Porous carbon carrier-supported catalyst, preparation method therefor and use thereof

Abstract

Disclosed in the present invention are a porous carbon carrier-supported catalyst, a preparation method therefor and a use thereof. In the catalyst of the present invention, on the basis of active metal oxide, the proportion of the content of active metal components distributed in pores of a porous carbon carrier accounts for more than 50% of the content of all active metal components in the catalyst. The catalyst of the present invention has stable properties in the system, and the active center is not easy to lose, solving the problems in the prior art of easy loss of active components in heterogeneous catalysts and short service life of the catalysts; in addition, when the catalyst of the present invention is used for preparing dialkyl carbonate, the catalyst shows excellent conversion rate and selectivity.

Description

Porous carbon carrier-supported catalyst, preparation method thereof and application thereof Technical Field

[0001] The present invention provides a supported catalyst, and more particularly relates to a catalyst in which active metal components are mainly supported in the pores of a porous carbon carrier, a method for preparing the catalyst, and use 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, and is non-toxic and readily biodegradable. It can be used as a solvent, gasoline additive, lithium-ion battery electrolyte, and as a reagent for carbonylation, methylation, and carbonylmethoxylation. It is widely used in the chemical industry. Currently, countries around the world are actively researching green chemical processes based on this environmentally friendly DMC raw material. Among them, transesterification is a method with great industrial potential due to its mild reaction conditions, high yield, and co-production of ethylene glycol or propylene glycol.

[0003] Typically, alkali metal hydroxides, alkali metal carbonates, and alkali metal alcohols (US2011040117A1; WO2010063780A1) are used as catalysts for transesterification reactions. However, these homogeneous catalysts are difficult to separate from the product and reuse. Commonly used heterogeneous catalysts include supported alkali metals or alkali metal salts, metal oxide catalysts, alkaline (earth) metal-exchanged zeolites or clay materials, and ion exchange resins. Alkali metals or alkali metal salts supported on a carrier, such as KF / Al2O3, NaOH / chitosan, and Cs2CO3 / SiO2-Al2O3 (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 alkaline (earth) metal-exchanged zeolites or clay materials, such as Cs-ZSM-5, Mg-smectite, etc. (WO2000073256A1), have the disadvantage that their activity or selectivity is generally low. Ion exchange resins, such as quaternary ammonium or tertiary amine resins, are generally not heat-resistant or swelling-resistant, and their activity decreases rapidly over time.

[0004] Therefore, finding a catalyst for preparing dialkyl carbonate with high stability and high conversion rate is still an urgent need in the art.

[0005] Summary of the Invention

[0006] In response to 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.

[0007] 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 an 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.

[0008] A second aspect of the present invention provides a method for preparing a catalyst, comprising the following steps:

[0009] (1) contacting the halogenated alkylated resin with a modifier to modify the resin and obtain a modified halogenated alkylated resin;

[0010] (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

[0011] (3) A calcination step of optionally drying the contact product and then calcining it in an inert gas atmosphere.

[0012] A 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 catalyst of the present invention or a catalyst prepared by the preparation method of the present invention to obtain dialkyl carbonate.

[0013] Technical Effects

[0014] In the catalyst of the present invention, the content of active metal components distributed within the pores of the porous carbon support is higher than that distributed on the surface of the porous carbon support, accounting for more than 50% of the content of all active metal components contained in the catalyst. As a result, the catalyst of the present invention exhibits excellent conversion rate and selectivity in the preparation of dialkyl carbonates, and has a long catalyst life, making it suitable for industrial use. Furthermore, when preparing dialkyl carbonates, the carbon-supported catalyst has stable properties of the catalyst system and is not prone to loss of active centers, thus solving the problems of easy loss of active components and short catalyst life in heterogeneous catalysts existing in the prior art.

[0015] 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, thereby solving the problem of low activity of heterogeneous catalysts existing in the prior art; by modifying the resin and then loading the active metal precursor, and then calcining, more active metal components are allowed to enter the pores of the carbon carrier, thereby making it possible to efficiently prepare the catalyst of the present invention.

[0016] 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

[0017] FIG1 is a scanning electron microscope image of catalyst C1 prepared in Example 1 of the present invention;

[0018] FIG2 is a scanning electron microscope image of catalyst S1 prepared in Comparative Example 1 of the present invention;

[0019] FIG3 is a transmission electron micrograph of catalyst C1 prepared in Example 1 of the present invention;

[0020] FIG4 is a transmission electron micrograph of catalyst S1 prepared in Comparative Example 1 of the present invention.

[0021] Figure 5 (a) is a scanning electron microscope image of the catalyst C1 prepared in Example 1 of the present invention at a scale of 100 microns; (b) is 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.

[0022] Figure 6 (a) is 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) is 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.

[0023] 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.

[0024] Figure 8 (a) is 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) is 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.

[0025] Figure 9 (a) is a scanning electron microscope image of the interior of catalyst S1 prepared in comparative example 1 of the present invention at a scale of 200 nanometers; (b) is a scanning electron microscope image of the interior of catalyst S1 prepared in comparative example 1 of the present invention at a scale of 100 nanometers.

[0026] Figure 10 shows the energy spectrum scan and EDX spectrum of catalyst S1 prepared in Comparative Example 1 of the present invention; (a) selected area scan spectrum; (b) carbon element distribution diagram; (c) EDX spectrum. DETAILED DESCRIPTION

[0027] The present invention is described in detail below in conjunction with specific embodiments. However, it should be noted that the protection scope of the present invention is not limited by these specific embodiments and principle explanations, but is determined by the claims.

