A catalyst, its preparation and use

Abstract

The application provides a catalyst and a preparation method and application thereof. The catalyst comprises a carrier, an active component, an auxiliary active component and a quaternary ammonium salt supported on the carrier, wherein the active component comprises PdCl2, and the quaternary ammonium salt coats the active component and the auxiliary active component. The quaternary ammonium salt contained in the catalyst can not only act as a surfactant to reduce the agglomeration of the active component, improve the dispersity of the active component, and thus improve the activity of the catalyst, but also act as an auxiliary agent to improve the selectivity of the catalyst. The catalyst exhibits good catalytic activity and selectivity for a reaction system of preparing dimethyl carbonate by carbonylation of nitrite.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a catalyst, its preparation method, and its application. Background Technology

[0002] Dimethyl carbonate (DMC) is a non-toxic, environmentally friendly, and widely used organic chemical raw material. In recent years, with the rapid development of new energy vehicles, the demand for DMC, as one of the commonly used solvents in lithium-ion battery electrolytes, has increased significantly. Driven by the development of new energy vehicles, the demand for electrolyte solvents may surpass that for polycarbonate, becoming the largest downstream application of dimethyl carbonate. Developing electronic-grade dimethyl carbonate preparation technology has significant forward-looking strategic importance for improving the supply of electrolyte solvents for power batteries in my country.

[0003] Existing DMC synthesis processes mainly include transesterification, urea method, oxalate decarbonylation, and methanol vapor-phase oxidative carbonylation. The methanol vapor-phase oxidative carbonylation method consists of two steps: the first step produces methyl nitrite, and the second step involves the carbonylation of methyl nitrite to generate DMC. This process uses low-cost raw materials, has high single-equipment production capacity, and offers significant advantages for large-scale production.

[0004] Catalytic technology for the carbonylation reaction of nitrite esters is a key technology for the gas-phase oxidative carbonylation of methanol to produce dimethyl carbonate. For example, patent application 202310003493 discloses a Pd-Cu-X monolithic catalyst for the preparation of dimethyl carbonate. Patent application 202111435891 discloses a catalyst using a mixture of alumina, silica, and calcium oxide as a support, palladium as the active component, and copper, titanium, and nickel as auxiliary agents. Patent application 202110543649 discloses a molecular sieve-supported palladium-carbon catalyst for the gas-phase synthesis of dimethyl carbonate. However, existing catalysts for the synthesis of dimethyl carbonate suffer from poor stability, low activity, and low selectivity. Providing a highly selective catalyst for the preparation of dimethyl carbonate is one of the urgent problems to be solved in this field. Summary of the Invention

[0005] To solve all or part of the above-mentioned technical problems, the present invention provides the following technical solutions:

[0006] One objective of this invention is to provide a catalyst comprising a support and an active component, a co-active component, and a quaternary ammonium salt supported on the support, wherein the active component comprises PdCl2, and the quaternary ammonium salt coats the active component and the co-active component.

[0007] The quaternary ammonium salt in the above catalyst can act as a surfactant to reduce the aggregation of active component particles and improve the dispersion of active components, thereby improving catalyst activity. It can also act as an additive to improve catalyst selectivity. The hydrophilic end of the quaternary ammonium salt is close to the active component and co-active component, while the lipophilic end is far from the active component and co-active component, thus forming a coating layer on the catalyst surface.

[0008] In some embodiments, the co-active ingredient includes at least one of CuCl2 and / or lanthanide metal chlorides. During the catalytic reaction, Cu can undergo +2, +1, and 0 oxidation states, thereby maintaining the stability of the +2 oxidation state of Pd. Lanthanide metal chlorides have the function of absorbing and fixing Cl-.

[0009] Furthermore, the lanthanide chloride is MCl3, wherein M includes at least one of La, Ce, and Pr.

[0010] In some preferred embodiments, the co-active ingredients include CuCl2 and MCl3.

