CN1583254A - Preparation of loaded molybdenum oxide catalyst for synthesis of phenyloxalate by ester interchange process - Google Patents

Abstract

The invention discloses a molybdenum oxide catalyst for synthesizing phenyl oxalate by transesterification and a preparation method thereof, belonging to the preparation of raw materials methyl phenyl oxalate and diphenyl oxalate catalyst for synthesizing diphenyl carbonate (DPC) technology. The preparation method is a slurry impregnation method, and the main process includes molybdenum trioxide slurry configuration, carrier grinding and mixing with the slurry, impregnation and drying. Roasting is not required. The catalyst prepared by the invention has high catalytic activity and good selectivity for synthesizing phenyl oxalate through the transesterification reaction between phenol and dimethyl oxalate, so that the yield of phenyl oxalate is greater than 50%. Catalyst preparation has the advantages of low cost, no pollution to the environment, no corrosion to equipment, easy separation of catalyst and product, recycling and reuse, etc.

Description

Preparation method of supported molybdenum oxide catalyst for synthesizing phenyl oxalate by transesterification

technical field

The invention relates to a supported molybdenum oxide catalyst for synthesizing phenyl oxalate by a transesterification method and a preparation method thereof, and relates to the transesterification synthesis of phenol and dimethyl oxalate as a raw material methyl phenyl oxalate for the production of diphenyl carbonate (DPC) Catalyst of acid ester and diphenyl oxalate and preparation method thereof.

Background technique

The preparation of methylphenyl oxalate and diphenyl oxalate from dimethyl oxalate and phenol is the key technology for all the preparation of diphenyl carbonate from dimethyl oxalate and phenol. The reaction steps experienced by this key technology are as follows:

or

The diphenyl carbonate preparation process with this key technology as the core appeared in the 1990s, but it developed rapidly. In particular, Ube Corporation in Japan has been committed to research in this area and has applied for many patents, such as EP1013633A1, US5811573, CN1164529A, TW438765 , US5834615, EP0832872A1, US5922827, EP0832910A2, etc. But in above-mentioned all patents, relate to when using dimethyl oxalate as raw material to prepare the raw material of synthetic diphenyl carbonate by transesterification, i.e. methyl phenyl oxalate or diphenyl oxalate, although the transesterification catalyst used is constantly Update, change and improve, it can be alkali metal, cadmium, zirconium, lead, iron, copper, zinc compound or organotin compound, aluminum, titanium, vanadium organic acid compound, etc., but all are homogeneous soluble in the reaction system Catalyst, that is, all transesterification reactions to be carried out are homogeneous reactions, so all the above-mentioned patented technologies have used complex separation systems or equipment to separate catalysts and reactions. The applicant mentioned in the 200410018842.6 patent that the molybdenum trioxide catalyst was used to synthesize phenyl oxalate, which has the advantages of high yield and good selectivity, but did not mention the preparation method of the catalyst.

Contents of the invention

The object of the present invention is to provide a kind of preparation method of supported molybdenum oxide catalyst for synthesizing phenyl oxalate by transesterification method, the method process is simple, and the prepared catalyst has high activity and good selectivity.

The present invention is achieved through the following technical scheme: the catalyst is a metal oxide supported catalyst composed of a carrier and molybdenum trioxide (MoO ₃ ), and the carrier is activated carbon, α-alumina or γ-alumina, Silicon oxide, molecular sieve, zirconium oxide or magnesium oxide, and the content of molybdenum as an active component in the catalyst is 0.1-40% by weight.

Its preparation method adopts the slurry dipping method, which is characterized in that it includes the following process:

(1) Grinding the molybdenum trioxide into fine particles of 120-200 meshes, placing them in a drying oven for drying at 60-200° C., and setting aside;

(2) Weigh the dried molybdenum trioxide, add deionized water, and configure a mixed solution with a mass concentration of 0.1% to 5.0% as the impregnating solution;

(3) Weigh 2 to 200 mesh carrier particles, place them in a rotary evaporator with a weight ratio of 0.1% to 40% of the carrier to the active component molybdenum, and impregnate with an impregnation solution at 75 to 95°C for 5 to 50 hours;

(4) drying the impregnated catalyst at a drying temperature of 60-200° C. for 4-16 hours; taking it out to obtain a molybdenum oxide-supported catalyst.

The above-mentioned carrier is activated carbon, γ-alumina or silicon oxide.

The mass concentration of the above-mentioned mixed solution of molybdenum trioxide and deionized water is 0.1%-1.0%.

The weight ratio of the above-mentioned carrier to the active component molybdenum is 8%-16%.

The above-mentioned drying temperature is 100-160°C.

The advantages of the present invention are that the slurry impregnation method used to prepare the supported molybdenum trioxide catalyst avoids high-temperature roasting, reduces energy consumption, saves energy, and there is no generation of waste liquid and nitrogen-containing compounds in the catalyst preparation process. A good monolayer dispersed catalyst can be obtained. This method conforms to the principle of equilibrium adsorption, that is, the loading of molybdenum oxide conforms to the close-packed monolayer model. It is a cheap, simple, clean and novel method for preparing supported catalyst. By adopting the supported molybdenum trioxide catalyst, not only the conversion rate of the raw material and the selectivity of the product are obviously improved compared with the homogeneous catalyst. The catalyst is easy to separate and recycle, saves the complex separation process and equipment for the catalyst and the reaction system, reduces the production cost, and has far-reaching significance for the industrialization of the transesterification of phenol and dimethyl oxalate.

