Anaerobic conversion of methane to acetonitrile over solid-state-pyrolysis-synthesized GaN catalysts

Abstract

The anaerobic conversion of methane to acetonitrile (AcCN) using GaN catalysts synthesized through the solid-state pyrolysis of gallium nitrate hydrate and melamine was investigated. A series of GaN catalysts (unsupported GaN, 50 wt% GaN/SiO2, and 5 wt% GaN/SiO2) were prepared, and their physicochemical properties were analyzed. The as-synthesized GaN catalysts had higher porosities, lower crystallinities, and better activities than those of the commercial GaN. Among tested catalysts, 5 wt% GaN/SiO2 displayed the highest methane conversion rate and AcCN productivity at 700 °C. Residual carbonaceous and nitrogen species, such as sp2-N (N = C) and cyano-N (NC), are likely to participate in the transformation of methane to AcCN. The activity of post-reaction 5 wt% GaN/SiO2 could be partially rejuvenated by a calcination-nitridation-activation process.