Porous carbon carrier supported catalyst, preparation method and application thereof

Abstract

The invention discloses a porous carbon carrier supported catalyst as well as a preparation method and application thereof. In the catalyst provided by the invention, the content of the active metal components distributed in the pore channels of the porous carbon carrier is more than 50% relative to the content of all the active metal components in the catalyst on the basis of the active metal oxide. The catalyst disclosed by the invention is stable in property in a system, an active center is not easy to lose, and the problems that active components of a heterogeneous catalyst are easy to lose and the service life of the catalyst is short in the prior art are solved; in addition, when the catalyst provided by the invention is used for preparing dialkyl carbonate, excellent conversion rate and selectivity are shown.

Description

Technical Field

[0001] The present invention provides a supported catalyst, and more specifically relates to a catalyst in which active metal components are mainly supported in pores of a porous carbon carrier, a preparation method of the catalyst, and application of the catalyst in preparing dialkyl carbonate. Background Art

[0002] Dimethyl carbonate (DMC) is a new low-pollution, environmentally friendly green basic chemical raw material with active chemical properties, excellent physical properties, non-toxicity and biodegradability. It can be used as a solvent, gasoline additive, lithium-ion battery electrolyte, and carbonylation, methylation and carbonyl methoxylation reagent. It is widely used in the field of chemistry and chemical engineering. At present, all countries are actively studying green chemical processes based on DMC, an environmentally friendly chemical raw material. Among them, the ester exchange method is superior to the mild reaction conditions, high yield and co-production of ethylene glycol or propylene glycol, making it a method with great industrial prospects.

[0003] Generally speaking, alkali metal hydroxides, alkali metal carbonates and alkali metal alcohols (US2011040117A1; WO2010063780A1) are used as catalysts in transesterification reactions. However, since they are homogeneous catalysts, they are not easily separated from the product and are difficult to reuse. Commonly used heterogeneous catalysts include alkali metals or alkali metal salts supported on a carrier, metal oxide catalysts, zeolites or clay materials exchanged with alkaline (earth) metals, and ion exchange resins. Alkali metals or alkali metal salts loaded on a carrier, such as KF / Al2O3, NaOH / chitosan and Cs2CO3 / SiO2-Al2O3, etc. (CN101249452A; CN101121147A; WO2001056971A1), have the disadvantage that they are easily affected by water and CO2 in the air, and are easily lost during the reaction, resulting in decreased activity; metal oxide catalysts, such as Al2O3, MgO, etc. (US2005080287A1; US6207850B1), and zeolites or clay materials exchanged with alkaline (earth) metals, such as Cs-ZSM-5, Mg-smectite, etc. (WO2000073256A1), these two types of catalysts have the disadvantage that their activity or selectivity is usually relatively low; ion exchange resins, such as quaternary ammonium or tertiary amine resins, these catalysts are usually not temperature-resistant or swelling-resistant, and their activity decreases rapidly over a long period of time.

[0004] Therefore, it is still an urgent need in the art to find a catalyst for preparing dialkyl carbonate with high stability and high conversion rate. Summary of the invention

[0005] In view of the above situation, the inventors of the present invention conducted in-depth research and surprisingly found that by loading the active metal components on a modified resin carrier and then calcining the resin carrier, a catalyst can be obtained in which the active metal components are mainly distributed in the pores of the porous carbon carrier. The catalyst shows excellent stability and high catalytic activity, thus completing the present invention.

[0006] Specifically, the first aspect of the present invention provides a porous carbon carrier-supported catalyst, characterized in that it includes a porous carbon carrier, an active metal component and at least one heteroatom selected from nitrogen, sulfur and phosphorus, wherein, relative to the total mass of the catalyst, the content of the porous carbon carrier is 50% to 99%, the content of the active metal component calculated as active metal oxide is 0.1% to 50%, and the content of the heteroatom calculated as element is 0.1% to 5%; the active metal is at least one selected from magnesium, aluminum, and calcium, and the content of the active metal component distributed in the pores of the porous carbon carrier, calculated as active metal oxide, accounts for more than 50% of the content of all active metal components in the catalyst.

[0007] A second aspect of the present invention provides a method for preparing a catalyst, comprising the following steps:

[0008] (1) a modification step of contacting the halogenated alkylated resin with a modifier to modify the resin and obtain a modified halogenated alkylated resin;

[0009] (2) a contacting step of contacting the modified halogenated alkylated resin with a metal precursor of an active metal to obtain a contact product; and

[0010] (3) A calcining step of optionally drying the contact product and then calcining it in an inert gas atmosphere.

[0011] The third aspect of the present invention provides a method for preparing dialkyl carbonate, wherein a carbonate and a lower alcohol are reacted in the presence of the above-mentioned catalyst of the present invention or a catalyst prepared by the preparation method of the present invention to obtain dialkyl carbonate.

[0012] Technical Effects

[0013] In the catalyst of the present invention, compared with the active metal components distributed on the surface of the porous carbon carrier, the content of the active metal components entering the pores of the porous carbon carrier and distributed in the pores is higher, and the proportion of the content of all active metal components contained in the catalyst exceeds 50%. Therefore, the catalyst of the present invention shows excellent conversion rate and selectivity in the preparation of dialkyl carbonate, and the catalyst has a long life and is suitable for industrial use. In addition, when the carbon carrier catalyst is used to prepare dialkyl carbonate, the properties of the catalyst system are stable, and the active center is not easy to lose, which solves the problem that the active components of the heterogeneous catalyst are easy to lose and the catalyst life is short in the prior art.

[0014] In the preparation method of the catalyst of the present invention, by adopting a spherical porous resin carrier, the carrier utilization rate and active center density can be effectively improved, and the problem of low activity of heterogeneous catalysts existing in the prior art is solved; by modifying the resin, and then loading the precursor of the active metal, and then calcining, the active metal component is allowed to enter the pores of the carbon carrier more, thereby, the catalyst of the present invention can be efficiently prepared.

[0015] In the preparation method of dialkyl carbonate of the present invention, the catalyst of the present invention or the catalyst prepared by the preparation method of the present invention is used to prepare dialkyl carbonate from carbonate and lower alcohol with high conversion rate of dialkyl carbonate and high selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a scanning electron microscope image of the catalyst C1 prepared in Example 1 of the present invention;

[0017] Figure 2 This is a scanning electron microscope image of the catalyst S1 prepared in Comparative Example 1 of the present invention;

[0018] Figure 3 Transmission electron microscopy image of catalyst C1 prepared in Example 1 of the present invention;

[0019] Figure 4 Transmission electron microscopy image of catalyst S1 prepared in Comparative Example 1 of the present invention.

[0020] Figure 5 (a) Scanning electron microscope image of catalyst C1 prepared in Example 1 of the present invention at a scale of 100 microns; (b) Scanning electron microscope image of the interior of the catalyst prepared in Example 1 of the present invention at a scale of 10 microns.

[0021] Figure 6 (a) A scanning electron microscope image of the interior of the catalyst C1 prepared in Example 1 of the present invention at a scale of 200 nanometers; (b) A scanning electron microscope image of the interior of the catalyst C1 prepared in Example 1 of the present invention at a scale of 100 nanometers.

[0022] Figure 7 Energy spectrum surface scan and EDX spectrum of catalyst C1 prepared in Example 1 of the present invention; (a) selected area surface scan spectrum; (b) carbon element distribution diagram; (c) oxygen element distribution diagram; (d) magnesium element distribution diagram; (e) EDX energy spectrum diagram.

[0023] Figure 8 (a) Scanning electron microscope image of the catalyst S1 prepared in comparative example 1 of the present invention at a scale of 100 microns; (b) Scanning electron microscope image of the interior of the catalyst S1 prepared in comparative example 1 of the present invention at a scale of 20 microns.

[0024] Fig. 9 (a) A scanning electron microscope image of the interior of the catalyst S1 prepared in Comparative Example 1 of the present invention at a scale of 200 nanometers; (b) A scanning electron microscope image of the interior of the catalyst S1 prepared in Comparative Example 1 of the present invention at a scale of 100 nanometers.

[0025] Fig.10 Energy spectrum surface scan and EDX spectrum of catalyst S1 prepared in comparative example 1 of the present invention; (a) selected area surface scan spectrum; (b) carbon element distribution diagram; (c) EDX energy spectrum diagram. DETAILED DESCRIPTION

[0026] The present invention is described in detail below in conjunction with specific implementations, but it should be noted that the protection scope of the present invention is not limited by these specific implementations and principle explanations, but is determined by the claims.

[0027] In the present invention, except for the contents explicitly described, any matters or items not mentioned are directly applicable to the contents known in the art without any changes. Moreover, any embodiment described herein can be freely combined with one or more other embodiments described herein, and the technical solutions or technical ideas formed thereby are regarded as part of the original disclosure or record of the present invention, and should not be regarded as new contents not disclosed or anticipated herein, unless a person skilled in the art considers that the combination is obviously unreasonable.

[0028] All features disclosed in the present invention may be combined arbitrarily, and these combinations shall be understood as the contents disclosed or recorded in the present invention, unless a person skilled in the art considers that the combination is obviously unreasonable, and shall be deemed to be specifically disclosed and recorded in the present invention. The numerical points disclosed in this specification, unless otherwise specified, include not only the numerical points specifically disclosed in the embodiments, but also the endpoints of each numerical range in the specification, and the range of any combination of these numerical points shall be deemed to be the range disclosed or recorded in the present invention.

[0029] The technical and scientific terms in the present invention shall be based on their definitions if they are defined, and shall be understood according to the general meaning in the art if no definitions are given.