[0011] In some embodiments, the active component and / or co-active component are loaded onto the carrier in the form of nanoparticles.

[0012] In some embodiments, the Pd content in the catalyst is 0.2 wt% to 2.0 wt%.

[0013] In some embodiments, the Cu content in the catalyst is 0.5 wt% to 5.0 wt%.

[0014] In some embodiments, the lanthanide metal content in the lanthanide chloride in the catalyst is 0.3 wt% to 3.0 wt%.

[0015] In some embodiments, the quaternary ammonium salt content in the catalyst is 0.2 wt% to 2.0 wt%. If the quaternary ammonium salt content is too high, the active component will be densely coated, making it difficult for the reactants to contact the active component, thus leading to a decrease in activity; if the quaternary ammonium salt content is too low, it will not have any effect.

[0016] In some embodiments, the mass ratio of Cu to Pd in ​​the catalyst is 2:1 to 4:1.

[0017] In some embodiments, the mass ratio of the sum of the masses of Pd, Cu, and M elements to the mass ratio of the quaternary ammonium salt in the catalyst is 4:1 to 5:1.

[0018] In some embodiments, the quaternary ammonium salt is R4NX, where X is at least one of Cl and Br, and R is an alkyl group, wherein the four R groups may be the same or different.

[0019] Furthermore, the quaternary ammonium salt includes at least one of tetrabutylammonium bromide, tetrabutylammonium chloride, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, tetramethylammonium bromide, tetramethylammonium chloride, dodecyltrimethylammonium chloride, and dodecyltrimethylammonium bromide.

[0020] In some embodiments, the carrier comprises Al2O3. The Al2O3 has, for example, a porous structure, and its morphology includes, but is not limited to, spherical, clover-shaped, etc.

[0021] A second objective of this invention is to provide a method for preparing the catalyst described in any of the above claims, the method comprising: impregnating a support in a homogeneous mixed solution containing PdCl2, a co-active component and a quaternary ammonium salt, and after impregnation, drying and calcining the support to obtain the catalyst.

[0022] In some embodiments, the preparation method specifically includes: impregnating the support in a mixed solution containing PdCl2, CuCl2, lanthanide metal chloride, quaternary ammonium salt and ammonia, and then drying and calcining the impregnation to obtain the catalyst.

[0023] In some embodiments, the impregnation temperature is 25–60°C.

[0024] In some embodiments, the immersion time is 2 hours or more. Preferably, the immersion time is 2 to 6 hours.

[0025] In some embodiments, the drying temperature is 100–120°C, and / or the drying time is 2 hours or more. Preferably, the drying time is 2–6 hours.

[0026] In some embodiments, the calcination temperature is 130–200°C, and / or the calcination time is 5 hours or more. Preferably, the calcination time is 5–12 hours.

[0027] In some embodiments, Pd in ​​the mixed solution 2+ The content is 0.3wt% to 3.0wt%.

[0028] In some embodiments, Cu in the mixed solution 2+ The content is 0.8wt% to 8.0wt%.

[0029] In some embodiments, the lanthanide content in the lanthanide chloride in the mixed solution is 0.5 wt% to 5.0 wt%.

[0030] In some embodiments, the quaternary ammonium salt content in the mixed solution is 0.3 wt% to 3.0 wt%.

[0031] In some embodiments, the ammonia content in the mixed solution is 5.0 wt% to 20 wt%.

[0032] A third objective of this invention is to provide the application of any of the catalysts described above in the carbonylation of nitrite esters to prepare dimethyl carbonate.

[0033] The fourth objective of this invention is to provide a method for preparing dimethyl carbonate by carbonylation of nitrite, the method comprising: catalytically reacting a mixed gas containing methyl nitrite and CO in the presence of the catalyst described in any of the above technical solutions to obtain dimethyl carbonate.

[0034] Using the above-mentioned catalyst for the carbonylation of nitrites to prepare dimethyl carbonate can make the reaction system highly selective.

[0035] In some embodiments, the methyl nitrite content in the mixed gas is 10-20%.

