Plasma-Assisted Synthesis and Mechanisms of Action of (Ni/Cu)/γ-Al2O3 Catalysts for Heavy Oil Upgrading

Abstract

In situ catalytic hydrocracking is a highly promising approach for improving heavy oil recovery. However, high reaction temperatures and prolonged processing times in the complex geological environments of oil reservoirs hinder the large-scale application of this method. In this study, dielectric barrier discharge (DBD) plasma was used to rapidly synthesize two catalysts, Ni/γ-Al₂O₃ and Ni-Cu/γ-Al₂O₃, for heavy oil upgrading. Changes in the physical properties (including density, viscosity, American Petroleum Institute (API) gravity) and chemical composition (including elemental composition, functional groups, and evolved gases) of the oil samples were analyzed prior and after upgrading. Based on these analyses, the mechanism of catalytic heavy oil upgrading was elucidated. Following catalytic upgrading, both catalysts achieved a viscosity reduction exceeding 53% within a short time. Notably, the catalyst with the nickel phase content of 1.28% exhibited a viscosity reduction ratio of 57.28% after a 10-min discharge treatment, while simultaneously achieving effective desulfurization. The results indicate that Ni/γ-Al₂O₃ catalysts are more favorable for the side-chain scission and ring-opening of saturated hydrocarbons and colloidal components, whereas Ni-Cu/γ-Al₂O₃ catalysts better suit for the hydrocracking and ring-opening of asphaltenes and aromatic hydrocarbons. This study provides an effective method for preparing high-performance catalysts for heavy oil upgrading using atmospheric pressure plasmas and offers insights into the catalytic effects of the heavy oil upgrading process.