Influence of Si/Ga and Si/Al ratios on propane aromatization over highly active H-GaAlMFI

Abstract

Conversion of propane to aromatics has been investigated at 550 ° C and space velocity range of 3000-12 000 cc/g/h over galloaluminosilicate zeolites (GaAlMFI) containing similar bulk Si/(Al + Ga) ratio but markedly different individual Si/Al and Si/Ga ratios. While Al showed a propensity to be distributed predominantly in the zeolite framework, a large fraction of total Ga was present as non-FW Ga species; due to this the strong acidity was higher for the GAlMFI zeolite with the larger bulk Al content. The zeolite with the larger bulk Al content (GAL1) showed superior propane aromatization (initial and time-on-stream) activity compared to the zeolite with the larger Ga content (GAL2). The aromatic distribution was also significantly influenced by the bulk Si/Al and Si/Ga ratios of the zeolites. While the benzene and C₈ aromatics selectivity was higher for GAL2, the selectivity for toluene was higher for GAL1.