A novel method of monitoring the sulfidation of hydrotreating catalysts: the conversion of carbonyl sulfide

During the sulfidation of hydrotreating catalysts under a H 2 S/H 2 flow, the conversion of carbonyl sulfide (COS), present as an impurity, allows one to determine the starting and ending temperatures of the formation of the active sulfide phase. This new and simple method is validated by comparing it with CO adsorption monitored by IR spectroscopy for two CoMo catalysts sulfided either after calcination or after drying. Both methods show that the formation of CoMoS sites occurs at higher temperature when the catalyst is dried instead of calcined before the sulfidation. The conversion of COS during the sulfidation of HDS catalysts allows one to determine the temperature range of formation of CoMoS sites.