a fluidized bed, the catalyst particles are preferably in the range of 10 to 500 μm, preferably 20 to 200 μm, and most preferably 20 to 100 μm, with maximum and minimum dimensions in the range of 10 to 500 μm.

[0047] The level of catalytic metal in the catalyst, either in atoms or weight percent per 100 atoms (silicon + zirconium and / or hafnium), can be determined by appropriately sampling and averaging such samples. Typically, 5 to 10 samples would be taken from a given batch of catalyst, and the levels of alkali metals would be determined and averaged using methods such as: XRF, atomic absorption spectroscopy, neutron activation analysis, ion-coupled plasma mass spectrometry (ICPMS), or ion-coupled plasma atomic emission spectroscopy (ICPAES).

[0048] The levels of specific types of metal oxides in the catalyst / support are determined by XRF, atomic absorption spectroscopy, neutron activation analysis, or ion-coupled plasma mass spectrometry (ICPMS). In any embodiment of the present invention, the typical average surface area of ​​the modified silica-supported catalyst is measured using a Micromeritics Tristar 3000 Surface Area and porosity analyzer by multipoint BET method and ranges from 20 to 600 m². 2 / g, more preferably 30-450m 2 / g, most preferably 35-350m 2 The range is / g. The standard material used to check the performance of the device is 30.6m 2 / g(±0.75m 2 This could be carbon black powder supplied by Micromeritics (part number 004-16833-00) having a surface area of ​​ / g).

[0049] If the catalyst is porous, it is typically a combination of mesoporous and macroporous materials with an average pore size of 2–1000 nm, more preferably 3–500 nm, and most preferably 5–250 nm. Macropore sizes (greater than 50 nm) can be measured by a mercury intrusion porosimeter using NIST standards, while mesopore sizes (2–50 nm) are determined using the Barrett-Joyner-Halenda (BJH) analysis method with 77 K liquid nitrogen. The average pore size is the weight-averaged pore volume versus pore size distribution.

[0050] The average pore volume of the catalyst particles was measured by the amount of fluid, such as water, taken in, and was 0.1 cm³. 3 Although less than / g, it is generally 0.1-5cm 3 It can be in the range of / g. However, microporous catalysts with extremely low porosity are not optimal because they may hinder the movement of reactants within the catalyst, and 0.2-2.0 cm 3The average pore volume per g is more preferable. Pore volume can also be measured by a combination of nitrogen adsorption at 77 K and mercury porosimeter. Pore volume is measured using the Micromeritics TriStar Surface Area and Porosity Analyser, employing the same standards as for surface area measurements.

[0051] Surprisingly, this invention has revealed that adjusting the size of the modified metal residues is advantageous. However, to obtain the greatest benefit, it is necessary to adjust the proximity of adjacent modified metal residues, because otherwise, the modified metal residues may link together, potentially increasing their size.

[0052] Therefore, in a fourth aspect of the present invention, A process for providing a silica support having silanol groups; A step of contacting the silica support with a monomeric and / or dimeric modified metal compound, wherein the modified metal is adsorbed onto the silica surface support through a reaction with the silanol group. A method for producing a modified silica support is provided, which includes [a specific component].

[0053] Typically, the modifying metal is selected from zirconium or hafnium. It is preferable that the adsorbed modified metal cations are sufficiently separated from each other to substantially prevent their oligomerization, and more preferably their trimerization, with neighboring modified metal cations.

[0054] In the contact step, typically at least 25%, more typically at least 30%, for example at least 35%, more preferably at least 40%, for example at least 45%, most preferably at least 50%, for example at least 55%, for example at least 60% or 65%, and most preferably at least 70%, for example at least 75% or 80%, more typically at least 85%, most typically at least 90%, and particularly at least 95%, of the modified metal in contact with the silica support is monomeric or dimeric modified metal. Accordingly, at least 25%, more typically at least 30%, for example at least 35%, more preferably at least 40%, for example at least 45%, most preferably at least 50%, for example at least 55%, for example at least 60% or 65%, most preferably at least 70%, for example at least 75% or 80%, more typically at least 85%, most typically at least 90%, and particularly at least 95%, of the modified metal adsorbed on the silica support exists in the form of modified metal residues having a total of up to two modified metal atoms.

[0055] In a further aspect of the present invention, A process for providing a silica support having silanol groups; A step of treating a silica support with a monomeric and / or dimeric modified metal compound, wherein the modified metal is adsorbed onto the silica surface support through a reaction with a silanol group. A method for producing a modified silica support, in any embodiment herein, is provided, including, where the adsorbed modified metal atoms are sufficiently spaced apart from each other to substantially prevent their oligomerization with neighboring modified metal atoms, and more preferably sufficiently spaced apart from each other to substantially prevent their trimerization with neighboring modified metal atoms.

[0056] Preferably, the spacing of the modified metal atoms is a) reducing the concentration of silanol groups on the silica support, and / or b) Before processing the silica support, attach a sufficiently sized, chemically resistant ligand to its modified metal. It will be carried out by [company name].

[0057] Furthermore, in even more extreme cases, i. Provide a silica support having isolated silanol groups, and optionally process the support to obtain a 1 nm 2 A process to provide isolated silanol groups (-SiOH) at a level of less than 2.5 groups per unit; ii. A step of contacting a optionally treated silica support with a monomeric zirconium-modified metal compound or a hafnium-modified metal compound to adsorb, typically up to 25% of the isolated silanol groups, onto the support; iii. Optionally, remove any solvent or liquid carrier for the modified metal compound; iv. A step of calcining the modified silica for a sufficient amount of time and temperature to convert the monomeric zirconium compound or hafnium compound adsorbed on its surface into an oxide or hydroxide of zirconium or hafnium; v. A step of treating the calcined modified silica with an alkali metal for catalyst to impregnate the modified silica with the catalyst metal to form a catalyst, and optionally calcining the catalyst. A method for producing a catalyst is provided, which includes [a specific component].

[0058] In a further aspect of the present invention, i. Provide a silica support having isolated silanol groups, and optionally process the support to obtain a 1 nm 2 A process to provide isolated silanol groups (-SiOH) at a level of less than 2.5 groups per unit; ii. A step of contacting a optionally treated silica support with a monomeric zirconium-modified metal compound or a hafnium-modified metal compound to adsorb, typically up to 25% of the isolated silanol groups, onto the support; iii. Optionally, remove any solvent or liquid carrier for the modified metal compound; iv. Optionally, in the preparation for catalyst impregnation, a step of calcining the modified support for a sufficient amount of time and temperature to convert the monomeric zirconium compound or hafnium compound adsorbed on its surface into an oxide or hydroxide of zirconium or hafnium. A method for producing a modified silica support for a catalyst is provided, which includes [a specific component].

[0059] The concentration of silanol groups is preferably reduced by calcination, chemical dehydration, or other appropriate method before treatment with the modified metal compound. Preferably, in this case, the cation source of the modified metal is a solution of the compound of the modified metal, so that the compound is in the solution when it comes into contact with the carrier to carry out adsorption onto the carrier.

[0060] Typically, the solvent for the aforementioned solution is something other than water. Typically, the solvent is an aliphatic alcohol selected from methanol, ethanol, propanol, isopropanol, butanol, pentanol, and hexanol, more typically from methanol, ethanol, or propanol.

[0061] Advantageously, the proximity of the adsorbed modified metal to nearby modified metal cations can be adjusted by the concentration of the modified metal in the contact process and the following: a) Concentration of silanol groups on the silica support, and / or b) The size of the ligand that is unlikely to undergo any desired chemical change when bound to the modified metal cation.

[0062] The silanol group concentration on the silica support before adsorption is preferably adjusted by calcination or other suitable methods known to those skilled in the art. Identification methods are described, for example, in LTZhuravlev, Colloids and Surfaces: Physicochemical and Engineering Aspects, vol. 173, pp. 1-38, 2000, where four forms of silanol are described: isolated silanol, geminal silanol, adjacent silanol, and internal silanol, which can coexist on the silica surface. Isolated silanol groups are most preferred. This can be determined by infrared spectroscopy at 3730-3750 cm⁻¹. -1 While it can be identified as a sharp absorption peak, other silanols are identified as 3460–3715 cm⁻¹. -1 It shows a broad peak (see The Surface Properties of Silicas, Edited by Andre P. Legrand, John Wiley and Sons, 1998 (ISBN 0-471-95332-6), pp. 147-234).

[0063] The term "chemically resistant ligand" refers to a ligand that coordinates to a modified metal and is not removed even when that metal is adsorbed onto a silica surface. Therefore, this chemically resistant ligand is typically coordinated to the modified metal in solution before the silica surface is treated with the modified metal. To avoid any ambiguity, this chemically resistant ligand is typically removed by treating the silica surface after the modified metal has been adsorbed.

[0064] The size of ligands that are less likely to undergo chemical reactions is effective in separating modified metals to prevent them from bonding together. In a further aspect of the present invention, a method for producing a modified silica support for a catalyst or one or more catalysts described in the claims is provided.

[0065] The present invention is extended to a modified silica support in any embodiment described herein, wherein the support comprises isolated silanol groups (-SiOH) at 1 nm 2 It contains fewer than 2.5 groups per unit. Typically, its support is 1 nm 2 The level is more than 0.1 and less than 2.5 groups per unit, more preferably 0.2 to 2.2 groups, and most preferably 1 nm. 2 Each molecule contains approximately 0.4 to 2.0 isolated silanol groups (-SiOH).

[0066] The present invention is further extended to catalysts or modified silica supports according to any aspect thereof, wherein the support has a total of up to two modified metal atoms and / or is present on the support at 1 nm 2 The zirconium-modified metal residue or hafnium-modified metal residue is derived from a monomeric and / or dimeric modified metal cation source, present at a level of fewer than 2.5 group residues per unit.

