Vanadium incorporated ammonium salt of 12-molybdophosphoric acid supported on titania: Effect of loading on the activity and selectivity of the catalysts during ammoxidation of 2-methylpyrazine

摘要

A series of catalysts was synthesized with varying quantities of vanadium incorporated into the ammonium salt of 12-molybdophosphoric acid (AMPV) Supported on titanium dioxide. The catalysts were characterized by XRD, FT-IR, TPD of ammonia and XPS techniques. The characterization data derived from XRD, FT-IR and XPS techniques reveal that the AMPV on titania support exists in the Keggin structure. These catalysts are studied for the vapor phase ammoxidation of 2-methylpyrazine (MP) to cynopyrazine (CP). The conversion of methylpyrazine increased with increase in loading on titania showing a maximum at 20 wt.% AMPV loading. A comparative study has been made among the catalytic functionalities of the 12-molybdophosphoric acid, its ammonium salt and vanadium incorporated ammonium salt. Vanadium incorporation led to substantial improvement in the selectivity to cynopyrazine. (c) 2005 Elsevier B.V. All rights reserved.