Hydroprocessing of hydrocracker bottom on Pd containing bifunctional catalysts

• Pd/ASA-Al2O3 catalyst has the highest selectivity to middle distillates.
• Pd/Beta-ASA-Al2O3 catalyst has high hydrocracking and hydroisomerization activities.
• Pd/ZSM-23-ASA-Al2O3 catalyst has the highest hydroisomerization activity.

Bifunctional catalysts Pd/ASA-Al2O3, Pd/Y-ASA-Al2O3, Pd/Beta-ASA-Al2O3, Pd/ZSM-23-ASA-Al2O3 were prepared. Catalysts were characterized by FTIR of adsorbed CO, nitrogen adsorption and CO chemisorption. Average sizes of palladium particles in the catalysts were found to be 1.2–2.9 nm. Zeolite-based catalysts contained stronger Brønsted acidic sites than amorphous silica-alumina (ASA) based catalyst Pd/ASA-Al2O3. Catalysts were tested in hydroconversion of hydrocracker bottom (HCB). Hydrocracking activities of Pd/Y-ASA-Al2O3 and Pd/Beta-ASA-Al2O3 catalysts were found to be significantly higher than that of Pd/ASA-Al2O3 and Pd/ZSM-23-ASA-Al2O3 catalysts. Conversion of 80% of HCB was achieved for catalysts with zeolites beta and Y at 250 °C. It was found that selectivity to middle distillates increases in following order: Pd/ZSM-23-ASA-Al2O3 < Pd/Beta-ASA-Al2O3 < Pd/Y-ASA-Al2O3 < Pd/ASA-Al2O3. The highest yield of middle distillates was achieved for Pd/ASA-Al2O3 catalyst at 370 °C. Ratio of hydroisomerization to hydrocracking activity was found to increase in the following order of catalysts: Pd/Y-ASA-Al2O3 ≤ Pd/ASA-Al2O3 < Pd/Beta-ASA-Al2O3 < Pd/ZSM-23-ASA-Al2O3. Middle distillate with pour and cloud points of −61.5 and −62.5 °C, respectively, was obtained at 240 °C with 31.3 wt.% yield using Pd/Beta-ASA-Al2O3 catalyst.

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