Precise control of heat-treatment conditions to improve the catalytic performance of VO/TiO for HS removal.

The purpose of this study is to investigate the influences of atmospheric gas and temperature while preparing VO/TiO catalysts to find a suitable heat-treatment method to improve catalytic performance during the process of HS removal. The catalysts prepared by wet-impregnation were heat-treated at different temperatures (400 or 600 ℃) under various atmospheres (Air, N, or H). The catalytic tests demonstrated that the catalyst heat-treated at 400 ℃ under N atmosphere (N-400) possessed excellent catalytic activities regarding HS 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 VO crystals and a strong V-Ti interaction owing to the anatase TiO phase, resulting in the high oxygen vacancies on the catalyst surface. However, severe reducing conditions (H or N with 600 ℃) or the higher temperature (600 ℃) induced highly reduced VO or rutile TiO 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 HS removal.