Catalyst used for resource utilization of a fixed bed aniline distillation residue and method for preparing said catalyst

Abstract

The present invention relates to a catalyst for fixed bed aniline rectification residue recycling and preparation method thereof. Based on the total weight of the catalyst, the catalyst comprises the following components in percentage by weight: 5-40% of an active component, 2-30% of a first cocatalyst component, 10-30% of a second cocatalyst component and the balance of carrier, wherein the active component is NiO; the first cocatalyst component is one or more of Fe, Mo, Cr or Co oxide; and the second cocatalyst component is one or more of La, Zr, Y or Ce oxide. The catalyst is prepared through co-precipitation. The catalyst shows high activity and stability in the waste liquid treatment process, and can still maintain high rectification residue cracking rate after reaction of 200 hours.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a catalyst and preparation method thereof, and more particularly to a catalyst for fixed bed aniline rectification residue recycling and preparation method thereof.BACKGROUND OF THE INVENTION[0002]Aniline is a colorless, oily liquid with a strong odor and toxicity. It is an important chemical intermediate, and thus is widely used for producing rubber processing aids, dyes, photographic chemicals, pharmaceuticals, pesticides, explosives, polyurethanes and the like. The production methods of aniline comprise phenol ammoniation, iron powder reduction and catalytic hydrogenation of nitrobenzene.[0003]Taking into account the source of raw materials, energy consumption, environmental protection and so on, most manufacturers use catalytic hydrogenation of nitrobenzene. The catalytic hydrogenation may be divided into two processes, i.e., the fixed bed gas phase hydrogenation and fluidized bed gas phase hydrogenation according to t...

AI Technical Summary

Benefits of technology

[0006]It is an object of the present invention to provide a catalyst for fixed bed aniline rectification residue recycling, which can hydrocrack aniline rectification residue to break molecular chains C—C, C—N of the high molecular weight substances contained in the residue, to make the C═C molecular chains saturated, to decrease their molecular weight, to reduce the viscosity of the system, to enhance the fluidity, and also to obtain useful substances such as cyclohexyl amine, dicyclohexyl amine and the like such that the subsequent separation operation is facilitated.

[0007]Another object of the present invention is to provide a method of preparing the catalyst for fixed bed aniline rectification residue recycling. Said method is simple, and the prepared catalyst has good stability.

[0024]The monofunctional saturated alcohol / aniline rectification residue in mass ratio of 0.1-0.7:1 is injected to a fixed bed reactor with the catalyst loading capacity of 10 ml by a micro-metering pump, and is completely evaporated at the upper end of the reaction tube. The liquid phase volume space velocity is 0.6-1.5 h−1, the reaction pressure is 1-4 MPa, the reaction temperature is between 250-320° C., the volume ratio of the hydrogen amount and the amount of aniline rectification residue is 500-3000:1, the hydrogen flow rate is 150-400 ml / min. Prior to initiation of the reaction, the catalyst needs to be reduced, and the reduction temperature and time are 350-500° C. and 4 h, respectively. The reducing gas is H2 (50 ml / min). When the reduction is ended and the temperature drops to the reaction temperature, the feeding and reaction is initiated, and the resulting product is quantitatively analyzed by gas chromatograph. The resulting catalyst has high activity and high selectivity, based on the mass of the rectification residue, the cyclohexylamine and dicyclohexylamine yields are up to 36.8% and 40% respectively, and the catalyst has good stability and the product selectivity is still not decreased after 200 h reaction.

[0026]In the catalyst of the present invention, the components have a synergic effect among them, so that the catalyst has high activity and stability. Ni catalyst has good catalytic activity, but is subjected to activity lowering due to the loss, sintering and coking of the active constituents in a high temperature reaction, and prone to sulfur poisoning. By changing the support and adding the first and second cocatalyst components, the loss of the active constituents may be reduced, and the degree of carbon deposition and sintering may be alleviated, thereby enhance the stability of the catalyst and prolong the service life of the catalyst. Y has effects of regulating the catalyst surface acidity, preventing carbon deposition and reducing ring opening reaction. Fe has the role of stabilizing the catalyst, and Mo, Cr, Zr, Ce, La or Co has the functions of reducing carbon deposition on the catalyst and prolonging the life of the catalyst.

Problems solved by technology

The fixed bed gas phase hydrogenation has the advantages of simple process, low maintenance cost, no need for separation of catalyst, low reaction temperature, good product quality and the like, but local overheating (hot spot) is prone to occur due to poor heat transfer of the fixed bed, which leads to side reactions and deactivation of the catalyst.

The fluidized bed reactor has the disadvantages of complicated operation, remarkable catalyst abrasion, and high operation and maintenance costs.

The liquid phase hydrogenation comprises a gas phase reaction and a liquid phase reaction and achieves easy reaction heat removal, and has the advantages of simple equipment and low operation and maintenance costs, but the cost of technology introduction is high.

These factors make aniline rectification residue have high viscosity and poor fluidity, and thus difficult to be reused.

Therefore, most of the aniline rectification residue, as waste liquid, is treated by incineration, but after incineration, it will produce nitrogen oxides and lead to acid rain and pollution environment, and further reduce the output of agriculture and fisheries.

At present, there is no effective method for the utilization of aniline rectification residue.

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