Precise control of heat-treatment conditions to improve the catalytic performance of V_2O_5/TiO_2 for H_2S removal

摘要

The purpose of this study is to investigate the influences of atmospheric gas and temperature while preparing V2O5/TiO2 catalysts to find a suitable heat-treatment method to improve catalytic performance during the process of H2S removal. The catalysts prepared by wet-impregnation were heat-treated at different temperatures (400 or 600 degrees C) under various atmospheres (Air, N-2, or H-2). The catalytic tests demonstrated that the catalyst heat-treated at 400 degrees C under N-2 atmosphere (N-400) possessed excellent catalytic activities regarding H2S conversion (96.4%) and sulfur yield (89.1%). The characterization results revealed that the mild reducing condition employed for N-400 led to the formation of partially reduced V2O5 crystals and a strong V-Ti interaction owing to the anatase TiO2 phase, resulting in the high oxygen vacancies on the catalyst surface. However, severe reducing conditions (H-2 or N-2 with 600 degrees C) or the higher temperature (600 degrees C) induced highly reduced V2O5-x or rutile TiO2 related to a weak V-Ti interaction, respectively, which facilitated lower oxygen vacancies. This study is the first to demonstrate the significance of a precisely controlled heat-treatment to enhance catalytic performance for H2S removal.