Sulfur-free liquid fuel production via continuous catalytic hydrotreating of crude bio-oils from straws

• Published in: Journal of analytical and applied pyrolysis Vol. 179; p. 106460
• Main Authors: Liu, Sai-Si, Wang, Bing, Wang, Feng, Zhang, Feng, Fan, Yun-Chang, Duan, Pei-Gao
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2024
• Subjects: Catalytic hydrotreating; Crude bio-oil; Heavy oil; Light oil; N-hexane; Straw; Light oil; Catalytic hydrotreating; Heavy oil; Crude bio-oil; Straw; N-hexane
• ISSN: 0165-2370
• DOI: 10.1016/j.jaap.2024.106460

In this study, four crude bio-oils (CBOs) obtained from hydrothermal liquefaction of soybean straw (SS), peanut straw (PS), corn straw (CS) and rice straw (RS) were hydrotreated with various amounts of n-hexane. Then the obtained oil was separated into light oil (LO) and heavy oil (HO) by centrifugation. The LO yields increased from 53.89 to 59.15 wt% to 76.25–78.54 wt% when the mass ratio of n-hexane to CBO (wnH/wCBO) increased from 1:1–3:1. Despite containing the least asphaltenes, the hydrotreating of SS-CBO with n-hexane produced the lowest LO yield and the highest solid yield. The obtained LOs were mainly composed of saturated hydrocarbons, aromatics, and phenolic compounds, which showed obviously higher saturation and HHVs, also lower O and N contents than the corresponding HOs. Further hydrotreating of LOs resulted in significantly higher yields of upgraded light oils (ULO), falling in a narrower range of 92.04–93.48 wt%. The N and S content (26–503 ppm and <1 ppm, respectively) of the four ULOs all showed a sharp decline relative to the corresponding LOs. Saturated hydrocarbons (51.08–61.48%) and aromatics (31.98–43.00%) accounted for the vast majority of the identified compounds in the four ULOs, indicating the conversion of phenolic compounds in LOs to benzene and cyclohexane and their alkyl derivatives in the further hydrotreating process. •Four CBOs from HTL of straws were hydrotreated with addition of n-hexane.•Hydrotreated oil was separated into LO and HO by centrifugation.•Increasing wnH/wCBO was conducive to improving the yield and quality of LOs.•Further hydrotreating of LOs produced the ULOs with trace N and S atoms.•The four ULOs mainly contained saturated hydrocarbons and aromatics.