Affiliation:
1. College of Chemistry and Chemical Engineering, Xi’an Shiyou University, No. 18, East Dianzier Road, Xi’an 710065, China
2. School of Chemistry & Chemical Engineering, Shaanxi Normal University, No. 620, West Chang’an Avenue, Xi’an 710119, China
Abstract
A series of Zn-modified HBeta (Zn/HBeta) catalysts were prepared via the wetness impregnation method with different zinc precursors such as ZnSO4·7H2O, ZnCl2, C4H6O4Zn·2H2O and Zn(NO3)2·6H2O, and their catalytic performance in the conversion of ethanol to propylene reaction was evaluated. Results indicate that the amount and strength distribution of the acid sites of the Zn/HBeta catalysts were easily tuned by employing different types of zinc precursors. More importantly, when the zinc species were introduced to the HBeta, the propylene yield was significantly enhanced, whereas the yields of ethylene and C2–C4 alkanes were remarkably suppressed. For the catalyst prepared by using the ZnCl2 precursor, a higher propylene yield of up to 43.4% for Zn/HBeta-C was achieved as a result of the moderate amount and strength distribution of acid sites. The average coking rate of the used Zn/HBeta catalysts strongly depended on the amount of total acid sites, especially the strong acid sites, i.e., the higher the amount of total acid sites of the catalyst, the greater the average coking rate. For the catalyst prepared by using the ZnSO4·7H2O precursor, Zn/HBeta-S exhibited a better stability even after depositing more coke, which was due to the higher amount of strong acid sites.
Funder
Key Research and Development Program of Shaanxi province of China
Natural Science Basic Research Plan in Shaanxi Province of China
Special Research Projects of Shaanxi Province of China