Catalyst for preparing 3, 4-dichlorobenzonitrile and preparation method and application thereof

Abstract

The invention discloses a special catalyst for preparing 3, 4-dichlorobenzonitrile. The carrier of the special catalyst is a silica gel-carbon nitride composite carrier formed by doping carbon nitridewith silica gel, and the composition of a loaded active component is shown as VSbbPcDdEeGgOx, wherein D is boron, lanthanum, cerium, samarium, europium, scandium, chromium, molybdenum, bismuth or tungsten, E is titanium, zirconium, manganese, iron, cobalt, nickel, copper, zinc or tin, and G is lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium or barium. The invention also discloses a preparation method and application of the catalyst. In the composite carrier of the special catalyst prepared by the method, carbon nitride is used as Lewis base to perform Lewis acid-base reaction with an active component used as Lewis acid so that the action of the active component and the carrier is enhanced, the loss of the active component is reduced, the active component is dispersed more uniformly, and the strength and wear resistance of the catalyst are improved; the service life is prolonged; and the oxidation-reduction capability of the catalyst and the coordination capability with reactants can be adjusted by utilizing the carbon nitride so that the activity and the selectivity of the catalyst are improved.

Description

technical field [0001] The invention relates to a catalyst for preparing 3,4-dichlorobenzonitrile by using 3,4-dichlorotoluene as a raw material through ammoxidation reaction, 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] 3,4-dichlorobenzonitrile, also known as 3,4-dichlorobenzonitrile, is an important fine chemical and an intermediate in organic synthesis. With the continuous emergence of new pesticides and pharmaceuticals containing fluorine, the demand for fluorinated aromatic compounds has increased sharply. The fluorinated derivatives of 3,4-dichlorobenzonitrile, 3,4-difluorobenzonitrile, 4-fluoro- 3-chlorobenzonitrile, 3,4-difluorobenzoic acid, 4-fluoro-3-chlorobenzoic acid, etc., can be widely used in pesticides, medicines, pigments, dyes and other industries; such as 3,4-difluorobenzonitrile It is an important intermedia...

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Problems solved by technology

[0003] The traditional preparation methods of 3,4-dichlorobenzonitrile are generally prepared from corresponding aldehydes, aldoximes or acids as raw materials. These methods have high raw material prices, long reaction routes, and serious environmental pollution.

Martin et al. (NH 4 ) 2 [(VO) 3 (P 2 o 7 ) 2 ] prepare 3,4-dichlorobenzonitrile as ammoxidation catalyst, product yield is only 50%, is difficult to reach the requirement of industrialized production; In addition, this catalyst mechanical strength is not high, also can't be used in fluidized bed reactor ( Catalysis Letters, 1995, 33:349; Catalysis Today, 1996, 32:279)

Wuhan University once applied for a patent (CN1328875A) on a method for preparing 3,4-dichlorobenzonitrile by ammonia oxidation and a special catalyst. Supported catalysts; however, silica gel supported catalysts generally have a short service life in industry

CN101759596A discloses a fluidized bed catalyst process prepared by co-precipitation method with V-Cr-B-Co as the main active component; Shanghai Petrochemical Institute has prepared silica sol type vanadium-chromium composite oxide fine particle catalyst ( CN102295581A), the catalyst particle size is tens of microns, and the activity and catalyst life are all improved compared with silica gel supported catalysts; however, the catalysts used in these patents are still difficult to meet the requirements of long life, high load, high activity and high selectivity of catalysts in industry

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