[0067] The carrier typically contains the zirconium-modified metal residue or hafnium-modified metal residue at a density of 1 nm. 2 The level of the groups is more than 0.025 and less than 2.5 per unit, more preferably 0.05 to 1.5 per unit, and most preferably 1 nm. 2 It contains approximately 0.1 to 1.0 residues per unit.

[0068] Here, preferred ligands may be chemically unresponsive ligands selected from molecules having lone pairs of electrons containing an oxygen or nitrogen atom capable of forming a five-membered or six-membered ring with a zirconium or hafnium atom. Examples include: diones, diimines, diamines, diols, dicarboxylic acids or their derivatives, such as esters, or molecules having two different such functional groups, and in either case, together with the respective N or O atom and an N or O atom separated by two or three atoms, thereby forming a five-membered or six-membered ring. Examples include: pentane-2,4-dione, 3-oxobutanoic acid, and esters of aliphatic alcohols containing 1 to 4 carbon atoms, such as ethyl 3-oxobutanoate, propyl 3-oxobutanoate, isopropyl 3-oxobutanoate, n-butyl 3-oxobutanoate, t-butyl 3-oxobutanoate, heptane-3,5-dione, 2,2,6,6-tetramethyl-3,5-heptanedione, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, and 1,3-butanediol. ol, 1,2-butanediol, 1,2-diaminoethane, ethanolamine, 1,2-diamino-1,1,2,2-tetracarboxylate, 2,3-dihydroxy-1,4-butanediate, 2,4-dihydroxy-1,5-pentanediate, salts of 1,2-dihydroxylbenzene-3-5-disulfonic acid, 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 t-butyl 3-oxobutanoate are most preferred. For example, smaller bidentate ligands having fewer than 10 carbon and / or heteroatoms in total can form smaller complexes, which can precipitate on the surface of silica at higher concentrations compared to larger ligands.Accordingly, the cation sources of the modified metals described herein may be in the form of complexes of zirconium and / or hafnium having such smaller ligands, preferably at least one such ligand. Examples of such compounds include ligands that readily undergo chemical change, such as solvent ligands in alcohol solvents, alkoxide ligands, such as ethoxides or propoxides.

[0069] Preferably, the concentration of isolated silanol groups determines the maximum number of sites for modification metal adsorption. By adjusting the concentration, the proximity of the adsorbed modification metal can be effectively determined because the distribution of silanol sites will generally be homogeneous. The silanol concentration for producing the modified silica support in this invention is 1 nm 2 Fewer than 2.5 groups per unit, more typically 1 nm 2 Fewer than 1.5 groups per unit, most typically 1 nm 2 The number of groups may be less than 0.8 per unit. A suitable range of silanol concentrations for producing modified silica supports is 1 nm 2 0.1 to 2.5 silanol groups per unit, more preferably 1 nm 2 0.15 to 1.0 silanol groups per unit, most preferably 1 nm 2 There may be 0.2 to 0.7 silanol groups per unit.

[0070] Generally, the concentration of the modified metal, which is in the form of a cation, should be set to a level that prevents the formation of significant structures such as bilayers on the surface of the support that could lead to modified metal-to-metal interactions. In addition, filling gaps in the initial monolayer, which could lead to weak adsorption that separates the modified metal from the silanol site, should also be avoided to prevent interactions between adjacent strongly adsorbed modified metals. Typical concentration ranges for the modified metal of the present invention may be as described herein.

[0071] When the source of the compound, more typically monomers, is brought into contact with the carrier to adsorb the compound onto the carrier, typically at least 30%, for example at least 35%, more preferably at least 40%, for example at least 45%, most preferably at least 50%, for example at least 55%, for example at least 60% or 65%, and most preferably at least 70%, for example at least 75% or 80%, more typically at least 85%, most typically at least 90%, and especially at least 95%, of the modified metal in the modified metal compound is a dimer and / or monomer.

[0072] In a further aspect of the present invention, Modified silica support, Modified silica support containing a modified metal, and The catalyst metal on the modified silica support A method for producing a catalyst comprising the modified metal, wherein the modified metal is selected from one or more of zirconium and / or hafnium, wherein at least a portion, typically at least 25%, of the modified metal is present in the form of monomeric modified metal residues, and the method is Process the silica support to 1 nm 2 A process to provide isolated silanol groups (-SiOH) at a level of less than 2.5 groups per unit; A step of reacting the treated support with a modified metal compound of a monomer zirconium or hafnium monomer to carry out the bonding of these compounds to at least 25% of the isolated silanol groups; A step of optionally removing a solvent or liquid carrier; A process of calcining the modified silica for a sufficient amount of time and temperature to convert the monomeric zirconium compound or hafnium compound adsorbed on its surface into zirconium or hafnium oxide or hydroxide; The process involves treating the calcined modified silica with an alkali metal catalyst to impregnate the modified silica with the catalyst metal. A method is provided that includes the following:

[0073] Advantageously, by reducing the number of isolated silanol sites and bonding monomeric zirconium or hafnium species to those sites, a catalyst support is obtained in which catalyst selectivity is improved, sintering rate is slowed, and catalyst aging is improved.

[0074] A suitable treatment method for imparting isolated silanol groups to silica is calcination. However, other treatments, such as hydrothermal treatment or chemical dehydration, are also possible. U.S. Patent No. 5,583,085 teaches a chemical dehydration method for silica using dimethyl carbonate or ethylene dicarbonate in the presence of an amine base. U.S. Patents No. 4,357,451 and 4,308,172 teach a chemical dehydration method using chlorination with SOCl2, then dechlorination with H2 or ROH, and then chemical dehydration with oxygen in a dry atmosphere. Chemical dehydration can remove up to 100% of silanols, compared to only 0.7 / nm by heat treatment. 2 Therefore, selectively, chemical dehydration methods may offer a further range of control over the silanol group.

[0075] The term “isolated silanol” (also called single silanol) is well known to those skilled in the art and is distinguished from neighboring silanols, or geminal silanols, or internal silanols. Suitable methods for determining the abundance of isolated silanols include surface high-sensitivity infrared spectroscopy and 1 1H NMR or 31 Si NMR is one example.

[0076] A fifth aspect of the present invention provides a method for producing a catalyst according to any of the above aspects of the present invention, comprising the steps of forming modified silica according to any of the above aspects, and impregnating the modified silica support with the catalyst metal by contacting the modified silica support with a solution containing a catalyst metal.

[0077] The silica support is preferably dried or calcined before being subjected to treatment using a cation source of the modifying metal. The formed modified silica can be dried or calcined before the addition of the catalyst metal, regardless of whether it has been dried or calcined beforehand.

[0078] Silica before treatment with a modified metal may be in the form of a gel. At the start of the modification, the gel may be in the form of a hydrogel, xerogel, or aerogel. The silica support may be a xerogel, hydrogel, or aerogel. The silica support is preferably a xerogel.

[0079] The silica support can be treated with a metal cation source using any of the various methods known to those skilled in the art for support formation. The silica support can be contacted with the metal cation source in such a manner that the modified metal is dispersed throughout the silica support. Typically, zirconium and / or hafnium can be homogeneously dispersed throughout the silica support. It is preferable to disperse the modified metal throughout the silica support by adsorption.

[0080] As used herein, terms such as “adsorption” in relation to modified metals mean incorporating the modified metal onto the surface of the silica support through interaction between a metal cation source and the silica support, typically by chemiadsorption. Typically, adding a modifier to a silica support involves adsorbing a metal cation source onto the silica support to form an organometallic complex, and then calcining the complex to convert it into a metal oxide residue. Thus, typically, a homogeneous dispersion of the modified metal exists throughout the silica support. Typically, zirconium and / or hafnium are dispersed throughout the silica support.

[0081] Examples of suitable metal cation sources used herein include, for example, the following organic complexes: zirconium(pentane-2,4-dione)4, zirconium(ethyl 3-oxobutanoate)4, zirconium(heptane-3,5-dione)4, zirconium(2,2,6,6-tetramethylheptane-3,5-dione)4, zirconium(propoxide)(pentane-2-3-dione)3, zirconium(propoxide)3(2,2,6,6-tetramethyl-3,5-heptanedione), zirconium(Ot-butyl)3(t-butyl 3-oxobutanoate), zirconium(Ot-butyl)2(t-butyl 3-oxobutanoate)2, and metal salts, such as zirconium perchlorate, zirconium oxynitrate, and zirconium oxychloride (typically, the metal cation source is supplied as an organic complex).

[0082] Typically, the modified metal is brought into contact with a silica support in a solution. The metal cation source is preferably supplied in any solvent in which the metal cation source is dissolved. Examples of suitable solvents include water or alcohol. Preferred solvents are alcohols such as methanol, ethanol, propanol, isopropanol, butanols, pentanols, and hexanols.

[0083] In such an alcoholic solution, it is preferable to add a metal cation source to silica as the metal salt. In one embodiment, the metal cation source is provided as a solution of one or more of the following in methanol, ethanol, isopropanol, propanol, butanol, isobutanol or 2-butanol: zirconium(IV) acetylacetonate (zirconium,tetrakis(2,4-pentanedionato-O,O')), zirconium(heptane-3,5-dione)4, zirconium(2,2,6,6-tetramethyl-3,5-heptanedione)4, zirconium(IV)3-oxobutanoate ethyl, zirconium(IV)3-oxobutanoate t-butyl or zirconium(IV)i-3-oxobutanoate propyl.

[0084] It is preferable to adsorb the modified metal onto the silica support and then remove the solvent by evaporation. Optionally, the modified silica support is calcined to remove all ligands or other organic substances from the modified support.

[0085] Those skilled in the art will understand that a catalytic metal can be added to modified silica by any suitable means. Typically, to produce a modified silica catalyst, modified silica is brought into contact with a catalytic metal.

