Method for preparing diphenyl carbonate through transesterification

Abstract

The invention discloses a method for preparing diphenyl carbonate through transesterification, which comprises the following steps: adding dimethyl carbonate, phenyl acetate and a catalyst into a reaction kettle for transesterification under the protection of nitrogen; the catalyst is prepared by the following method: uniformly mixing tin oxide, molybdenum oxide, titanium dioxide, lithium hydroxide and a ZSM molecular sieve to obtain a mixture; adding water into the mixture, granulating and drying to obtain particles; and roasting the particulate matters to obtain the catalyst. According to the method for preparing diphenyl carbonate through transesterification, through limitation of specific raw materials and catalyst types, the transesterification reaction can be promoted, and the conversion efficiency of dimethyl carbonate and the selectivity of diphenyl carbonate are improved; in addition, the method is simple in process, controllable in reaction and good in reaction stability.

Description

Technical Field

[0001] The invention relates to the technical field of diphenyl carbonate preparation, and in particular to a method for preparing diphenyl carbonate through ester exchange. Background Art

[0002] Diphenyl carbonate (DPC) is a white crystalline solid that is insoluble in water but soluble in organic solvents such as hot ethanol, benzene, ether, carbon tetrachloride, glacial acetic acid, etc. It can be decomposed by hot alkali. It is mainly used as a synthetic raw material for engineering plastics such as polycarbonate and polyparaben, and can also be used as a plasticizer and solvent for nitrocellulose.

[0003] Diphenyl carbonate is an important new type of engineering plastic intermediate. It is pollution-free and low-toxic. It is mainly used in the plastics industry and is often used to synthesize polycarbonate. The main methods for synthesizing diphenyl carbonate are phosgene method, transesterification method and phenol oxidative carbonylation method.

[0004] At present, the preparation method of diphenyl carbonate is generally to synthesize diphenyl carbonate by reacting phenol with dimethyl carbonate in the presence of a catalyst. However, this method has the problems of low conversion rate and selectivity of diphenyl carbonate.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing diphenyl carbonate by ester exchange, which method can improve the conversion efficiency of dimethyl carbonate and the selectivity of diphenyl carbonate by selecting various raw materials and catalyst types.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] The present invention provides a method for preparing diphenyl carbonate by transesterification, wherein the method for preparing diphenyl carbonate by transesterification comprises the following steps:

[0009] Under nitrogen protection conditions, dimethyl carbonate, phenyl acetate and a catalyst are added into a reactor to carry out an ester exchange reaction;

[0010] The catalyst is prepared by the following method:

[0011] (a) mixing tin oxide, molybdenum oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve to obtain a mixture;

[0012] (b) adding water to the mixture, granulating, and drying to obtain granules;

[0013] (c) calcining the particles to obtain the catalyst.

[0014] Preferably, the molar ratio of dimethyl carbonate to phenyl acetate is 1:(2-2.5).

[0015] Preferably, the reaction temperature is 140-160° C., and the reaction time is 5-10 h.

[0016] Preferably, the mass ratio of the added amount of the catalyst to phenyl acetate is (2-10):100.

[0017] Preferably, the mass ratio of the tin oxide, molybdenum oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve is (2-4): (0.5-2): (2-4): (0.5-1): (89-95).

[0018] Preferably, the particle size is 2 to 4 mm.

[0019] Preferably, the drying temperature is 60-80° C., and the drying time is 5-8 hours.

[0020] Preferably, the roasting comprises:

[0021] The particles are first calcined at 300-500°C for 4-6 hours, and then calcined at 600-800°C for 2-4 hours.

[0022] Preferably, the calcining comprises:

[0023] The particles were calcined at 400 °C for 5 h and then at 700 °C for 3 h.

[0024] Compared with the prior art, the beneficial effects of the present invention include at least:

[0025] The method for preparing diphenyl carbonate by ester exchange of the present invention can promote the ester exchange reaction and improve the conversion efficiency of dimethyl carbonate and the selectivity of diphenyl carbonate by limiting the types of specific raw materials and catalysts; in addition, the method of the present invention has simple process, controllable reaction and good reaction stability.

