Method for directly preparing aniline through reaction between supported molybdenum dioxide catalyzed benzene and hydroxylamine salt

Abstract

The invention discloses a method for directly preparing aniline through reaction between supported molybdenum dioxide catalyzed benzene and hydroxylamine salt. The method comprises the following steps: respectively adding acetic acid, water, hydroxylamine salt, benzene and a catalyst to a normal pressure reactor provided with a reflux condensation device, heating up the raw materials to 70 to 80 DEG, stirring, and ensuring that the reaction time is 2-5 hours, and obtaining the aniline, wherein the volume ratio of the acetic acid, the water to the benzene is 5:5:1; the mass ratio of the benzene to the catalyst is (5-20):1; the molar rate of the benzene to the hydroxylamine salt is 1:1; the catalyst adopts a carbon material supported molybdenum dioxide catalyst (MoO2 / C for short); the mass of the active component MoO2 is 3-15 percent of the total mass of the catalyst. The method has the advantages that the selectivity of the aniline can reach 99 percent, the yield can reach 54 percent, the preparation process of the catalyst is simple, the cost is low, and the method is easy to operate .

Description

technical field [0001] The invention relates to a method for directly preparing aniline by reacting benzene with hydroxylamine salt, in particular to a method for directly catalyzing the reaction of benzene and hydroxylamine salt to synthesize aniline in one step under mild reaction conditions using a molybdenum dioxide catalyst supported by a carbon material. Background technique [0002] Aniline is an important organic chemical raw material and fine chemical intermediate. It is widely used in industries such as medicine, dyestuff, rubber, and spices. It is also the main raw material for the production of diphenylmethane diisocyanate (MDI). With the increase of MDI demand, the The demand for aniline has also increased significantly. At present, the industrial production methods of aniline are mainly catalytic hydrogenation of nitrobenzene and gas-phase ammonolysis of phenol. The first step of catalytic hydrogenation of nitrobenzene is to nitrate benzene with a mixture of c...

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Problems solved by technology

This patent also uses ammonia as an aminating agent and hydrogen peroxide as an oxidizing agent. Although the reaction conditions are mild, the yield of aniline is only 0.038%, and the catalyst requires multi-stage roasting, the preparation process is complicated, and hydrogen reduction activation is required before use.

In addition, the research group proposed in the patent 200510020505 a method for synthesizing aniline in one step in aqueous acetic acid using soluble vanadium salts (vanadyl sulfate, ammonium metavanadate, sodium metavanadate) as a catalyst and hydroxylamine hydrochloride as an aminating agent. The method makes the yield of aniline reach 68%, although this method has improved the yield of aniline greatly, soluble vanadium salt catalyst is expensive, and the cost is higher, thereby also limited the industrial application of this method

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