Unpredictable properties of industrial HY zeolite for tetralin hydrocracking

Abstract

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.