[0028] In the present invention, except for the contents explicitly described, any matters or issues 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 considered part of the original disclosure or description of the present invention and should not be regarded as new content not disclosed or anticipated herein, unless a person skilled in the art considers that the combination is obviously unreasonable.

[0029] All features disclosed in the present invention may be combined in any combination, and such combinations should be understood as disclosed or described in the present invention. Unless a person skilled in the art considers such combination to be obviously unreasonable, such combinations should be considered as specifically disclosed and described in the present invention. Unless otherwise specified, the numerical values ​​disclosed in this specification include not only the numerical values ​​specifically disclosed in the examples but also the endpoints of the numerical ranges in the specification. Any combination of these numerical values ​​should be considered as the range disclosed or described in the present invention.

[0030] Technical and scientific terms in the present invention shall be understood according to their definitions if they are defined, and shall be understood according to their general meanings in the art if they are not defined.

[0031] [Carbon-supported catalyst]

[0032] The present invention provides a porous carbon support-supported catalyst, which includes a porous carbon support, an active metal component and at least one heteroatom selected from nitrogen, sulfur and phosphorus, wherein the content of the porous carbon support 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 an 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 support, calculated as active metal oxide, accounts for more than 50% of the content of all active metal components in the catalyst.

[0033] In the catalyst of the present invention, the porous carbon carrier comes from the calcination of the porous resin material in an inert gas.

[0034] In the catalyst of the present invention, the particle size of the porous carbon support is not particularly limited and can be 0.1 mm to 3 mm, preferably 0.3 mm to 2 mm. The pore size of the porous carbon support of the present invention is not particularly limited and can be, for example, 5 to 500 nm, preferably 50 to 300 nm.

[0035] In one embodiment of the present invention, the content of the porous carbon support is 50% to 99% relative to the total mass of the catalyst, preferably 55 to 90%, and more preferably 60 to 85%.

[0036] 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.

[0037] In one embodiment of the present invention, the content of at least one heteroatom selected from nitrogen, sulfur and phosphorus, calculated as an element, is 0.1% to 5% relative to the total mass of the catalyst; preferably 0.3 to 4.5%, more preferably 0.5 to 4%.

[0038] In the present invention, the catalyst further contains oxygen, but the present invention is not intended to limit the content of oxygen. Generally, the content of oxygen is calculated within the oxide of the present invention.

[0039] In one embodiment of the present invention, the catalyst may also contain halogen elements, which are derived from the halogenated alkylated resin. Typically, the halogen elements are removed during calcination; however, some halogen elements may remain as impurities. The present invention is not intended to limit the halogen element content.

[0040] In the present invention, the content of the active metal component as oxide, the content of heteroatoms as elements, and the content of any halogen atoms as elements contained in the catalyst can be determined by means known in the art, such as elemental analysis. After deducting the content of the active metal oxide, heteroatoms, and any halogen atoms, 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 active metal precursor introduced during the catalyst preparation process.

[0041] 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.

[0042] 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.

[0043] 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 is usually present in the form of a metal oxide, which is the product of calcining the active metal precursor.

[0044] In the present invention, unless otherwise specified, the active metal component is usually measured in the form of active metal oxide.

[0045] In the catalyst of the present invention, the content of active metal components distributed in the pores of the porous carbon support (sometimes also referred to as the inner surface or interior in the present invention) is higher than that of active metal components distributed on the surface of the porous carbon support (sometimes also referred to as the outer surface or exterior in the present invention).

[0046] In one embodiment of the present invention, the content of the active metal component distributed within the pores of the porous carbon support, calculated as active metal oxide, relative to the content of the active metal component in the catalyst is greater than 50%, preferably greater than 55%, more preferably greater than 60%, even more preferably greater than 65%, and most preferably greater than 75%. The upper limit of the content of the active metal component distributed within the pores of the porous carbon support relative to the content of the active metal component in the catalyst is not particularly limited and is preferably 100%. However, from the perspective of actual production costs, the upper limit may be 99%, 98%, 96%, 96%, or 95%.

[0047] 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 support, calculated as active metal oxide, 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 limit of the content of the active metal component distributed on the surface (external surface or exterior) of the porous carbon support relative to the content of the active metal component contained in the catalyst is as low as possible, preferably 0. However, from the perspective of actual production costs, the lower limit may be 5%, 4%, 3%, 2%, or 1%.

[0048] In the present invention, the content of the active metal component distributed on the surface (external surface or exterior) of the porous carbon support can be measured by XPS. That is, in the present invention, the content of the active metal of the porous carbon support measured by XPS is regarded as the content of the active metal on the surface (external surface or exterior) of the porous carbon support.

[0049] It should be noted that, in the present invention, the content of the active metal component in the pores (inner surface or inside) of the porous carbon support can be obtained by subtracting the content of the active metal component distributed on the surface (outer surface or outside) of the porous carbon support from the total content of the active metal component in the porous carbon support. Here, for the total content of the active metal component in the catalyst, the content of the active metal component contained in the catalyst can be determined by elemental analysis, etc. On the other hand, in the present invention, the content of the active metal component of the porous carbon support measured by XPS is used as the content of the active metal component on the surface (outer surface or outside) of the porous carbon support. Thus, based on these two, the content of the active metal component distributed in the pores (inner surface or inside) of the porous carbon support can be calculated, and the content of the active metal component in the pores (inner surface or inside) = the total content of the active metal component in the porous carbon support - the content of the active metal component distributed on the surface (outer surface or outside) of the porous carbon support measured by XPS.

