以MCM-14为载体担载Ni-Mo硫化物制备柴油深度加氢脱硫催化剂

PREPARATION OF Ni-Mo SULFIDE CATALYST SUPPORTED BY MCM-41 FOR DIESEL DEEP HYDRODESULFURIZATION

用全硅MCM-41担载Ni-Mo双金属活性组分制备了高活性加氢脱硫催化剂,并考察了其对二苯并噻吩(DBT)、4-甲基二苯并噻吩(4-MDBT)、4,6-二甲基二苯并噻吩(4,6-DMDBT)和高硫直馏柴油加氢脱硫反应的活性。结果表明,所研制的催化剂对DBT、4-MDBT、4,6-DMDBT和高硫直馏柴油(w_S=2.83％)均具有很高的加氢脱硫活性。该系列催化剂的最佳Ni/Mo原子比为0.75,高于以γ-Al_2O_3作载体的传统Ni-Mo催化剂的最佳原子比。在DBT的加氢脱硫反应中,双组分催化剂低温下(<300℃)生成环己烷基苯(CHB)的选择性高于联苯(BP),与MoO_3/MCM-41的产物分布不同。随着温度的升高,CHB的选择性显著下降,而生成苯和环己烷的选择性显著提高,说明裂解产物主要由CHB分解而得。由TPR谱图可知,Mo和Ni活性组分在表面存在相互作用,从而使得氢耗特征温度发生变化。在Ni/Mo原子比为0.75时,TPR谱上出现4个特征峰,说明Mo和Ni的配伍性和协同作用对于提高催化剂活性很重要。

High performance hydrodesulfurization (HDS) catalysts were prepared by depositing Ni-Mo bimetallic species on siliceous MCM-41. The prepared catalysts were evaluated by the HDS reactions of dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT), 4, 6-dimethyldibenzothiophene (4,6-DMDBT) and a straight-run diesel fraction with an atomic sulfur content of 2.83%. It is shown that all the Ni-Mo/MCM-41 catalysts exhibited high HDS performance, and the maximum HDS activity was observed at a Ni/Mo atomic ratio of 0.75, which was higher than that of γ-Al2O3-supported Ni-Mo catalysts. The Ni-promoted Mo sulfide catalysts yielded more cyclohexyl benzene (CHB) than biphenyl (BP) in HDS of DBT at low temperatures ( <300°C ). Nevertheless, the selectivity of CHB decreased sharply while that of benzene and cyclohexane increased remarkably with increasing reaction temperature. It is suggested that the formation of benzene and cyclohexane mainly be resulted from the hydrocracking of CHB. The TPR patterns revealed that the interaction and synergic effect between Ni and Mo species might play an important role in enhancing HDS activity of the catalysts.