[0030] [Carbon Support Catalyst]

[0031] The present invention provides a porous carbon carrier-supported catalyst, which comprises a porous carbon carrier, an active metal component and at least one heteroatom selected from nitrogen, sulfur and phosphorus, wherein the content of the porous carbon carrier is 50% to 99% relative to the total mass of the catalyst, the content of the active metal component calculated as active metal oxide is 0.1% to 50%, and the content of the heteroatom calculated as element is 0.1% to 5%; the active metal is at least one selected from magnesium, aluminum, and calcium, and the content of the active metal component distributed in the pores of the porous carbon carrier, calculated as active metal oxide, accounts for more than 50% of the content of all active metal components in the catalyst.

[0032] In the catalyst of the present invention, the porous carbon carrier comes from the calcination of the porous resin material in an inert gas.

[0033] In the catalyst of the present invention, the particle size of the porous carbon carrier is not particularly limited, and the particle size can be 0.1 mm to 3 mm, preferably 0.3 mm to 2 mm. The pore size of the porous carbon carrier of the present invention is not particularly limited, and can be, for example, 5 to 500 nm, preferably 50 to 300 nm.

[0034] In one embodiment of the present invention, the content of the porous carbon support is 50% to 99%, preferably 55 to 90%, and more preferably 60 to 85%, relative to the total mass of the catalyst.

[0035] In the present invention, at least one heteroatom selected from nitrogen, sulfur and phosphorus comes from the modifier used in preparing the catalyst. In the calcination step, the modifier is calcined to leave at least one heteroatom selected from nitrogen, sulfur and phosphorus.

[0036] In one embodiment of the present invention, the content of at least one heteroatom selected from nitrogen, sulfur and phosphorus is 0.1% to 5% by element relative to the total mass of the catalyst; preferably 0.3 to 4.5%, more preferably 0.5 to 4%.

[0037] In the present invention, the catalyst further contains oxygen element, but the present invention is not intended to limit the content of oxygen element. Generally, the content of oxygen element is calculated in the oxide of the present invention.

[0038] In one embodiment of the present invention, the catalyst may also contain halogen elements, which come from the halogenated alkylated resin. Generally, during calcination, the halogen elements are calcined and removed, but there may still be halogen elements as impurities, and the present invention does not intend to limit the content of the halogen elements.

[0039] In the present invention, the content of active metal components in terms of oxides, the content of heteroatoms in terms of elements, and the content of halogen atoms in terms of elements contained in the catalyst can be determined by means known in the art such as elemental analysis. After deducting the content of active metal oxides, the content of heteroatoms, and the content of halogen atoms in terms of elements, the remaining content is recorded as the content of the porous carbon support of the present invention. In the present invention, the active metal oxide is derived from the calcined product of the precursor of the active metal introduced during the catalyst preparation process.

[0040] In one embodiment of the present invention, the content of the active metal component calculated as active metal oxide is 0.1% to 50%, preferably 5 to 45%, and more preferably 10 to 40%, relative to the total mass of the catalyst.

[0041] In one embodiment of the present invention, the active metal is at least one selected from magnesium, aluminum, and calcium, preferably at least one selected from magnesium and calcium.

[0042] In the catalyst of the present invention, the active metal component in the catalyst of the present invention includes any valence state and any oxidation state of the active metal. Generally, in the catalyst of the present invention, the active metal component usually exists in the form of metal oxide, which is the product of the calcination of the precursor of the active metal.

[0043] In the present invention, unless otherwise specified, the active metal component is usually measured in the form of active metal oxide.

[0044] In the catalyst of the present invention, the content of active metal components distributed in the pores of the porous carbon carrier (sometimes also referred to as the inner surface or interior in the present invention) is higher than that distributed on the surface of the porous carbon carrier (sometimes also referred to as the outer surface or exterior in the present invention).

[0045] In one embodiment of the present invention, the content of the active metal component distributed in the pores of the porous carbon carrier relative to the content of the active metal component contained in the catalyst is more than 50%, preferably 55% or more, more preferably 60% or more, further preferably 65% ​​or more, and most preferably 75% or more. The upper limit of the content of the active metal component distributed in the pores of the porous carbon carrier relative to the content of the active metal component contained in the catalyst is not particularly limited, preferably 100%, but from the perspective of actual production cost, the upper limit can be 99%, 98%, 96%, 96%, 95%.

[0046] In one embodiment of the present invention, the content of the active metal component distributed on the surface (external surface or exterior) of the porous carbon carrier relative to the content of the active metal component contained in the catalyst is less than 50%, preferably less than 45%, more preferably less than 40%, further preferably less than 35%, and most preferably less than 30%. The lower the lower limit of the content of the active metal component distributed on the surface (external surface or exterior) of the porous carbon carrier relative to the content of the active metal component contained in the catalyst, the better, preferably 0, but from the perspective of actual production cost, the lower limit can be 5%, 4%, 3%, 2%, 1%.

[0047] In the present invention, the content of the active metal component distributed on the surface (external surface or outside) of the porous carbon carrier can be measured by XPS. That is, in the present invention, the content of the active metal of the porous carbon carrier measured by XPS is used as the content of the active metal on the surface (external surface or outside) of the porous carbon carrier.

[0048] It should be noted that, in the present invention, the content of active metal components in the pores (inner surface or inside) of the porous carbon carrier can be obtained by subtracting the content of active metal components distributed on the surface (outer surface or outside) of the porous carbon carrier from the total content of active metal components in the porous carbon carrier. Here, for the total content of active metal components in the catalyst, the content of active metal components contained in the catalyst can be determined by elemental analysis, etc.; on the other hand, in the present invention, the content of active metal components in the porous carbon carrier determined by XPS is taken as the content of active metal components on the surface (outer surface or outside) of the porous carbon carrier. Thus, based on these two, the content of active metal components distributed in the pores (inner surface or inside) of the porous carbon carrier can be calculated, and the content of active metal components in the pores (inner surface or inside) = the total content of active metal components in the porous carbon carrier - the content of active metal components distributed on the surface (outer surface or outside) of the porous carbon carrier determined by XPS.

[0049] In the present invention, by making the active metal components mainly (for example, more than 50%) distributed in the pores of the porous carbon carrier, and more preferably making most of the active metal components (for example, more than 55%, preferably more than 60%, further preferably more than 65%, most preferably more than 70%) distributed in the pores of the porous carbon carrier, the catalyst exhibits excellent conversion rate and high selectivity, and the catalyst life is greatly extended.

[0050] In one embodiment of the present invention, a catalyst for preparing dimethyl carbonate is provided, comprising a carrier and an active component, characterized in that the mass percentages of the carrier and the active component in the catalyst are: 50% to 99.9% of the carrier, and 0.1% to 50% of the active component; the carrier is carbon, and the active component is selected from at least one of magnesium, calcium, and aluminum; the carbon is obtained by carbonizing a modified chloromethyl resin;

[0051] The active components are distributed on the surface of the carrier and in the pores of the carrier, and the content of the active components in the pores of the carrier is greater than the content of the active components on the surface of the carrier.

[0052] Method for preparing catalyst

[0053] A second aspect of the present invention provides a method for preparing a catalyst, comprising the following steps:

[0054] (1) a modification step of contacting the halogenated alkylated resin with a modifier to modify the resin and obtain a modified halogenated alkylated resin;

[0055] (2) a contacting step of contacting the modified halogenated alkylated resin with a metal precursor of an active metal to obtain a contact product; and

[0056] (3) a calcination step of optionally drying the contact product and then calcining it in an inert gas atmosphere,

[0057] The modifier is at least one compound selected from nitrogen-containing compounds, sulfur-containing compounds and phosphorus-containing compounds.

[0058] The inventors of the present invention have found that by modifying the halogenated alkylated resin with a modifier, allowing the modified resin to interact with an active metal precursor, and then calcining it, a catalyst in which the active metal components are mainly distributed in the pores of a porous carbon carrier can be obtained.

[0059] In the present invention, examples of the halide or halogen include fluorine, chlorine, bromine and iodine, preferably chlorine or iodine, more preferably chlorine.

[0060] In the present invention, the alkyl group in the alkylation may be a C1-C6 alkyl group, preferably a C1-C4 alkyl group, and more preferably a methyl group, an ethyl group, a propyl group, and an isopropyl group.

[0061] In one embodiment of the present invention, the haloalkylation is preferably halomethylation, more preferably chloromethylation.

[0062] In the present invention, the halogenated alkylated resin can be obtained by halogenated alkylation (preferably halomethylation, more preferably chloromethylation) of a common resin, or a commercially available halogenated alkylated resin can be used as long as the resin has a porous structure.

[0063] In the present invention, examples of the halogenated alkylated resin include halogenated alkylated styrene resins, such as chloromethyl resins, particularly chloromethyl styrene resins.

[0064] As halogenated alkylated styrene resin, it can be a commercial product, and it can also be prepared by methods known in the art, including but not limited to the following method: using halogenated olefins (C2-C6 halogenated olefins) to alkylate polystyrene to produce halogenated alkyl polystyrene (CN1137788A). In addition, as chloromethyl styrene resin, it can be a commercial product, and it can also be prepared by methods known in the art, including but not limited to the following method: preparing polystyrene microsphere resin by suspension polymerization, and reacting with chloromethyl ether to obtain chloromethyl styrene resin (CN103864973A). In addition, it is also possible to prepare halogenated alkylated styrene resin or chloromethyl styrene resin with reference to the method recorded in CN103709278A, CN104788592A, etc.

[0065] In one embodiment of the present invention, the particle size of the halogenated alkylated resin is 0.1 mm to 3 mm, preferably 0.3 mm to 2 mm.

[0066] In one embodiment of the present invention, the pore size of the halogenated alkylated resin is 5 to 500 nm, preferably 50 to 300 nm.

[0067] In one embodiment of the present invention, the halogenated alkylated resin is spherical.

[0068] In step (1) of the present invention, the modifier is brought into contact with the halogenated alkylated resin for modification to obtain a modified halogenated alkylated resin (hereinafter sometimes referred to as a modified product or modified resin). The present invention does not intend to restrict the reaction at this time, and it is speculated that it may be due to the interaction between the nitrogen, phosphorus or sulfur heteroatoms contained in the modifier and the halogenated alkyl group. In addition, the introduced heteroatoms can promote the dispersion of the subsequent active metal precursor inside the carrier, increase the dispersion of the metal active component, promote alkalinity, and promote the deposition of the active metal component in the pores of the porous carbon carrier after calcination.

