One-Pot Synthesis of CeO2 Modified SBA-15 With No Pore Clogging for NO Reduction by CO

Kaili Ma,Hongliang Zhang,Changjin Tang,Lin Dong

doi:10.3389/fenvc.2021.670431

Abstract

CeO2 modified SBA-15 composites have been prepared by adding cerium precursor (Ce(NO3)3·6H2O) directly into the mixture of soft template (P123), silica precursor (TEOS) and urea aqueous solution but without mineral acid. The products were characterized by X-ray fluorescence (XRF), powder X-ray diffraction (XRD), N2 physisorption and transmission electron microscopy (TEM). Results indicated that ceria were successfully grafted onto mesoporous silica matrix and no pore clogging was observed. Both ceria content and mesoporous ordering of the final products were found to depend on urea amount. Compared to CeO2/SBA-15 from conventional impregnation method, the one-pot synthesis not only showed simple and green operation, but also superior catalytic performance in NO+CO reaction after loaded with CuO. It was revealed that both the presence and location of ceria had great influence on the reducibility of CuO, and the catalytic performances were intimately related to the redox properties of crystalline CuO. That is, higher NO conversion and N2 selectivity were achieved over catalyst with easier reduction of crystalline CuO.

Highlights

Ceria and ceria-based materials have received numerous attention in heterogeneous catalysis, in the field of environmental catalysis, such as CO oxidation (Slavinskaya et al, 2020), NO reduction (Tang et al, 2016), soot oxidation (Wang et al, 2021), and elimination of VOCs (Shi et al, 2021)
The formation of ordered mesoporous structures was studied by small angle X-ray diffraction (XRD) (SAXRD)
We can conclude that well-ordered ceria modified SBA-15 composites are successfully prepared by the one-pot synthesis

Summary

INTRODUCTION

Ceria and ceria-based materials have received numerous attention in heterogeneous catalysis, in the field of environmental catalysis, such as CO oxidation (Slavinskaya et al, 2020), NO reduction (Tang et al, 2016), soot oxidation (Wang et al, 2021), and elimination of VOCs (Shi et al, 2021). The conventional method of obtaining ordered mesoporous CeO2/SiO2 is impregnation of mesoporous silica materials, i.e., MCM-41 (Akondi et al, 2012) and SBA-15 (Mikheeva et al, 2019), with cerium salts. Since SBA-15 is usually prepared in strong acidic condition, it is hard to introduce guest species directly into the mesoporous matrix This may account for the well-known fact that most preparation of CeO2/SBA-15 composites involve two steps. Much higher catalytic activity over NO+CO reaction is obtained after loaded with CuO, suggesting the great potential of this method in fabricating CeO2-mesoporous silica composites. In order to investigate the catalytic performance of CeO2 modified SBA-15, the CuO-loaded catalysts were prepared. Column A with Paropak Q for separating N2O and CO2, and column B, packed with 5A and 13X molecular sieves (40–60 mesh) for separating N2, NO and CO

RESULTS AND DISCUSSION

CONCLUSIONS

DATA AVAILABILITY STATEMENT