Abstract: In this paper, the effects of ZSM-5, MOR, 4A and 5A zeolites on the selective hydrogenation of maleic anhydride over copper-based catalysts were investigated by using ammonia evaporation method to treat CuSi catalysts. The results showed that the dispersion of copper particles in CuSi-4A catalyst was poor, which resulted in a small specific surface area; the adsorption capacity of H₂ on CuSi-4A catalyst was the weakest, and the activity of CuSi-4A was significantly lower than that of CuSi-MOR, CuSi-ZSM-5 and CuSi-5A catalysts. The CuSi-MOR catalyst was rich in Cu⁺, and the copper particles were smaller. Under the reaction conditions of a temperature of 280 ℃, a molar ratio of hydrogen to anhydride of 79 and a WHSV of 0.12 h^-1, the maleic anhydride conversion rate was as high as 99.6%, and the selectivity of γ-butyrolactone anhydride was 47.9%. Compared with CuSi catalysts without zeolite doping, the catalytic activity was significantly lower than that of the zeolite doped catalysts. Therefore, the use of zeolite as part of the silicon source in the process of preparing catalyst by ammonia evaporation can provide certain reference for improving metal dispersion and catalyst design.

Key words: maleic anhydride, CuSi catalyst, selective hydrogenation, molecular sieve, succinic anhydride