[0069] Therefore, in the present invention, the modifier is at least one compound selected from the group consisting of nitrogen-containing compounds, sulfur-containing compounds and phosphorus-containing compounds.

[0070] In one embodiment of the present invention, the nitrogen-containing compound is a nitrogen-containing organic compound.

[0071] In one embodiment of the present invention, the nitrogen-containing organic compound is not particularly limited as long as it is an organic compound containing a nitrogen atom, and alkylamines or 5-membered or 6-membered nitrogen-containing heterocyclic aromatic compounds can be used. As alkylamines, for example, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, cyclohexylamine, octylamine, decylamine, dimethylamine, diethylamine, dibutylamine, trimethylamine, triethylamine, tributylamine, etc. can be listed. As a 5-membered or 6-membered nitrogen-containing heterocyclic aromatic compound, at least one of a 5-membered or 6-membered nitrogen-containing heterocyclic aromatic compound optionally substituted by a C1-C6 alkyl group can be listed. As a 5-membered or 6-membered nitrogen-containing heterocyclic aromatic compound, at least one of piperazine, pyridine, imidazole, 1-methylimidazole, quinoline, pyrrole, indole, carbazole, isoindole, and thiazole can be listed. These nitrogen-containing heterocyclic aromatic compounds are optionally substituted by a C1-C6 alkyl group. In the present invention, the C1-C6 alkyl group is preferably a C1-C4 alkyl group, more preferably a methyl group, an ethyl group, a propyl group, or an isopropyl group. In one embodiment of the present invention, the number of substituents "substituted by a C1-C6 alkyl group" may be 1, 2, 3, 4 or 5, preferably 1, 2 or 3, more preferably 1 or 2.

[0072] In one embodiment of the present invention, the sulfur-containing compound is a sulfur-containing organic compound.

[0073] In one embodiment of the present invention, the sulfur-containing organic compound is not particularly limited as long as it is an organic compound containing a sulfur atom, and examples thereof include sulfides such as dimethyl sulfide, diethyl sulfide, dipropyl sulfide, dihexyl sulfide, dicyclohexyl sulfide and diphenyl sulfide; dialkyl disulfide compounds such as dimethyl disulfide, diethyl disulfide, dipropyl disulfide, dibutyl disulfide, dihexyl disulfide, dicyclohexyl disulfide and ethyl methyl disulfide; thiophenes such as thiophene, 2-methylthiophene, 3-methylthiophene, 2,3-dimethylthiophene, 2-ethylthiophene and benzothiophene optionally substituted with a C1-C6 alkyl group; heterocyclic sulfur compounds such as tetrahydrothiophene and thiopyran; aromatic sulfur compounds such as diphenyl sulfide, diphenyl disulfide, methyl phenyl disulfide and methyl phenyl sulfide: thiourea; and sulfides such as methyl sulfide, ethyl sulfide and butyl sulfide.

[0074] In one embodiment of the present invention, the phosphorus-containing compound is a phosphorus-containing organic compound.

[0075] In one embodiment of the present invention, the phosphorus-containing organic compound is not particularly limited as long as it is an organic compound containing a phosphorus atom, and examples thereof include triphenylphosphine, triethylphosphine, tributylphosphine, tripropylphosphine, trioctylphosphine, and tricyclohexylphosphine.

[0076] In one embodiment of the present invention, the modifier is preferably at least one selected from imidazole optionally substituted by C1-C6 alkyl, pyridine optionally substituted by C1-C6 alkyl, thiophene optionally substituted by C1-C6 alkyl, thiazole optionally substituted by C1-C6 alkyl, piperazine optionally substituted by C1-C6 alkyl and triphenylphosphine, more preferably at least one selected from imidazole, 1-methylimidazole, pyridine, piperazine and thiophene.

[0077] In one embodiment of the present invention, the mass ratio of the halogenated alkylated resin to the modifier is 1:(0.1-1.2), preferably 1:(0.15-1), for example 1:1, 1:0.8, 1:0.6.

[0078] In one embodiment of the present invention, the modification step can be carried out in a solvent, and the solvent can be at least one selected from toluene, methanol, ethanol, n-propanol, n-butanol, isobutanol, tert-butanol, tetrahydrofuran, dichloromethane, chloroform, N,N-dimethylformamide, ether, and water.

[0079] In one embodiment of the present invention, the mass ratio of the halogenated alkylated resin to the solvent is 1:(1-10), preferably 1:(2-8), for example 1:3.792, 1:5.688.

[0080] In one embodiment of the present invention, the modification step can be performed at a temperature of 30° C. to 150° C., preferably 40° C. to 120° C., for example, 70° C., 80° C., 90° C. The temperature of the solution containing the resin raw material can be increased before the resin raw material contacts the modifier, and the temperature of the solution can also be increased during the contact between the resin raw material and the modifier.

[0081] In the present invention, there is no particular limitation on the modification time of the modification step. In one embodiment of the present invention, the modification time of the modification step is 1 h to 24 h, preferably 2 h to 18 h, for example 12 h or 15 h.

[0082] In one embodiment of the present invention, during the modification process, the solution containing the resin raw material and the modifier may be mixed and stirred at a rate of 50 rpm to 1000 rpm, preferably 100 rpm to 800 rpm, such as 500 rpm and 800 rpm. The stirring time is not particularly limited, and may be 2 h, for example.

[0083] In one embodiment of the present invention, in step (1), the modified product can be washed and dried as needed. In this case, the above-mentioned solvent can be used for washing and then drying. The drying conditions can be a drying temperature of 80°C to 180°C, such as 100°C or 120°C; and a drying time of 1h to 48h, such as 24h.

[0084] In step (2) of the present invention, the modified halogenated alkylated resin (modified product) is brought into contact with a metal precursor of an active metal to obtain a contact product.

[0085] In the present invention, the metal precursor of the active metal is loaded on the modified halogenated alkylated resin through step (2).

[0086] In the present invention, the active metal is at least one selected from magnesium, calcium and aluminum, preferably at least one selected from magnesium and calcium.

[0087] In one embodiment of the present invention, the metal precursor of the active metal is at least one of a nitrate form, a chloride form, and a sulfate form of the active metal.

[0088] In one embodiment of the present invention, the mass ratio of the modified halogenated alkylated resin to the metal precursor of the active metal is 1:0.1-3, preferably 1:0.2-2.

[0089] In one embodiment of the present invention, the metal precursor of the active metal exists in the form of a solution, and the solvent at this time can be selected from the above-mentioned solvents, preferably water. In summary, in one embodiment of the present invention, the mass concentration of the metal precursor solution of the active metal is 5% to 50%, for example, 6.5%, 7%, 8%, 8.8%, 17.6%, 26.4%, 35.2%.

[0090] In one embodiment of the present invention, the mass ratio of the modified halogenated alkylated resin to the solution of the metal precursor containing the active metal is 1:(1-10), preferably 1:(2-6).

[0091] In one embodiment of the present invention, the contacting step is carried out in the presence of a solvent, and the solvent may be at least one selected from toluene, methanol, ethanol, n-propanol, n-butanol, isobutanol, tert-butanol, tetrahydrofuran, dichloromethane, chloroform, N,N-dimethylformamide, ether, and water.

[0092] In one embodiment of the present invention, a solution of a metal precursor containing a modified resin and an active metal is mixed and stirred, and the conditions of the mixing and stirring are not particularly limited. For example, the mixing and stirring rate is 100 rpm to 800 rpm, preferably 200 rpm to 600 rpm; the stirring temperature is 30°C to 100°C, preferably 50°C to 80°C, for example 50°C, 80°C, and the stirring time is 1h to 10h, preferably 2h to 8h, for example 2h, 6h, 8h.

[0093] In step (3) of the present invention, the product obtained in the contacting step is calcined in an inert gas atmosphere to obtain the catalyst of the present invention.

[0094] In one embodiment of the present invention, in step (3) of the present invention, the product obtained in the contacting step is first dried and then calcined. The drying conditions are not particularly limited. For example, the temperature is 80°C to 180°C, preferably 90°C to 150°C, for example 100°C, and the time is 1h to 48h, preferably 2h to 36h, for example 14h, 24h.

[0095] In the present invention, the modified resin particles of the metal precursor loaded with active metal are calcined. During the calcination process, the resin particles are carbonized and converted into a porous carbon carrier. The porous carbon carrier serves as a porous carbon carrier of the catalyst of the present invention, and the active metal components on the porous carbon carrier are mainly enriched in the pores (inner surface or inside) of the porous carbon carrier. At the same time, the modifier is removed and at least one heteroatom selected from nitrogen, sulfur and phosphorus remains in the carbon carrier.

[0096] In the present invention, the inert gas is not limited as long as it is an inert gas known in the art. In one embodiment of the present invention, the inert gas may include nitrogen, a rare gas selected from argon, and the like.

[0097] In one embodiment of the present invention, the calcination temperature is 200°C to 1000°C, preferably 250°C to 600°C, such as 400°C, 500°C, 600°C, and the calcination time is 1h to 48h, preferably 2h to 24h, such as 4h, 5h, 8h.

