New formulations of oxoanion promoted zirconia catalysts for the upgrade of heavy paraffinic cuts

The effect of the addition of Pd on the catalytic activity and selectivity of Pt/WZ for isomerization-cracking of linear heavy paraffins was assessed using n-octane as model feedstock. A focus was put on obtaining an optimized catalyst with good isomerization activity and minimum cracking in order to get a product with improved RON and a minimum production of light gases. The results were compared with those obtained with a Pt/SO42−–ZrO2 (Pt/SZ) catalyst used as reference. The catalysts were further characterized by means of N2 adsorption, X-ray diffraction, temperature programmed desorption of probe molecules and cyclohexane dehydrogenation. The n-C8 results indicate that the simultaneous addition of Pt and Pd to a WZ catalyst produces a decrease of the total acidity and an increase of the de/hydrogenating capacity as compared to the monometallic Pt/WZ and Pd/WZ catalysts. This effects allows the tuning of the metal and acid functions of the catalysts, optimizing the balance for the mild isomerization-cracking reaction. In this sense, high values of RON gain were measured in the product and a high C5+ liquid yield was obtained.