The present invention will be further described below through specific examples, but the present invention will not be limited.

Detailed ways

【Example 1】

The present invention is the implementation and investigation of molybdenum oxide supported catalyst for the preparation of phenol and dimethyl oxalate transesterification method for synthesizing phenyl oxalate by slurry impregnation method. Grind molybdenum trioxide into 200-mesh fine particles, dry in a drying oven at 120°C, and set aside. Weigh 1.278g of dried molybdenum trioxide and add 70ml of deionized water to form a mixed solution. Weigh 20 g of 80-mesh activated carbon carrier particles, place them in a rotary evaporator, and impregnate them with an impregnation solution at 95° C. for 8 hours. The impregnated catalyst was dried at a drying temperature of 120° C. for 6 hours; taken out to obtain a molybdenum oxide-supported catalyst with a molybdenum loading of 4 wt%.

Catalyst that the present invention makes is under heterogeneous catalyzed reaction condition with dimethyl oxalate and phenol as raw material to prepare methyl phenyl oxalate and diphenyl oxalate technical method implementation investigation, carry out in the there-necked flask of 250 milliliters , Collective electromagnetic stirring heating, equipped with a thermometer to display the temperature of the reaction system. The consumption of industrial grade DMO is 0.1 mole, the consumption of chemically pure phenol is 0.5 mole, the consumption of the loaded type molybdenum trioxide catalyst MoO ₃ /C prepared by slurry state impregnation method is 1.8 grams, adds under normal pressure, wherein the metal molybdenum The loading amount is 4wt% (the same below). Stir and heat up, the reaction temperature is controlled at 180.0±2°C, and the reaction time is 2 hours. Reaction (1)-(3) The reaction equilibrium constants of each step are extremely small, in order to break the restriction of thermodynamic equilibrium and improve the conversion rate of raw materials, a constant temperature of 70 ° C (slightly higher than the boiling point of methanol) is installed in the middle of the flask. The reflux condenser of the circulating water, the methanol generated by the reaction can be continuously distilled from the reaction mixture system, and the distillate is collected in the cold trap. After the reaction is over, the reaction material and the catalyst are simply separated by means of suction filtration, and the reaction result can be analyzed by gas chromatography. The conversion rate of DMO and the selectivity of MPO and DPO were used as indicators to investigate the reaction performance.

[Example 2-4]

Change the loaded amount of molybdenum in the supported molybdenum trioxide catalyst MoO ₃ /C, respectively 8%, 16%, 32%, while other conditions are exactly the same as in Example 1, carry out the transesterification reaction, respectively form the embodiment 2-4, examine the reaction results.

Table 1: Preparation method of MoO ₃ /C series catalysts and catalytic transesterification reaction results (weight percentage)

Molybdenum trioxide Deionization Impregnation Impregnation Drying

Molybdenum Loading DMO Yield, %

Example Quality Water Volume Temperature Time Time Temperature

Quantity, % Conversion %

                                                                                 

1 4 1.28 70 90 8 120 49.5 40.6 8.7

2 8 2.73 80 90 12 120 59.0 48.0 10.8

3 16 6.32 90 95 24 120 64.3 54.2 9.7

4 32 18.48 110 95 36 120 56.8 47.2 7.4

[Example 5-7]

The SiO ₂ carrier was used instead, and the MoO ₃ /SiO ₂ series catalyst was prepared by the slurry impregnation method. The molybdenum loading in the supported molybdenum trioxide catalyst MoO ₃ /SiO ₂ was 4%, 8%, and 16%, respectively. Under the identical situation with embodiment 1, carry out transesterification reaction, form embodiment 5-7 respectively, investigate reaction result.

Table 2: Preparation method of MoO ₃ /SiO ₂ series catalysts and catalytic transesterification reaction results (weight percentage)

Molybdenum trioxide Deionization Impregnation Impregnation Drying

Molybdenum Loading DMO Yield, %

Example Quality Water Volume Temperature Time Time Temperature

Quantity, % Conversion %

                                                                                                                                                                       

5 4 1.28 80 80 12 140 46.1 38.1 6.8

6 8 2.73 100 90 24 140 57.8 47.3 10.3

7 16 6.32 120 95 36 140 54.6 46.0 8.2

[Example 8-11]

Al _{2 O 3} carrier was used instead, _and MoO ₃ /Al ₂ O ₃ series catalysts were prepared by slurry impregnation method _. 14%, 16%, under the completely identical situation of other conditions and embodiment 1, carry out transesterification reaction, form embodiment 8-11 respectively, investigate reaction result.

