Characterization of the VS-1 catalyst using various spectroscopic techniques and its unique photocatalytic reactivity for the decomposition of NO in the absence and presence of C 3H 8

Abstract

A Vanadium silicalite (VS-1) catalyst was prepared by hydrothermal synthesis. In situ characterizations were carried out and the photocatalytic reactivity of VS-1 were investigated using dynamic photoluminescence, XAFS (XANES, EXAFS), UV–Vis and FT-IR techniques, along with an analysis of the reaction products. It was found that VS-1 involves a highly dispersed tetrahedrally coordinated V-oxide species having a VO bond within the zeolite framework. VS-1 exhibits photocatalytic reactivity for the decomposition of NO under UV irradiation, leading to the formation of N 2, O 2, N 2O and NO 2. The photocatalytic reaction of NO was dramatically enhanced in the presence of propane, leading to the formation of N 2, propylene, and oxygen-containing compounds such as CH 3COCH 3 and CO 2, etc. with a good stoichiometry. The photocatalytic reactivity of VS-1 was found to be much higher than that of V/SiO 2. The efficiency of the dynamic quenching of the photoluminescence of the V-oxide species in the excited state of VS-1 by small molecules such as NO or propane was found to be larger than that of V/SiO 2. These results indicate that the high reactivity of the charge transfer excited triplet state of the V–O moieties, (V 4+–O −) *, of the VS-1 catalyst plays a significant role in the higher photocatalytic performance as compared with the V/SiO 2 catalyst.