Study of hydrodesulfurization of 4,6-DM-DBT over Pd supported on mesoporous USY zeolite Original Research Article

Two ultra-stable Y zeolites (USY550 and USY600) with mesoporous volumes of 0.15 and 0.25 cm3/g were prepared by steam dealumination at 550 and 600 °C, respectively. Pd catalysts were supported on γ-Al2O3, H-forms of zeolite Y (HY), mesoporous USY for hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DM-DBT). The 4,6-DM-DBT conversions over Pd/USY550 (85.7%) and Pd/USY600 (76.9%) are higher than over Pd/HY (43.7%) due to the facilitated mass transfer of 4,6-DM-DBT in the mesopores USY. The better HDS performance of Pd/USY than Pd/γ-Al2O3 is attributed to the stronger acidity of USY, as demonstrated by the stepwise temperature-programmed desorption of ammonia. Thermogravimetric and X-ray photoelectron spectroscopic analysis of the used catalysts showed that the poison of Pd particles over the supports by sulfur was responsible for the catalyst deactivation.