Combining USY and ZSM-23 in Pt/zeolite hydrocracking catalyst to produce diesel and lube base oil with improved cold flow properties

Abstract

The effect of the combined use of three-dimensional large-pore USY zeolite and one-dimensional medium-pore ZSM-23 zeolite to enhance the cold flow properties of hydrocracking products was studied. Based on the results of monozeolite catalysts testing in hexadecane hydroconversion, the compositions of bizeolite catalysts for vacuum gas oil hydrocracking were selected. The catalyst compositions were selected, considering that both zeolite components operate in a similar temperature range and contribute to hexadecane conversion. It has been shown that due to an appropriately selected combination of USY and ZSM-23 zeolites in the catalyst, both zeolites perform together, complementing each other, which ensures good conversion of both n-alkanes and isoalkanes during vacuum gas oil hydrocracking. As a result, it is possible to significantly improve the cold flow properties of the obtained hydrocracking products while maintaining the activity and selectivity for the target products of Pt/USY-ZSM-23 catalyst at the level of conventional Pt/USY catalyst. The cold filter plugging point of the diesel fraction decreases from −10 to less than −44 °C and the pour point from −17 to less than −50 °C. The pour point of lube base oil decreases from 23 to less than −27 °C. The improvement of the cold flow properties is accompanied by only a slight worsening of the other important product characteristics, such as diesel fraction cetane index and lube base oil viscosity index.