[0098] In one embodiment of the present invention, a method for preparing a catalyst for preparing dimethyl carbonate is provided, wherein, when preparing a modified chloromethyl resin, the chloromethyl resin is mixed with a solvent, a modifier is added, and the modified chloromethyl resin is obtained by modification; preferably, the modifier is a nitrogen-containing five-membered or six-membered heterocyclic aromatic compound, the modified chloromethyl resin is a modified chloromethyl styrene resin, and the solvent is at least one of toluene, methanol, ethanol, n-propanol, n-butanol, isobutanol, tert-butanol, tetrahydrofuran, dichloromethane, chloroform, N,N-dimethylformamide, ether, and water; further preferably, the chloromethyl resin is styrene-based, and the modifier is at least one of piperazine, imidazole, and pyridine; further preferably, the particle size of the chloromethyl resin is 0.1 mm to 3 mm, preferably 0.3 mm to 2 mm; the chloromethyl resin is spherical;

[0099] And / or, the mass ratio of the chloromethyl resin to the solvent is 1:(1-10), preferably 1:(2-8);

[0100] And / or, the mass ratio of the chloromethyl resin to the modifier is 1:(0.1-1.2), preferably 1:(0.15-1);

[0101] And / or, before adding the modifier, a heating step is also included; the temperature after the heating is 30°C to 150°C, preferably 40°C to 120°C;

[0102] And / or, the mixing and stirring rate is 50 rpm to 1000 rpm, preferably 100 rpm to 800 rpm; the mixing and stirring time is 2 h;

[0103] And / or, the modification time is 1h to 24h, preferably 2h to 18h; preferably, after the modification, the steps of cooling, separating, washing the product, and drying the product are also included; further preferably, the drying temperature is 80 to 180°C, and the drying time is 1h to 48h;

[0104] And / or, the preparation method comprises the step of using a carrier to load the active component.

[0105] In one embodiment of the present invention, when the active component is loaded on a carrier, the carrier is mixed and stirred with a metal precursor solution containing the active component, dried, and then calcined in an inert gas atmosphere to obtain the catalyst.

[0106] In one embodiment of the present invention, the metal precursor solution containing active components is at least one of nitrate solutions, chloride solutions and sulfate solutions of magnesium, calcium and aluminum, and the mass concentration of the metal precursor solution containing active components is 5% to 50%.

[0107] In one embodiment of the present invention, when the active component is loaded on a carrier, the mass ratio of the carrier to the metal precursor solution containing the active component is 1:(1-10), preferably 1:(2-6);

[0108] And / or, the stirring rate is 100 rpm to 800 rpm, the stirring temperature is 50° C. to 80° C., and the stirring time is 2 h to 8 h;

[0109] And or, the drying temperature is 80°C to 180°C, and the drying time is 1h to 48h;

[0110] and / or, the inert gas is nitrogen or argon;

[0111] And / or, the calcination temperature is 200°C to 1000°C, and the time is 1h to 48h. Preferably, the calcination temperature is 250°C to 600°C, and the time is 2h to 24h.

[0112] [Method for preparing dialkyl carbonate]

[0113] The third aspect of the present invention provides a method for preparing a dialkyl carbonate represented by the following general formula (I), comprising the step of reacting a carbonate represented by the following general formula (II) and a lower alcohol represented by the following general formula (III) under the action of a catalyst to obtain the dialkyl carbonate represented by the general formula (I); the catalyst is the catalyst of the present invention described above or a catalyst prepared by the catalyst preparation method of the present invention described above,

[0114] R1-OCOO-R1(I)

[0115] In formula (I), each R1 is independently selected from C1-C6 alkyl;

[0116] R2-OCOO-R2(II)

[0117] In formula (II), each R2 is independently selected from a C1-C6 alkyl group, and at least one R2 is different from at least one R1; or two R2s are bonded to each other to form a C2-C6 alkylene group;

[0118] R1-OH(III)

[0119] In formula (III), R1 is selected from C1-C6 alkyl.

[0120] In one embodiment of the present invention, the reaction temperature for preparing the dialkyl carbonate represented by the general formula (I) is 40°C to 130°C, preferably 50°C to 120°C, for example 70°C, 80°C, 90°C, 110°C, 120°C.

[0121] In one embodiment of the present invention, the reaction time for preparing the dialkyl carbonate represented by the general formula (I) is 1 h to 15 h, preferably 2 h to 12 h, for example 4 h, 6 h, 8 h, 10 h.

[0122] In one embodiment of the present invention, in the preparation of the dialkyl carbonate represented by the general formula (I), the molar ratio of the lower alcohol represented by the general formula (III) to the carbonate represented by the general formula (II) is (0.5-15):1, preferably (1-12):1, for example 4:1, 6:1, 8:1.

[0123] In one embodiment of the present invention, in the preparation of the dialkyl carbonate represented by the general formula (I), the mass ratio of the catalyst to the carbonate represented by the general formula (II) is (0.001-0.5):1, preferably (0.05-0.5):1. For example, 0.2:1, 0.3:1, 0.4:1.

[0124] In one embodiment of the present invention, in the dialkyl carbonate shown in the general formula (I), two R1s may be the same or different. When the two R1s are the same, the dialkyl carbonate is a symmetrical dialkyl carbonate. When the two R1s are different, the dialkyl carbonate is an asymmetrical dialkyl carbonate. In the present invention, R1 may include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and sec-butyl. Therefore, in the present invention, the dialkyl carbonate shown in the general formula (I) may include dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, dibutyl carbonate, etc.

[0125] In one embodiment of the present invention, in the carbonate represented by the general formula (II), each R2 is independently selected from a C1-C6 alkyl group, and at least one R2 is different from at least one R1. In the present invention, R2 can include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, sec-butyl, pentyl, and hexyl.

[0126] In one embodiment of the present invention, in the carbonate represented by the general formula (II), two R2 are connected to each other to form a C2-C6 alkylene group. In this case, the carbonate represented by the general formula (II) is a cyclic carbonate, for example, ethylene carbonate or propylene carbonate.

[0127] In the present invention, the lower alcohol represented by the general formula (III) may be used alone or in combination of two or more. Examples of the lower alcohol in the present invention include methanol, ethanol, propanol, isopropanol, butanol, and isomers thereof.

[0128] In the present invention, R1 in the lower alcohol represented by the general formula (III) is the same as at least one of the two R1 in the dialkyl carbonate represented by the general formula (I).

[0129] In the present invention, R2 and R1 may be the same, but at least one R2 is different from at least one R1.

[0130] In other words, in the present invention, the carbonate represented by the general formula (II) and the lower alcohol represented by the general formula (III) undergo an ester exchange reaction, so that R1 in the lower alcohol represented by the general formula (III) becomes at least one end of the dialkyl carbonate represented by the general formula (I).

[0131] In one embodiment of the present invention, a method for preparing dimethyl carbonate is provided, characterized in that it includes the steps of reacting alkylene carbonate and methanol under the action of a catalyst to obtain dimethyl carbonate; the catalyst is the catalyst of the present invention;

[0132] and / or, the reaction temperature is 40°C to 130°C, preferably 50°C to 120°C;

[0133] And / or, the reaction time is 1 h to 15 h, preferably 2 h to 12 h,

[0134] and / or, the molar ratio of methanol to alkylene carbonate is (2-15):1, preferably (3-12):1;

[0135] And / or, the mass ratio of the catalyst to the alkylene carbonate is (0.001-0.5):1, preferably (0.05-0.5):1;

[0136] And / or, the alkylene carbonate is one or more of ethylene carbonate or propylene carbonate.

[0137] The catalyst of the present invention or the catalyst prepared by the catalyst preparation method of the present invention is used in the reaction of preparing dialkyl carbonate by ester exchange reaction of carbonate represented by general formula (II) and lower alcohol represented by general formula (III). Even if it is reused multiple times (for example, more than 10 times), the activity decreases by less than 5%, achieving good technical effects.

[0138] As an example of the reaction conditions for preparing dialkyl carbonate, the reaction temperature is 80° C., the molar ratio of the lower alcohol to the cyclic carbonate is 8:1, and the mass ratio of the catalyst to the cyclic carbonate is 0.3:1, and the reaction is carried out for 10 hours. At this time, the conversion rate of the cyclic carbonate is 80.4%, and the selectivity of the dialkyl carbonate is 99.9%.

[0139] Example

[0140] The present invention will be further described below in conjunction with the embodiments, but the present invention is not limited by these embodiments.

[0141] The gas chromatograph in the present invention is an Agilent 7890 chromatograph. The analysis conditions are: chromatographic column HP-FFAP, injection port temperature 280°C, FID detector, column box program heating, 50°C for 3 minutes, 10°C / min to 230°C for 10 minutes, split ratio 50:1, and component content analysis using the calibration normalization method.

[0142] The elemental analysis of heteroatom content was performed using a Therm2000 instrument.

[0143] XPS tests were carried out on an X-ray photoelectron spectrometer (XPS, AXIS ULTRA DLD) from Kratos, Japan.

[0144] The metal element analysis test was carried out by ICP-OES using Varian 725ES.

[0145] SEM was performed using a scanning electron microscope (SEM, Merlin) from ZEISS, Germany.

[0146] TEM images were obtained on a Tecnai 20S-TWIN transmission electron microscope with an operating voltage of 200 kV.

[0147] The conversion rate of the raw materials in the examples is calculated as follows: (mass of input raw materials - mass of product after reaction * content of raw materials) / mass of input raw materials * 100%.

[0148] The selectivity calculation method of carbonate in the embodiment is: carbonate product yield after reaction / theoretical carbonate yield of consumed raw materials*100%.

[0149] The calculation method for the proportion of the active metal component distributed in the pores of the porous carbon carrier is: (the content of the active metal component in the catalyst calculated as active metal oxide - the content of the active metal component in the catalyst calculated as active metal oxide detected by XPS) / the content of the active metal component in the catalyst calculated as active metal oxide.

