Isomerization of ethylbenzene in the gaseous phase over bifunctional Pt/AI^a nd Pt-zeolite catalysts was investigated in a microcatalytic fixed bed reactor using the pulse method. Over the Pt/Al203 catalyst, where the carrier displays only weak acidity, xylenes are formed from ethylbenzene mainly via the route ethylbenzene-ethylcyclohexene-1,2-methylethylcyclopentene-1,2-dimethylcyclohexene-o-xylene, which corresponds to predictions from a bifunctional mechanism in which skeletal rearrangements of tertiary carbocations only are considered to be the rate-determining steps. Over Pt-zeolite catalysts with higher acidity, skeletal isomerizations in which secondary carbocations are involved contribute-in addition to the route mentioned above-to the measured product distributions.

According to Constantinides and Arich (1964), most V can be removed by precipitation of asphaltenes. This suggests that V content increases relative to Ni in the direction of heavy asphaltene fractions. This is supported by a number Literature Cited

With simultaneous isomerization and cracking of the five hexane isomers on a bifunctional Pt/Al2 O3‐catalyst as a model reaction, which has been shown to follow pseudo mass action kinetics, it is demonstrated how the microcatalytic pulse technique can be applied for the kinetic analysis of complex linear reaction networks. From the experimental data relative rate constants for the individual reaction steps have been obtained by use of the Wei‐Prater‐method. The results are compared with results from continuous operation.