Preparation Of Selective Hydrocracking Catalyst For Inferior Diesel Based On Y/? Composite Zeolite

In recent years,with the economic development in China,the diesel-to-gas consumption ratio has continued to decline,and the demand for chemical raw materials has gradually increased.Diesel hydrocracking technology is an effective technical means to cope with today's changes.The catalyst is the core of the hydrocracking process.The hydrocracking catalyst is a typical dual-functional catalyst,in which the zeolite provides an acidic center and the metal component provides hydrogenation activity.The key to the reaction is the selective conversion of polycyclic aromatic hydrocarbons into monocyclic aromatic hydrocarbons.In this thesis,The Y zeolite is compounded with the ? zeolite.Y/? zeolites with different composite ratios were prepared by adjusting the p H value,crystallization temperature,crystallization time,and the amount of Y zeolite in the mother liquor during hydrothermal synthesis.A series of characterizations of Y/? composite zeolites synthesized by in situ method were carried out,and the results showed that the zeolite synthesized in situ has suitable acidity and pore structure.A hydrocracking reaction evaluation experiment was performed on the composite zeolite catalyst.It was found that the hydrocracking activity was the highest when the ratio of Y: ? was 1.5.Then using methods of impregnation method,ion exchange method and in-situ method were introduced to modify the Y zeolite by introducing Ni atoms into the Y zeolite.The effects of the amount of Ni introduced and the modification method on the physical and chemical properties of the Y zeolite were investigated.Hydrocracking experiments of modified Y zeolites were carried out using naphthalene and LCO as raw materials.The results show that when 2% nickel is introduced into the Y zeolite,the BTX yield of the product is the highest.The impregnated modified Y zeolites showed the best hydrocracking effect on the model compound naphthalene,and the ion exchange modified Y zeolites had the best effect in the treatment of catalytic cracked diesel.On the basis of the above research,the Ni modified Y zeolite and ? zeolite were combined,and hydrocracking experiments were carried out with naphthalene raw materials at different temperatures,and the maximum BTX yield was 59.4%.Catalytic cracking diesel oil was used as the raw material.Evaluation of the hydrogen cracking reaction showed that the yield of gasoline reached 41.5%.