Synthesis of SO4 2−/Zr-silicalite-1 zeolite catalysts for upgrading and visbreaking of heavy oil

Catalyst is crucially important to reduce the viscosity of heavy oil during the catalytic aquathermolysis. SO4 2−-modified ZrO2-based nanoparticle catalyst is a commonly used catalyst. But less acid sites and poor hydrothermal stability limited further improving its catalytic performance and practical application. In this study, the Zr-doped silicalite zeolite catalysts with large surface area were prepared as a support matrix, and SO4 2−-modified Zr-doped silicalite zeolite (denoted as SO4 2−/Zr-silicalite-1 zeolite) was used as a solid superacid catalyst to crack the heavy oil. A reference catalyst of SO4 2−/Zr-SiO2 nanoparticles (NPs) was also prepared, which has the same composition with the SO4 2−/Zr-silicalite-1 zeolite catalyst. Compared with the SO4 2−/Zr-SiO2 NP catalyst, the amount of acid sites for the SO4 2−/Zr-silicalite-1 zeolite catalyst is significantly increased and the viscosity reduction efficiency is also enhanced by 40%. More importantly, the SO4 2−/Zr-silicalite-1 zeolite catalyst exhibits a high hydrothermal stability. After catalytic aquathermolysis, the quality of the heavy oil was also ameliorated. The heavy resins and asphaltenes reduced, while the light saturated and aromatic hydrocarbon increased. The results suggest metal element-doped silicalite zeolite catalyst is a potential useful way to solving the less acid sites and poor hydrothermal stability for the SO4 2−-modified nanoparticle catalyst.