Hydrogenation of synthetic PYGAS—Effects of zirconia on Pd/Al2O3

Pd-based catalysts supported on ZrO2 and xZrO2/Al2O3 (x = 0, 10 and 20 wt.%) were prepared and characterized by X-ray diffraction, diffuse reflectance spectroscopy, temperature programmed reduction and chemisorption of H2. Catalysts were evaluated via hydrogenation of a model mixture representative of pyrolysis gasoline, containing styrene, 1,7-octadiene, 1-octene and dicyclopentadiene in a batch reactor operated at 30 bar and 60 °C. The Pd/Al2O3 catalyst presented the higher metallic dispersion and hydrogenation activity. In spite of the occurrence of reduction at high temperatures and no H2 consumption at room temperature, the catalyst Pd/ZrO2 presented the lowest dispersion, ascribed to the weak Pd–ZrO2 interaction. The initial hydrogenation rate of styrene was the highest as compared to that of other components. The results suggest that hydrogenation of 1,7-octadiene to octane occurs via series reaction, with 1-octene as intermediate.