[0036] In some embodiments, the CO content in the mixed gas is 10-20%.

[0037] In some embodiments, the mixed gas further includes a balance gas. The balance gas is, for example, nitrogen.

[0038] In some embodiments, the mixed gas further includes HCl gas. Further, the content of the HCl gas is 10–500 ppm.

[0039] In some embodiments, the temperature of the catalytic reaction is 110–140°C.

[0040] In some embodiments, the pressure of the catalytic reaction is 0.1 to 1 MPa.

[0041] In some embodiments, the reaction space velocity of the catalytic reaction is 1500–5500 h⁻¹. -1 .

[0042] Compared with the prior art, the present invention has at least the following beneficial effects: the quaternary ammonium salt contained in the catalyst provided by the present invention can act as a surfactant to reduce the aggregation of active components, improve the dispersion of active components, and thus improve catalyst activity, and can also act as an additive to improve catalyst selectivity; the catalyst provided by the present invention uses PdCl2 as the main active component, Pd... +2 It is more conducive to the selective formation of dimethyl carbonate; the catalyst provided by this invention has high catalytic activity and selectivity for the reaction system of carbonylation of nitrite to prepare dimethyl carbonate. Detailed Implementation

[0043] The technical solutions of the present invention will be described in detail below with reference to specific embodiments, so that those skilled in the art can better understand and implement the technical solutions of the present invention. The specific functional details disclosed herein should not be construed as limiting, but are merely intended to form the basis of the claims and to teach those skilled in the art to employ the representative basis of the invention in different ways in any suitable detailed embodiment.

[0044] Example 1

[0045] This embodiment relates to a catalyst and its preparation method, including the following steps:

[0046] PdCl2, CuCl2, PrCl3, tetrabutylammonium bromide (TBAB), and ammonia solution were mixed and dissolved to obtain a mixed solution. The Pd in ​​the mixed solution... 2+ The mass fraction is 0.8 wt%, Cu 2+ The mass fraction is 2.5 wt%, Pr 3+ The mass fraction of the substance is 1.3 wt%, the mass fraction of TBAB is 1 wt%, and the mass fraction of ammonia is 10 wt%.

[0047] 100g of Al₂O₃ support particles were added to the above mixed solution and impregnated at room temperature for 5 hours. After impregnation, the particles were removed, dried at 120℃ for 2 hours, and then calcined at 160℃ for 5 hours to obtain the catalyst. In the catalyst prepared in this example, the loading rates of Pd, Cu, Pr, and TBAB were 0.5wt%, 1.5wt%, 0.8wt%, and 0.6wt%, respectively.

[0048] The reaction for the carbonylation of nitrite to prepare dimethyl carbonate using the above-mentioned catalyst specifically includes: placing the synthesized catalyst in a fixed-bed reactor with an inner diameter of 18 mm, a catalyst loading of 50 ml, and 50 ml of inert quartz sand at the top and bottom of the catalyst bed; using a three-stage temperature control system in the reaction tube; the feed gas being a mixture of CO, methyl nitrite, nitrogen (equilibrium gas), and trace amounts of HCl, wherein the CO content is 15%, the methyl nitrite content is 15%, and the HCl content is 200 ppm; and the catalytic space velocity is 3000 h⁻¹. -1 The reaction temperature was controlled at 120℃-130℃, and the reaction pressure was controlled at 0.18-0.22MPa. After the catalyst reaction stabilized for 1 hour, the product in the collection tank was removed, and the synthesis reaction was allowed to continue for 8 hours before the product was collected. The feed gas, tail gas, and product were analyzed by weighing and gas chromatography to calculate the conversion rate of methyl nitrite and the selectivity of dimethyl carbonate. This reaction method is the method for testing the activity of the catalyst.

[0049] The conversion rate of methyl nitrite is calculated using the following formula:

[0050]

[0051] The method for calculating the selectivity of dimethyl carbonate is as follows: the dimethyl carbonate content in the product is obtained by analyzing the product by gas chromatography, which is the selectivity.