[0086] Typically, to produce a catalyst, a modified silica support is brought into contact with an acidic, neutral, or alkaline aqueous solution containing the catalyst metal, such as cesium, in the form of a salt of the catalyst metal and a base. Alternatively, the support may be brought into contact with a water-miscible solution of the catalyst 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. It is most preferable to add the catalyst metal as a salt solution in methanol. The solution may contain low levels of water, typically up to 20% by volume.

[0087] Typically, the temperature, contact time, and pH conditions at each stage of the catalyst manufacturing process are such that the silica support modified with the catalyst metal is impregnated to form a modified silica-supported catalyst.

[0088] The temperature conditions for this process are typically 5–95°C, more typically 10–80°C, and most typically 20–70°C. The temperature for this process can be as low as 5°C, more typically as low as 10°C, and most typically as low as 20°C.

[0089] For this process, the contact time between the modified carrier and the solution containing the catalyst metal can typically be 0.05 to 48 hours, more typically 0.1 to 24 hours, and most typically 0.5 to 18 hours. The contact time can be at least 0.05 hours, more typically at least 0.1 hours, and most typically at least 0.5 hours.

[0090] The concentration of the catalyst metal salt solution for this process depends on many factors, including: the solubility limit of the catalyst metal compound, the porosity of the modified silica support, the desired amount of catalyst metal to be loaded onto the support, the amount of liquid used to impregnate the support, the pH, and the method of addition, including the selection of the catalyst metal compound. The concentration in the solution is best determined experimentally.

[0091] Suitable catalyst metal salts for incorporating the catalyst metal can generally be selected from one or more of the following groups: formate, acetate, propionate, bicarbonate, hydrochloride, nitrate, hydroxide, and carbonate; more typically hydroxide, acetate, or carbonate; most typically hydroxide and / or carbonate. The pH during impregnation can be adjusted by adding ammonia with the metal compound or by using a suitable catalyst metal compound, such as formate, carbonate, acetate, or hydroxide, more preferably hydroxide or carbonate (used alone, in combination, or with a suitable carboxylic acid). Adjusting the pH to a preferred range is of paramount importance for satisfactory adsorption at the end of impregnation. 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 inherently basic, mixtures of one or more of the above salts with a specific catalyst metal, such as a cesium hydroxide salt, can be conveniently prepared.

[0092] Those skilled in the art will understand that the catalyst metal of the present invention can be added to a modified silica support by any suitable means. Optionally, the catalyst can be immobilized on the support by using a suitable aqueous salt, then drying the surface-coated support to precipitate the compound on the support, and typically by calcination.

[0093] Generally, drying of modified silica supports is achieved by suitable methods known to those skilled in the art, such as drying units or ovens. The catalyst typically contains 0.01–25% (w / w) water, more typically 0.1–15% (w / w) water, and most typically 0.5–5.0% (w / w) water.

[0094] The modified silica-supported catalyst containing the catalytic metal can be optionally dried or calcined, and the calcination process is known to those skilled in the art. In some cases, the support formed in the modification step may need to be calcined at 200–1000°C, more typically 300–800°C, and most typically 350–600°C, before adding the catalyst metal. In the preferred calcination of the support formed in the modification step, the temperature is at least 375°C, for example, 400°C or 450°C. The calcination atmosphere should typically contain some oxygen, preferably 1–30% oxygen, most preferably 2–20% oxygen, to remove organic residues as carbon dioxide and water. The calcination time can typically be 0.01–100 hours, preferably 0.5–40 hours, and most preferably 1–24 hours. The calcined support, such as a xerogel material, should be cooled to a temperature suitable for impregnation. The addition of catalytically active metals can be carried out by the methods described for uncalcined materials, or by any other conventional method used to impregnate a catalyst support, such as a xerogel support, such as a solvent other than water, such as an alcohol, preferably methanol, ethanol, propanol, or isopropanol, or by an initial wetting method in which sufficient solution is added to the xerogel support to fill the pores of the xerogel support. In this case, the concentration of catalytically active metals is better calculated by the methods described above to introduce a target amount of catalytically active metal into the xerogel support rather than using an excess of a lower concentration solution. Any preferred method known to those skilled in the art can be used for the addition of catalytically active metals. When using organic complexes as sources of zirconium and / or hafnium, calcination is particularly advantageous because it may be necessary to modify the subsequent catalyst preparation procedure to remove at least some of the organic complex salts before impregnation with cesium. Advantageously, it was found that by calcining the modified support, the catalyst metal:modifying metal ratio, and therefore the amount of catalyst metal required, could be reduced. This was unexpected and provides a further improvement to the present invention.

[0095] A sixth aspect of the present invention provides a method for producing an ethylenically unsaturated carboxylic acid or ester, typically an α,β-ethylenically unsaturated carboxylic acid or ester, the method comprising the step of contacting formaldehyde or a suitable source thereof with the carboxylic acid or ester in the presence of a catalyst and optionally in the presence of an alcohol, the catalyst being according to the first or any other aspect of the present invention as defined herein.

[0096] Advantageously, catalysts containing modified silica as defined herein and a catalytic metal are remarkably high-performance catalysts for producing α,β-ethylenically unsaturated carboxylic acids or esters by condensation of the corresponding acid or ester with a methylene source, such as formaldehyde, and have also been found to reduce catalyst surface sintering, improve selectivity, and provide a high catalyst surface area. Specifically, high performance is found when monomeric and / or dimeric modified metal residues are used and / or when the modified silica support is calcined before treatment with the catalytic metal. Furthermore, the use of certain metal complexes to incorporate the modified metal onto the support by adsorption provides a convenient source of monomeric and / or dimeric modified metal residues. Such sources allow for further adjustment of the properties of the modified metal and result in a more homogeneous dispersion of the modified metal residues.

[0097] In relation to formaldehyde according to a fourth aspect of the present invention, the term “suitable source” means either that free formaldehyde can be produced in situ from the source under the reaction conditions, or that the source can act as equivalent to free formaldehyde under the reaction conditions, for example, by forming an intermediate as reactive as formaldehyde, resulting in a homogeneous reaction. The appropriate source of formaldehyde is given by formula (I):

[0098] [ka]

[0099] (In the formula, R 5 and R 6 These are, independently, C1~C 12 It may be a compound of hydrocarbons or H, where X is O, n is an integer from 1 to 100, and m is 1.

[0100] Typically, R 5 and R 6 These are independently C1-C as defined herein. 12 Alkyl, alkenyl, or aryl compounds, and more preferably C1-C, derived from H. 10 The alkyl group or H is selected most preferably from C1-C6 alkyl groups or H, and more preferably from methyl groups or H. Typically, n is an integer preferably from 1 to 10, more preferably from 1 to 5, and more preferably from 1 to 3.

[0101] However, other formaldehyde-derived substances, including trioxane, may be used. Therefore, suitable source substances for formaldehyde include various equilibrium compositions capable of providing formaldehyde. Examples of such compositions include dimethoxymethane, trioxane, and polyoxymethylene R. 1 -O-(CH2-O) i -R 2 (In the formula, R 1 and / or R 2 Examples of equilibrium compositions include, but are not limited to, alkyl groups or hydrogen atoms (where i = 1 to 100), paraformaldehyde, formalin (formaldehyde, methanol, water), and other equilibrium compositions such as a mixture of formaldehyde, methanol, and methyl propionate.

[0102] Polyoxymethylene is a higher formal or hemiformal of formaldehyde and methanol, with the structure CH3-O-(CH2-O) i -CH3 ("Formal-i") or CH3-O-(CH2-O) i-H("hemiformal-i") (where i = 1 to 100, preferably 1 to 5, particularly 1 to 3) or other polyoxymethylene having at least one nonmethyl terminal group. Thus, the source substance of formaldehyde is of formula R 31 -O-(CH2-O-) i R 32 It can be a polyoxymethylene (where R 31 and R 32 These may be the same group or different groups, and at least one of them is C1~C 10 Selected from alkyl groups, for example R 31 = Isobutyl, R 32 (=methyl)

[0103] Generally, suitable source materials for formaldehyde are selected from the following: dimethoxymethane, lower hemiformal (formaldehyde and methanol), CH3-O-(CH2-O) i -H (where i = 1 to 3), a mixture containing formalin or formaldehyde, methanol and methyl propionate.

[0104] Typically, the term "formalin" refers to a mixture in which the ratio of formaldehyde:methanol:water is 25–65% by weight:0.01–25% by weight:25–70% by weight. More typically, the term "formalin" refers to a mixture in which the ratio of formaldehyde:methanol:water is 30–60% by weight:0.03–20% by weight:35–60% by weight. Most typically, the term "formalin" refers to a mixture in which the ratio of formaldehyde:methanol:water is 35–55% by weight:0.05–18% by weight:42–53% by weight.

[0105] Typically, the mixture containing formaldehyde, methanol, and methyl propionate contains less than 5% water by weight. More preferably, the mixture containing formaldehyde, methanol, and methyl propionate contains less than 1% water by weight. Most preferably, the mixture containing formaldehyde, methanol, and methyl propionate contains only 0.1–0.5% water by weight.

[0106] In a seventh aspect of the present invention, a process for preparing an ethylenically unsaturated acid or ester is provided, the process being based on the formula R 1 -CH2-COOR 3 (wherein R1 is hydrogen or an alkyl group having 1 to 12, more preferably 1 to 8, most preferably 1 to 4 carbon atoms, and R3 is also independently hydrogen or an alkyl group having 1 to 12, more preferably 1 to 8, most preferably 1 to 4 carbon atoms) an alkanoic acid or ester of formaldehyde or formula (I) defined below:

[0107] [ka]

[0108] (In the formula, R5 is methyl and R6 is H; X is O; m is 1; and n is any value between 1 and 20. This involves contacting a suitable source of formaldehyde or any mixture thereof with the catalyst described in any aspect of the present invention and optionally in the presence of an alkanol.

