Bioenergy carrier's production through decentralized intermediate pyrolysis from corn stover

Decentralized biomass valorization requires thermochemical systems capable of producing clean reformer gas alongside upgraded bio-oil and biochar; however, conventional gasification is hindered by tar formation, low energy density, and variable product quality, while fast pyrolysis yields corrosive, storage-unstable bio-oil and limited low-calorific-value reformer gas. To overcome these challenges, this study evaluates pelletized corn stover using integrated intermediate pyrolysis and biochar-mediated reforming at systematically varied reactor/reformer temperatures (400-500/500-675°C) in the TCR-2 unit to produce clean reformer gas and upgraded bio-oil. Corn stover feedstock, with its high volatile content (66.07 wt%) and heating value of 16.84 MJ/kg, was found to support efficient devolatilization. As reforming temperature increased, the bio-oil became progressively upgraded; oxygen content dropped from 40.40 to 9.88 wt%, the total acid number decreased from 117.51 to 47.51 mg KOH/g, and its heating value rose from 29.44 to 37.52 MJ/kg, reflecting substantial deoxygenation and aromatic enrichment. Biochar also evolved with temperature, showing lower volatile matter (8.96-5.55 wt%), higher fixed carbon (43.66-58.77 wt%), and greater stability, enhancing its suitability for carbon storage and soil amendment. Reformer gas quality improved significantly, with H 2 concentration reaching 58.41 mol% and the heating value increasing to 14.23 MJ Nm 3 . Cold gas efficiency (CGE) rose from 27 to 55% across the temperature range, while carbon conversion efficiency increased from 18.82 to 30% before slightly declining at the highest temperature. Overall, the two-stage intermediate pyrolysis system produced H 2 -rich, tar-free reformer gas, upgraded bio-oil, and stable biochar with competitive CGE (41-54%), supporting its suitability for decentralized biomass valorization.