[0050] In the present invention, by distributing the active metal components mainly (e.g., more than 50%) in the pores of the porous carbon support, and more preferably distributing the majority of the active metal components (e.g., more than 55%, preferably more than 60%, further preferably more than 65%, and most preferably more than 70%) in the pores of the porous carbon support, the catalyst exhibits excellent conversion rate and high selectivity, and the catalyst life is greatly extended.

[0051] 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;

[0052] 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.

[0053] Preparation method of catalyst

[0054] A second aspect of the present invention provides a method for preparing a catalyst, comprising the following steps:

[0055] (1) contacting the halogenated alkylated resin with a modifier to modify the resin and obtain a modified halogenated alkylated resin;

[0056] (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

[0057] (3) a calcination step of optionally drying the contact product and then calcining it in an inert gas atmosphere,

[0058] The modifier is at least one compound selected from nitrogen-containing compounds, sulfur-containing compounds and phosphorus-containing compounds.

[0059] The inventors of the present invention have discovered that by modifying a halogenated alkylated resin with a modifier, allowing the modified resin to interact with an active metal precursor, and calcining the modified resin, a catalyst can be obtained in which the active metal components are mainly distributed in the pores of a porous carbon support.

[0060] In the present invention, halo or halogen includes fluorine, chlorine, bromine and iodine, preferably chlorine or iodine, more preferably chlorine.

[0061] In the present invention, the alkyl group in the alkylation can be a C1-C6 alkyl group, preferably a C1-C4 alkyl group, and more preferably a methyl group, an ethyl group, a propyl group, or an isopropyl group.

[0062] In one embodiment of the present invention, the haloalkylation is preferably halomethylation, more preferably chloromethylation.

[0063] In the present invention, the haloalkylated resin can be obtained by haloalkylating a conventional resin (preferably halomethylating, more preferably chloromethylating). Commercially available haloalkylated resins can also be used as long as the resin has a porous structure.

[0064] In the present invention, examples of the halogenated alkylated resin include halogenated alkylated styrene resins, such as chloromethyl resins, particularly chloromethyl styrene resins.

[0065] As a halogenated alkylated styrene resin, it can be a commercial product and can also be prepared by methods known in the art, including but not limited to the following method: using a haloolefin (C2-C6 haloolefin) to carry out alkylation of polystyrene, to produce a haloalkyl polystyrene (CN1137788A). In addition, as a chloromethyl styrene resin, it can be a commercial product and can also be prepared by methods known in the art, including but not limited to the following method: using a suspension polymerization method to prepare polystyrene microsphere resin, and reacting with chloromethyl ether to obtain a chloromethyl styrene resin (CN103864973A). In addition, the method of recording in CN103709278A, CN104788592A etc. can also be used to prepare a halogenated alkylated styrene resin or a chloromethyl styrene resin.

[0066] 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.

[0067] In one embodiment of the present invention, the pore diameter of the haloalkylated resin is 5 to 500 nm, preferably 50 to 300 nm.

[0068] In one embodiment of the present invention, the halogenated alkylated resin is spherical.

[0069] In step (1) of the present invention, the modifier is brought into contact with the haloalkylated resin for modification to obtain a modified haloalkylated resin (hereinafter sometimes also referred to as a modified product or modified resin). The present invention does not intend to limit the reaction occurring at this time, but it is speculated that this may be due to the interaction between the nitrogen, phosphorus, or sulfur heteroatoms contained in the modifier and the haloalkyl group. In addition, the introduced heteroatoms can promote the subsequent dispersion of the active metal precursor within the support, increase the dispersion of the metal active components, promote alkalinity, and promote the deposition of the active metal components in the pores of the porous carbon support after calcination.

[0070] 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.

[0071] In one embodiment of the present invention, the nitrogen-containing compound is a nitrogen-containing organic compound.

[0072] 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, amylamine, hexylamine, cyclohexylamine, octylamine, decylamine, dimethylamine, diethylamine, dibutylamine, trimethylamine, triethylamine, tributylamine, etc. can be listed. As 5-membered or 6-membered nitrogen-containing heterocyclic aromatic compounds, at least one of the 5-membered or 6-membered nitrogen-containing heterocyclic aromatic compounds optionally substituted with C1-C6 alkyl groups can be listed. As 5-membered or 6-membered nitrogen-containing heterocyclic aromatic compounds, 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 with C1-C6 alkyl groups. 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, and more preferably 1 or 2.

[0073] In one embodiment of the present invention, the sulfur-containing compound is a sulfur-containing organic compound.

[0074] 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. 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, methylphenyl disulfide and methylphenyl sulfide; thiourea; and sulfides such as methyl sulfide, ethyl sulfide and butyl sulfide.

[0075] In one embodiment of the present invention, the phosphorus-containing compound is a phosphorus-containing organic compound.

[0076] 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. Examples thereof include phosphines such as triphenylphosphine, triethylphosphine, tributylphosphine, tripropylphosphine, trioctylphosphine, and tricyclohexylphosphine.

[0077] In one embodiment of the present invention, the modifier is preferably at least one selected from imidazole optionally substituted by a C1-C6 alkyl group, pyridine optionally substituted by a C1-C6 alkyl group, thiophene optionally substituted by a C1-C6 alkyl group, thiazole optionally substituted by a C1-C6 alkyl group, piperazine optionally substituted by a C1-C6 alkyl group and triphenylphosphine, more preferably at least one selected from imidazole, 1-methylimidazole, pyridine, piperazine and thiophene.