[0150] Example 1

[0151] This embodiment provides a method for preparing dimethyl carbonate:

[0152] Preparation of a catalyst for preparing dimethyl carbonate: In a 500 ml three-necked flask, add 50 g of chloromethylstyrene resin and 200 ml (189.6 g) of N,N-dimethylformamide, stir at a rate of 500 rpm for 2 h, heat to 90°C, add 50 g of imidazole, keep the temperature for 12 h, cool and separate the product, wash with deionized water, and dry the product at 100°C for 24 h to obtain a modified resin; then in another In a 500ml three-necked flask, add 20g of modified resin and 8.8g of magnesium nitrate to prepare a solution of 100g with water, stir at 80°C at a rate of 500 rpm for 6h, put into an oven at 100°C for drying for 14h, transfer to a muffle furnace, and roast at 500°C for 5h in a nitrogen atmosphere to obtain catalyst C1. The mass percentage of magnesium oxide in catalyst C1 is 10%. The scanning electron microscope image of catalyst C1 is as follows: Figure 1 The transmission electron microscope image of catalyst C1 is shown in Figure 3 The catalyst has a nitrogen content of 2.6%, a pore size of 150 nm, and a magnesium oxide content of 86.7% inside the pores.

[0153] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 0.5 mm.

[0154] Preparation of dimethyl carbonate: 22.0 g (0.25 mol) of ethylene carbonate, 64.0 g (2 mol) of methanol and 4.4 g of catalyst C1 were placed in a 100 mL autoclave and reacted at 120°C for 4 hours, wherein the molar ratio of methanol to ethylene carbonate was 8:1, and the mass ratio of catalyst C1 to ethylene carbonate was 0.2:1. After the reaction, the autoclave was cooled to room temperature and vented; the liquid product was taken for gas chromatography analysis and calculated, and the conversion rate of ethylene carbonate was 80.4%, and the selectivity of dimethyl carbonate was 99.9%.

[0155] Furthermore, after the reaction is completed, the catalyst particles in the reaction liquid are filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours, and then reused, which is consistent with the conditions of the above-mentioned dimethyl carbonate preparation process. After the reaction, the liquid product is taken for gas chromatography analysis and then the ethylene carbonate conversion rate is calculated.

[0156] The catalyst was recycled and reused 10 times, and the conversion rate of ethylene carbonate was greater than 80%, and the selectivity of dimethyl carbonate was maintained at 99.9%.

[0157] Figure 5In the figure, (a) shows a scanning electron microscope image of the catalyst C1 prepared in Example 1 of the present invention at a scale of 100 microns; (b) shows a scanning electron microscope image of the interior of the catalyst prepared in Example 1 of the present invention at a scale of 10 microns. It can be seen that the outer surface of the carbon carrier is smooth, and magnesium oxide is mainly distributed on the inner surface of the carbon carrier.

[0158] Figure 6 In the figure, (a) shows a scanning electron microscope image of the interior of the catalyst C1 prepared in Example 1 of the present invention at a scale of 200 nanometers; (b) shows a scanning electron microscope image of the interior of the catalyst C1 prepared in Example 1 of the present invention at a scale of 100 nanometers. It can be seen that the pores are filled to a certain extent, indicating that magnesium oxide is deposited inside.

[0159] Figure 7 The energy spectrum scan and EDX spectrum of the catalyst C1 prepared in Example 1 of the present invention are shown; (a) shows the selected area scan spectrum; (b) shows the carbon element distribution diagram; (c) shows the oxygen element distribution diagram; (d) shows the magnesium element distribution diagram; (e) shows the EDX energy spectrum diagram. It can be seen that magnesium oxide is mainly distributed inside the carbon carrier, and the EDX is relatively abundant.

[0160] Example 2

[0161] This embodiment provides a method for preparing dimethyl carbonate:

[0162] Preparation of a catalyst for preparing dimethyl carbonate: In a 500ml three-necked flask, 50g of chloromethylstyrene resin and 200ml (189.6g) of N,N-dimethylformamide were added, and the mixture was stirred at a rate of 500 rpm for 2h, the temperature was raised to 90°C, 50g of imidazole was added, the mixture was kept warm for reaction for 12h, the product was separated after cooling, and the product was washed with deionized water, and then dried at a temperature of 100°C for 24h to obtain a modified resin; then in another 500ml three-necked flask, 20g of the modified resin was added, 17.6g of magnesium nitrate was added with water to prepare a solution of 100g, the solution was stirred at a rate of 600 rpm for 8h at a temperature of 50°C, the solution was placed in an oven and dried at a temperature of 100°C for 24h, and then the solution was transferred to a muffle furnace and calcined at a temperature of 400°C for 8h under a nitrogen atmosphere to obtain a catalyst C2, wherein the mass percentage of magnesium oxide in the catalyst C2 is 20%. The catalyst has a nitrogen content of 2.2%, a pore diameter of 200nm, and the magnesium oxide content inside the pores accounts for 71.1%.

[0163] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 0.9 mm.

[0164] Preparation of dimethyl carbonate: 22.0 g (0.25 mol) of ethylene carbonate, 48.0 g (1.5 mol) of methanol and 4.4 g of catalyst C2 were placed in a 100 mL autoclave and reacted at a temperature of 110°C for 6 hours, wherein the molar ratio of methanol to ethylene carbonate was 6:1, and the mass ratio of catalyst C2 to ethylene carbonate was 0.2:1. After the reaction, the autoclave was cooled to room temperature and vented; the liquid product was taken for gas chromatography analysis and calculated, and the conversion rate of ethylene carbonate was 74.5%, and the selectivity of dimethyl carbonate was 99.9%.

[0165] Furthermore, after the reaction is completed, the catalyst particles in the reaction liquid are filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours, and then reused, which is consistent with the conditions of the above-mentioned dimethyl carbonate preparation process. After the reaction, the liquid product is taken for gas chromatography analysis and then the ethylene carbonate conversion rate is calculated.

[0166] The catalyst was recycled and reused 10 times, and the conversion rate of ethylene carbonate was greater than 74%, and the selectivity of dimethyl carbonate was maintained at 99.9%.

[0167] Example 3

[0168] This embodiment provides a method for preparing dimethyl carbonate:

[0169] Preparation of a catalyst for preparing dimethyl carbonate: In a 500ml three-necked flask, 50g of chloromethylstyrene resin and 300ml (284.4g) of N,N-dimethylformamide were added, and the mixture was stirred at a rate of 800 rpm for 2h, the temperature was raised to 80°C, 40g of imidazole was added, the mixture was kept warm for reaction for 12h, the product was separated after cooling, and the product was washed with deionized water, and then dried at a temperature of 120°C for 24h to obtain a modified resin; then in another 500ml three-necked flask, 20g of the modified resin was added, 26.4g of magnesium nitrate was added with water to prepare a solution of 100g, the solution was stirred at a rate of 300 rpm for 8h at a temperature of 50°C, the solution was placed in an oven and dried at a temperature of 100°C for 24h, and then the solution was transferred to a muffle furnace and calcined at a temperature of 500°C for 4h under a nitrogen atmosphere to obtain a catalyst C3, in which the magnesium oxide content of the catalyst C3 was 30%. The catalyst has a nitrogen content of 1.7%, a pore diameter of 250nm, and the magnesium oxide content inside the pores accounts for 63.3%.

[0170] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 0.7 mm.

[0171] Preparation of dimethyl carbonate: 22.0 g (0.25 mol) of ethylene carbonate, 32.0 g (1.0 mol) of methanol and 4.4 g of catalyst C3 were placed in a 100 mL autoclave and reacted at a temperature of 110° C. for 10 h, wherein the molar ratio of methanol to ethylene carbonate was 4:1, and the mass ratio of catalyst C3 to ethylene carbonate was 0.2:1. After the reaction, the autoclave was cooled to room temperature and vented; the liquid product was taken for gas chromatography analysis and calculated, and the conversion rate of ethylene carbonate was 61.4%, and the selectivity of dimethyl carbonate was 99.9%.

[0172] Furthermore, after the reaction is completed, the catalyst particles in the reaction liquid are filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours, and then reused, which is consistent with the conditions of the above-mentioned dimethyl carbonate preparation process. After the reaction, the liquid product is taken for gas chromatography analysis and then the ethylene carbonate conversion rate is calculated.

[0173] The catalyst was recycled and reused 10 times, and the conversion rate of ethylene carbonate was greater than 60%, and the selectivity of dimethyl carbonate was maintained at 99.9%.

[0174] Example 4

[0175] This embodiment provides a method for preparing dimethyl carbonate:

[0176] Preparation of a catalyst for preparing dimethyl carbonate: In a 500ml three-necked flask, 50g of chloromethylstyrene resin and 300ml (284.4g) of N,N-dimethylformamide were added, and the mixture was stirred at a rate of 800 rpm for 2h, the temperature was raised to 70°C, 30g of imidazole was added, the mixture was kept warm for reaction for 15h, the product was separated after cooling, and the product was washed with deionized water, and then dried at a temperature of 120°C for 24h to obtain a modified resin; then in another 500ml three-necked flask, 20g of the modified resin was added, 35.2g of magnesium nitrate was added with water to prepare a solution of 100g, the solution was stirred at a rate of 400 rpm for 2h at a temperature of 50°C, the solution was placed in an oven and dried at a temperature of 100°C for 24h, and then the solution was transferred to a muffle furnace and calcined at a temperature of 500°C for 4h under a nitrogen atmosphere to obtain a catalyst C4, in which the magnesium oxide content of the catalyst C4 was 40%. The catalyst has a nitrogen content of 1.8%, a pore diameter of 300nm, and the magnesium oxide content inside the pores accounts for 63.3%.

[0177] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 1.0 mm.

[0178] Preparation of dimethyl carbonate: 22.0 g (0.25 mol) of ethylene carbonate, 64.0 g (2 mol) of methanol and 8.8 g of catalyst C4 were placed in a 100 mL autoclave and reacted at 90°C for 8 h, wherein the molar ratio of methanol to ethylene carbonate was 8:1, and the mass ratio of catalyst C4 to ethylene carbonate was 0.4:1. After the reaction, the autoclave was cooled to room temperature and vented; the liquid product was taken for gas chromatography analysis and calculated to obtain a conversion rate of ethylene carbonate of 80.9% and a selectivity of dimethyl carbonate of 99.9%.

