Selective monochlorination of methane via elimination of dichloromethane from the oxychlorination product stream

Abstract

Through exploring the impact of dichloromethane on the chloromethane to olefins reaction, it is shown in this paper that a small amount of dichloromethane in the chloromethane feed has a drastically negative impact on the performance of SAPO-34 catalyst for the chloromethane to olefins reaction. Such impact on the catalyst performance is due to dichloromethane reacting with hydroxyl groups on the catalyst surface through a reaction that produces chloromethane. Based on this learning, we show that dichloromethane can be converted to chloromethane while performing the methane oxychlorination reaction using a layered catalyst bed approach by placing a bed of γ-Al2O3 catalyst below a CeO2 oxychlorination catalyst. Our results were successful in showing that a layered catalyst design using γ-Al2O3 as catalyst is an effective means of eliminating dichloromethane from the oxylchorination product stream and simultaneously providing an uplift to the chloromethane production rate. Such approach can serve as a one-step selective monochlorination route for production of chloromethane from methane.