[0078] 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, or 1:0.6.

[0079] 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.

[0080] 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.

[0081] 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., or 90° C. The temperature of the solution containing the resin raw material can be increased before the resin raw material and the modifier are contacted, or the temperature of the solution can be increased during the contact between the resin raw material and the modifier.

[0082] In the present invention, the modification time of the modification step is not particularly limited. 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.

[0083] 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 to 1000 rpm, preferably 100 to 800 rpm, for example, 500 or 800 rpm. The stirring time is not particularly limited and may be, for example, 2 hours.

[0084] 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 can be performed. The drying conditions can be a drying temperature of 80°C to 180°C, for example, 100°C or 120°C, and a drying time of 1 hour to 48 hours, for example, 24 hours.

[0085] 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.

[0086] In the present invention, the metal precursor of the active metal is loaded on the modified halogenated alkylated resin through step (2).

[0087] 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.

[0088] 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.

[0089] 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.

[0090] In one embodiment of the present invention, the metal precursor of the active metal is present in the form of a solution. The solvent in this case can be selected from the aforementioned 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%, or 35.2%.

[0091] 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).

[0092] In one embodiment of the present invention, the contacting step is carried out in the presence of 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.

[0093] 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. 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.

[0094] 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.

[0095] 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 or 24h.

[0096] In the present invention, modified resin particles of a metal precursor loaded with an active metal are calcined. During the calcination process, the resin particles are carbonized and converted into a porous carbon support. The porous carbon support serves as a porous carbon support for the catalyst of the present invention, and the active metal component on the porous carbon support is mainly enriched in the pores (inner surface or interior) of the porous carbon support. At the same time, the modifier is removed and at least one heteroatom selected from nitrogen, sulfur and phosphorus remains in the carbon support.

[0097] 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.

[0098] 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, or 600°C, and the calcination time is 1h to 48h, preferably 2h to 24h, such as 4h, 5h, or 8h.

[0099] In one embodiment of the present invention, a method for preparing a catalyst for preparing dimethyl carbonate is provided, wherein, during the preparation of the 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 hydrocarbon compound, the modified chloromethyl resin is a modified chloromethylstyrene 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 styryl, 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; and the chloromethyl resin is spherical;

[0100] and / or, the mass ratio of the chloromethyl resin to the solvent is 1:(1-10), preferably 1:(2-8);

[0101] and / or, the mass ratio of the chloromethyl resin to the modifier is 1:(0.1-1.2), preferably 1:(0.15-1);

[0102] And / or, before adding the modifier, a heating step is further included; the temperature after the heating is 30°C to 150°C, preferably 40°C to 120°C;

[0103] 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;

[0104] And / or, the modification time is 1 hour to 24 hours, preferably 2 hours to 18 hours; preferably, after the modification, the steps of cooling, separating, washing the product, and drying the product are further included; further preferably, the drying temperature is 80 to 180° C., and the drying time is 1 hour to 48 hours;

[0105] And / or, the preparation method includes the step of using a carrier to load the active component.

[0106] In one embodiment of the present invention, when the active component is loaded on a carrier, the carrier is mixed with a metal precursor solution containing the active component, stirred, dried, and then calcined in an inert gas atmosphere to obtain the catalyst.

[0107] In one embodiment of the present invention, the metal precursor solution containing active components is at least one of nitrate solution, chloride solution, and sulfate solution of magnesium, calcium, and aluminum, and the mass concentration of the metal precursor solution containing active components is 5% to 50%.

[0108] 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);

[0109] 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;

[0110] And or, the drying temperature is 80°C to 180°C, and the drying time is 1h to 48h;

[0111] and / or, the inert gas is nitrogen or argon;

[0112] And / or, the calcination temperature is 200° C. to 1000° C., and the calcination time is 1 hour to 48 hours. Preferably, the calcination temperature is 250° C. to 600° C., and the calcination time is 2 hours to 24 hours.

[0113] [Preparation method of dialkyl carbonate]

[0114] In a third aspect, the present invention provides a method for preparing a dialkyl carbonate represented by the following general formula (I), comprising the steps of reacting a carbonate represented by the following general formula (II) and a lower alcohol represented by the following general formula (III) in the presence 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.

[0115] R1-OCOO-R1 (I)

[0116] In formula (I), each R1 is independently selected from C1-C6 alkyl;

[0117] R2-OCOO-R2 (II)

[0118] 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;

[0119] R1-OH (III)

[0120] In formula (III), R1 is selected from C1-C6 alkyl.

[0121] In one embodiment of the present invention, the reaction temperature for preparing the dialkyl carbonate represented by 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, or 120°C.

[0122] In one embodiment of the present invention, the reaction time for preparing the dialkyl carbonate represented by general formula (I) is 1 h to 15 h, preferably 2 h to 12 h, for example 4 h, 6 h, 8 h, or 10 h.

[0123] 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.

[0124] In one embodiment of the present invention, in the preparation of the dialkyl carbonate represented by general formula (I), the mass ratio of the catalyst to the carbonate represented by general formula (II) is (0.001-0.5):1, preferably (0.05-0.5):1, for example, 0.2:1, 0.3:1, or 0.4:1.

