以全硅MCM-41为载体制备W系深度加氢脱硫催化剂

PREPARATION OF W-BASED CATALYSTS SUPPORTED BY SILICEOUS MCM-41 FOR DEEP HYDRODESULFURIZATION

用全硅MCM 41担载Ni W和Co W制备了深度加氢脱硫催化剂 ,并在中压固定床反应器上分别考察了对二苯并噻吩 (DBT)和高硫直馏柴油的加氢脱硫性能。结果表明 ,全硅MCM 41担载制成的W系催化剂表现出很高的加氢脱硫活性 ,其中Ni W /MCM 41活性高于Co W /MCM 41,但两类催化剂的最佳Ni(Co) /W原子比均为 0 75。从加氢脱硫产物分布看 ,两类催化剂的脱硫反应路径不同 ,在Co W /MCM 41上主要通过氢解脱硫 ,而在Ni W /MCM 41上则是通过氢解以及先经芳环加氢后脱硫的两条路径来进行。对Ni W /MCM 41来说 ,加氢活性随温度升高而升高。

W-based deep hydrodesulfurization (HDS) catalysts were prepared by impregnating Ni-W and Co-W species on siliceous MCM-41. The HDS activity of prepared catalysts was evaluated in a fixed bed reactor by using a model fuel containing 0.5% dibenzothiophen (DBT) in decalin and a straight-run diesel containing 2.83% S as the feedstocks. Results indicated that the optimal atomic ratio of n (Ni or Co)/n (W) for both Ni-W/MCM-41 and Co-W/MCM-41 are 0.75, while Ni-W/MCM-41 exhibited much higher HDS activity than Co-W/MCM-41. The product distribution suggested that the two catalysts took different reaction routes for hydrodesulfurization. For Co-W/MCM-41 catalyst, hydrodesulfurization took place mainly through hydrogenolysis, i.e. DBT to form BP (biphenyl). As for Ni-W/MCM-41 catalyst, both hydrogenolysis and hydrogenation took place, i.e. DBT firstly hydrogenated to form tetrahydro-DBT (TH-DBT), then desulfurized to form cyclohexyl benzene (CHB). Ni-W/MCM-41 catalysts showed excellent performance in the hydrodesulfurization of both DBT and a high sulfur-containing straight-run diesel, suggesting that siliceous MCM-41 is a promising support for deep HDS catalysts.