CN1186801A

CN1186801A - Synthesis method of diester carbonate

Info

Publication number: CN1186801A
Application number: CN96123070A
Authority: CN
Inventors: 李兆基
Original assignee: Fujian Institute of Research on the Structure of Matter of CAS
Current assignee: Fujian Institute of Research on the Structure of Matter of CAS
Priority date: 1996-12-28
Filing date: 1996-12-28
Publication date: 1998-07-08
Anticipated expiration: 2016-12-28
Also published as: CN1072204C

Abstract

Carbon monoxide and nitrous acid ester are synthesized through coupling reaction into diester carbonate in the presence of catalyst and at relatively low pressure and temperature. The catalyst used is one three-metal system including palladium chloride, ferric chloride and the chloride of one first main group element. Nitrous acid ester gas and carbon monoxide used have volume ratio of 1/6 to 2, airspeed is 800-4000/hr, and reaction temperature and pressure are 60-180 deg.c and 0.1-0.2 MPa. The said catalyst system can constrain the production of side product oxilic ester, and thus has high activity and selectivity to diester carbonate.

Description

Synthesis method of carbonic diester

The invention relates to a preparation method for catalytically synthesizing carbonic diester (dimethyl carbonate, diethyl carbonate and the like) by using carbon monoxide, alcohol and oxygen, in particular to the preparation of dimethyl carbonate.

The carbonic ester is an important chemical raw material, in particular dimethyl carbonate can be used as a methylating agent, and is favored by people because the carbonic ester can replace raw materials for producing polycarbonate, special isocyanate and the like by a phosgene method. Because of the high oxygen content of dimethyl carbonate, dimethyl carbonate is popular as an oil additive for improving octane number and reducing pollution. The application prospect of the carbonic ester is extremely wide.

The production of carbonic acid diesters generally employs the phosgene process, sodium alkoxide process, transesterification process and alcoholic oxidative carbonylation process. These methods have the disadvantages of more or less toxic raw materials, complex process, serious corrosion, low activity and selectivity, etc.

In 1985, (Japanese) Kokai Sho 60-181051 discloses a process for the catalytic synthesis of carbonic acid diesters from carbon monoxide by gas phase oxidation of nitrites in the presence of platinum group metal catalysts. The selectivity was up to 72% and the yield 121 g/l.h.

This was also published in 1990, ep.appl.425197a, ep.559001a. They have improved the synthesis process of carbonic acid diester and the catalyst respectively, the space-time yield is 500 g/l.h, the selectivity is 97%, although it is improved, it is still not ideal.

The present invention aims at overcoming the demerits of available technology, and aims at providing one kind of method of synthesizing carbonic diester capable of inhibiting the formation of side product, such as oxalate, and raising the selectivity and space-time yield of carbonic diester.

The synthesis method adopted by the invention is to synthesize the carbonic diester by coupling carbon monoxide and nitrite ester under the existence of the catalyst and at lower pressure and lower temperature. The synthesis method is based on the following processes:

the nitrite is generated by reacting alcohol (mainly alcohol with 1-4 carbon atoms) with sodium nitrite in the presence of sulfuric acid or by reacting nitric oxide with alcohol. The carbon monoxide is obtained by dehydrating formic acid in the presence of sulfuric acid or purifying water gas by copper ammonia pressure swing adsorption. Nitric oxide in tail gas after reaction can be regenerated and recycled through oxidation and esterification.

The reaction is carried out in a glass reaction tube with the inner diameter of 20mm and embedded with a sand core, and the reaction tube is vertically fixed. The outer sleeve type electric furnace is also provided with temperature measuring and controlling equipment, so as to be beneficial to heating, temperature controlling and temperature measuring.

The reaction raw material gas, namely nitrite gas and carbon monoxide gas are dried, mixed and then enter a reactor for reaction. The volume ratio of the nitrite gas to the carbon monoxide gas is within the range of 2: 1 to 1: 6, and inert nitrogen is charged for dilution, wherein the space velocity is 800-4000 (hours)^-1To (c) to (d); the reaction temperature is in the range of 60-180 ℃; the reaction pressure is in the range of 0.1-0.2 MPa.

The catalyst consists of palladium chloride, ferric trichloride and one of chlorides of the first main group elements to form a trimetal system. The first main group element may be: lithium, sodium, potassium, rubidium, and cesium, and among them, lithium chloride is preferable.

The preparation process of the catalyst comprises the following steps: dissolving palladium chloride, adding one of ferric trichloride and first main group element chloride, dissolving, adding pretreated and dried carrier, impregnating, and drying the catalyst.

The carrier of the catalyst can be activated carbon, activated alumina, silica gel, etc. Among them, activated carbon is most preferable. The larger the specific surface area of the support, the better the catalyst activity.