[0125] In one embodiment of the present invention, in the dialkyl carbonate shown in 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 can include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and sec-butyl. Therefore, in the present invention, the dialkyl carbonate shown in general formula (I) can include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, dibutyl carbonate, etc.

[0126] In one embodiment of the present invention, in the carbonate represented by 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.

[0127] In one embodiment of the present invention, in the carbonate represented by general formula (II), two R2 are connected to each other to form a C2-C6 alkylene group. In this case, the carbonate represented by general formula (II) is a cyclic carbonate, for example, ethylene carbonate or propylene carbonate.

[0128] 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.

[0129] 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).

[0130] In the present invention, R2 and R1 may be the same, but at least one R2 is different from at least one R1.

[0131] In other words, in the present invention, the carbonate represented by general formula (II) and the lower alcohol represented by general formula (III) undergo an ester exchange reaction, so that R1 in the lower alcohol represented by general formula (III) becomes at least one end of the dialkyl carbonate represented by general formula (I).

[0132] 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;

[0133] and / or, the reaction temperature is 40°C to 130°C, preferably 50°C to 120°C;

[0134] And / or, the reaction time is 1h to 15h, preferably 2h to 12h,

[0135] and / or, the molar ratio of methanol to alkylene carbonate is (2-15):1, preferably (3-12):1;

[0136] and / or, the mass ratio of the catalyst to the alkylene carbonate is (0.001-0.5):1, preferably (0.05-0.5):1;

[0137] And / or, the alkylene carbonate is one or more of ethylene carbonate or propylene carbonate.

[0138] The catalyst of the present invention or the catalyst prepared by the catalyst preparation method of the present invention is used in the transesterification reaction of the carbonate represented by the general formula (II) and the lower alcohol represented by the general formula (III) to prepare a dialkyl carbonate. Even if it is reused multiple times (for example, more than 10 times), the activity decreases by less than 5%, achieving good technical effects.

[0139] An example of reaction conditions for preparing dialkyl carbonate includes a reaction temperature of 80°C, a molar ratio of lower alcohol to cyclic carbonate of 8:1, and a mass ratio of catalyst to cyclic carbonate of 0.3:1 for 10 hours. At this time, the conversion of the cyclic carbonate is 80.4%, and the selectivity for dialkyl carbonate is 99.9%.

[0140] Example

[0141] The present invention will be further described below with reference to the following examples, but the present invention is not limited to these examples.

[0142] The gas chromatograph used in the present invention is an Agilent 7890 chromatograph. The analytical conditions are: a chromatographic column, HP-FFAP, an inlet temperature of 280°C, an FID detector, a column oven temperature program: maintain at 50°C for 3 minutes, then increase to 230°C at a rate of 10°C / min and maintain for 10 minutes, a split ratio of 50:1, and component content analysis using the calibration normalization method.

[0143] The elemental analysis of heteroatom content was performed using a Therm2000 instrument.

[0144] XPS tests were performed on an X-ray photoelectron spectrometer (XPS, AXIS ULTRA DLD) from Kratos, Japan.

[0145] Metal element analysis was performed using ICP-OES using a Varian 725ES instrument.

[0146] SEM was performed using a scanning electron microscope (SEM, Merlin) from ZEISS, Germany.

[0147] TEM images were obtained on a Tecnai 20 S-TWIN transmission electron microscope with an operating voltage of 200 kV.

[0148] The conversion rate of the raw materials in the examples is calculated as follows: (mass of the input raw materials - mass of the product after reaction * content of the raw materials) / mass of the input raw materials * 100%.

[0149] The selectivity of carbonate in the examples is calculated as follows: carbonate product yield after reaction / theoretical carbonate yield of consumed raw materials*100%.

[0150] The calculation method for the proportion of active metal components distributed in the pores of the porous carbon support is: (the content of active metal components in the catalyst calculated as active metal oxides - the content of active metal components in the catalyst calculated as active metal oxides detected by XPS) / the content of active metal components in the catalyst calculated as active metal oxides.

[0151] Example 1

[0152] This embodiment provides a method for preparing dimethyl carbonate:

[0153] Preparation of catalyst for preparing dimethyl carbonate: In a 500ml three-necked flask, add 50g of chloromethylstyrene resin and 200ml (189.6g) of N,N-dimethylformamide, stir at 500 rpm for 2h, heat to 90℃, add 50g of imidazole, and keep the temperature for 12h. After cooling, the product was separated, washed with deionized water, and dried at 100°C for 24 hours to obtain a modified resin. Then, in another 500ml three-necked flask, 20g of the modified resin and 8.8g of magnesium nitrate were added to water to prepare a 100g solution. The solution was stirred at 500 rpm at 80°C for 6 hours, placed in an oven at 100°C for 14 hours, and then transferred to a muffle furnace and calcined at 500°C under a nitrogen atmosphere for 5 hours to obtain catalyst C1. The mass percentage of magnesium oxide in catalyst C1 was 10%. The scanning electron microscope image of catalyst C1 is shown in Figure 1, and the transmission electron microscope image of catalyst C1 is shown in Figure 3. The catalyst has a nitrogen content of 2.6%, a pore diameter of 150nm, and a magnesium oxide content of 86.7% inside the pores.

[0154] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 0.5 mm.

[0155] 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 h. 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 analyzed by gas chromatography and calculated to have a conversion of ethylene carbonate of 80.4% and a selectivity of dimethyl carbonate of 99.9%.

[0156] Furthermore, after the reaction is completed, the particulate catalyst in the reaction liquid is filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours before being reused, 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 the ethylene carbonate conversion rate is calculated.