[0052] The performance of the catalyst in this embodiment is shown in Table 1.

[0053] Example 2

[0054] This embodiment relates to a catalyst and its preparation method, including the following steps:

[0055] PdCl2, CuCl2, LaCl3, tetrabutylammonium chloride (TBAC), and ammonia solution were mixed and dissolved to obtain a mixed solution. The Pd in ​​the mixed solution... 2+ The mass fraction is 0.8 wt%, Cu 2+ The mass fraction was 2.2 wt%, La 3+ The mass fraction of the ammonia solution is 1.1 wt%, the mass fraction of TBAC is 0.8 wt%, and the mass fraction of ammonia is 10 wt%.

[0056] 100g of Al₂O₃ support particles were added to the above mixed solution and impregnated at room temperature for 5 hours. After impregnation, the particles were removed, dried at 120℃ for 2 hours, and then calcined at 160℃ for 5 hours to obtain the catalyst. In the catalyst prepared in this example, the loading rates of Pd, Cu, La, and TBAC were 0.49 wt%.

[0057] The reaction of carbonylation of nitrite to prepare dimethyl carbonate using the catalyst prepared in this embodiment differs from that in Example 1 only in that the catalyst in Example 1 is replaced with the catalyst in this embodiment. The performance evaluation of the catalyst in this embodiment is shown in Table 1.

[0058] Example 3

[0059] This embodiment relates to a catalyst and its preparation method, including the following steps:

[0060] PdCl2, CuCl2, CeCl3, tetradecyltrimethylammonium bromide (TTAB) were dissolved in an ammonia solution to obtain a mixed solution. The PdCl2 content in the mixed solution was... 2+ The mass fraction is 0.8 wt%, Cu 2+ The mass fraction was 3.2 wt%, Ce 3+ The mass fraction of the substance is 1.5 wt%, the mass fraction of TTAB is 1.2 wt%, and the mass fraction of ammonia is 10 wt%.

[0061] 100g of Al₂O₃ support particles were added to the above mixed solution and impregnated at room temperature for 5 hours. After impregnation, the particles were removed, dried at 120℃ for 2 hours, and then calcined at 160℃ for 5 hours to obtain the catalyst. In the catalyst prepared in this example, the loading rates of Pd, Cu, Ce, and TTAB were 0.71 wt%.

[0062] The reaction of carbonylation of nitrite to prepare dimethyl carbonate using the catalyst prepared in this embodiment differs from that in Example 1 only in that the catalyst in Example 1 is replaced with the catalyst in this embodiment. The performance evaluation of the catalyst in this embodiment is shown in Table 1.

[0063] Example 4

[0064] This embodiment relates to a catalyst and its preparation method, including the following steps:

[0065] PdCl2, CuCl2, LaCl3, and hexadecyltrimethylammonium bromide (CTAB) were mixed and dissolved in an ammonia solution to obtain a mixed solution. The Pd in ​​the mixed solution... 2+ The mass fraction is 3 wt%, Cu 2+ The mass fraction is 8 wt%, Ce 3+ The mass fraction of the substance is 5 wt%, the mass fraction of CTAB is 3 wt%, and the mass fraction of ammonia is 20 wt%.

[0066] 100g of Al₂O₃ support particles were added to the above mixed solution and impregnated at 60°C for 2 hours. After impregnation, the particles were removed, dried at 120°C for 4 hours, and then calcined at 200°C for 5 hours to obtain the catalyst. In the catalyst prepared in this example, the loading rates of Pd, Cu, La, and CTAB were 2 wt%.

[0067] The reaction of carbonylation of nitrite to prepare dimethyl carbonate using the catalyst prepared in this embodiment differs from that in Example 1 only in that the catalyst in Example 1 is replaced with the catalyst in this embodiment. The performance evaluation of the catalyst in this embodiment is shown in Table 1.