The carbonic diester is synthesized by using chlorides of palladium and iron and adding one of chlorides of lithium, sodium, potassium, rubidium and cesium of the first main group elements to form a trimetallic catalyst. Due to the synergistic effect of the two, the generation of the by-product oxalate is fully inhibited, and the activity and the selectivity of the catalyst to the carbonic diester are improved. The method is suitable for synthesizing carbonic diester (dimethyl carbonate, diethyl carbonate, dipropyl carbonate and dibutyl carbonate) with 1-4 carbon atoms.

Example 1. preparation of catalyst: taking 0.3 g of palladium chloride, adding 2 drops of hydrochloric acid, adding 30 ml of methanol for dissolving, adding 0.27 g of ferric trichloride and 0.10 g of lithium chloride (containing 1 crystal water), adding 10 g of activated carbon for soaking after dissolving, and then drying for later use.

8 ml of the catalyst is filled in a glass reaction tube with the inner diameter of 20mm and embedded with a sand core. The reaction tube is sheathed with a tubular electric furnace, and the reaction temperature is controlled and measured by a temperature controller. The reaction temperature is controlled at 80 ℃, the gas pressure is 0.11-0.15 MPa, and the gas can flow. Raw materialsThe volume ratio of methyl nitrite to carbon monoxide to nitrogen is 1: 1.04: 1.08, and the space velocity is 2800 (hours)^-1. The space-time yield of dimethyl carbonate was 401 g/l (catalyst) h, and the selectivity was 98%.

Example 2. preparation of catalyst: taking 0.3 g of palladium chloride, 0.27 g of ferric trichloride and 0.10 g of sodium chloride, adding 2 drops of hydrochloric acid and 30 ml of methanol, adding 10 g of activated carbon for impregnation after dissolution, and then drying for later use.

The catalyst 8 ml is filled in a reactor (the reactor is the same as the above example), the reaction temperature is controlled at 80 ℃, the volume ratio of raw material gas methyl nitrite to carbon monoxide and nitrogen is 1: 1.04: 1.08, and the space velocity 2800 (hours)^-1. The space-time yield of dimethyl carbonate was 283 g/l (catalyst) h, with a selectivity of 98%.

Example 3. preparation of catalyst: taking 0.3 g of palladium chloride, 0.27 g of ferric trichloride and 0.13 g of potassium chloride, adding 2 drops of hydrochloric acid and 30 ml of methanol, adding 10 g of activated carbon for impregnation after dissolution, and then drying.

The catalyst 8 ml is loaded in the reactor (the reactor is the same as the above example), the reaction temperature is controlled at 80 ℃, the volume ratio of methyl nitrite to carbon monoxide and nitrogen is 1: 1.04: 1.08, and the space velocity 2800 (hours)^-1. The space-time yield of dimethyl carbonate was 241 g/l (catalyst) h, the selectivity 98%.

Example 4. preparation of catalyst: taking 0.2 g of palladium chloride, 0.5 g of ferric trichloride and 0.5 g of lithium chloride (containing 1 crystal water), adding 2 drops of hydrochloric acid and 30 ml of methanol, mixing and dissolving, adding 10 g of activated carbon for impregnation, and drying for later use.

6 ml of the catalyst was charged in a reactor (the reactor is as in the above example), the reaction temperature was controlled at 100 ℃, the volume ratio of methyl nitrite to carbon monoxide and nitrogen was 1: 1.5, and the space velocity 2700 (hr)^-1. The selectivity was 98% when the space-time yield of dimethyl carbonate was 545 g/l (catalyst).

Claims

1. A method for synthesizing carbonic acid diester by coupling and synthesizing carbonic acid diester by using carbon monoxide and nitrite in the presence of a catalyst and using lower pressure and lower temperature, is characterized in that: the catalyst used is a trimetallic system consisting of palladium chloride and ferric trichloride plus one of the chlorides of the elements of the first main group.

2. The method for synthesizing a carbonic acid diester according to claim 1, wherein: the chloride of the first main group element, which is one of the components of the catalyst, is preferably lithium chloride.

3. The method for synthesizing a carbonic acid diester according to claim 1, wherein: the support of the catalyst is preferably activated carbon.

4. The method for synthesizing a carbonic acid diester according to claim 1, wherein: the method is suitable for synthesizing carbonic diester with 1-4 carbon atoms, namely dimethyl carbonate, diethyl carbonate, dipropyl carbonate and dibutyl carbonate.

5. The method for synthesizing a carbonic acid diester according to claim 1, wherein: the volume ratio of the nitrous acid ester gas to the carbon monoxide gas is 2: 1-1: 6, and the airspeed is 800-4000 (hours)^-1。

6. The method for synthesizing a carbonic acid diester according to claim 1, wherein: the reaction temperature is 60-180 ℃.

7. The method for synthesizing a carbonic acid diester according to claim 1, wherein: the reaction pressure is 0.1-0.2 MPa.