Jiayao Qi,Yanni Guo,Hanqiong Jia,Binbin Fan,Hang Gao,Bo Qin,Jinghong Ma,Yanze Du,Ruifeng Li
The commercial Y zeolites are widely used in catalytic cracking and hydrocracking in industry, the efficient hydrocracking of polycyclic aromatics is a challenging task in petroleum and coal refining. The acidic zeolite in the hydrocracking bi-functional catalyst dominates largely the product selectivity, so understanding the independent effect of acid sites is favorable to the design of the catalyst. Herein, five industrial HY zeolites with different ratios of Si/Al were applied to tetralin hydrocracking to produce high-value benzene, toluene, and xylenes (BTX) in a high-pressure fixed bed reactor . The result indicated that mesoporous HUSY not only improved the catalytic activity but also exhibited longer-term stability compared with micropore HY. Interestingly, tetralin conversion in the hydrocracking showed a high-similar value when the Si/Al ratio of the zeolites is above 26 with almost identical porous structure , regardless of the distribution of acidity. And the yield of products is associated with the acidity of the HY zeolites, the lower the Si/Al ratio is, the more favorable the monocyclic aromatic hydrocarbons form. Therefore, it is beneficial for the industrial process to reduce the zeolite post-treatment procedure which achieves the high activity and BTX yield in the hydrocracking of tetralin and to abate the cost consumption, although it is still impractical to get rid of the trial-error scheme for the designing of an efficient catalyst in practice.
Liuyi Pan,Yulong He,Menglong Niu,Yong Dan,Wenhong Li
Ni–M/SiO2 with different binary metals M (M = Ce, Co, Sn, Fe) prepared by an incipient impregnation method was used in the hydrodeoxygenation (HDO) of low-temperature coal tar distillate, which is rich in phenolic compounds. p-Cresol, as a model compound of the distillate, was used to evaluate the activity and selectivity of BTX products on the series of reduced Ni–M/SiO2 catalysts in a fixed bed reactor. The properties of the catalysts were characterized by N2 adsorption–desorption, ICP-AES, XRD, H2-TPR, and XPS. Benzene and toluene as the direct deoxygenation (DDO) products and cyclohexane and methylcyclohexane as the hydrogenolysis (HYD) products were detected to evaluate the selectivity of the path in the deoxygenation process. In this series of catalysts, the order of reactivity was Ni–Ce > Ni–Sn > Ni–Co > Ni–Fe > monometallic Ni. Meanwhile, the addition of Ce and Co loaded in the Lewis acid sites of the catalyst affected the electron distribution of nickel atom and its atomic arrangement on the surface of the carrier. Compared to monometallic Ni, the DDO path become dominant on Ni–Ce and Ni–Co and the selectivity for BTX products increased from 58.8% to 77.4% and 71.1%, respectively. The binary metal Sn, unlike the former two metals, formed a Ni3Sn crystal form with Ni, which resulted in significant enhancement of the HYD path while obviously increasing the reactivity.
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