Plasma and Ball Milling Pretreatment for Enhanced Production of Levoglucosenone from Catalytic Conversion of Cellulose over a Sulfonated Carbon Catalyst

Levoglucosenone (LGO) holds great promise for sustainable chemical production. This study demonstrates the enhanced production of LGO from cellulose via solvothermal catalysis over sulfonated carbon (SC), enabled by tailored pretreatments. Air plasma modification of the catalyst introduced nitrogen doping and additional oxygen-containing groups (−COOH, −OH), which facilitated cellulose adsorption and promoted glycosidic bond cleavage. This boosted the LGO yield to 22.5 wt %, a significant increase from the 16.4 wt % obtained with the untreated system. Alternatively, ball milling pretreatment of cellulose dramatically reduced its crystallinity and particle size, achieving an even higher LGO yield to 24.7 wt % (31.8% mole yield) at 200 °C for 4 h with a cellulose to catalyst mass ratio of 3, which increased by 50% compared to the untreated system. Interestingly, applying both plasma and ball milling pretreatments simultaneously did not yield a synergistic effect, indicating that the observed enhancements are predominantly governed by single-mode modifications. Furthermore, the sulfonated carbon catalyst exhibited excellent stability, retaining high activity over five consecutive cycles. This work provides efficient pretreatment strategies and insight into their distinct roles, highlighting a practical pathway for valorizing cellulose into high-value chemicals.