[0068] Example 5

[0069] This embodiment relates to a catalyst and its preparation method, including the following steps:

[0070] PdCl2, CuCl2, PrCl3, and tetramethylammonium bromide (TMAB) were mixed and dissolved in an ammonia solution to obtain a mixed solution. The Pd in ​​the mixed solution... 2+The mass fraction is 0.3 wt%, Cu 2+ The mass fraction is 0.8 wt%, Pr 3+ The mass fraction of the substance is 0.5 wt%, the mass fraction of TMAB is 0.3 wt%, and the mass fraction of ammonia is 5 wt%.

[0071] 100g of Al₂O₃ support particles were added to the above mixed solution and impregnated at room temperature for 5 hours. After impregnation, the particles were removed, dried at 100℃ for 2 hours, and then calcined at 130℃ for 5 hours to obtain the catalyst. In the catalyst prepared in this example, the loading rates of Pd, Cu, Pr, and TMAB were 0.2wt%, 0.5wt%, 0.3wt%, and 0.2wt%, respectively.

[0072] The reaction of carbonylation of nitrite to prepare dimethyl carbonate using the catalyst prepared in this embodiment differs from that in Example 1 only in that the catalyst in Example 1 is replaced with the catalyst in this embodiment. The performance evaluation of the catalyst in this embodiment is shown in Table 1.

[0073] Example 6

[0074] This embodiment relates to a catalyst and its preparation method, including the following steps:

[0075] PdCl2, CuCl2, CeCl3, tetramethylammonium chloride (TMAC), and ammonia solution were mixed and dissolved to obtain a mixed solution. The Pd in ​​the mixed solution... 2+ The mass fraction is 1.6 wt%, Cu 2+ The mass fraction is 5 wt%, pr 3+ The mass fraction of the substance is 2.5 wt%, the mass fraction of TMAC is 1.8 wt%, and the mass fraction of ammonia is 10 wt%.

[0076] 100g of Al₂O₃ support particles were added to the above mixed solution and impregnated at room temperature for 5 hours. After impregnation, the particles were removed, dried at 120℃ for 2 hours, and then calcined at 160℃ for 5 hours to obtain the catalyst. In the catalyst prepared in this example, the loading rates of Pd, Cu, Ce, and TMAC were 1.1 wt%.

[0077] The reaction of carbonylation of nitrite to prepare dimethyl carbonate using the catalyst prepared in this embodiment differs from that in Example 1 only in that the catalyst in Example 1 is replaced with the catalyst in this embodiment. The performance evaluation of the catalyst in this embodiment is shown in Table 1.

[0078] Example 7

[0079] This embodiment relates to a catalyst and its preparation method, including the following steps:

[0080] PdCl2, CuCl2, LaCl3, and dodecyltrimethylammonium chloride (DTAC) were mixed and dissolved in an ammonia solution to obtain a mixed solution. The Pd in ​​the mixed solution... 2+ The mass fraction is 1.6 wt%, Cu 2+ The mass fraction is 4 wt%, Pr 3+ The mass fraction of the ammonia solution is 2.2 wt%, the mass fraction of DTAC is 1.8 wt%, and the mass fraction of ammonia is 10 wt%.

[0081] 100g of Al₂O₃ support particles were added to the above mixed solution and impregnated at room temperature for 5 hours. After impregnation, the particles were removed, dried at 120℃ for 2 hours, and then calcined at 160℃ for 5 hours to obtain the catalyst. In the catalyst prepared in this example, the loading rates of Pd, Cu, La, and DTAC were 1.1 wt%.

[0082] The reaction of carbonylation of nitrite to prepare dimethyl carbonate using the catalyst prepared in this embodiment differs from that in Example 1 only in that the catalyst in Example 1 is replaced with the catalyst in this embodiment. The performance evaluation of the catalyst in this embodiment is shown in Table 1.

