Biocrude production from rice husk: a refinery-compatible approach using light cycle oil and guaiacol

Biocrude can be produced through the direct thermal liquefaction of lignocellulosic biomass. This biocrude can then be further upgraded in conventional petroleum refineries to produce transportation fuels. This study presents a process for converting rice husk into biocrude using light cycle oil (LCO), a refinery stream, as the solvent while optimizing key liquefaction parameters in a batch autoclave reactor. Additionally, guaiacol was introduced into LCO to enhance biomass conversion and improve biocrude yield. Liquefaction experiments showed that LCO alone yielded ∼ 70 wt% liquid (biocrude) at 280 °C with a 1  min reaction time. The addition of guaiacol (50:50 by weight with LCO) significantly increased the liquid yield to ∼ 84 wt% at the same process conditions. The liquid yield further increased to 87 wt% when the reaction time increased to 20 mins. TGA analysis revealed that LCO alone primarily liquefied volatile matter, whereas the LCO-guaiacol mixture also facilitated fixed carbon liquefaction. Elemental analysis indicated a more than twofold increase in higher heating value and a 50 % reduction in oxygen content in the biocrude compared to the feed rice husk. Gel permeation chromatography (GPC) analysis confirmed the presence of very high-molecular-weight compounds. These findings highlight the potential of LCO-based solvent systems for efficient biomass liquefaction and refinery-compatible biofuel production.