Electric-field-induced electrochemical transformation of shale oil for in situ upgrading: Molecular evolution, interfacial regulation and hydrogen generation

Abstract

Simultaneous shale-oil upgrading, hydrogen evolution, and interfacial regulation through electrically induced electrochemical transformation represents a potential strategy for enhancing hydrocarbon resource utilization. In this study, a shale oil–water system was subjected to direct-current stimulation at different applied voltages, and the electrical and thermal responses, gaseous products, oil composition, molecular structure, aqueous-phase chemistry, and oil–water interfacial properties were systematically characterized to elucidate the transformation behavior and underlying physicochemical processes. At 40 V, the current reached 0.92 A and the system temperature increased to 78 °C, demonstrating pronounced electrical and Joule-heating responses. Gas analysis revealed the evolution of H 2 together with C 1 –C 6 gaseous hydrocarbons, while the liquid-phase carbon-number distribution showed enrichment of intermediate C 11 –C 24 hydrocarbons, indicating redistribution and partial transformation of hydrocarbon components. Group-composition and Fourier-transform infrared (FTIR) further revealed a decrease in saturated hydrocarbons, enrichment of resin-like polar components, and changes in aliphatic and oxygen-containing structures, collectively supporting the molecular restructuring and functionalization of shale oil during electrical treatment. Concurrently, the aqueous-phase pH increased from 6.0 to 14.0, while the oil–water interfacial tension decreased by 78.74%, from 11.95 to 2.54 mN m⁻ 1 , demonstrating substantial electrochemically induced interfacial regulation. This work establishes an experimental connection among hydrocarbon molecular evolution, hydrogen evolution, aqueous-phase chemistry, and interfacial regulation within a unified shale oil–water electrochemical system, providing a new perspective for electrically assisted in situ hydrocarbon upgrading and enhanced resource utilization.