Catalytic Hydrothermal Gasification of Corn Steep Liquor over Raney Nickel: Product Characterization and Kinetic Analysis

Catalytic hydrothermal gasification (CHG) of corn steep liquor (CSL) was studied in a continuous fixed-bed reactor to clarify its gasification behavior, reaction mechanism, and kinetics for process scale-up and catalyst development. After screening commercial catalysts, Raney nickel was selected. Temperature was found to be the dominant factor: increasing it from 280 to 360 °C raised the carbon gasification efficiency from 42.67 to 93.47%. Under 320 °C, 8.50 min, and 5.28 wt %, the methane yield reached 4.86 mol/kg. Reaction analysis indicated that lignin, proteins, and carbohydrates were converted into intermediates such as phenols, amines, nitrogen-containing compounds, and polycyclic aromatic hydrocarbons (PAHs), which then decomposed or polymerized. Kinetic results showed that PAH decomposition is the rate-controlling step, with high activation energies of 325.33–384.49 kJ/mol, providing guidance for CHG optimization and scale-up.