[0179] Furthermore, after the reaction is completed, the catalyst particles in the reaction liquid are filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours, and then reused, which is consistent with the conditions of the above-mentioned dimethyl carbonate preparation process. After the reaction, the liquid product is taken for gas chromatography analysis and then the ethylene carbonate conversion rate is calculated.

[0180] The catalyst was recycled and reused 10 times, and the conversion rate of ethylene carbonate was greater than 80%, and the selectivity of dimethyl carbonate was maintained at 99.9%.

[0181] Example 5

[0182] This embodiment provides a method for preparing dimethyl carbonate:

[0183] Preparation of a catalyst for preparing dimethyl carbonate: In a 500ml three-necked flask, 50g of chloromethylstyrene resin and 300ml (284.4g) of N,N-dimethylformamide were added, and the mixture was stirred at a rate of 800 rpm for 2h, the temperature was raised to 70°C, 30g of imidazole was added, the mixture was kept warm for reaction for 15h, the product was separated after cooling, and the product was washed with deionized water, and then dried at a temperature of 120°C for 24h to obtain a modified resin; then in another 500ml three-necked flask, 20g of the modified resin was added, 26.4g of magnesium nitrate was added with water to prepare a solution of 100g, the solution was stirred at a rate of 400 rpm for 2h at a temperature of 50°C, the solution was placed in an oven and dried at a temperature of 100°C for 24h, and then the solution was transferred to a muffle furnace and calcined at a temperature of 500°C for 4h under a nitrogen atmosphere to obtain a catalyst C5, in which the magnesium oxide content of the catalyst C5 was 30%. The catalyst has a nitrogen content of 1.8%, a pore diameter of 180 nm, and the magnesium oxide content inside the pores accounts for 64.4%.

[0184] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 1.0 mm.

[0185] Preparation of dimethyl carbonate: 22.0 g (0.25 mol) of ethylene carbonate, 64.0 g (2 mol) of methanol and 6.6 g of catalyst C5 were placed in a 100 mL autoclave and reacted at 80°C for 10 h, wherein the molar ratio of methanol to ethylene carbonate was 8:1, and the mass ratio of catalyst C5 to ethylene carbonate was 0.3:1. After the reaction, the autoclave was cooled to room temperature and vented; the liquid product was taken for gas chromatography analysis and calculated, and the conversion rate of ethylene carbonate was 80.5%, and the selectivity of dimethyl carbonate was 99.9%.

[0186] Furthermore, after the reaction is completed, the catalyst particles in the reaction liquid are filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours, and then reused, which is consistent with the conditions of the above-mentioned dimethyl carbonate preparation process. After the reaction, the liquid product is taken for gas chromatography analysis and then the ethylene carbonate conversion rate is calculated.

[0187] The catalyst was recycled and reused 10 times, and the conversion rate of ethylene carbonate was greater than 80%, and the selectivity of dimethyl carbonate was maintained at 99.9%.

[0188] Example 6

[0189] This embodiment provides a method for preparing dimethyl carbonate:

[0190] Preparation of a catalyst for preparing dimethyl carbonate: In a 500 ml three-necked flask, 50 g of chloromethylstyrene resin and 300 ml (284.4 g) of N,N-dimethylformamide were added, and the mixture was stirred at a rate of 800 rpm for 2 h. The mixture was heated to 70° C., 30 g of thiophene was added, and the mixture was kept warm for reaction for 15 h. The product was separated after cooling, and then washed with deionized water. The product was dried at a temperature of 120° C. for 24 h to obtain a modified resin. Then, in another 500 ml three-necked flask, 20 g of the modified resin was added, 26.4 g of magnesium nitrate was added with water to prepare a solution of 100 g, and the solution was stirred at a rate of 400 rpm for 2 h at a temperature of 50° C. The solution was placed in an oven and dried at a temperature of 100° C. for 24 h. The solution was then transferred to a muffle furnace and calcined at a temperature of 500° C. for 4 h under a nitrogen atmosphere to obtain a catalyst C6, in which the magnesium oxide content of the catalyst C6 was 30%. The catalyst has a sulfur content of 2.7%, a pore diameter of 100nm, and the magnesium oxide content inside the pores accounts for 66.4%.

[0191] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 1 mm.

[0192] Preparation of dimethyl carbonate: 22.0 g (0.25 mol) of ethylene carbonate, 64.0 g (2 mol) of methanol and 8.8 g of catalyst C6 were placed in a 100 mL autoclave and reacted at 70°C for 8 h, wherein the molar ratio of methanol to ethylene carbonate was 8:1, and the mass ratio of catalyst C6 to ethylene carbonate was 0.4:1. After the reaction, the autoclave was cooled to room temperature and vented; the liquid product was taken for gas chromatography analysis and calculated, and the conversion rate of ethylene carbonate was 80.2%, and the selectivity of dimethyl carbonate was 99.9%.

[0193] Furthermore, after the reaction is completed, the catalyst particles in the reaction liquid are filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours, and then reused, which is consistent with the conditions of the above-mentioned dimethyl carbonate preparation process. After the reaction, the liquid product is taken for gas chromatography analysis and then the ethylene carbonate conversion rate is calculated.

[0194] The catalyst was recycled and reused 10 times, and the conversion rate of ethylene carbonate was greater than 80%, and the selectivity of dimethyl carbonate was maintained at 99.9%.

[0195] Example 7

[0196] This embodiment provides a method for preparing dimethyl carbonate:

[0197] Preparation of a catalyst for preparing dimethyl carbonate: In a 500ml three-necked flask, 50g of chloromethylstyrene resin and 300ml (284.4g) of N,N-dimethylformamide were added, and the mixture was stirred at a rate of 800 rpm for 2h, the temperature was raised to 70°C, 30g of imidazole was added, the mixture was kept warm for reaction for 15h, the product was separated after cooling, and the product was washed with deionized water, and then dried at a temperature of 120°C for 24h to obtain a modified resin; then in another 500ml three-necked flask, 20g of the modified resin was added, 8g of calcium nitrate was added with water to prepare a solution of 100g, the solution was stirred at a rate of 300 rpm for 2h at a temperature of 50°C, the solution was placed in an oven and dried at a temperature of 100°C for 24h, and then the solution was transferred to a muffle furnace and calcined at a temperature of 500°C for 4h under a nitrogen atmosphere to obtain a catalyst C7, wherein the calcium oxide content in the catalyst C7 was 20%. The catalyst has a nitrogen content of 2.2%, a pore diameter of 120 nm, and the calcium oxide content inside the pores accounts for 68.8%.

[0198] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 1.0 mm.

[0199] Preparation of dimethyl carbonate: 22.0 g (0.25 mol) of ethylene carbonate, 64.0 g (2 mol) of methanol and 8.8 g of catalyst C7 were placed in a 100 mL autoclave and reacted at 70°C for 8 h, wherein the molar ratio of methanol to ethylene carbonate was 8:1, and the mass ratio of catalyst C7 to ethylene carbonate was 0.4:1. After the reaction, the autoclave was cooled to room temperature and vented; the liquid product was taken for gas chromatography analysis and calculated, and the conversion rate of ethylene carbonate was 80.4%, and the selectivity of dimethyl carbonate was 99.9%.

[0200] Furthermore, after the reaction is completed, the catalyst particles in the reaction liquid are filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours, and then reused, which is consistent with the conditions of the above-mentioned dimethyl carbonate preparation process. After the reaction, the liquid product is taken for gas chromatography analysis and then the ethylene carbonate conversion rate is calculated.

[0201] The catalyst was recycled and reused 10 times, and the conversion rate of ethylene carbonate was greater than 80%, and the selectivity of dimethyl carbonate was maintained at 99.9%.

[0202] Example 8

[0203] This embodiment provides a method for preparing dimethyl carbonate:

[0204] Preparation of a catalyst for preparing dimethyl carbonate: In a 500ml three-necked flask, 50g of chloromethylstyrene resin and 300ml (284.4g) of N,N-dimethylformamide were added, and the mixture was stirred at a rate of 800 rpm for 2h, the temperature was raised to 70°C, 30g of triphenylphosphine was added, the mixture was kept warm for reaction for 15h, the product was separated after cooling, and the product was washed with deionized water, and then dried at a temperature of 120°C for 24h to obtain a modified resin; then in another 500ml three-necked flask, 20g of the modified resin and 17.6g of magnesium nitrate were added with water to prepare 80g of the solution, and the solution was stirred at a temperature of 50°C for 2h at a rate of 500 rpm, the solution was placed in an oven and dried at a temperature of 100°C for 24h, and then the solution was transferred to a muffle furnace and calcined at a temperature of 500°C for 4h under a nitrogen atmosphere to obtain a catalyst C8, in which the magnesium oxide content of the catalyst C8 was 20%. The catalyst has a phosphorus content of 2.2%, a pore diameter of 150nm, and the magnesium oxide content inside the pores accounts for 71.6%.

[0205] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 1.0 mm.

[0206] Preparation of dimethyl carbonate: 22.0 g (0.25 mol) of ethylene carbonate, 64.0 g (2 mol) of methanol and 8.8 g of catalyst C8 were placed in a 100 mL autoclave and reacted at 90°C for 8 h, wherein the molar ratio of methanol to ethylene carbonate was 8:1, and the mass ratio of catalyst C8 to ethylene carbonate was 0.4:1. After the reaction, the autoclave was cooled to room temperature and vented; the liquid product was taken for gas chromatography analysis and calculated, and the conversion rate of ethylene carbonate was 80.3%, and the selectivity of dimethyl carbonate was 99.9%.

[0207] Furthermore, after the reaction is completed, the catalyst particles in the reaction liquid are filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours, and then reused, which is consistent with the conditions of the above-mentioned dimethyl carbonate preparation process. After the reaction, the liquid product is taken for gas chromatography analysis and then the ethylene carbonate conversion rate is calculated.

[0208] The catalyst was recycled and reused 10 times, and the conversion rate of ethylene carbonate was greater than 80%, and the selectivity of dimethyl carbonate was maintained at 99.9%.

