EFFECT OF USY ZEOLITE MODIFICATIONS ON ACTIVITY AND MIDDLE DISTILLATES SELECTIVITY IN THE HYDROCRACKTNG OF A HEAVY FEEDSTOCK

摘要

The worldwide increase in middle distillates demand, the tightening in fuel quality specifications and the necessity to process heavier feedstocks have urged the implementation of technologies such as hydrocracking.In this technology, the catalyst plays a key role. USY zeolite is the typical support used in hydrocracking because of its acid characteristics to induce great activity. However, its selectivity to middle distillates is deficient. Some recent studies focus in the development of USY zeolites with suitable pore system and acid strength as essential properties for a middle distillates hydrocracking catalyst. The enhancement of the proximity between hydrogenation/dehydrogenation sites and zeolite acid sites has also been studied. However, some influencing factors are not systematically covered in literature. In some cases, aspects such as differences in acid strength distribution6 or textural properties are underestimated when comparing different solids. In this work, we studied the effect of the content of USY zeolite in the catalyst, the degree of dealumination by changing the temperature in the hydrothermal treatment, and the partial removal of extra-framework aluminum species by mild acid leaching on the conversion and selectivity to middle distillates in the hydrocracking of a heavy feedstock.