[0026] In addition, the present invention has specific restrictions on the catalyst preparation process, so that the prepared catalyst has higher catalytic efficiency, can significantly improve the conversion efficiency of dimethyl carbonate and the selectivity of diphenyl carbonate, at the same time, the preparation method is simple in process and easy to produce, and the prepared catalyst has good stability and can be repeatedly recycled. DETAILED DESCRIPTION

[0027] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0028] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0029] This embodiment is a method for preparing diphenyl carbonate by transesterification, and the method for preparing diphenyl carbonate by transesterification comprises the following steps:

[0030] Under nitrogen protection conditions, dimethyl carbonate, phenyl acetate and a catalyst are added into a reactor to carry out an ester exchange reaction;

[0031] The catalyst is prepared by the following method:

[0032] (a) mixing tin oxide, molybdenum oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve to obtain a mixture;

[0033] (b) adding water to the mixture, granulating, and drying to obtain granules;

[0034] (c) calcining the particles to obtain the catalyst.

[0035] The method for preparing diphenyl carbonate by ester exchange of the present invention can promote the ester exchange reaction and improve the conversion efficiency and selectivity of diphenyl carbonate by limiting the types of specific raw materials and catalysts; in addition, the method of the present invention has simple process, controllable reaction and good reaction stability.

[0036] In addition, the present invention has specific restrictions on the catalyst preparation process, so that the prepared catalyst has higher catalytic efficiency and can significantly improve the conversion efficiency and selectivity of diphenyl carbonate. At the same time, the preparation method is simple in process and easy to produce, and the prepared catalyst has good stability and can be repeatedly recycled.

[0037] In some embodiments, the molar ratio of dimethyl carbonate to phenyl acetate is 1:(2-2.5).

[0038] In some embodiments, the reaction temperature is 140-160° C., and the reaction time is 5-10 h.

[0039] In some embodiments, the mass ratio of the added amount of the catalyst to phenyl acetate is (2-10):100.

[0040] In some embodiments, the mass ratio of tin oxide, molybdenum oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve is (2-4): (0.5-2): (2-4): (0.5-1): (89-95).

[0041] In some embodiments, the particle size is 2 to 4 mm.

[0042] In some embodiments, the drying temperature is 60-80° C., and the drying time is 5-8 hours.

[0043] In some embodiments, the calcining comprises:

[0044] The particles are first calcined at 300-500°C for 4-6 hours, and then calcined at 600-800°C for 2-4 hours.

[0045] In some embodiments, the calcining comprises:

[0046] The particles were calcined at 400 °C for 5 h and then at 700 °C for 3 h.

[0047] The technical solution of the present invention is further described in detail below through specific embodiments.

[0048] Example 1

[0049] This embodiment is a method for preparing diphenyl carbonate by transesterification, and the method for preparing diphenyl carbonate by transesterification comprises the following steps:

[0050] Under nitrogen protection, dimethyl carbonate, phenyl acetate and a catalyst were added into a reactor for transesterification reaction at 140° C. for 10 hours, wherein the molar ratio of dimethyl carbonate to phenyl acetate was 1:2; the mass ratio of the added amount of the catalyst to the phenyl acetate was 2:100;

[0051] The catalyst is prepared by the following method:

[0052] (a) mixing tin oxide, molybdenum oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve to obtain a mixture, wherein the mass ratio of tin oxide, molybdenum oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve is 2:0.5:2:1:94.5;

[0053] (b) adding water to the mixture, granulating the mixture, and drying the mixture at 60° C. for 8 h to obtain granules having a particle size of 2 to 4 mm;

[0054] (c) The particles are first calcined at 300° C. for 6 h and then calcined at 800° C. for 4 h to obtain the catalyst.