[0109] Accordingly, the inventors have discovered that the presence of zirconium and / or hafnium in the form of metal oxide residues in the present invention makes it possible to bring about a remarkable improvement in the selectivity for the condensation of a methylene source, such as formaldehyde, with a carboxylic acid or alkyl ester, such as methyl propionate, for the formation of an ethylenically unsaturated carboxylic acid. In addition, the sintering rate of the catalyst surface during the condensation reaction is significantly and remarkably reduced.

[0110] Therefore, one specific process in which the catalyst of the present invention has proven particularly advantageous is the condensation reaction of formaldehyde and methyl propionate in the presence of methanol for the production of MMA.

[0111] In the production of MMA, the catalyst is typically brought into contact with a mixture containing formaldehyde, methanol, and methyl propionate. Processes according to the sixth or seventh aspect of the present invention are particularly suitable for producing acrylic acids and alk-acrylic acids and their alkyl esters and further methylene-substituted lactones. Suitable methylene-substituted lactones include 2-methylenevalerolactone and 2-methylenebutyrolactone, derived from valerolactone and butyrolactone, respectively. Suitable (alk)acrylic acids and their esters are typically obtained by the reaction of the corresponding alkanic acid or their ester with a methylene source, such as formaldehyde, in the presence of a catalyst (C 0~8 (Arc) Acrylic acid or (C) 0~8 Alk) alkyl acrylate, preferably methacrylic acid, acrylic acid, methyl methacrylate, ethyl acrylate or butyl acrylate, more preferably propanoic acid or methyl propionate, respectively, are used to produce methacrylic acid or methyl methacrylate (MMA). Therefore, in the production of methyl methacrylate or methacrylic acid, preferred formula R 1 -CH2-COOR 3 The ester or acid is methyl propionate or propionic acid, respectively, and therefore the preferred alkanol is methanol. However, it will be understood that in the preparation of other ethylenically unsaturated acids or esters, the preferred alkanol or acid will be different.

[0112] The reaction of the present invention may be a batch reaction or a continuous reaction. Typical temperature and gauge pressure conditions in the process of the sixth or seventh aspect of the present invention are 100°C to 400°C, more preferably 200°C to 375°C, most preferably 275°C to 360°C; and / or 0.001 MPa to 1 MPa, more preferably 0.03 MPa to 0.5 MPa, most preferably 0.03 MPa to 0.3 MPa. Typical residence times of the reactants in the presence of the catalyst are 0.1 to 300 seconds, more preferably 1 to 100 seconds, most preferably 2 to 50 seconds, and particularly 3 to 30 seconds.

[0113] In the process for manufacturing a product in the present invention, it is not necessary to precisely define the amount of the catalyst used, but it will be determined from the practicality of the process employing it. However, the amount of the catalyst is generally selected such that an optimal selectivity, product yield, and acceptable operating temperature can be obtained. Nevertheless, those skilled in the art will understand that the amount of the catalyst should be the minimum sufficient to effect an effective contact of the reactants with the catalyst surface. In addition, those skilled in the art will also understand that there will be substantially no upper limit to the amount of the catalyst relative to the reactants, but in practice, this may also be governed by the required contact time and / or economic considerations.

[0114] The relative amounts of the reactants in the sixth or seventh process of the present invention can be varied within wide limits, but generally, the molar ratio of formaldehyde or a carboxylic acid or ester of a suitable source thereof is in the range of 20:1 to 1:20, more preferably 5:1 to 1:15. The most preferred ratio will depend on the form of formaldehyde and the ability of the catalyst to release formaldehyde from formaldehyde-containing species. Thus, 31 O-(CH2-O) i R 32 In R 31 and R 32 Formaldehyde-containing substances with high reactivity such that one or both of them are H require only relatively low ratios. Typically, in this case, the molar ratio of formaldehyde or a carboxylic acid or ester of a suitable source thereof is in the range of 1:1 to 1:9. For example, when neither R 31 nor R 32 is H, as in CH3O-CH2-OCH3 or trioxane, higher ratios, typically 6:1 to 1:3, are most preferred.

[0115] As mentioned above, water may also be present in the reaction mixture due to the source of formaldehyde. Depending on the source of formaldehyde, it may be necessary to partially or completely remove the water from it before the catalytic reaction. Maintaining a water level lower than that of the formaldehyde source may be advantageous for catalytic efficiency and / or subsequent purification of the reaction product. It is preferable, more preferably less than 5 mol%, and most preferably less than 2 mol% of water in the reactor.

[0116] The molar ratio of alcohol to acid or ester is typically in the range of 20:1 to 1:20, preferably 10:1 to 1:10, and most preferably 5:1 to 1:5, for example, 1:1.5. However, the most preferred ratio will depend on the amount of water in the reactant fed to the catalyst plus the amount produced by the reaction, so the preferred molar ratio of alcohol to total water in the reaction will be at least 1:1, more preferably at least 2:1.

[0117] The reactants of the sixth or seventh embodiment may be fed into the reactor independently or after premixing, and the reaction process may be continuous or batch. Typically, however, a continuous process is used.

[0118] Typically, the method according to the sixth or seventh aspect of the present invention is carried out when the reactant is in the gas phase. In a further embodiment, the present invention is extended to a process for producing an ethylenically unsaturated carboxylic acid or ester according to any of the relevant embodiments herein, comprising the step of first producing a catalyst according to any of the relevant embodiments herein. definition In this specification, the term "alkyl" means C1-C11 unless otherwise specified. 12means alkyl and includes methyl, ethyl, ethenyl, propyl, propenyl, butyl, butenyl, pentyl, pentenyl, hexyl, hexenyl, heptyl groups. Typically, the alkyl group is selected from methyl, ethyl, propyl, butyl, pentyl and hexyl, more typically methyl. Unless otherwise specified, the alkyl group may be linear or branched if there are sufficient carbon atoms, may be cyclic, acyclic or partially cyclic / acyclic, and may be unsubstituted, substituted, or halo, cyano, nitro, -OR 19 、-OC(O)R 20 、-C(O)R 21 、-C(O)OR 22 、-NR 23 R 24 、-C(O)NR 25 R 26 、-SR 29 、-C(O)SR 30 、-C(S)NR 27 R 28 、and may have the terminus of one or more substituents selected from unsubstituted or substituted aryl or unsubstituted or substituted Het (where R 19 ~R 30 each independently represents hydrogen, halo, unsubstituted or substituted aryl or unsubstituted or substituted alkyl here and generally in this specification, or in the case of R 21 represents halo, nitro, cyano and amino) and / or may be interrupted by one or more (typically less than 4) oxygen, sulfur, silicon atoms or silano or dialkylsilicon groups, or a mixture thereof. Typically, the alkyl group is unsubstituted, typically linear, and typically saturated.

[0119] The term "alkenyl" should be understood as the above-mentioned "alkyl", provided that at least one of the carbon-carbon bonds therein is unsaturated. Thus, this term relates to C2~C 12 alkenyl groups.

[0120] Unless otherwise stated, the term "alk" or similar terms shall follow the definition of "alkyl" as described above, except that "C0 alc" means that it is not substituted with alkyl.

[0121] As used herein, the term "aryl" includes five- to ten-membered, typically five- to eight-membered, carbocyclic aromatic or pseudoaromatic groups, such as phenyl, cyclopentadienyl and indenyl anions and naphthyl, which may be unsubstituted or substituted with one or more substituents selected from the following: unsubstituted or substituted aryl, alkyl (the group itself may be unsubstituted, substituted, or have terminal groups as defined herein), het (the group itself may be unsubstituted, substituted, or have terminal groups as defined herein), halo, cyano, nitro, OR 19 ,OC(O)R 20 , C(O)R 21 , C(O)OR 22 , NR 23 R 24 , C(O)NR 25 R 26 , SR 29 , C(O)SR 30 Or C(S)NR 27 R 28 (Here, R 19 ~R 30 Each is independently hydrogen, an unsubstituted or substituted aryl or alkyl group (the alkyl group itself may be unsubstituted, substituted, or have a terminal group as defined herein), or R 21 (In this case, it is halo, nitro, cyano, or amino.)

[0122] As used herein, the term "halo" means a chloro, bromo, iodine, or fluoro group, typically a chlorofluoro group. As used herein, the term "Het" includes 4- to 12-membered, typically 4- to 10-membered ring structures, where the ring contains one or more heteroatoms selected from nitrogen, oxygen, sulfur, and mixtures thereof, and the ring may contain one or more double bonds, or may be non-aromatic, partially aromatic, or fully aromatic in nature. The ring structure may be monocyclic, dicyclic, or fused. Each "Het" group identified herein may be unsubstituted or substituted with one or more substituents selected from: halo, cyano, nitro, oxo, alkyl (where the alkyl group itself may be unsubstituted, substituted, or have terminal groups 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 )R 26 , -SR 29 -C(O)SR 30 or -C(S)N(R 27 )R 28 (Here, R 19 ~R 30 Each is independently hydrogen, an unsubstituted or substituted aryl or alkyl group (the alkyl group itself may be unsubstituted, substituted, or have a terminal group as defined herein), or R 21 (In this case, it is halo, nitro, amino, or cyano). Therefore, the term "Het" includes, for example, the following optionally substituted groups: azetidinyl, pyrrolidinyl, imidazolyl, indolyl, furanyl, oxazolyl, isoxazolyl, oxadiazolyl, thiazolyl, thiadiazolyl, triazolyl, oxatriazolyl, thiatriazolyl, pyridadinyl, morpholinyl, pyrimidinyl, pyrazinyl, quinolinyl, isoquinolinyl, piperidinyl, pyrazolyl, and piperazinyl. Substitutions in Het may be at the carbon atoms of the Het ring, and, where appropriate, at one or more heteroatoms.