[0209] Example 9

[0210] This embodiment provides a method for preparing dimethyl carbonate:

[0211] Preparation of a catalyst for preparing dimethyl carbonate: In a 500 ml three-necked flask, 50 g of chloromethylstyrene resin and 300 ml (284.4 g) of N,N-dimethylformamide were added, and the mixture was stirred at a rate of 800 rpm for 2 h. The temperature was raised to 70° C., 30 g of piperazine was added, and the mixture was kept warm for reaction for 15 h. The product was separated after cooling, and then washed with deionized water. The product was dried at a temperature of 120° C. for 24 h to obtain a modified resin; then in another 500 ml three-necked flask, 20 g of the modified resin was added, 11.4 g of aluminum nitrate was added with water to prepare a solution of 100 g, and the solution was stirred at a rate of 500 rpm for 2 h at a temperature of 50° C., and the solution was placed in an oven and dried at a temperature of 100° C. for 24 h. The solution was then transferred to a muffle furnace and calcined at a temperature of 600° C. for 4 h under a nitrogen atmosphere to obtain a catalyst C9, in which the alumina content of the catalyst C9 was 20%. The catalyst has a nitrogen content of 0.8%, a pore diameter of 100nm, and an alumina content of 67.6% inside the pores.

[0212] During the catalyst preparation process, the chloromethylstyrene resin was spherical and had a particle size of 1.2 mm.

[0213] Preparation of dimethyl carbonate: 22.0 g (0.25 mol) of ethylene carbonate, 64.0 g (2 mol) of methanol and 8.8 g of catalyst C9 were placed in a 100 mL autoclave and reacted at 90°C for 8 h, wherein the molar ratio of methanol to ethylene carbonate was 8:1, and the mass ratio of catalyst C9 to ethylene carbonate was 0.4:1. After the reaction, the autoclave was cooled to room temperature and vented; the liquid product was taken for gas chromatography analysis and calculated, and the conversion rate of ethylene carbonate was 80.6%, and the selectivity of dimethyl carbonate was 99.9%.

[0214] Furthermore, after the reaction is completed, the catalyst particles in the reaction liquid are filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours, and then reused, which is consistent with the conditions of the above-mentioned dimethyl carbonate preparation process. After the reaction, the liquid product is taken for gas chromatography analysis and then the ethylene carbonate conversion rate is calculated.

[0215] The catalyst was recycled and reused 10 times, and the conversion rate of ethylene carbonate was greater than 80%, and the selectivity of dimethyl carbonate was maintained at 99.9%.

[0216] Example 10

[0217] This embodiment provides a method for preparing dimethyl carbonate:

[0218] Preparation of a catalyst for preparing dimethyl carbonate: In a 500ml three-necked flask, 50g of chloromethylstyrene resin and 300ml (284.4g) of N,N-dimethylformamide were added, and the mixture was stirred at a rate of 800 rpm for 2h, the temperature was raised to 70°C, 30g of 1-methylimidazole was added, the mixture was kept warm for reaction for 15h, the product was separated after cooling, and the product was washed with deionized water, and then dried at a temperature of 120°C for 24h to obtain a modified resin; then in another 500ml three-necked flask, 20g of the modified resin was added, 26.4g of magnesium nitrate was added with water to prepare a solution of 100g, the solution was stirred at a rate of 500 rpm for 2h at a temperature of 50°C, the solution was placed in an oven and dried at a temperature of 100°C for 24h, and then the solution was transferred to a muffle furnace and calcined at a temperature of 500°C for 4h under a nitrogen atmosphere to obtain a catalyst C10, wherein the magnesium oxide content in the catalyst C10 is 30%. The catalyst has a nitrogen content of 1.6%, a pore diameter of 150nm, and the magnesium oxide content inside the pores accounts for 66.5%.

[0219] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 1.0 mm.

[0220] Preparation of dimethyl carbonate: 22.0 g (0.25 mol) of ethylene carbonate, 64.0 g (2 mol) of methanol and 6.6 g of catalyst C10 were placed in a 100 mL autoclave and reacted at 80°C for 10 h, wherein the molar ratio of methanol to ethylene carbonate was 8:1, and the mass ratio of catalyst C10 to ethylene carbonate was 0.3:1. After the reaction, the autoclave was cooled to room temperature and vented; the liquid product was taken for gas chromatography analysis and calculated, and the conversion rate of ethylene carbonate was 80.5%, and the selectivity of dimethyl carbonate was 99.9%.

[0221] Furthermore, after the reaction is completed, the catalyst particles in the reaction liquid are filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours, and then reused, which is consistent with the conditions of the above-mentioned dimethyl carbonate preparation process. After the reaction, the liquid product is taken for gas chromatography analysis and then the ethylene carbonate conversion rate is calculated.

[0222] The catalyst was recycled and reused 10 times, and the conversion rate of ethylene carbonate was greater than 80%, and the selectivity of dimethyl carbonate was maintained at 99.9%.

[0223] Embodiment 11

[0224] This embodiment provides a method for preparing ethyl methyl carbonate:

[0225] Preparation of ethyl methyl carbonate: 22.5 g (0.25 mol) of dimethyl carbonate, 46.0 g (1 mol) of ethanol and 6.75 g of catalyst C10 were placed in a 100 mL autoclave and reacted at a temperature of 100° C. for 10 h, wherein the molar ratio of ethanol to dimethyl carbonate was 4:1, and the mass ratio of catalyst C10 to dimethyl carbonate was 0.3:1. After the reaction, the autoclave was cooled to room temperature and vented; the liquid product was taken for gas chromatography analysis and calculated, and the conversion rate of dimethyl carbonate was 91.6%, and the selectivity of ethyl methyl carbonate was 92.4%.

[0226] Example 12

[0227] This embodiment provides a method for preparing ethyl methyl carbonate:

[0228] Preparation of ethyl methyl carbonate: 22.5 g (0.25 mol) of dimethyl carbonate, 11.5 g (0.25 mol) of ethanol and 4.5 g of catalyst C10 were placed in a 100 mL autoclave and reacted at 100° C. for 10 h, wherein the molar ratio of ethanol to dimethyl carbonate was 1:1, and the mass ratio of catalyst C10 to dimethyl carbonate was 0.2:1. After the reaction, the autoclave was cooled to room temperature and vented; the liquid product was taken for gas chromatography analysis and calculated, and the conversion rate of dimethyl carbonate was 64.5%, and the selectivity of ethyl methyl carbonate was 73.1%.

[0229] Comparative Example 1

[0230] This comparative example provides a method for preparing dimethyl carbonate:

[0231] Preparation of a catalyst for preparing dimethyl carbonate: In a 500 ml three-necked flask, add 20 g of chloromethylstyrene resin and 8.8 g of magnesium nitrate, add water to prepare a solution of 100 g, stir at 80° C. for 6 h, put into an oven at 100° C. for drying for 14 h, transfer to a muffle furnace, and roast at 500° C. for 5 h in a nitrogen atmosphere to obtain a catalyst S1. The mass percentage of magnesium oxide in the catalyst S1 is 10%. The scanning electron microscope image of the catalyst S1 is as follows: Figure 2 The transmission electron microscopy image of catalyst S1 is shown in Figure 4 As shown in Figure 2, the active metal components in the pores are almost non-existent after measurement and calculation.

[0232] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 0.5 mm.

[0233] Preparation of dimethyl carbonate: 22.0 g (0.25 mol) of ethylene carbonate, 64.0 g (2 mol) of methanol and 4.4 g of catalyst S1 were placed in a 100 mL autoclave and reacted at 120°C for 4 h, wherein the molar ratio of methanol to ethylene carbonate was 8:1, and the mass ratio of catalyst S1 to ethylene carbonate was 0.2:1. After the reaction, the autoclave was cooled to room temperature and vented; the liquid product was taken for gas chromatography analysis and calculated, and the conversion rate of ethylene carbonate was 59.6%, and the selectivity of dimethyl carbonate was 99.8%.

[0234] Figure 8 In the figure, (a) shows a scanning electron microscope image of the catalyst S1 prepared in comparative example 1 of the present invention at a scale of 100 microns; (b) shows a scanning electron microscope image of the interior of the catalyst S1 prepared in comparative example 1 of the present invention at a scale of 20 microns. It can be seen that the outer surface of the carbon support is rough, where magnesium oxide is attached, while magnesium oxide is almost not seen on the inner surface of the carbon support.

[0235] Fig. 9 In the figure, (a) shows a scanning electron microscope image of the interior of the catalyst S1 prepared in comparative example 1 of the present invention at a scale of 200 nanometers; (b) shows a scanning electron microscope image of the interior of the catalyst S1 prepared in comparative example 1 of the present invention at a scale of 100 nanometers. It can be seen that the interior of the carbon carrier maintains its pore structure and magnesium oxide does not enter.

[0236] Fig.10 The energy spectrum scan and EDX spectrum of the catalyst S1 prepared in comparative example 1 of the present invention are shown; (a) shows the selected area scan spectrum; (b) shows the carbon element distribution diagram; (c) shows the EDX spectrum diagram. It can be seen that there is basically no magnesium oxide distributed in the internal pores of the carbon carrier, and the EDX result basically cannot detect magnesium.

[0237] Comparative Example 2

[0238] This comparative example provides a method for preparing dimethyl carbonate:

[0239] Preparation of a catalyst for preparing dimethyl carbonate: 20 g of magnesium nitrate was transferred into a muffle furnace and calcined at 500° C. for 5 h under a nitrogen atmosphere to obtain a powder catalyst S2.

[0240] Preparation of dimethyl carbonate: 22.0 g (0.25 mol) of ethylene carbonate, 64.0 g (2 mol) of methanol and 4.4 g of catalyst S2 were placed in a 100 mL autoclave and reacted at a temperature of 120°C for 4 hours, wherein the molar ratio of methanol to ethylene carbonate was 8:1, and the mass ratio of catalyst S2 to ethylene carbonate was 0.2:1. After the reaction, the autoclave was cooled to room temperature and vented; the liquid product was taken for gas chromatography analysis and calculated, and the conversion rate of ethylene carbonate was 32.7%, and the selectivity of dimethyl carbonate was 99.9%.