[0055] Example 2

[0056] This embodiment is a method for preparing diphenyl carbonate by transesterification, and the method for preparing diphenyl carbonate by transesterification comprises the following steps:

[0057] Under nitrogen protection, dimethyl carbonate, phenyl acetate and a catalyst were added into a reactor for transesterification reaction at 160° C. for 5 h, wherein the molar ratio of dimethyl carbonate to phenyl acetate was 1:2.5; the mass ratio of the added amount of the catalyst to the phenyl acetate was 10:100;

[0058] The catalyst is prepared by the following method:

[0059] (a) mixing tin oxide, molybdenum oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve to obtain a mixture, wherein the mass ratio of tin oxide, molybdenum oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve is 4:2:4:0.5:89.5;

[0060] (b) adding water to the mixture, granulating the mixture, and drying the mixture at 80° C. for 5 h to obtain granules having a particle size of 2 to 4 mm;

[0061] (c) The particles are first calcined at 500° C. for 4 h and then calcined at 800° C. for 2 h to obtain the catalyst.

[0062] Example 3

[0063] This embodiment is a method for preparing diphenyl carbonate by transesterification, and the method for preparing diphenyl carbonate by transesterification comprises the following steps:

[0064] Under nitrogen protection, dimethyl carbonate, phenyl acetate and a catalyst were added into a reactor for transesterification reaction at 150° C. for 8 h, wherein the molar ratio of dimethyl carbonate to phenyl acetate was 1:2.2; the mass ratio of the added amount of the catalyst to the phenyl acetate was 5:100;

[0065] The catalyst is prepared by the following method:

[0066] (a) mixing tin oxide, molybdenum oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve to obtain a mixture, wherein the mass ratio of tin oxide, molybdenum oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve is 3:1:3:0.8:92.2;

[0067] (b) adding water to the mixture, granulating the mixture, and drying the mixture at 70° C. for 6 h to obtain granules having a particle size of 2 to 4 mm;

[0068] (c) The particles are first calcined at 400° C. for 5 h and then calcined at 700° C. for 3 h to obtain the catalyst.

[0069] Comparative Example 1

[0070] This comparative example is a method for preparing diphenyl carbonate by transesterification, and the method for preparing diphenyl carbonate by transesterification comprises the following steps:

[0071] Under nitrogen protection, dimethyl carbonate, phenyl acetate and a catalyst were added into a reactor for transesterification reaction at 150° C. for 8 h, wherein the molar ratio of dimethyl carbonate to phenyl acetate was 1:2.2; the mass ratio of the added amount of the catalyst to the phenyl acetate was 5:100;

[0072] The catalyst is prepared by the following method:

[0073] (a) mixing tin oxide, molybdenum oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve to obtain a mixture, wherein the mass ratio of tin oxide, molybdenum oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve is 3:1:3:0.8:92.2;

[0074] (b) adding water to the mixture, granulating the mixture, and drying the mixture at 70° C. for 6 h to obtain granules having a particle size of 2 to 4 mm;

[0075] (c) calcining the particles at 700° C. for 8 h to obtain the catalyst.

[0076] Comparative Example 2

[0077] This comparative example is a method for preparing diphenyl carbonate by transesterification, and the method for preparing diphenyl carbonate by transesterification comprises the following steps:

[0078] Under nitrogen protection, dimethyl carbonate, phenyl acetate and a catalyst were added into a reactor for transesterification reaction at 150° C. for 8 h, wherein the molar ratio of dimethyl carbonate to phenyl acetate was 1:2.2; the mass ratio of the added amount of the catalyst to the phenyl acetate was 5:100;

[0079] The catalyst is prepared by the following method:

[0080] (a) mixing tin oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve to obtain a mixture, wherein the mass ratio of tin oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve is 3:4:0.8:92.2;

[0081] (b) adding water to the mixture, granulating the mixture, and drying the mixture at 70° C. for 6 h to obtain granules having a particle size of 2 to 4 mm;

[0082] (c) calcining the particles at 700° C. for 8 h to obtain the catalyst.

