In order to determine how the properties of USY zeolite are associated to middle distillate selectivity in hydrocracking of heavy feedstocks, a series of extruded NiMoP/(modified-USY + Alumina) catalysts were prepared. Modified-USY zeolites were obtained by hydrothermal treatment and subsequent mild acid leaching. The catalysts were then tested in a pilot plant with a pretreated VGO in conditions near to the applied in the industrial process. The results show that conversion of fraction 370�C+ decreases with the temperature employed in the hydrothermal treatment, but at the same time, selectivity to fraction 180-370�C increases. Catalysts containing mild acid leached zeolites show increased conversion presumably because of improved access to the acid sites after the partial removal of extra-framework aluminum species. However, this improvement in activity was accompanied with lost in selectivity to middle distillates apparently due to secondary cracking reactions.

Effect of USY zeolite modifications on activity and middle distillates selectivity in the hydrocracking of a heavy feedstock

244th National Meeting (2012)

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