[0241] Comparative Example 3

[0242] This comparative example provides a method for preparing dimethyl carbonate:

[0243] Preparation of catalyst for preparing dimethyl carbonate: In a 500ml three-necked flask, add 20g of styrene resin, 8.8g of magnesium nitrate and water to prepare a solution of 100g, stir at 80°C for 6h, put into an oven at 100°C for drying for 14h, transfer to a muffle furnace, and roast at 500°C for 5h in a nitrogen atmosphere to obtain catalyst S3, in which the mass percentage of magnesium oxide in catalyst S3 is 6.5%. According to measurement and calculation, there is almost no active metal component in the pores.

[0244] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 0.5 mm.

[0245] Preparation of dimethyl carbonate: 22.0 g (0.25 mol) of ethylene carbonate, 64.0 g (2 mol) of methanol and 4.4 g of catalyst S3 were placed in a 100 mL autoclave and reacted at 120°C for 4 h, wherein the molar ratio of methanol to ethylene carbonate was 8:1, and the mass ratio of catalyst S3 to ethylene carbonate was 0.2:1. After the reaction, the autoclave was cooled to room temperature and vented; the liquid product was taken for gas chromatography analysis and calculated, and the conversion rate of ethylene carbonate was 39.4%, and the selectivity of dimethyl carbonate was 99.9%.

[0246] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A porous carbon carrier-supported catalyst, characterized in that: It includes a porous carbon carrier, an active metal component and at least one heteroatom selected from nitrogen, sulfur and phosphorus, wherein, relative to the total mass of the catalyst, the content of the porous carbon carrier is 50% to 99%, the content of the active metal component calculated as active metal oxide is 0.1% to 50%, and the content of the heteroatom calculated as element is 0.1% to 5%; the active metal is at least one selected from magnesium, aluminum, and calcium, and the content of the active metal component distributed in the pores of the porous carbon carrier, calculated as active metal oxide, accounts for more than 50% of the content of all active metal components in the catalyst.

2. The catalyst according to claim 1, characterized in that The particle size of the porous carbon carrier is 0.1 mm to 3 mm, preferably 0.3 mm to 2 mm; the pore size of the porous carbon carrier is 5 to 500 nm, preferably 50 to 300 nm.

3. The catalyst according to claim 1 or 2, characterized in that It satisfies at least one of the following conditions: The content of the active metal component distributed in the pores of the porous carbon support relative to the content of all active metal components in the catalyst is 55% or more, preferably 60% or more, more preferably 65% ​​or more, and most preferably 70% or more, calculated as active metal oxide; The content of the porous carbon support is 55 to 90%, preferably 60 to 85%, relative to the total mass of the catalyst, and the content of the active metal component calculated as active metal oxide is 5 to 45%, preferably 10 to 40%; and The content of heteroatoms calculated as elements is 0.3 to 4.5%, preferably 0.5 to 4%.

4. The catalyst according to any one of claims 1 to 3, characterized in that The content of active metal components distributed on the outer surface of the porous carbon carrier measured by XPS is less than 50% relative to the content of all active metal components in the catalyst, calculated as active metal oxides, and is preferably less than 45%, more preferably less than 40%, further preferably less than 35%, and most preferably less than 30%.

5. A method for preparing a porous carbon carrier-supported catalyst, comprising the following steps: (1) a modification step of contacting the halogenated alkylated resin with a modifier to modify the resin and obtain a modified halogenated alkylated resin; (2) a contacting step of contacting the modified halogenated alkylated resin with a metal precursor of an active metal to obtain a contact product; and (3) a calcination step of optionally drying the contact product and then calcining it in an inert gas atmosphere, The modifier is at least one compound selected from nitrogen-containing compounds, sulfur-containing compounds and phosphorus-containing compounds, and the active metal is at least one compound selected from magnesium, aluminum and calcium.

6. The method for preparing a catalyst according to claim 5, wherein: Step (1) satisfies at least one of the following conditions: The halogenated alkylated resin is a halogenated methylated resin, preferably a chloromethylated resin, and more preferably a chloromethylated styrene resin; The modifier is a nitrogen-containing organic compound, a sulfur-containing organic compound or a phosphorus-containing organic compound, preferably an alkylamine (such as methylamine, ethylamine, hexylamine, propylamine, dimethylamine, diethylamine), a 5-membered or 6-membered nitrogen-containing heterocyclic aromatic hydrocarbon compound, a thiophene or triphenylphosphine, more preferably a 5-membered or 6-membered nitrogen-containing heterocyclic aromatic hydrocarbon compound optionally substituted with a C1-C6 alkyl group, a thiophene or triphenylphosphine optionally substituted with a C1-C6 alkyl group, and particularly preferably a piperidine optionally substituted with a C1-C6 alkyl group. At least one of oxazine, pyridine optionally substituted by C1-C6 alkyl, imidazole optionally substituted by C1-C6 alkyl, quinoline optionally substituted by C1-C6 alkyl, pyrrole optionally substituted by C1-C6 alkyl, indole optionally substituted by C1-C6 alkyl, carbazole optionally substituted by C1-C6 alkyl, isoindole optionally substituted by C1-C6 alkyl, thiazole optionally substituted by C1-C6 alkyl, thiophene optionally substituted by C1-C6 alkyl, and triphenylphosphine; The mass ratio of the halogenated alkylated resin to the modifier is 1:(0.1-1.2), preferably 1:(0.15-1); The modification step is carried out in a solvent, and the solvent is at least one selected from toluene, methanol, ethanol, n-propanol, n-butanol, isobutanol, tert-butanol, tetrahydrofuran, dichloromethane, chloroform, N,N-dimethylformamide, ether, and water, and the mass ratio of the halogenated alkylated resin to the solvent is 1:(1-10), preferably 1:(2-8); The temperature of the modification step is 30°C to 150°C, preferably 40°C to 120°C; The modification time of the modification step is 1h to 24h, preferably 2h to 18h; The modification step is carried out under mixing and stirring, and the mixing and stirring rate is 50 rpm to 1000 rpm, preferably 100 rpm to 800 rpm; In the modification step, the obtained modified halogenated alkylated resin is washed and dried. The drying conditions are as follows: a drying temperature of 80° C. to 180° C. and a drying time of 1 hour to 48 hours.

7. The method for preparing a catalyst according to claim 5 or 6, wherein: Step (2) satisfies at least one of the following conditions: The metal precursor of the active metal is at least one of a nitrate form, a chloride form, and a sulfate form of the active metal; The mass ratio of the modified halogenated alkylated resin to the metal precursor of the active metal is 1:0.1-3, preferably 1:0.2-2; The metal precursor of the active metal is contacted with the modified halogenated alkylated resin obtained in step (1) in the form of a solution, and the solvent is at least one selected from toluene, methanol, ethanol, n-propanol, n-butanol, isobutanol, tert-butanol, tetrahydrofuran, dichloromethane, chloroform, N,N-dimethylformamide, ether, and water; Step (2) is carried out under mixing and stirring conditions, wherein the mixing and stirring rate is 100 rpm to 800 rpm, preferably 200 rpm to 600 rpm; the mixing and stirring temperature is 30°C to 100°C, preferably 50°C to 80°C, and the mixing and stirring time is 1h to 10h, preferably 2h to 8h.

8. The method for preparing a catalyst according to any one of claims 5 to 7, wherein: Step (3) satisfies at least one of the following conditions: The contact product obtained in step (2) is dried under the following conditions: temperature of 80°C to 180°C, preferably 90°C to 150°C, time of 1h to 48h, preferably 2h to 36h; The inert gas is at least one of nitrogen and a rare gas; The calcination temperature is 200° C. to 1000° C., preferably 250° C. to 900° C., and the calcination time is 1 h to 48 h, preferably 2 h to 24 h.

9. A method for preparing a dialkyl carbonate represented by the following general formula (I), characterized in that: Under the action of the catalyst according to any one of claims 1 to 4 or the catalyst prepared by the preparation method according to any one of claims 5 to 8, a carbonate represented by the following general formula (II) and a lower alcohol represented by the following general formula (III) are reacted to obtain a dialkyl carbonate represented by the general formula (I); R1-OCOO-R1(I) In formula (I), each R1 is independently selected from C1-C6 alkyl; R2-OCOO-R2(II) In formula (II), each R2 is independently selected from a C1-C6 alkyl group, and at least one R2 is different from at least one R1; or two R2s are bonded to each other to form a C2-C6 alkylene group; R1-OH(III) In formula (III), R1 is selected from C1-C6 alkyl.

10. The preparation method according to claim 9, characterized in that: At least one of the following conditions is met: The reaction temperature is 40°C to 130°C, preferably 50°C to 120°C; The reaction time is 1 h to 15 h, preferably 2 h to 12 h.

11. The preparation method according to claim 9 or 10, characterized in that: At least one of the following conditions is met: The molar ratio of the lower alcohol represented by the general formula (III) to the carbonate represented by the general formula (II) is (0.5-15):1, preferably (1-12):1; The mass ratio of the catalyst to the carbonate ester represented by the general formula (II) is (0.001-0.5):1, preferably (0.05-0.5):1; In formula (I), two R1 are the same as each other; and In formula (II), two R2 are bonded to each other to form a C2-C6 alkylene group.

12. The preparation method according to any one of claims 9 to 11, characterized in that: At least one of the following conditions is met: The carbonate represented by the general formula (II) is at least one of ethylene carbonate and propylene carbonate. The lower alcohol is at least one selected from methanol, ethanol, propanol, isopropanol, and butanol; The dialkyl carbonate represented by the general formula (I) is at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate and dibutyl carbonate.

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