Catalytic conversion of high-GWP gases N2O and CH4 to syngas (H2 + CO) on SiO2@Ni-Cr layered nano-oxide-coated monolithic catalyst.

Abstract

Layered double hydroxides (LDHs) are 2D nano-sheets where different M2+ and M3+ metal cations are uniformly distributed in Mg(OH)2 brucite-like sheets and various charge-compensating anions (An-) are present in their interlayer spaces. This work includes preparation of different SiO2@Ni/Cr mixed-metal layered nano-oxide-type catalysts by the calcination of SiO2@Ni-Cr LDH nano-composite-based alcogel coated over a honeycomb monolithic substrate and their use as a catalytic device for the study of catalytic partial oxidation (CPO) of CH4 both in the presence of O2 and in the presence of N2O under atmospheric pressure at different temperatures not exceeding 500°C to study the effect of N2O on the CPO of CH4. It was observed that in the presence of O2 the yield of syngas (H2 + CO) did not exceed 90% whereas in the presence of N2O about 99.9% syngas (H2 + CO) was observed. The selectivity towards syngas production reached a maximum value when an optimal reaction condition was maintained at 1:1 CH4:N2O mol ratio with a temperature of 500°C. XPS analysis showed that a NiO-type compound formed on the decomposition of the LDH component after H2 treatment was reduced to disperse Ni0, which acted as an active catalytic species. Graphical abstract Schematic representation of catalytic partial oxidation of CH4 in the presence of N2O by SiO2@Ni-Cr-LDH-based mixed-metal nano-oxide.