Published September 2000
Worldwide production of styrene is mainly via the dehydrogenation of ethylbenzene diluted with steam over a fixed-bed catalyst under adiabatic conditions. The ethylbenzene is obtained by alkylating benzene with ethylene. In the subject patent (US 6031143, to Snamprogetti, Buonomo, F., et al., February 29, 2000), an alternative process and dehydrogenation catalyst composition are disclosed that use ethane rather than ethylene as feed to the process. The ethane is fed together with ethylbenzene to a circulating fluidizedbed reactor system that simultaneously produces styrene and ethylene and allows continuous catalyst regeneration. The ethylene is recovered and used as feed to the alkylation step. The microspheroidal catalyst particles are composed of Ga/Pt/K supported on alumina with a silica binder; the reactor technology is one that was disclosed in an earlier patent assigned to Snamprogetti (US 5994258, Buonomo, F., et al., November 30, 1999).
The disclosure provides data for three dehydrogenation experiments carried out in a laboratory-scale fluidized-bed reactor system at 600°C (1,112°F), 1.1 atm, and covering a range of feed compositions and space velocities. Ethylbenzene conversion varied from 45 to 58% at 94% selectivity and ethane conversion from 7.1 to 12% at 95% selectivity.