[0083] Comparative Example 3

[0084] This comparative example is a method for preparing diphenyl carbonate by transesterification, and the method for preparing diphenyl carbonate by transesterification comprises the following steps:

[0085] Under nitrogen protection, dimethyl carbonate, phenyl acetate and a catalyst were added into a reactor for transesterification reaction at 150° C. for 8 h, wherein the molar ratio of dimethyl carbonate to phenyl acetate was 1:2.2; the mass ratio of the added amount of the catalyst to the phenyl acetate was 5:100;

[0086] The catalyst is prepared by the following method:

[0087] (a) mixing tin oxide, molybdenum oxide, lithium hydroxide and ZSM molecular sieve to obtain a mixture, wherein the mass ratio of tin oxide, molybdenum oxide, lithium hydroxide and ZSM molecular sieve is 3:4:0.8:92.2;

[0088] (b) adding water to the mixture, granulating the mixture, and drying the mixture at 70° C. for 6 h to obtain granules having a particle size of 2 to 4 mm;

[0089] (c) calcining the particles at 700° C. for 8 h to obtain the catalyst.

[0090] Experimental example

[0091] Diphenyl carbonate was prepared according to the methods of Example 3 and Comparative Examples 1 to 3 respectively;

[0092] The conversion rate of dimethyl carbonate and the selectivity of diphenyl carbonate in the product were determined by chromatographic analysis; the results are shown in Table 1:

[0093] Table 1

[0094] Group Conversion rate of dimethyl carbonate (%) Selectivity (%) Example 3 92.1 98.5 Comparative Example 1 85.4 97.1 Comparative Example 2 77.8 81.6 Comparative Example 3 80.3 72.5

[0095] From Table 1, we can see that:

[0096] Compared with the comparative example, the examples of the present application can better improve the conversion efficiency of dimethyl carbonate and the selectivity of diphenyl carbonate.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for preparing diphenyl carbonate by transesterification, characterized in that: The steps include: Under nitrogen protection conditions, dimethyl carbonate, phenyl acetate and a catalyst are added into a reactor to carry out an ester exchange reaction; The catalyst is prepared by the following method: (a) mixing tin oxide, molybdenum oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve to obtain a mixture; (b) adding water to the mixture, granulating, and drying to obtain granules; (c) calcining the particles to obtain the catalyst.

2. The method for preparing diphenyl carbonate by transesterification according to claim 1, characterized in that: The molar ratio of dimethyl carbonate to phenyl acetate is 1:(2-2.5).

3. The method for preparing diphenyl carbonate by transesterification according to claim 1, characterized in that: The reaction temperature is 140-160° C., and the reaction time is 5-10 hours.

4. The method for preparing diphenyl carbonate by transesterification according to claim 1, characterized in that: The mass ratio of the added amount of the catalyst to phenyl acetate is (2-10):

100.

5. The method for preparing diphenyl carbonate by transesterification according to claim 1, characterized in that: The mass ratio of the tin oxide, molybdenum oxide, titanium dioxide, lithium hydroxide and ZSM molecular sieve is (2-4): (0.5-2): (2-4): (0.5-1): (89-95).

6. The method for preparing diphenyl carbonate by transesterification according to claim 1, characterized in that: The particle size is 2 to 4 mm.

7. The method for preparing diphenyl carbonate by transesterification according to claim 1, characterized in that: The drying temperature is 60-80° C., and the drying time is 5-8 hours.

8. The method for preparing diphenyl carbonate by transesterification according to claim 1, characterized in that: The roasting comprises: The particles are first calcined at 300-500°C for 4-6 hours, and then calcined at 600-800°C for 2-4 hours.

9. The method for preparing diphenyl carbonate by transesterification according to claim 1, characterized in that: The roasting comprises: The particles were calcined at 400 °C for 5 h and then at 700 °C for 3 h.