Catalytic Conversion of Chloromethane to Olefins and Aromatics Over Zeolite Catalysts

Abstract

We report the tunable conversion of chloromethane to olefins and aromatics using different metal-promoted zeolites as catalysts. Despite SAPO-34 was industrially used as catalysts for methanol to olefins reaction (MTO), the SAPO-34 based zeolites exhibited low activity and short lifetime when using chloromethane as the feed. Higher chloromethane conversion and longer catalyst lifetime were found on H-ZSM-5. The activity and product distribution can be improved by optimizing the reaction temperature and space velocity. Impregnating the H-ZSM-5 zeolite with 1 wt% and 5 wt% metal oxide as promoters significantly enhanced the conversion efficiency and altered the product distribution. The highest aromatics selectivity (38%) was obtained on the H-ZSM-5 zeolite promoted by 5 wt% Ni, whereas on 5 wt% Mg and 5 wt% Mn promoted H-ZSM-5, the aromatics selectivity is merely 5%. Therefore, different modified H-ZSM-5 could be used to convert chloromethane to either aromatics or olefin-heavy products. It was found that the aromatics yield is strongly correlated to the acidity of the H-ZSM-5 zeolite.