Synthesis of cis-1,3,3,3-tetrafluoropropene by catalytic isomerization of trans-1,3,3,3-tetrafluoropropene over alumina catalysts

Low global warming potential (GWP) refrigerant cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)) is a promising alternative working fluid for high-temperature heat pump designed for heat recovery in the industrial sector. As part of an effort to mass production of HFO-1234ze(Z), the isomerization of trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) to HFO-1234ze(Z) is performed to develop a process with high selectivity and high yield. Herein, we prepared the alumina catalysts via calcination, fluorination, and alkaline modification and tested for the trans-cis isomerization of HFO-1234ze. As a result, the alumina catalyst with appropriate weak Lewis acid sites tended to form HFO-1234ze(Z) with selectivity levels of about 97 %–99 % and no deactivation was observed following time on stream of 200 h. Proposed reaction mechanisms were described to understand the reactions over alumina surface. The present work provides a highly efficient synthetic process for industrial production of HFO-1234ze(Z).