[0157] 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%.

[0158] Figure 5 (a) shows a scanning electron micrograph of Catalyst C1 prepared in Example 1 of the present invention at a scale of 100 microns; (b) shows a scanning electron micrograph of the interior of the catalyst prepared in Example 1 of the present invention at a scale of 10 microns. As can be seen, the outer surface of the carbon support is smooth, while the magnesium oxide is primarily distributed on the inner surface of the carbon support.

[0159] Figure 6 shows (a) a scanning electron micrograph of the interior of Catalyst C1 prepared in Example 1 of the present invention at a 200-nanometer scale; (b) a scanning electron micrograph of the interior of Catalyst C1 prepared in Example 1 of the present invention at a 100-nanometer scale. As can be seen, the pores are filled to a certain extent, indicating that magnesium oxide is deposited within the catalyst.

[0160] Figure 7 shows the energy spectrum scan and EDX spectrum of Catalyst C1 prepared in Example 1 of the present invention; (a) shows the selected area scan; (b) shows the carbon distribution; (c) shows the oxygen distribution; (d) shows the magnesium distribution; and (e) shows the EDX spectrum. As can be seen, magnesium oxide is primarily distributed within the carbon support and has a relatively high EDX abundance.

[0161] Example 2

[0162] This embodiment provides a method for preparing dimethyl carbonate:

[0163] 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, stirred at a rate of 500 rev / min for 2h, heated to 90°C, 50g of imidazole was added, and the reaction was kept warm for 12h. The product was separated after cooling and washed with deionized water. The product was 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 to water to prepare a 100g solution, stirred at a rate of 600 rev / min for 8h at a temperature of 50°C, placed in an oven and dried at a temperature of 100°C for 24h, then transferred to a muffle furnace and calcined at a temperature of 400°C for 8h under a nitrogen atmosphere to obtain catalyst C2, wherein the mass percentage of magnesium oxide in catalyst C2 is 20%. The catalyst has a nitrogen content of 2.2%, a pore diameter of 200 nm, and the magnesium oxide content inside the pores accounts for 71.1%.

[0164] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 0.9 mm.

[0165] 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 110° C. for 6 h, 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 analyzed by gas chromatography and calculated to have a conversion of ethylene carbonate of 74.5% and a selectivity of dimethyl carbonate of 99.9%.

[0166] Furthermore, after the reaction is completed, the particulate catalyst in the reaction liquid is filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours before being reused, 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 the ethylene carbonate conversion rate is calculated.

[0167] 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%.

[0168] Example 3

[0169] This embodiment provides a method for preparing dimethyl carbonate:

[0170] 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, stirred at 800 rpm for 2h, heated to 80°C, 40g of imidazole was added, and the reaction was kept warm for 12h. The product was separated after cooling and washed with deionized water. The product was dried at 120°C for 24h to obtain a modified resin; then in another 500ml three-necked flask, 20g of the modified resin and 26.4g of magnesium nitrate were added to water to prepare a 100g solution. The solution was stirred at 300 rpm for 8h at 50°C, dried in an oven at 100°C for 24h, and then transferred to a muffle furnace and calcined at 500°C for 4h under a nitrogen atmosphere to obtain catalyst C3. The magnesium oxide content in 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%.

[0171] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 0.7 mm.

[0172] 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 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 analyzed by gas chromatography and calculated to have a conversion of ethylene carbonate of 61.4% and a selectivity of dimethyl carbonate of 99.9%.

[0173] Furthermore, after the reaction is completed, the particulate catalyst in the reaction liquid is filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours before being reused, 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 the ethylene carbonate conversion rate is calculated.

[0174] 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%.

[0175] Example 4

[0176] This embodiment provides a method for preparing dimethyl carbonate:

[0177] 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, stirred at 800 rpm for 2h, heated to 70°C, 30g of imidazole was added, and the reaction was kept warm for 15h. The product was separated after cooling and washed with deionized water. The product was dried at 120°C for 24h to obtain a modified resin; then in another 500ml three-necked flask, 20g of the modified resin and 35.2g of magnesium nitrate were added to water to prepare a 100g solution. The solution was stirred at 400 rpm for 2h at 50°C, dried in an oven at 100°C for 24h, and then transferred to a muffle furnace and calcined at 500°C for 4h under a nitrogen atmosphere to obtain catalyst C4. The magnesium oxide content in 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%.

[0178] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 1.0 mm.

[0179] 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 analyzed by gas chromatography and calculated to have a conversion of ethylene carbonate of 80.9% and a selectivity of dimethyl carbonate of 99.9%.

[0180] Furthermore, after the reaction is completed, the particulate catalyst in the reaction liquid is filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours before being reused, 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 the ethylene carbonate conversion rate is calculated.

[0181] 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%.

[0182] Example 5

[0183] This embodiment provides a method for preparing dimethyl carbonate:

[0184] 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, stirred at 800 rpm for 2h, heated to 70°C, 30g of imidazole was added, and the reaction was kept warm for 15h. The product was separated after cooling and washed with deionized water. The product was dried at 120°C for 24h to obtain a modified resin; then in another 500ml three-necked flask, 20g of the modified resin and 26.4g of magnesium nitrate were added to water to prepare a 100g solution. The solution was stirred at 400 rpm for 2h at 50°C, dried in an oven at 100°C for 24h, and then transferred to a muffle furnace and calcined at 500°C for 4h under a nitrogen atmosphere to obtain catalyst C5. The magnesium oxide content in 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%.

