Special catalyst for preparing p-chlorobenzonitrile by ammonoxidation process, preparation method and use

Abstract

The invention discloses a special catalyst for preparing p-chlorobenzonitrile by an ammonoxidation process. Organosilicone modified silica gel serves as a carrier of the special catalyst, a main catalyst comprises vanadium and phosphorus, a cocatalyst comprises at least one of an ingredient G, an ingredient D and an ingredient E, and an active ingredient of the special catalyst is represented as VPbGcDdEeOx; and the G is molybdenum, chromium, titanium, nickel or bismuth, the D is boron, manganese, ferrum, cobalt, copper, zinc or tin, and the E is potassium, lithium, sodium, cesium, magnesium or calcium. The invention further discloses a preparation method for the catalyst and use of the catalyst. According to the special catalyst, the preparation method and the use, electron donating groups on organosilicone and inorganic elements are subjected to an Lewis acid alkali reaction, and thus, actions of inorganic oxides and the carrier are strengthened; and meanwhile, the inorganic oxides can be more uniformly dispersed, catalyst ingredients are low in loss, the catalytic activity is high, the selectivity is good, and the service life of a commercial catalyst is prolonged to 2 years ormore from 1 year. The catalyst is simple in preparation method, low in cost and good in thermal stability and mechanical strength and can be applied to fixed-bed and fluidized-bed reactors.

Description

technical field [0001] The invention relates to a special catalyst for preparing p-chlorobenzonitrile through an ammoxidation method, a preparation method and an application. It belongs to the technical field of organic chemistry and also belongs to the technical field of organic fine chemicals. Background technique [0002] p-Chlorobenzonitrile is an important organic intermediate. Starting from p-chlorobenzonitrile, p-chlorobenzoic acid, p-chlorobenzamide, p-fluorobenzonitrile, p-fluorobenzoic acid, p-fluoroaniline, etc. can be prepared, which are widely used in industries such as dyes, medicines, pesticides and photosensitive materials. A new type of high-performance pigment C.I. Pigment Red 254[1,4-diketone-3,6-bis(4-chlorophenyl)pyrrole launched by Ciba-Geigy after 25 years of research Pyrrole] is produced using p-chlorobenzonitrile as a raw material, thus causing more attention to p-chlorobenzonitrile. [0003] The classic preparation method of p-chlorobenzonitrile ...

AI Technical Summary

Problems solved by technology

At present, the research on the preparation of p-chlorobenzonitrile by ammoxidation has reached a relatively high level in the world. Among them, Martin et al. used unsupported vanadium phosphorus oxide as a catalyst, and the yield of p-chlorobenzonitrile reached 92.6%. However, the unsupported catalyst The specific surface area is small and the mechanical strength is poor, so it is not suitable for large-scale preparation of p-chlorobenzonitrile in an industrial fluidized bed

The inventors of the present invention have developed a silica gel-loaded multi-component composite oxide catalyst. The metal oxide loading is 10%, and the molar yield can reach more than 90%. The silica gel-loaded catalyst uses silica gel as a carrier, which not only provides a lot of The large specific surface area reduces the cost of the catalyst, and improves the high temperature sintering resistance, mechanical strength and wear resistance of the catalyst; therefore, it is suitable for both fixed bed and fluidized bed; however, the silica gel supported catalyst is in In the process of industrial production, the catalytic activity begins to decline after half a year to one year. After one or two years, the activity declines seriously and needs to be replaced, resulting in a waste of resources and an increase in product cost.

After analysis, the main reason for the decline in activity is the loss of active components on the surface of the catalyst; silica gel-loaded catalysts are prepared by silica gel impregnation method, that is, silica gel absorbs mixed metal salt solutions and then activated by high-temperature calcination; composite metal oxides are mainly attached by physical adsorption. On the surface of silica gel, the force between the metal oxide and the silica gel carrier is weak. In the fluidized bed reactor, the catalyst microspheres collide and rub against each other, and the metal oxide is easy to fall off. In addition, some components in the composite metal oxide under long-term high temperature The volatilization of the catalyst will lead to the loss of the active components of the catalyst and the change of the proportion, which will lead to the decline of the catalyst activity and affect the service life of the catalyst to a certain extent.

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