[0123] The "Het" group can also be in the form of an N oxide. The optionally suitable alcohols used in the catalytic reactions of the fourth and fifth aspects of the present invention are C1 to C 30 Alkanols (including aryl alcohols) may be selected, and they may be optionally substituted with one or more substituents selected from the following: alkyl, aryl, Het, halo, cyano, nitro, OR as defined herein. 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 30Particularly preferred alkanols are C1-C8 alkanols, such as methanol, ethanol, propanol, isopropanol, isobutanol, t-butyl alcohol, phenol, n-butanol, and chlorocaprylic alcohol, especially methanol. Monoalkanols are most preferred, but typically polyalkanols selected from diols to octaols, such as diols, triols, and tetraols, as well as sugars, can be used. Typically, such polyalkanols are selected from the following: 1,2-ethanediol, 1,3-propanediol, glycerol, 1,2,4-butanetriol, 2-(hydroxymethyl)-1,3-propanediol, 1,2,6-trihydroxyhexane, pentaerythritol, 1,1,1-tri(hydroxymethyl)ethane, nanose, sorbates, 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 precise. Generally, an excess amount is used compared to the amount of substrate being esterified. Therefore, while the alcohol can serve as the reaction solvent, another solvent or additional solvent may be used if necessary.

[0124] The term "aging" is used, for example, in the brochure for International Publication of Patent Application No. 2009 / 003722. The general principle of aging is described in the following document: The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface Properties and Biochemistry of Silica, by Ralph K Iler, 1979, John Wiley and Sons Inc. (ISBN 0-471-02404-X), pages 358-364. If this process is adopted, the hydrogel is then washed again to remove the substances used in the aging process, and the solution is brought to the correct pH for adding the catalytically active metal (this depends on the selection of the salt for the catalytically active metal).

[0125] Any aspect of the present invention or any preferred or feature thereof may include the metal, metal oxide, and metal oxide residues, respectively, which may be zirconium or hafnium and zirconia or hafnia, but are typically zirconium and zirconia and zirconia residues.

[0126] As used herein, the term “gel” is also known to those skilled in the art, but if there is any doubt, it can be understood as a solid network in which a fluid is dispersed. Generally, a gel is a polymer network in which a fluid is dispersed. “Co-gel” is a term used to indicate that two or more original compounds / residues are incorporated into a polymeric network, usually silica and a metal oxide or salt, such as zirconia. Thus, co-gelation, as used herein, means the formation of a co-gel.

[0127] Therefore, a gel is a sol having a "set". Thus, a hydrogel is a gel as defined herein, whose fluid is water. A xerogel is a gel that has been dried to remove the fluid. An aerogel is a gel whose fluid has been replaced with gas, and therefore does not exhibit the same kind of shrinkage as a xerogel.

[0128] In this specification, the term “start” means the beginning of the formation of modified silica. The term “residue,” when used herein in relation to metals, is used to refer to the form of the modified metal on the modified carrier. The modified metal generally constitutes part of a network, and the modified metal will be in the form of loose residues on the silica substrate. Where “up to two metal atoms in total” or similar references are made, it should be understood that these refer to the monomeric and / or dimeric forms of the residues. In the embodiments of the invention herein, it has been found to be advantageous to preferably have residues that are in the form of monomeric residues. Thus, “up to two modified metal atoms” or similar references herein mean one and / or two modified metal atoms in total. Herein, one is preferred over two modified metal atoms, and particularly preferred are one and / or two zirconium atoms in total in the residue, and most particularly, one zirconium atom in the residue.

[0129] The term "monomer or dimer" in the case of residues on silica means that they have a monomeric or dimeric form, i.e., they have the form of monomeric or dimeric residues. The percentage of modified metals in this specification has no units because it refers to the number of a particular metal atom per total number of metal atoms. While residues may take the form of nonmonomer or nondimer clusters, it will be understood that these clusters are still made up of modified metal atoms.

[0130] Hereinafter, embodiments of the present invention are defined by reference to the accompanying examples and the following drawings. [Brief explanation of the drawing]

[0131] [Figure 1] HRTEM images of Zr-modified silica (Example 5) are shown. [Figure 2] HRTEM images of Zr-modified silica (Example 7) are shown. [Figure 3] HRTEM images of Zr-modified silica (Example 14) are shown. [Figure 4] HRTEM images of Zr-modified silica (implementation 15) are shown. [Figure 5] HRTEM images of Zr-modified silica (implementation 17) are shown. [Figure 6] HRTEM images of Zr-modified silica (implementation 18) are shown. [Figure 7] The (MMA+MAA) selectivity (%) versus catalytic activity for the catalysts prepared in Examples 20 to 74 is shown. [Figure 8] The catalyst selectivity for the mixed monomer / trimer catalysts prepared in Examples 75 to 79 is shown. [Figure 9] The catalyst sintering constants obtained by the accelerated aging test described in Example 81 are shown. [Modes for carrying out the invention]

