The Preparation Of Indole From Industrial-Byproduct O-nitroethylbenzene

Indole has been widely applied in some industries, for example, used as intermediate of the production of L-tryptophan and the raw material for some medicaments, biological active materials, dyestuffs, spiceries and chemical product. In this paper, the preparation methods of indole have been reviewed and the method of o-nitroethylbenzene, byproduct of chloramphenicol, used as the raw material for the production of indole was selected.This study mainly included the following contents: Preparation of o-ethylaniline was conducted through hydrogenation of o-nitroethylbenzene. By using T-1RanyNi as catalyst, in the high-pressure reactor, the conversion of the reaction and the yield of production were over 99.5% and more than 99.0% respectively. Within the specified initial pressure, the correlation between the rate of catalytic reaction and hydrogen press is direct ratio and the apparent activation energies for reaction is 61.61kJ·mol-1. By using CuAB-1 as catalyst through selecting from the catalyst of dehydrocyclization and aromatization, in the designed de-hydrogen retort, the conversion of the reaction and the selectivity of indole were 100% and over 90% respectively. The selectivity of indole still remains over 90% after 175 hours reaction. The half-life of this catalyst was over 200 hours. According to the experimental results, this catalyst possibly has double active centers, one was copper center and another was solid-acid center. Study on optimization of technique conditions for synthesizing indole through dehydrocyclization and aromatization of o-ethylaniline. The optimum range of the temperature for catalytic dehydrogenation was from 600℃ to 630℃. The optimum space velocity of the bed was 0.1h-1. The optimum ratio between water and material was 10. The cost of production of indole from o-nitroethylbenzene was 19,500￥ per ton. The cost of the production produced by this technological process of is lower than the market value markedly. Preparation of a suit of fixed bed reactor referring to the theory of chemical equipments design was also studied. In the reaction of dehydrocyclization and aromatization, the residence time of the material in the reactor could be accommodate by modulating current speed of carrier gas and the flux of metric pump. In addition, the temperature of the reactionrequired was high in this study. The temperature could be adjusted to reaction in the suit of equipment. The result indicated that high temperature dehydrogenation reaction could be carried through primely in the equipment.