Zhou Wenwu, Zhou Yasong, Wei Qiang, Du Lin, Ding Sijia, Jiang Shujiao, Zhang Yanan, Zhang Qing
State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing, 102249, P. R. China.
Chemistry. 2017 Jul 12;23(39):9369-9382. doi: 10.1002/chem.201701307. Epub 2017 Jun 14.
The effects of metal-modified acidic co-supports on the hydrodesulfurization (HDS) activity and isomerization selectivity of highly refractory organosulfur compounds such as 4,6-dimethyldibenzothiophene have been investigated. Y zeolite crystals with high Si/Al ratios and small crystallite sizes were successfully synthesized by a new hydrothermal synthesis approach. The synthesized Y zeolite crystals were ion-exchanged and stabilized. The prepared samples were then modified with different gallium contents using an impregnation method to adjust their acidity properties, and these modified samples were used as co-supports for NiMo sulfide HDS catalysts. The catalyst containing 10 wt.% zeolite Y modified by 2 wt.% gallium (NiMo/2GaY-ASA-A) exhibited the highest HDS activity, with 4,6-dimethyldibenzothiophene (4,6-DMDBT) conversion nearly double the rate of the catalyst without zeolite at 563 K, 4.0 MPa and liquid hourly space velocity (LHSV) of 40 h . NiMo/2GaY-ASA-A also exhibited superior isomerization ability, with 3,4'-DMBP, 4,4'DMBP, and 3,6-DMDBT as the main products, indicating that the isomerization pathway was the main reaction route over NiMo/2GaY-ASA-A. The superior catalytic performance is related to the synergistic effect of the proper amount of medium and strong Brønsted acid sites. The compounds 3,6-DMDBT and 3,7-DMDBT (isomers of 4,6-DMDBT) and 3,4,6-TMDBT and tetra-methyl-DBT (transmethyl products) were detected simultaneously in the HDS product of 4,6-DMDBT for the first time over NiMo/GaY-ASA-A catalysts. Finally, a new reaction network over NiMo/2GaY-ASA-A was proposed.
研究了金属改性酸性共载体对4,6-二甲基二苯并噻吩等高难熔有机硫化合物加氢脱硫（HDS）活性和异构化选择性的影响。通过一种新的水热合成方法成功合成了具有高硅铝比和小晶粒尺寸的Y型沸石晶体。对合成的Y型沸石晶体进行离子交换和稳定化处理。然后采用浸渍法用不同含量的镓对制备的样品进行改性，以调节其酸性性质，并将这些改性样品用作NiMo硫化物HDS催化剂的共载体。含2 wt.%镓改性的10 wt.% Y型沸石的催化剂（NiMo/2GaY-ASA-A）表现出最高的HDS活性，在563 K、4.0 MPa和液时空速（LHSV）为40 h⁻¹的条件下，4,6-二甲基二苯并噻吩（4,6-DMDBT）转化率几乎是不含沸石催化剂的两倍。NiMo/2GaY-ASA-A还表现出优异的异构化能力，以3,4'-二甲基联苯并噻吩（3,4'-DMBP）、4,4'-二甲基联苯并噻吩（4,4'-DMBP）和3,6-二甲基二苯并噻吩（3,6-DMDBT）为主要产物，表明异构化途径是NiMo/2GaY-ASA-A上的主要反应路线。优异的催化性能与适量的中强布朗斯台德酸位的协同效应有关。在NiMo/GaY-ASA-A催化剂上，首次在4,6-DMDBT的HDS产物中同时检测到3,6-DMDBT和3,7-DMDBT（4,6-DMDBT的异构体）以及3,4,6-三甲基二苯并噻吩（3,4,6-TMDBT）和四甲基二苯并噻吩（四甲基-DBT，甲基转移产物）。最后，提出了NiMo/2GaY-ASA-A上的新反应网络。