[0132] experiment Description of silica support Example 1 Fuji Silysia CARiACT Q10 silica (Q10) was dried in a laboratory oven at 160°C for 16 hours. After removal from the oven, it was cooled to room temperature in a sealed flask in a desiccator. The silica was determined to be 333m³ by nitrogen adsorption / desorption isothermal analysis (Micromeretics Tristar II). 2 It had a surface area of ​​1 / g, a pore volume of 1.0 mL / g, and an average pore diameter of 10 nm. TGA analysis revealed 0.8 OH / nm 2 It was found to have a silanol number of . This silica mainly consists of spherical silica bead-like molded products with a diameter range of 2 to 4 mm. Example 2 Fuji Silysia CARiACT Q30 silica (Q30) was calcined in a tubular furnace under a nitrogen stream at a heating rate of 5°C / min to 900°C for 5 hours. It was then cooled to room temperature and stored in a sealed flask in a desiccator. This silica was 112m 2It had a surface area of ​​1.0 mL / g, a pore volume of 1.0 mL / g, and an average pore diameter of 30 nm, but mainly consisted of spherical silica bead-like molded products with a diameter in the range of 2 to 4 mm. Zr modification of silica support Example 3 (0.92 wt% Zr, on Q10, monomer Zr) 0.542 g of Zr(acac)4 (97%, Sigma Aldrich) was dissolved in 11 mL of MeOH (99%, Sigma Aldrich). 10 g of silica from Example 1 was weighed into a separation flask. The weighed silica was then added to the Zr(acac)4 solution with stirring. Stirring was continued until all of the Zr(acac)4 solution was completely incorporated into the pore volume of the silica. Once the pores were filled, the Zr-modified silica was left in a sealed flask for 16 hours with periodic stirring. After that time, the excess porous solution was removed by filtration. A drying step was then performed, in which the organic solvent in the pores was removed by passing a stream of nitrogen gas over the wet Zr-modified silica at room temperature. Alternatively, the solvent in the pores was removed under reduced pressure on a rotary evaporator. After all the solvent had been removed, the Zr-modified silica support was calcined in a tubular furnace under flowing air (1 L / min) at 500°C, with a heating rate of 5°C / min and a final holding time of 5 hours. Upon cooling, a Zr-grafted silica support was obtained with 100% Zr utilization efficiency. The amount of Zr loaded onto the Zr-modified support (weight %) was determined by powder energy-dispersive X-ray fluorescence analysis (Oxford Instruments X-Supreme8000). Example 4 (1.5 wt% Zr, on Q10, monomer Zr) Carrier modification was carried out as described in Example 3, except that 0.874 g of Zr(acac)4 was used. Example 5 (2.3 wt% Zr, on Q10, monomer Zr) The carrier modification was carried out as described in Example 3, except that 1.38 g of Zr(acac)4 was used and 20 mL of 1-PrOH (99%, Sigma Aldrich) was used instead of MeOH. In addition, stirring was continued for a 16-hour aging process, after which the solvent was removed. This resulted in a Zr utilization efficiency of 90%. Example 6 (2.7 wt% Zr, on Q10, monomer Zr) The carrier modification was carried out as described in Example 5, however, 1.67 g of Zr(acac)4 was used, and 20 mL of MeOH (99%, Sigma Aldrich) was used instead of 1-PrOH. This resulted in a Zr utilization efficiency of 89%. Example 7 (4.2 wt% Zr, on Q10, monomer Zr) The carrier modification was carried out as described in Example 5, however, 2.56 g of Zr(acac)4 was used, and 20 mL of toluene (99%, Sigma Aldrich) was used instead of 1-PrOH. This resulted in a Zr utilization efficiency of 93%. Example 8 (0.7 wt% Zr, on Q30, monomer Zr) The carrier modification was carried out as described in Example 6, except that 0.43 g of Zr(acac)4 was used and silica from Example 2 was used. This resulted in a Zr utilization efficiency of 93%. Example 9 (1.1% by weight Zr, on Q10, monomer Zr) The carrier modification was carried out as described in Example 5, however, 2.15 g of Zr(thd)4 was used and 20 mL of MeOH was used instead of 1-PrOH. This resulted in a Zr utilization efficiency of 47%. Example 10 (2.2 wt% Zr, on Q10, monomer Zr) The carrier modification was carried out as described in Example 9, except that 20 mL of toluene was used instead of MeOH. This resulted in a Zr utilization efficiency of 93%. Example 11 (3.9% by weight Zr, on Q10, monomer Zr) The carrier modification was carried out as described in Example 5, however, 3.19 g of Zr(siRNA)4 was used, and 20 mL of heptane (99%, Sigma Aldrich) was used instead of 1-PrOH. This resulted in a Zr utilization efficiency of 86%. Example 12 (6.7 wt% Zr, on Q10, dimerized Zr) The carrier modification was carried out as described in Example 5, however, 3.12 g of [Zr(OPr)3(acac)]2 was used, and 20 mL of heptane was used instead of 1-PrOH. This resulted in a Zr utilization efficiency of 95%. Example 13 (2.2 wt% Zr, on Q30, trimer Zr) (Comparative Example) 1.16 g of Zr(nOPr)4 (70 wt% in 1-propanol, Sigma Aldrich) was used. Furthermore, the carrier was modified as described in Example 5, except for 10 g of silica from Example 2 which replaced the silica from Example 1. This resulted in a 100% Zr utilization efficiency. Example 14 (6.0 wt% Zr, on Q10, trimer Zr) (Comparative Example) Except for 3.35 g of Zr(nOPr)4 (70% by weight in 1-propanol, Sigma Aldrich), the carrier was modified as described in Example 5. This resulted in a 100% Zr utilization efficiency. Example 15 (8.0 wt% Zr, on Q10, pentamer Zr) (Comparative Example) The carrier modification was carried out as described in Example 5, however, 2.67 g of zirconium(IV) ethoxide (97%, Sigma Aldrich) was dissolved in 20 mL of ethanol (anhydrous, Sigma Aldrich) along with 1.77 g of acetic acid (glacial acetic acid, Sigma Aldrich) instead of 1-PrOH. This resulted in a 100% Zr utilization efficiency. Hf modification of silica support Example 16 (5.4 wt% Hf, on Q10, monomer Hf) The carrier modification was carried out as described in Example 5, however, 1.37 g of Hf(iOPr)4 (99%, Sigma Aldrich) was dissolved together with 1.32 g of acetylacetone (99%, Sigma Aldrich) in 20 mL of 1-PrOH, mixed for 30 minutes, and then 10 g of silica from Example 1 was introduced. This resulted in an Hf utilization efficiency of 98%. Example 17 (7.8 wt% Hf, on Q10, monomer Hf) The carrier modification was carried out as described in Example 5, however, 2.00 g of Hf(iOPr)4 was dissolved in 20 mL of toluene together with 1.93 g of acetylacetone, mixed for 30 minutes, and then 10 g of silica from Example 1 was introduced. This resulted in 100% Hf utilization efficiency. Example 18 (11.8 wt% Hf, on Q10, trimer Hf) (Comparative Example) The carrier modification was carried out as described in Example 5, except that 3.19 g of Hf(iOPr)4 was dissolved in 20 mL of toluene instead of 1-PrOH. This resulted in a 100% Hf utilization efficiency. HRTEM analysis of modified carriers Example 19 (HRTEM analysis of monomeric Zr) High-resolution transmission electron microscopy (HRTEM) analysis was performed on selected examples of modified silica. For this purpose, the modified silica was thinned using a microtome to produce particles with a thickness of 100–200 nm. These thinned particles were placed on a copper mesh and coated with antistatic osmium vapor deposition. The mounted samples were then analyzed in transmission mode using a Tecnaql G2 F20 (FEI). The electron beam was set to an acceleration voltage of 100–300 kV and a spatial resolution of 1 nm. The electron beam was focused using a 30 μm diaphragm. HRTEM images were recorded at a magnification of 25 million times, with 50–200 metal nanoparticles per image. This analysis was performed on modified silica examples 5, 7, 14, 15, 17, and 18. Their HRTEM images are shown in Figures 1–6. Cs modification of modified carriers Example 20 (3.2 wt% Cs, 0.9 wt% Zr, monomer Zr) 0.458 g of CsOH·H2O (99.5%, Sigma Aldrich) was weighed out in a glove box and dissolved in 20 mL of MeOH:H2O (9:1 v / v) solvent mixture. With stirring, 10 g of modified silica from Example 3 was added to the CsOH solution. Stirring was continued for another 15 minutes, and then the sample was left in a sealed flask for 16 hours with periodic stirring. After that time, the excess porous solution was removed by filtration. A drying step was then performed, in which the solvent in the porous material was removed by passing a stream of nitrogen gas over the wet Zr-modified silica at room temperature. Alternatively, the solvent in the porous material was removed under reduced pressure on a rotary evaporator. Following this step, the catalyst bead-shaped molded material was placed in a drying oven at 110-120°C and left to dry for 16 hours. Upon cooling, this yielded a Cs / Zr / SiO2 catalyst with a Cs utilization efficiency of 90%. The amount of Cs supported on the catalyst (by weight %) was determined by powder energy-dispersive X-ray fluorescence analysis (Oxford Instruments X-Supreme8000). Example 21 (3.7 wt% Cs, 0.9 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 20, except that 0.534 g of CsOH·H2O was used. Example 22 (4.0 wt% Cs, 0.9 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 20, except that 0.588 g of CsOH·H2O was used. Example 23 (4.8 wt% Cs, 0.9 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 20, except that 0.716 g of CsOH·H2O was used. Example 24 (5.1 wt% Cs, 1.5 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 20, except that 0.754 g of CsOH·H2O was used and the modified silica from Example 4 was used. Example 25 (5.7 wt% Cs, 1.5 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 24, except that 0.852 g of CsOH·H2O was used. Example 26 (6.7 wt% Cs, 1.4 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 24, except that 1.00 g of CsOH·H2O was used. Example 27 (7.7 wt% Cs, 1.4 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 24, except that 1.17 g of CsOH·H2O was used. Example 28 (9.7 wt% Cs, 2.0 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 20, except that 1.37 g of CsOH·H2O was used and the modified silica from Example 5 was used. In addition, the Cs adsorption time was shortened from 16 hours to 2 hours and the filtration step was omitted. When the excess organic solvent was dried into the pore volume of the modified silica support, the Cs utilization efficiency was 100%. Example 29 (10.2 wt% Cs, 2.0 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 28, except that 1.45 g of CsOH·H2O was used. Example 30 (10.8 wt% Cs, 2.0 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 28, except that 1.54 g of CsOH·H2O was used. Example 31 (11.3 wt% Cs, 2.0 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 28, except that 1.62 g of CsOH·H2O was used. Example 32 (9.2 wt% Cs, 2.4 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 20, except that 1.44 g of CsOH·H2O was used and the modified silica from Example 6 was used. Example 33 (10.9 wt% Cs, 2.4 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 32, except that 1.74 g of CsOH·H2O was used. Example 34 (13.0 wt% Cs, 2.3 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 32, except that 2.12 g of CsOH·H2O was used. Example 35 (14.0 wt% Cs, 2.3 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 32, except that 2.30 g of CsOH·H2O was used. Example 36 (12.3 wt% Cs, 3.7 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 20, except that 2.00 g of CsOH·H2O was used and the modified silica from Example 7 was used. Example 37 (12.6 wt% Cs, 3.7 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 36, except that 2.05 g of CsOH·H2O was used. Example 38 (13.9 wt% Cs, 3.6 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 36, except that 2.30 g of CsOH·H2O was used. Example 39 (15.4 wt% Cs, 3.6 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 36, except that 2.60 g of CsOH·H2O was used. Example 40 (2.8 wt% Cs, 0.7 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 28, except that 0.37 g of CsOH·H2O was used and the modified silica from Example 8 was used. Example 41 (3.4 wt% Cs, 0.7 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 40, except that 0.45 g of CsOH·H2O was used. Example 42 (3.9 wt% Cs, 0.7 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 40, except that 0.51 g of CsOH·H2O was used. Example 43 (4.1 wt% Cs, 1.0 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 20, except that 0.60 g of CsOH·H2O was used and the modified silica from Example 9 was used. Example 44 (4.6 wt% Cs, 1.0 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 43, except that 0.68 g of CsOH·H2O was used. Example 45 (5.5 wt% Cs, 1.0 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 43, except that 0.82 g of CsOH·H2O was used. Example 46 (9.1% Cs by weight, 2.0% Zr by weight, Zr monomer) The catalyst was prepared as described in Example 20, except that 1.42 g of CsOH·H2O was used and the modified silica from Example 10 was used. Example 47 (9.9 wt% Cs, 1.9 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 46, except that 1.55 g of CsOH·H2O was used. Example 48 (13.8 wt% Cs, 3.3 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 20, except that 2.28 g of CsOH·H2O was used and the modified silica from Example 11 was used. Example 49 (15.0 wt% Cs, 3.3 wt% Zr, monomer Zr) The catalyst was prepared as described in Example 48, except that 2.51 g of CsOH·H2O was used. Example 50 (14.0 wt% Cs, 5.7 wt% Zr, dimer Zr) (Comparative Example) The catalyst was prepared as described in Example 20, except that 2.34 g of CsOH·H2O was used and the modified silica from Example 12 was used. Example 51 (15.0 wt% Cs, 5.7 wt% Zr, dimer Zr) (Comparative Example) The catalyst was prepared as described in Example 50, except that 2.54 g of CsOH·H2O was used. Example 52 (16.1% Cs by weight, 5.6% Zr by weight, dimer Zr) (Comparative Example) The catalyst was prepared as described in Example 50, except that 2.76 g of CsOH·H2O was used. Example 53 (17.3 wt% Cs, 5.5 wt% Zr, dimer Zr) (Comparative Example) The catalyst was prepared as described in Example 50, except that 3.01 g of CsOH·H2O was used. Example 54 (6.0 wt% Cs, 2.1 wt% Zr, trimer Zr) (Comparative Example) The catalyst was prepared as described in Example 28, except that 0.81 g of CsOH·H2O was used and the modified silica from Example 13 was used. Example 55 (7.7 wt% Cs, 2.0 wt% Zr, trimer Zr) (Comparative Example) The catalyst was prepared as described in Example 54, except that 1.06 g of CsOH·H2O was used. Example 56 (13.6 wt% Cs, 5.2 wt% Zr, trimer Zr) (Comparative Example) The catalyst was prepared as described in Example 28, except that 2.03 g of CsOH·H2O was used and the modified silica from Example 14 was used. Example 57 (14.9 wt% Cs, 5.1 wt% Zr, trimer Zr) (Comparative Example) The catalyst was prepared as described in Example 56, except that 2.26 g of CsOH·H2O was used. Example 58 (16.1% Cs by weight, 5.0% Zr by weight, trimer Zr) (Comparative Example) The catalyst was prepared as described in Example 56, except that 2.48 g of CsOH·H2O was used. Example 59 (17.3 wt% Cs, 5.0 wt% Zr, trimer Zr) (Comparative Example) The catalyst was prepared as described in Example 56, except that 2.70 g of CsOH·H2O was used. Example 60 (12.3 wt% Cs, 7.0 wt% Zr, Zr pentamer) (Comparative Example) The catalyst was prepared as described in Example 28, except that 1.82 g of CsOH·H2O was used and the modified silica from Example 15 was used. Example 61 (14.0 wt% Cs, 6.9 wt% Zr, Zr pentamer) (Comparative Example) The catalyst was prepared as described in Example 60, except that 2.12 g of CsOH·H2O was used. Example 62 (15.7 wt% Cs, 6.7 wt% Zr, Zr pentamer) (Comparative Example) The catalyst was prepared as described in Example 60, except that 2.42 g of CsOH·H2O was used. Example 63 (18.9% by weight Cs, 6.5% by weight Zr, Zr pentamer) (Comparative Example) The catalyst was prepared as described in Example 60, except that 2.99 g of CsOH·H2O was used. Example 64 (8.8 wt% Cs, 4.9 wt% Hf, monomer Hf) The catalyst was prepared as described in Example 28, except that 1.23 g of CsOH·H2O was used and the modified silica from Example 16 was used. Example 65 (10.1% Cs by weight, 4.9% Hf by weight, Hf monomer) The catalyst was prepared as described in Example 64, except that 1.43 g of CsOH·H2O was used. Example 66 (11.4 wt% Cs, 4.8 wt% Hf, monomer Hf) The catalyst was prepared as described in Example 64, except that 1.64 g of CsOH·H2O was used. Example 67 (12.6 wt% Cs, 4.7 wt% Hf, monomer Hf) The catalyst was prepared as described in Example 64, except that 1.84 g of CsOH·H2O was used. Example 68 (11.1% Cs by weight, 6.9% Hf by weight, Hf monomer) The catalyst was prepared as described in Example 28, except that 1.60 g of CsOH·H2O was used and the modified silica from Example 17 was used. Example 69 (12.7 wt% Cs, 6.8 wt% Hf, monomer Hf) The catalyst was prepared as described in Example 68, except that 1.86 g of CsOH·H2O was used. Example 70 (14.3 wt% Cs, 6.7 wt 5 Hf, monomer Hf) The catalyst was prepared as described in Example 68, except that 2.14 g of CsOH·H2O was used. Example 71 (15.8 wt% Cs, 6.6 wt% Hf, monomer Hf) The catalyst was prepared as described in Example 68, except that 2.41 g of CsOH·H2O was used. Example 72 (13.7 wt% Cs, 10.2 wt% Hf, trimer Hf) (Comparative Example) The catalyst was prepared as described in Example 20, except that 2.28 g of CsOH·H2O was used and the modified silica from Example 18 was used. Example 73 (14.9 wt% Cs, 10.0 wt% Hf, trimer Hf) (Comparative Example) The catalyst was prepared as described in Example 72, except that 2.51 g of CsOH·H2O was used. Example 74 (16.2 wt% Cs, 9.9 wt% Hf, trimer Hf) (Comparative Example) The catalyst was prepared as described in Example 72, except that 2.77 g of CsOH·H2O was used. Example 75 (16.0 wt% Cs, 3.4 wt% Zr, 100% monomer Zr) The catalyst was prepared as described in Example 20, except that 2.71 g of CsOH·H2O was used and 10 g of the modified silica from Example 7 was used. Furthermore, after drying the catalyst, it was ground using a mortar and pestle and sieved to obtain a size fraction of 0.1 to 1.0 mm. This yielded a 100% monomer catalyst based on weight %Zr. Example 76 (15.8% Cs by weight, 3.6% Zr by weight, 79% monomer Zr) (Comparative Example) The catalyst was prepared as described in Example 75, except that 2.67 g of CsOH·H2O was used. Furthermore, 8.5 g of modified silica from Example 7 and 1.5 g of modified silica from Example 14 were used as catalyst supports. This yielded a catalyst with a monomer content of 79% based on weight %Zr. Example 77 (15.4 wt% Cs, 3.9 wt% Zr, 61% monomer Zr) (Comparative Example) The catalyst was prepared as described in Example 75, except that 2.60 g of CsOH·H2O was used. Furthermore, 7 g of modified silica from Example 7 and 3 g of modified silica from Example 14 were used as catalyst supports. This yielded a catalyst with a monomer content of 61% based on weight %Zr. Example 78 (15.7 wt% Cs, 4.4 wt% Zr, 31% monomer Zr) (Comparative Example) The catalyst was prepared as described in Example 75, except that 2.66 g of CsOH·H2O was used. Furthermore, 4 g of modified silica from Example 7 and 6 g of modified silica from Example 14 were used as catalyst supports. This yielded a catalyst with a monomer content of 31% based on weight %Zr. Example 79 (16.9% Cs by weight, 5.0% Zr by weight, 0% monomer Zr) (Comparative Example) The catalyst was prepared as described in Example 75, except that 2.92 g of CsOH·H2O was used. Furthermore, 10 g of modified silica from Example 14 was used as the catalyst support. This resulted in a catalyst with 0% monomer content based on weight %Zr. Example 80 (Catalyst Performance Test) The catalysts from Examples 20 to 79 were tested in a laboratory-scale microreactor for the reaction between methyl propionate and formaldehyde. For this purpose, 3 g of catalyst was supported in a fixed-bed reactor with a tube inner diameter of 10 mm. The reactor was heated to 330°C, and pretreatment was carried out by feeding a stream of 70 wt% methyl propionate, 20 wt% methanol, 6 wt% water, and 4 wt% formaldehyde, evaporated from an evaporator fed at a rate of 0.032 mL / min via a Gilson pump. This pretreatment was continued overnight. After pretreatment, a feedstream containing 75.6 wt% methyl propionate, 18.1 wt% methanol, 5.7 wt% formaldehyde, and 0.6 wt% water was pumped by a Gilson pump to an evaporator set to 330°C, and then fed into a heated reactor set to 330°C containing the catalyst. The reactor outlet vapor was cooled and condensed, and samples were collected at five different liquid feed rates (0.64–0.032 mL / min) to determine the conversion rates at different vapor / catalyst contact times. The liquid feed and the condensed liquid product from the reactor outlet were analyzed using a Shimadzu 2010 Gas Chromatograph fitted with a DB1701 column. The composition of each sample was determined from its chromatogram, and the yield and selectivity at different contact times were calculated. Activity was defined as the reciprocal of the contact time (in seconds) required to obtain a 10% (MMA+MAA) yield relative to the fed methyl propionate, and was determined by interpolating the graph of contact time versus (MMA+MAA) yield. The (MMA+MAA) selectivity at a 10% (MMA+MAA) yield was then obtained using this interpolated contact time.

