Selective methylation of anisole to 2,6-xylenol over rare earth promoted SnO2 catalysts

Abstract

Rare earth promoted SnO₂ catalysts are found to be active in the selective conversion of anisole to 2,6-xylenol in the presence of methanol. A maximum 2,6-xylenol selectivity of 82% was achieved at 400 °C under optimized conditions at an anisole conversion of 65%. The dealkylation of anisole to phenol and other side reactions such as the formation of polymethylated products is not favoured over these catalysts systems. The activity of these catalysts in the selective formation of 2,6-xylenol is ascribed to the presence of weak Lewis acid sites and comparatively stronger basic sites. The secondary reactions are suppressed over rare earth promoted SnO₂ catalysts due to the unavailability of strong acid sites.