Influence of alkali catalysts on product yield and Si-containing products from hydrothermal liquefaction of corn stover

This study investigated the effects of different alkali catalysts (K₂CO₃, KOH, NaOH, and Na₂CO₃) on the yield and composition of biocrude oil and aqueous products obtained from hydrothermal liquefaction (HTL) of corn stover. HTL was performed in a laboratory-scale tubular reactor at 320 °C for 90 min and catalyst loading of 5.0 and 7.5 % (by weight of biomass). The composition of the biocrude oil and aqueous products was determined using GC-MS. Results revealed that hydroxide catalysts are more effective than carbonate catalysts in increasing biocrude oil yield. Notably, NaOH achieved a high conversion rate of 92-94 % daf (dry and ash-free basis), significantly surpassing the uncatalyzed HTL (69.4 % daf). The highest biocrude oil yield of 22.12-22.57 % daf was obtained using KOH. Si-containing compounds (e.g., silanes and siloxanes) were identified as the most abundant components in the biocrude oil, suggesting potential for further exploration in producing platform chemicals from these compounds.