Highly selective and stable alkylation of benzene with ethane into ethylbenzene over bifunctional PtH-MFI catalysts

Benzene alkylation with ethane into ethylbenzene (EB) was studied at 370 DegC over two Pt-contg. MFI catalysts with the Si/Al ratios of 36 and 140, and the reaction temp. and catalysts were selected based on the anal. of the thermodn. and kinetic limitations assocd. with this reaction. The exptl. results suggest that EB formation proceeds via ethane dehydrogenation into ethene over Pt sites and subsequent benzene alkylation with ethene over acid sites. Under selected reaction conditions the whole process of EB formation is driven by the alkylation reaction and many side reactions (including coke formation) are suppressed due to the inherently low ethene concn. at 370 DegC. Also, the low and moderate acidity of the catalysts allows decoupling of EB formation steps and the steps of its subsequent transformation into side products. As a consequence, both catalysts demonstrate a remarkably stable performance (during 45-49 h on stream) with EB selectivity in the arom. products in the range between 92.6 and 95.3 mol%, with the highest (benzene-based) EB yield of 10.7%. These obsd. EB selectivities and yield are essentially higher than those reported previously both for the zeolite and superacidic catalytic systems. [on SciFinder (R)]