The liquid phase synthesis of methyl tert-butyl ether (MTBE) from methanol and isobutene over II-Beta and US-Y zeolite catalysts was studied in the temperature range 30-120 degrees C. Up to 100 degrees C, commercial II-Beta zeolite samples with small crystal size were more active than acid Amberlyst-15 (reference catalyst) and noticeably more active than US-Y, confirming results obtained under vapour phase conditions. The influence of methanol/isobutene (MeOH/IB) molar ratio, pressure, and space time on the conversion and MTBE selectivity was investigated. At optimized reaction conditions, MTBE yields of 85-90% can be reached with zeolite Ii-Beta as well as Amberlyst-15. On zeolites, side reactions of isobutene are more important than on Amberlyst-15, necessitating operation at MeOH/IB ratios higher than 1:1. For the same reason, at high conversion on Ii-Beta, the MTBE yields are more sensitive to contact time compared to Amberlyst-15. On II-Beta zeolite, no deactivation was observed during a period of more than 50 h on stream at 65 degrees C, 1.4 MPa pressure, and a WHSV of 14 h(-1). The catalytic activity of the zeolites is related to the external specific surface area, and to the concentration of bridging hydroxyls and silanol groups in the mesopores. A zeolite H-Beta sample with a Si/Al ratio of 36 has an optimum silanol and bridging hydroxyl content leading to stoichiometric methanol and isobutene adsorption, highest activity and MTBE yields. (C) 1999 Academic Press.
Collignon, F., Loenders, R., Martens, JA., Jacobs, P., & Poncelet, G. (1999). Liquid phase synthesis of MTBE from methanol and isobutene over acid zeolites and amberlyst-15. Journal of Catalysis, 182(2), 302-312. https://doi.org/10.1006/jcat.1998.2366 (Original work published 1999)