[0185] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 1.0 mm.

[0186] 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 analyzed by gas chromatography and calculated to have a conversion of ethylene carbonate of 80.5% and a selectivity of dimethyl carbonate of 99.9%.

[0187] Furthermore, after the reaction is completed, the particulate catalyst in the reaction liquid is filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours before being reused, 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 the ethylene carbonate conversion rate is calculated.

[0188] 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%.

[0189] Example 6

[0190] This embodiment provides a method for preparing dimethyl carbonate:

[0191] 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, stirred at 800 rpm for 2h, heated to 70°C, 30g of thiophene was added, and the reaction was kept warm for 15h. The product was separated after cooling and washed with deionized water. The product was dried at 120°C for 24h to obtain a modified resin; then in another 500ml three-necked flask, 20g of the modified resin and 26.4g of magnesium nitrate were added to water to prepare a 100g solution. The solution was stirred at 400 rpm for 2h at 50°C, dried in an oven at 100°C for 24h, and then transferred to a muffle furnace and calcined at 500°C for 4h under a nitrogen atmosphere to obtain catalyst C6. The magnesium oxide content in catalyst C6 was 30%. The catalyst has a sulfur content of 2.7%, a pore diameter of 100 nm, and the magnesium oxide content inside the pores accounts for 66.4%.

[0192] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 1 mm.

[0193] 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 analyzed by gas chromatography and calculated to have a conversion of ethylene carbonate of 80.2% and a selectivity of dimethyl carbonate of 99.9%.

[0194] Furthermore, after the reaction is completed, the particulate catalyst in the reaction liquid is filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours before being reused, 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 the ethylene carbonate conversion rate is calculated.

[0195] 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%.

[0196] Example 7

[0197] This embodiment provides a method for preparing dimethyl carbonate:

[0198] 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, stirred at 800 rpm for 2h, heated to 70°C, 30g of imidazole was added, and the reaction was kept warm for 15h. The product was separated after cooling and washed with deionized water. The product was dried at 120°C for 24h to obtain a modified resin; then in another 500ml three-necked flask, 20g of the modified resin and 8g of calcium nitrate were added to water to prepare a 100g solution. The solution was stirred at 300 rpm for 2h at 50°C, dried in an oven at 100°C for 24h, and then transferred to a muffle furnace. Under a nitrogen atmosphere, the solution was calcined at 500°C for 4h to obtain catalyst C7. The calcium oxide content in catalyst C7 was 20%. The nitrogen content of the catalyst is 2.2%, the pore diameter is 120nm, and the calcium oxide content inside the pores accounts for 68.8%.

[0199] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 1.0 mm.

[0200] 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 analyzed by gas chromatography and calculated to have a conversion of ethylene carbonate of 80.4% and a selectivity of dimethyl carbonate of 99.9%.

[0201] Furthermore, after the reaction is completed, the particulate catalyst in the reaction liquid is filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours before being reused, 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 the ethylene carbonate conversion rate is calculated.

[0202] 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%.

[0203] Example 8

[0204] This embodiment provides a method for preparing dimethyl carbonate:

[0205] 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, stirred at 800 rev / min for 2h, heated to 70°C, 30g of triphenylphosphine was added, and the reaction was kept warm for 15h. The product was separated after cooling and washed with deionized water. The product was dried at 120°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 80g of the solution, stirred at 50°C for 2h, placed in an oven and dried at 100°C for 24h, and then transferred to a muffle furnace and calcined at 500°C for 4h under a nitrogen atmosphere to obtain catalyst C8, wherein the magnesium oxide content in catalyst C8 is 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%.

[0206] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 1.0 mm.

[0207] 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 to have a conversion rate of ethylene carbonate of 80.3% and a selectivity of dimethyl carbonate of 99.9%.

[0208] Furthermore, after the reaction is completed, the particulate catalyst in the reaction liquid is filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours before being reused, 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 the ethylene carbonate conversion rate is calculated.

[0209] 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%.

[0210] Example 9

[0211] This embodiment provides a method for preparing dimethyl carbonate:

[0212] 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, stirred at 800 rpm for 2h, heated to 70°C, 30g of piperazine was added, and the reaction was kept warm for 15h. The product was cooled and separated, washed with deionized water, and dried at 120°C for 24h to obtain a modified resin; then, in another 500ml three-necked flask, 20g of the modified resin and 11.4g of aluminum nitrate were added to water to prepare a 100g solution, stirred at 50°C for 2h, dried in an oven at 100°C for 24h, and then transferred to a muffle furnace and calcined at 600°C for 4h under a nitrogen atmosphere to obtain catalyst C9, wherein the aluminum oxide content in catalyst C9 is 20%. The catalyst has a nitrogen content of 0.8%, a pore diameter of 100 nm, and an alumina content inside the pores of 67.6%.

[0213] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 1.2 mm.

[0214] 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 analyzed by gas chromatography and calculated to have a conversion of ethylene carbonate of 80.6% and a selectivity of dimethyl carbonate of 99.9%.

[0215] Furthermore, after the reaction is completed, the particulate catalyst in the reaction liquid is filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours before being reused, 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 the ethylene carbonate conversion rate is calculated.

[0216] 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%.

