Novel insights into diethylamine catalytic combustion over CuO catalysts supported by SSZ-13: Undesirable product NOx as a crucial intermediate for N2 generation

Abstract

Catalytic combustion of nitrogen-containing volatile organic compounds (NVOCs) could effectively control N2 generation rather than NOx, but its mechanism is still not well answered. Herein, a series of CuO supported by SSZ-13 catalysts (denoted as Cu/S) were prepared for the catalytic combustion of diethylamine (DEA), a typical NVOCs. The effects of CuO loading and calcined temperature of catalysts on the catalytic performance were investigated. Among the Cu/S catalysts, the 10CuO/S-450 catalyst exhibits the highest oxidation activity (lowest T99 of 240 °C), and widest temperature window (△T = 120 °C) for high N2 selectivity (>99%). This result is ascribed to its highest ratio of easily reduced CuO active species. Importantly, there are two important steps for DEA combustion (I: catalytic oxidation to NOx; II: selective catalytic reduction of NOx with DEA to N2). Selective catalytic reduction of NOx with DEA is the very crucial pathway for N2 generation. The easily reduced CuO species play crucial roles on both catalytic oxidation and selective catalytic reduction. In addition, water vapor (5 vol.%) slightly improved oxidation activity of DEA, and increased N2 selectivity at high temperature (>350 °C), but the catalytic oxidation activity of intermediate CO was decreased caused by the competitive adsorption of water vapor.