Effect of biochar-based nano‑nickel catalyst on heavy crude oil upgrading and oil shale pyrolysis

This study involved the preparation of a biochar-based nano‑nickel (Ni/C) catalyst, achieving high dispersion of the nano‑nickel catalyst by utilizing waste coffee grounds as a biochar carrier. The Ni/C catalyst demonstrated commendable catalytic performance in heavy crude oil upgrading. Compared with the control group, the viscosity reduction rate of heavy crude oil was increased by 21.53 %, and the contents of heteroatoms, resins and asphaltenes were effectively reduced, while increasing the ratio of C 2 -C 4 and saturated components. Additionally, the catalyst reduced the initial decomposition temperature and the maximum thermal decomposition rate temperature of oil shale by 10 °C and 8 °C, respectively. The results of DFT calculations also indicated that the catalyst effectively improved the pyrolysis activity of kerogen molecules. Noteworthy characteristics of the catalyst include its low cost, simple operation, and high catalytic activity, making it highly promising for broad applications in unconventional petroleum energy exploitation. Table of Contents: The high dispersion of the nano‑nickel catalyst was achieved by using waste coffee grounds as a biochar carrier. The Ni/C catalyst exhibits excellent catalytic performance in heavy crude oil upgrading and oil shale pyrolysis at low reaction temperatures. The catalyst features low cost, ease of operation, and high catalytic activity, making it a promising option for broad applications in unconventional petroleum energy development. • Ni/C catalyst was synthesized from low-cost waste coffee grounds. • The catalyst increased the viscosity reduction rate of heavy crude oil by 21.53 %. • The catalyst reduced the pyrolysis reaction temperature of oil shale.