The removal of N2O from gas stream by catalytic decomposition over Pt-alkali metal/SiO2

Abstract

Using promoters is an efficient way to improve catalytic activity in many chemical and industrial applications. In this paper, the effects of the impregnation method and alkali metals in a series of 1%wt Pt-M/SiO 2 (M=Na, K, and Cs) catalysts were comprehensively examined on the decomposition of N2O. To reveal the physical and chemical properties of samples for analyzing obtained results of catalytic activity, catalysts were characterized by BET, XRD, ICP, H2-TPR, CO2-TPD, TGA, XPS and HRTEM. Catalysts were also synthesized by wet impregnation as a simple and efficient method. In order to find the effects of the synthesis method, different treatments of both sequential and co-impregnation were applied. The optimum results are acquired when Pt precursor was loaded on alkali metal oxide modified SiO 2. According to achieved results, Na and Cs prompters drop the conversion from 65% to 25% and 35%, respectively. Among the alkali metals, only K element has shown promotional characteristics despite 50% reduction of surface area and 75% growth of Pt particles. Also, the impact of alkali metal loading indicates that 5%wt KNO3 yielded an 18% promotion in conversion. Donating electron, facilitating oxygen surface diffusion and uniform distribution of KOx clusters are significant factors for the improvement of the PtK reactivity.