Abstract In order to improve the synthesis process of indole by alcoholamine method and increase the yield of indole, the reaction mechanism and process conditions under the new catalyst were investigated. Gas chromatography-mass spectrometer was used to analyze the by-products of indole synthesized by alcoholamine method. The structural information of 18 specific by-products was obtained, among which the presence of two by-products N,N'-diphenyl-1,2-ethylenediamine and N-phenylmorpholine proved that the intermediate 2-aniline ethanol was formed in the indole synthesis, so the main mechanism of indole synthesis was determined as such: the intermediate 2-aniline ethanol was firstly formed by the catalytic reaction of aniline and ethylene glycol , then dehydration and dehydrogenation were followed to obtain indole. Based on this mechanism, the process conditions were adjusted, and the carrier of the catalyst was improved. The self made GC6 catalyst was used to synthesize indole and the service life of catalyst was significantly improved. The results of the 500 hours stabilization experiment showed good catalytic activity and the indole yield remained above 70%.