[0133] [Table 1]

[0134] [Table 2]

[0135] [Table 3]

[0136] [Table 4]

[0137] Example 81 (Accelerated Aging Test) The sintering resistance of the catalyst was evaluated in an accelerated aging test. For this purpose, 1 g of catalyst was supported in a U-tube stainless steel reactor and placed in an oven. The oven was heated to 385°C, and a nitrogen stream (10 mL / min) was passed through a saturated evaporator containing water heated to 92°C. This allowed a feedstream with a partial pressure of water of 0.75 bar to pass over the catalyst heated to 385°C. Periodically, the surface area of ​​the catalyst sample was determined by excision using nitrogen adsorption / desorption isothermal analysis (Micromeretics Tristar II). The sintering rate constant for each catalyst was determined using the measured surface area values. 3 ·m -6 ·d -1 The units were expressed as follows. A higher sintering constant indicates lower sintering resistance of the catalyst. This test was performed on Examples 32, 38, 57, and 63.

[0138] [Table 5]

[0139] Comparative Examples 82 and 83 Examples were prepared according to the experimental examples described in European Patent No. 1233330. The silica used in these examples was gel silica in the form of spheres with a diameter ranging from 2 to 4 mm, with a purity exceeding 99% and approximately 300 to 350 ml. 2 Total surface area and 1.04 cm² / g 3 It has a pore volume of 1 / g, and 76% of that pore volume is occupied by pores with diameters in the range of 7 to 23 nm.

[0140] Two catalysts were prepared by impregnating silica with an aqueous solution of zirconium nitrate sufficient to fill the pores of the support, and then drying in a rotary evaporator and then in an air oven at 120 °C for 2 hours. In one case (Example 82), impregnation of the zirconium solution was assisted by evacuating the pores of the support before adding the solution. In another case (Example 83), impregnation of the zirconium solution was carried out under atmospheric air. Then, cesium was incorporated by a similar procedure using an aqueous solution of cesium carbonate to obtain a cesium content of 4 wt% (expressed as a metal). Then, the catalysts were calcined in air at 450 °C for 3 hours.

[0141] The catalysts were tested under the same conditions as described in Example 80. One catalyst (Example 82) was unable to achieve a 10% yield, but the selectivity showed the highest yield obtained (9.6%).

[0142]

Table 6

[0143] HRTEM results for silica supports modified with Zr and Hf HRTEM images (Example 19) of examples of silica modified with Zr and Hf (Examples 5, 7, 14, 15, 17 and 18) are shown in Figures 1 to 6. In the case of the HRTEM images of monomeric Zr and Hf, it is difficult to clearly distinguish Zr or Hf particles, which suggests that they are very fine Zr / Hf nanoparticles present on the modified silica surface. This is because Zr or Hf exists as single atoms. In the case of examples of trimeric Zr and Hf and pentameric Zr, distinct clusters of Zr or Hf can be distinguished on the HRTEM images of the modified supports. This data indicates that the polynuclearity of the Zr or Hf species in the solution phase is carried over from the solution to the final catalyst formulation. Graph data Data on activity and selectivity constructed from Tables 1 and 2.

