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

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 N 2 O. To reveal the physical and chemical properties of samples for analyzing obtained results of catalytic activity, catalysts were characterized by BET, XRD, ICP, H 2 -TPR, CO 2 -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 KNO 3 yielded an 18% promotion in conversion. Donating electron, facilitating oxygen surface diffusion and uniform distribution of KO x clusters are significant factors for the improvement of the PtK reactivity. • Using of alkali metals over Pt/SiO 2 into de-N 2 O. • Consideration to importance of the sequence of impregnated precursors on SiO 2 • 40% and 60% decline of catalytic activity by Cs and Na, respectively. • 18% increase of catalytic activity by K.