CuO‐CuAl 2 O 4 Catalyst for Synthesis of 1‐Methylindole by Alcohol Amine Method

ABSTRACT Cu‐based catalysts used for the vapor‐phase synthesis of 1‐methylindole from N‐methylaniline and ethylene glycol are prone to Cu sintering and deactivation under the reaction conditions. In this work, CuO‐CuAl 2 O 4 catalysts were prepared by a coprecipitation method and applied to the synthesis of 1‐methylindole via alcohol amine route. The effects of calcination temperature and Cu/Al molar ratio on the textural properties, crystalline phases, reducibility, surface composition, and catalytic performance were investigated. The catalyst calcined at 700°C with a Cu/Al molar ratio of 1:2 showed the highest 1‐methylindole yield, exceeding 85% under the investigated conditions. Characterization results indicate that an appropriate balance between non‐spinel CuO and CuAl 2 O 4 spinel improves the reducibility of Cu species and reduces the agglomeration of Cu particles to a certain degree. The catalyst maintained a 1‐methylindole yield above 80% during the first 8 h, while gradual deactivation was observed during the 28 h stability test.