[0083] Example 8

[0084] This embodiment relates to a catalyst and its preparation method, including the following steps:

[0085] PdCl2, CuCl2, CeCl3, and dodecyltrimethylammonium bromide (DTAB) were mixed and dissolved in an ammonia solution to obtain a mixed solution. The Pd in ​​the mixed solution... 2+ The mass fraction is 2.5 wt%, Cu 2+ The mass fraction was 5.2 wt%, Pr 3+ The mass fraction of the substance is 3 wt%, the mass fraction of DTAB is 2.7 wt%, and the mass fraction of ammonia is 10 wt%.

[0086] 100g of Al₂O₃ support particles were added to the above mixed solution and impregnated at room temperature for 5 hours. After impregnation, the particles were removed, dried at 120℃ for 2 hours, and then calcined at 160℃ for 5 hours to obtain the catalyst. In the catalyst prepared in this example, the loading rates of Pd, Cu, Ce, and DTAB were 1.6 wt%.

[0087] The reaction of carbonylation of nitrite to prepare dimethyl carbonate using the catalyst prepared in this embodiment differs from that in Example 1 only in that the catalyst in Example 1 is replaced with the catalyst in this embodiment. The performance evaluation of the catalyst in this embodiment is shown in Table 1.

[0088] Comparative Example 1

[0089] PdCl2 was dissolved in an ammonia solution to form a mixed solution. The Pd in ​​the mixed solution... 2+ The mass fraction of the ammonia solution is 1.6 wt%, and the mass fraction of the ammonia solution is 10 wt%.

[0090] 100g of Al2O3 support particles were added to the mixed solution and impregnated at room temperature for 5h. The particles were then removed and dried at 120℃ for 2h and calcined at 160℃ for 5h to obtain the catalyst. In the catalyst prepared in this comparative example, the Pd loading rate was 1wt%.

[0091] Comparative Example 2

[0092] The only difference between Comparative Example 2 and Example 6 is that tetramethylammonium chloride (TMAC) was not added; otherwise, the procedures were the same as in Example 6. The resulting catalyst had a Pd loading of 1 wt%, a Cu loading of 3 wt%, and a Ce loading of 1.5 wt%.

[0093] Comparative Example 3

[0094] The only difference between Comparative Example 3 and Example 6 is that CeCl3 was not added; otherwise, the procedures were the same as in Example 6. The resulting catalyst had a Pd loading of 1 wt%, a Cu loading of 3 wt%, and a TMAC loading of 1.1 wt%.

[0095] Comparative Example 4

[0096] The only difference between Comparative Example 4 and Example 6 is that CuCl2 was not added; otherwise, the procedures were the same as in Example 6. The resulting catalyst had a Pd loading of 1 wt%, a Ce loading of 1.5 wt%, and a TMAC loading of 1.1 wt%.

[0097] The relevant properties of the catalysts prepared in Examples 1-8 and Comparative Examples 1-4 were tested, and the results are shown in Table 1.

[0098] Table 1. Performance of the catalysts in Examples 1-8 and Comparative Examples 1-4

[0099]

[0100] As shown in Table 1, the catalysts conforming to the technical solution of this invention all exhibited good catalytic activity and high dimethyl carbonate selectivity in the reaction system for the carbonylation of nitrite esters to prepare dimethyl carbonate.

[0101] Comparing Example 6 and Comparative Example 2, it can be seen that the catalyst prepared without the addition of tetramethylammonium chloride has lower selectivity for dimethyl carbonate and lower catalyst space-time yield in the reaction system for the carbonylation of nitrite to prepare dimethyl carbonate.

[0102] Comparing Example 6 and Comparative Example 3, and Example 6 and Comparative Example 4, it can be seen that the catalyst without the addition of CeCl3 and CuCl2 exhibits lower conversion of methyl nitrite, lower selectivity of dimethyl carbonate, and lower catalyst space-time yield in the reaction system for the carbonylation of nitrite to prepare dimethyl carbonate.

