Styrene synthesis in a reverse-flow reactor

Abstract

Multifunctional reactor concepts for thermal coupling of endothermic synthesis reactions with an exothermic auxiliary reaction are presented. The processes are carried out in an autothermal operation mode incorporating regenerative heat exchange within the reactor through periodic flow reversal. Catalytic dehydrogenation of ethylbenzene to styrene is considered as a particular example, where catalytic combustion of the produced hydrogen serves as a heat source. Two alternative operation modes are discussed, the asymmetric operation mode, where the synthesis reaction and the combustion are separated in time and the symmetric operation mode with external combustion and hot gas injection, or with air injection and in situ hydrogen combustion. A lab-scale reactor with an integrated catalytic burner has been set-up and experiments with the symmetric operation mode have been performed. The symmetric operation mode with hot gas injection proves to be an attractive alternative to conventional processes for styrene synthesis: it allows for high conversions and high selectivities, combined with an efficient heat recovery.