Table 3: MoO ₃ /Al ₂ O ₃ series catalysts catalyzed transesterification results (weight percentage)

Molybdenum trioxide Deionization Impregnation Impregnation Drying

Molybdenum Loading DMO Yield, %

EXAMPLES Quality Water Volume Temperature Time Temperature

Quantity, % Conversion %

                                                                                   

8 4 1.28 80 85 12 130 64.2 35.1 3.9

9 8 2.73 90 85 24 130 70.5 46.2 6.5

10 14 5.32 100 90 24 120 76.3 46.8 6.6

11 16 6.32 120 95 36 140 69.7 36.4 4.1

It can be seen from the reaction results of the above examples that when the supported molybdenum trioxide prepared by the mud impregnation method is used as a catalyst in the process of the present invention, better reaction results can be obtained. Among them, for the molybdenum trioxide active component, the catalyst supported by _SiO2 and activated carbon showed higher selectivity; the catalyst supported on activated carbon with appropriate Mo content showed the highest activity and selectivity.

【Comparative example 1-4】

Zn(OAc) ₂ , Ti(OC ₄ H ₉ ) ₄ , SnOBu ₂ , and dibutyltin dilaurate were used as transesterification catalysts respectively, and the loading amount of the catalysts was 0.01mol. In the same reaction device, the same reaction operation Under the conditions of feed and feed, a homogeneous transesterification reaction is carried out. The reaction results of the comparative examples are shown in Table 4.

Table 4: Comparative Example Transesterification Results

DMO Selectivity, % Yield, %

Comparative example Catalyst

% Conversion % By-product MPO DPO MPO DPO

1 Zn(OAc) ₂ 28.1 43.5 53.9 2.6 16.4 0.1

2 Ti(OC ₄ H ₉ ) ₄ 92.5 76.6 20.6 2.8 19.0 2.6

3 SnOBu ₂ 25.7 6.7 80.8 12.5 20.8 3.2

4 dibutyltin dilaurate 54.1 65.3 21.0 13.7 11.4 7.4

As can be seen from the examples and comparative examples, in the process of preparing diphenyl carbonate with dimethyl oxalate and phenol as raw materials, the key technology is the preparation of methyl phenyl oxalate by transesterification of dimethyl oxalate and phenol and in the step of diphenyl oxalate, if the use of supported molybdenum trioxide as a catalyst, the selectivity of the target product is far higher than the selectivity in the comparative example, and its activity is also higher, thereby having a higher target product yield. Rate. And if traditional transesterification catalysts, such as organozinc, organotitanium and organotin compounds widely used as transesterification catalysts, are used as catalysts, it can be seen from Comparative Examples 1 to 4 that, except for dibutyltin oxide, other catalysts The selectivity of the target product is extremely low; and when dibutyltin oxide is used as a catalyst, in addition to being expensive, dibutyltin oxide decomposes on its own and forms a homogeneous phase with the system, and the catalyst cannot be recycled, and a complicated separation system and equipment.

In summary, the supported molybdenum trioxide prepared by the mud impregnation method is characterized by the transesterification reaction of dimethyl oxalate and phenol, and the synthesis of methyl phenyl oxalate and Diphenyl oxalate, which is to synthesize methylphenyl oxalate and diphenyl oxalate by using dimethyl oxalate and phenol as raw materials, and then prepare diphenyl carbonate by further transesterification with phenol and/or direct decarbonylation Esters provide a more favorable key core technology.

The present invention is not limited to the above embodiments, and the patent applicants can make various changes and deformations according to the present invention, as long as they do not depart from the spirit of the present invention, all should belong to the scope of the present invention.

Claims (5)

1. a kind of preparation method of synthetic phenyl oxalate with supported molybdenum oxide catalyst by transesterification method is to adopt slurry dipping method, it is characterized in that comprising following process: (1) Grinding the molybdenum trioxide into fine particles of 120-200 meshes, placing them in a drying oven for drying at 60-200° C., and setting aside; (2) Weigh the dried molybdenum trioxide, add deionized water, and configure a mixed solution with a mass concentration of 0.1% to 5.0% as the impregnating solution; (3) Weighing 20-200 mesh carrier particles, placing them in a rotary evaporator with a weight ratio of 0.1%-40% of the carrier to the active component molybdenum, and impregnating them with an impregnating solution at 75-95°C for 5-50 hours; (4) drying the impregnated catalyst at a drying temperature of 60-200° C. for 4-16 hours; taking it out to obtain a molybdenum oxide-supported catalyst. 2. According to the preparation method of the supported molybdenum oxide catalyst according to claim 1, it is characterized in that: the carrier of the catalyst is activated carbon, gamma-alumina or silicon oxide. 3. The preparation method of the supported molybdenum oxide catalyst according to claim 1, characterized in that: the mass concentration of the mixed solution of molybdenum trioxide and deionized water is 0.1% to 1.0%. 4. The preparation method of the supported molybdenum oxide catalyst according to claim 1, characterized in that: the weight ratio of the carrier to the molybdenum active component is 8% to 16%. 5. The preparation method of the supported molybdenum oxide catalyst according to claim 1, characterized in that: the drying temperature is 100-160°C.