GB1305457A - - Google Patents

Abstract

1305457 Dehydrogenating alkyl benzenes INSTITUTUL PETROCHIM 19 Feb 1970 8083/70 Heading C5E Styrene and homologues thereof are produced by catalytic dehydrogenation of corresponding alkyl benzenes under adiabatic conditions, the catalyst being in two layers; the upper layer catalyst having a high activation energy for the dehydrogenation reaction and a small difference between the same and the apparent overall activation energy for the side reactions, and the lower layer catalyst having an activation energy for the dehydrogenation reaction equal to or less than that of the upper catalyst but not necessarily equal to that for the side reactions. The two layers may comprise different catalysts, or the same catalyst may be used undiluted in the lower layer and diluted in the upper layer. In examples, dopropyl benzene is dehydrogenated to alpha-methyl styrene. In Example 2 the lower catalyst comprises 85-90% Fe 2 O 3 , 5-8% K 2 O and 2-5% Cr 2 O 3 and has a specific surface above 10m.<SP>2</SP>/g., whilst the upper catalyst comprises 65-70% Fe 2 O 3 , 30-35% K 2 O and 2-3% Cr 2 O 3 and has a specific surface below 10m.<SP>2</SP>/g. In Example 3 the lower catalyst is the same as in Example 2 and the upper catalyst is the same as the lower except that it is diluted with an equal volume of quartz or alumina.