[0103] All aspects, embodiments, features, and examples of this invention are to be regarded as illustrative in all respects and are not intended to limit the invention, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0104] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0105] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated otherwise, any use of the terms first, second, etc., does not indicate any order or importance, but is used to distinguish one element from another.

Claims

1. The application of a catalyst in the carbonylation of nitrite esters to prepare dimethyl carbonate, characterized in that: The catalyst includes a support and an active component, a co-active component, and a quaternary ammonium salt supported on the support; The active component includes PdCl2, and the co-active component includes CuCl2 and lanthanide metal chloride MCl3, wherein M in MCl3 includes at least one of La, Ce and Pr; the active component and / or co-active component are loaded on the support in the form of nanoparticles. The quaternary ammonium salt is R4NX, where X is at least one of Cl and Br, and R is an alkyl group, wherein the four R groups are the same or different, and the quaternary ammonium salt coats the active component and the co-active component. The catalyst contains 0.2wt% to 2.0wt% Pd, 0.5wt% to 5.0wt% Cu, 0.3wt% to 3.0wt% lanthanide metals in the lanthanide chloride, and 0.2wt% to 2.0wt% quaternary ammonium salt.

2. The application according to claim 1, characterized in that: In the catalyst, the mass ratio of Cu to Pd is 2:1 to 4:

1.

3. The application according to claim 1, characterized in that: In the catalyst, the mass ratio of the sum of the masses of Pd, Cu, and M elements to the mass ratio of the quaternary ammonium salt is 4:1 to 5:

1.

4. The application according to claim 1, characterized in that: The quaternary ammonium salt includes at least one of tetrabutylammonium bromide, tetrabutylammonium chloride, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, tetramethylammonium bromide, tetramethylammonium chloride, dodecyltrimethylammonium chloride, and dodecyltrimethylammonium bromide.

5. The application according to claim 1, characterized in that: The carrier includes Al2O3.

6. The application according to any one of claims 1-5, characterized in that, The preparation method of the catalyst includes: impregnating the support in a mixed solution containing PdCl2, CuCl2, lanthanide metal chloride, quaternary ammonium salt and ammonia water, and drying and calcining the support after impregnation to obtain the catalyst.

7. The application according to claim 6, characterized in that: The impregnation temperature is 25~60℃.

8. The application according to claim 6, characterized in that: The soaking time is more than 2 hours.

9. The application according to claim 6, characterized in that: The drying process is carried out at a temperature of 100-120°C and / or for a drying time of 2 hours or more.

10. The application according to claim 6, characterized in that: The roasting temperature is 130~200℃, and / or the roasting time is more than 5 hours.

11. The application according to claim 6, characterized in that: In the mixed solution, Pd 2+ The content is 0.3wt%~3.0wt%; and / or, Cu 2+ The content of lanthanides is 0.8wt%~8.0wt%; and / or, the lanthanide content in lanthanide chlorides is 0.5wt%~5.0wt%; and / or, the quaternary ammonium salt content is 0.3wt%~3.0wt%; and / or, the ammonia content is 5.0wt%~20wt%.

12. A method for preparing dimethyl carbonate by carbonylation of nitrite esters, characterized in that, include: In the presence of the catalyst in any one of the applications described in claims 1 to 11, a mixed gas containing methyl nitrite and CO is subjected to a catalytic reaction to obtain dimethyl carbonate.

13. The method according to claim 12, characterized in that: The methyl nitrite content in the mixed gas is 10-20%; and / or, the CO content in the mixed gas is 10-20%.

14. The method according to claim 12, characterized in that: The mixed gas also includes a balance gas.

15. The method according to claim 12, characterized in that: The mixed gas also includes HCl gas.

16. The method according to claim 15, characterized in that: The content of the HCl gas is 10~500ppm.

17. The method according to claim 12, characterized in that: The temperature of the catalytic reaction is 110~140℃; and / or the pressure of the catalytic reaction is 0.1~1MPa; and / or the space velocity of the catalytic reaction is 1500~5500 h⁻¹. -1 .

Images