[0217] Example 10

[0218] This embodiment provides a method for preparing dimethyl carbonate:

[0219] 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, stirred at 800 rpm for 2h, heated to 70°C, 30g of 1-methylimidazole was added, and the reaction was kept warm for 15h. The product was separated after cooling and washed with deionized water. The product was then dried at 120°C for 24h to obtain a modified resin; then in another 500ml three-necked flask, 20g of the modified resin and 26.4g of magnesium nitrate were added to water to prepare a 100g solution. The solution was stirred at 500 rpm for 2h at 50°C, dried in an oven at 100°C for 24h, and then transferred to a muffle furnace and calcined at 500°C for 4h under a nitrogen atmosphere to obtain catalyst C10. The magnesium oxide content in catalyst C10 was 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%.

[0220] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 1.0 mm.

[0221] 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 analyzed by gas chromatography and calculated to have a conversion of ethylene carbonate of 80.5% and a selectivity of dimethyl carbonate of 99.9%.

[0222] Furthermore, after the reaction is completed, the particulate catalyst in the reaction liquid is filtered and recovered, washed with deionized water, placed in an oven at a temperature of 100° C. and dried for 24 hours before being reused, 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 the ethylene carbonate conversion rate is calculated.

[0223] 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%.

[0224] Example 11

[0225] This embodiment provides a method for preparing ethyl methyl carbonate:

[0226] 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 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 analyzed by gas chromatography and calculated to have a conversion of dimethyl carbonate of 91.6% and a selectivity of ethyl methyl carbonate of 92.4%.

[0227] Example 12

[0228] This embodiment provides a method for preparing ethyl methyl carbonate:

[0229] 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 analyzed by gas chromatography and calculated to have a conversion of dimethyl carbonate of 64.5% and a selectivity of ethyl methyl carbonate of 73.1%.

[0230] Comparative Example 1

[0231] This comparative example provides a method for preparing dimethyl carbonate:

[0232] Preparation of a catalyst for preparing dimethyl carbonate: In a 500ml three-necked flask, 20g of chloromethylstyrene resin and 8.8g of magnesium nitrate were added to water to prepare a 100g solution. The solution was stirred at 80°C for 6 hours, dried in an oven at 100°C for 14 hours, and then calcined in a muffle furnace at 500°C under a nitrogen atmosphere for 5 hours to obtain Catalyst S1. The mass percentage of magnesium oxide in Catalyst S1 was 10%. A scanning electron micrograph of Catalyst S1 is shown in Figure 2, and a transmission electron micrograph of Catalyst S1 is shown in Figure 4. Measurements and calculations revealed that there was virtually no active metal component within the pores.

[0233] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 0.5 mm.

[0234] 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. 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 analyzed by gas chromatography and calculated to have a conversion of ethylene carbonate of 59.6% and a selectivity of dimethyl carbonate of 99.8%.

[0235] Figure 8 shows (a) a scanning electron micrograph of Catalyst S1 prepared in Comparative Example 1 of the present invention at a 100-micrometer scale; (b) a scanning electron micrograph of the interior of Catalyst S1 prepared in Comparative Example 1 of the present invention at a 20-micrometer scale. As can be seen, the outer surface of the carbon support is rough, where magnesium oxide adheres, while the inner surface of the carbon support is almost devoid of magnesium oxide.

[0236] Figure 9 shows (a) a scanning electron micrograph of the interior of Catalyst S1 prepared in Comparative Example 1 of the present invention at a 200-nanometer scale; (b) a scanning electron micrograph of the interior of Catalyst S1 prepared in Comparative Example 1 of the present invention at a 100-nanometer scale. As can be seen, the interior of the carbon support maintains its pore structure, with no intrusion of magnesium oxide.

[0237] Figure 10 shows the energy spectrum scan and EDX spectrum of Catalyst S1, prepared in Comparative Example 1 of the present invention. (a) shows the selected area scan; (b) shows the carbon element distribution; and (c) shows the EDX spectrum. As can be seen, magnesium oxide is essentially absent from the internal pores of the carbon support, with virtually no magnesium detected by EDX.

[0238] Comparative Example 2

[0239] This comparative example provides a method for preparing dimethyl carbonate:

[0240] Preparation of the 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 powdered catalyst S2.

[0241] 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 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 analyzed by gas chromatography and calculated to have a conversion rate of ethylene carbonate of 32.7% and a selectivity of dimethyl carbonate of 99.9%.

[0242] Comparative Example 3

[0243] This comparative example provides a method for preparing dimethyl carbonate:

[0244] Preparation of a catalyst for preparing dimethyl carbonate: In a 500ml three-necked flask, 20g of styrene resin and 8.8g of magnesium nitrate were added to water to prepare a 100g solution. The solution was stirred at 80°C for 6 hours, dried in an oven at 100°C for 14 hours, and then calcined in a muffle furnace at 500°C under a nitrogen atmosphere for 5 hours to obtain Catalyst S3. The mass percentage of magnesium oxide in Catalyst S3 was 6.5%. Measurement and calculation showed that there was almost no active metal component in the pores.

[0245] During the catalyst preparation process, the chloromethylstyrene resin was spherical with a particle size of 0.5 mm.

[0246] 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. 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 analyzed by gas chromatography and calculated to have a conversion of 39.4% for ethylene carbonate and a selectivity for dimethyl carbonate of 99.9%.

[0247] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation of 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 function.

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) The contact product is optionally dried and then calcined in an inert gas atmosphere. Burning steps, 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 in the form of nitrate, chloride or the like of the active metal. At least one of the following forms: 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, the carbonate represented by the following general formula (II) and the 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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