The remarkable promotional effect of Sn on CeVO4 catalyst for wide temperature NH3-SCR process by citric acid-assisted solvothermal synthesis and post-hydrothermal treatment

Abstract

A series of CeVO₄ catalysts were prepared by citric acid-assisted solvothermal synthesis and hydrothermal methods. The Sn-CeVO₄ exhibited superior NH₃-SCR performance since abundant of cerium vanadate coexisting with a spot of CeO₂ and a mass of surface acid sites forming in the solvothermal synthesis process. A number of structural defects increased after Sn was doped into the CeVO₄ system, and the electron transfer between cerium and vanadium was also accelerated significantly. Thus the temperature window of Sn-CeVO₄ was broadened and its tolerance to H₂O and SO₂ was improved dramatically. In addition, post-hydrothermal treatment was essential for the fresh CeVO₄ catalyst to achieve better catalytic activity. The results illustrated that surface reconstruction and the chemical states of surface active species occurred slight changes after the post-hydrothermal treatment, which was conducive to expose more active sites to enhance its catalytic activity. Totally, the large surface area of cerium vanadate, strong interaction among tin, cerium and vanadium, large number of acid sites and oxygen vacancies, structural defects as well as exposed active sites were beneficial to the improvement of Sn-CeVO₄ catalytic performance in NH₃-SCR process.