[0144] Figure 7 shows the (MMA+MAA) selectivity (%) versus catalytic activity for the catalysts prepared in Examples 20 to 74. From this graph, it is clear that trimer Zr and Hf, and even pentamer Zr, yield lower (MMA+MAA) selectivity across the entire activity range examined. Dimer Zr catalysts show improved selectivity compared to trimer Zr catalysts, even with equivalent Zr and Cs loading rates. Activity and selectivity data were constructed from Table 3.

[0145] Figure 8 shows the catalyst selectivity for the mixed monomer / trimer catalysts prepared in Examples 75 to 79. The Zr monomer content is calculated as the percentage of Zr present as monomers. In these examples, the catalyst was ground and sieved to obtain particles of 0.1 to 1.0 mm in order to improve the homogeneity of the samples. From this graph, it is clear that reducing the amount of Zr monomer in the formulation will result in a decrease in the (MMA+MAA) selectivity. Sintering resistance data constructed from Table 4.

[0146] Figure 9 shows the catalyst sintering constants obtained by the accelerated aging test described in Example 81. From Figure 9, it is clear that for equivalent catalytic activity, monomeric Zr catalysts exhibit lower sintering rates.

[0147] Attention is paid to all papers and documents related to this application that were filed concurrently with or prior to this specification and made available to the public together with this specification, and the contents of all such papers and documents are cited and incorporated herein by reference.

[0148] All features and / or all steps of any method or process disclosed herein (including the appended claims, abstract and drawings) may be combined in any combination, except in any combination in which at least some of such features and / or steps are incompatible with one another.

[0149] Each feature disclosed herein (including the attached claims, abstract and drawings) may be replaced by an alternative feature serving the same, equivalent, or similar purpose, unless expressly otherwise stated. Therefore, unless expressly otherwise stated, each disclosed feature is merely one example of a general series of equivalent or similar features.

[0150] The present invention is not limited to the details of the embodiments described above. The present invention extends to any novel or novel combination of any preferred, typical or any feature of the present invention disclosed herein (including the appended claims, abstract or drawings), or to any novel or novel combination of any preferred, typical or any step of the present invention of any method or process so disclosed herein.

Claims

1. A modified silica support for a catalyst comprising a silica support and a modified metal, wherein the modified metal is selected from at least one of zirconium and hafnium, characterized in that at least a portion of the modified metal exists as residues of monomeric and / or dimeric metal oxides, or is induced from a monomeric and / or dimeric modified metal cation source at the start of modification, and the level of the modified metal present is up to 7.6 × 10⁻² mol / mol of silica.

2. The modified silica support according to claim 1, wherein at least 25% of the modified metal exists as residues of monomeric and / or dimeric metal oxides, or is derived from a cation source of monomeric and / or dimeric modified metal at the start of modification.

3. The modified metal is an adsorbent adsorbed on the surface of the silica support. The modified metal residue is a residue of a modified metal oxide. The silica support is in the form of silica gel. The modified metal is present in the carrier in the form of a cogel. The modified metal is present in the modified silica support in an amount effective in reducing sintering and improving the selectivity of the catalyst. The level of the modified metal is 0.067 × 10⁻⁶ of silica. －２ ~7.3 x 10 －２ Being mol / mol, The level of the modified metal present is at least 0.1 × 10⁻⁶ of silica. －２ Being mol / mol, The modified silica support is a calcined modified silica support. The catalyst metal is one or more alkali metals. The catalyst metal is selected from potassium, rubidium, and cesium, and The aforementioned support has isolated silanol groups (-SiOH) at 1 nm ２ A modified silica support according to claim 1 or 2, wherein at least one of the following is required: containing at a level of less than 2.5 groups per unit.

4. The monomeric and / or dimeric modified metal cation is present in a compound having one or more chemically unresponsive ligands bonded to the modified metal cation at the start of the modification. The ligands that are less susceptible to the aforementioned chemical changes are selected from molecules having lone pairs of electrons containing oxygen or nitrogen atoms capable of forming a five-membered or six-membered ring together with zirconium or hafnium atoms, or from diones, diimines, diamines, diols, dicarboxylic acids or their derivatives, or molecules having two different such functional groups and in either case forming a five-membered or six-membered ring together with the respective N or O atoms and N or O atoms separated by two or three atoms, and The modified silica support according to any one of claims 1 to 3, wherein the ligand that is less susceptible to the aforementioned chemical change forms a complex with the modifying element, at least one of the above.

5. A method for producing a modified silica support according to any one of claims 1 to 4, A step of providing a silica support having a silanol group, A step of treating the silica support with a monomeric and / or dimeric modified metal compound, wherein the modified metal is adsorbed onto the surface of the silica support through a reaction with silanol groups, and the adsorbed modified metal atoms are sufficiently separated from each other to prevent oligomerization with neighboring modified metal atoms, Having, The spacing of the modified metal atoms is a) To reduce the concentration of silanol groups on the silica support, and b) A method comprising at least one of the following: binding a sufficiently sized, chemically inactive ligand to the modified metal before processing the silica support.

6. A method for producing a modified silica support for a catalyst according to any one of claims 1 to 4, i. A step of providing a silica support having isolated silanol groups; ii. A method comprising the step of contacting the silica support with a monomeric zirconium-modified metal compound or a hafnium-modified metal compound to adsorb at least 25% of the isolated silanol groups of the modified metal on the support.

7. The silanol group concentration is reduced by calcination, chemical dehydration or other appropriate method before treatment with the modified metal compound, and The method according to claim 5 or 6, wherein the cation source of the modified metal is a solution of the compound, and the compound is in the solution when it is brought into contact with the carrier to carry out adsorption onto the carrier.

8. One or more chemically unresponsive ligands are selected from molecules having lone pairs of electrons containing oxygen or nitrogen atoms that can bond to the modified metal cation to form at least partially the compound and form a five-membered or six-membered ring together with a zirconium or hafnium atom, or from molecules having two different such functional groups and in either case together with the respective N or O atoms and two or three atoms separated by N or O atoms to form a five-membered or six-membered ring. The silanol concentration on the silica support when in contact with the modified metal compound is 1 nm ２ Each compound has 0.1 to 2.5 silanol groups, and The method according to any one of claims 5 to 7, wherein, when the source is in contact with the carrier to carry out the adsorption of the compound onto the carrier, at least 30% of the modified metal in the modified metal compound is in monomeric modified metal compound.

9. The silica support is dried or calcined before treatment with the modified metal compound. The modified silica formed by contacting the modified metal compound is dried or calcined before the addition of the catalyst metal. The silica is in the form of a gel before treatment with the modified metal compound, and The method according to any one of claims 5 to 8, wherein at least one of the following is required: the modified metal is dispersed on the inner surface and the outer surface of the silica carrier by adsorption.

10. The modified metal compound is in a form selected from organometallic complexes. The modified metal compound is zirconium(pentane-2,4-dione) ４ , zirconium(ethyl 3-oxobutanoate) ４ , zirconium(heptane-3,5-dione) ４ , zirconium(2,2,6,6-tetramethylheptane-3,5-dione) ４ , zirconium(propoxide)(pentane-2,3-dione) ３ , zirconium(propoxide) ３ (2,2,6,6-tetramethyl-3,5-heptanedione), zirconium(butyl) ３ (t-butyl 3-oxobutanoate), zirconium(Ot-butyl) ２ (t-butyl 3-oxobutanoate) ２ and is an organometallic complex selected from metal salts The catalyst metal is one or more alkali metals. The catalyst metal is selected from potassium, rubidium, and cesium, and The method according to any one of claims 5 to 9, wherein the formed catalyst is subsequently calcined, the method comprising at least one of these.

11. The modified metal compound is in a form selected from organometallic complexes, and The modified metal compound is zirconium (pentane-2,4-dione). ４ Zirconium (3-ethyl oxobutanoate) ４ Zirconium (heptane-3,5-dione) ４ Zirconium (2,2,6,6-tetramethylheptane-3,5-dione) ４ Zirconium (propoxide) (pentan-2-3-dione) ３ Zirconium (propoxide) ３ (2,2,6,6-tetramethyl-3,5-heptanedione), zirconium (butyl) ３ (3-oxobutanoate t-butyl), zirconium (Ot-butyl) ２ (3-T-butyl oxobutanoate) ２ A modified silica support according to any one of claims 1 to 4, wherein at least one of the following is required: it is an organometallic complex selected from metal salts.

12. A method for producing a modified silica support according to any one of claims 1 to 4, A step of providing a silica support having silanol groups; A method comprising the step of treating the silica support with a monomeric and / or dimeric modified metal compound, wherein the modified metal is adsorbed onto the surface of the silica support through a reaction with a silanol group, and the adsorbed modified metal atoms are sufficiently separated from each other to prevent oligomerization with neighboring modified metal atoms.

13. The aforementioned support has isolated silanol groups (-SiOH) at 1 nm ２ It must contain fewer than 2.5 elements per unit. The carrier is 1 nm ２ It contains the zirconium-modified metal residue or hafnium-modified metal residue present at a level of less than 2.5 residues per unit. The aforementioned support has isolated silanol groups (-SiOH) at 1 nm ２ It contains more than 0.1 and less than 2.5 elements per unit, and The carrier has the zirconium-modified metal residue or hafnium-modified metal residue at 1 nm ２ A modified silica support according to any one of claims 1 to 4, wherein it is required to contain at least one of the following: more than 0.025 groups and less than 2.5 groups per unit.

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