Investigation of Cotton Stalk-Derived Hydrothermal Bio-Oil: Effects of Mineral Acid/Base and Oxide Additions

Libo Zhang (), Jianing Wang, Hui Ming, Hanjun Hu, Xintong Dou, Yepeng Xiao, Lihua Cheng and Zhun Hu ()
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Libo Zhang: School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an 710049, China
Jianing Wang: Guangdong Provincial Engineering & Technology Center for Corrosion and Safety in Petrochemical Industry, School of Chemical Engineering, Guangdong University of Petrochemical Technology, Maoming 525000, China
Hui Ming: State Key Laboratory of Heavy Oil Processing, College of Engineering, China University of Petroleum-Beijing at Karamay, Karamay 834000, China
Hanjun Hu: School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an 710049, China
Xintong Dou: State Key Laboratory of Heavy Oil Processing, College of Engineering, China University of Petroleum-Beijing at Karamay, Karamay 834000, China
Yepeng Xiao: Guangdong Provincial Engineering & Technology Center for Corrosion and Safety in Petrochemical Industry, School of Chemical Engineering, Guangdong University of Petrochemical Technology, Maoming 525000, China
Lihua Cheng: Guangdong Provincial Engineering & Technology Center for Corrosion and Safety in Petrochemical Industry, School of Chemical Engineering, Guangdong University of Petrochemical Technology, Maoming 525000, China
Zhun Hu: School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an 710049, China

Energies, 2024, vol. 17, issue 19, 1-16

Abstract: Hydrothermal liquefaction technology (HTL) is a promising thermochemical method to convert biomass into novel liquid fuels. The introduction of oxides and inorganic acids/bases during the hydrothermal process significantly impacts the yield and composition of bio-oil. However, systematic research on their effects, especially at lower temperatures, remains limited. In this paper, we examine the effects of acidity and alkalinity on cotton stalk hydrothermal bio-oil by introducing homogeneous acids and bases. Given the operational challenges associated with product separation using homogeneous acids and bases, this paper further delves into the influence of heterogeneous oxide catalysts (possessing varying degrees of acidity and alkalinity, as well as distinct microstructures and pore architectures) on the production of cotton stalk hydrothermal bio-oil. The effects of nanoscale oxides (CeO 2 , TiO 2 , ZnO, Al 2 O 3 , MgO and SiO 2 ) and homogeneous acid–base catalysts (NaOH, K 2 CO 3 , Na 2 CO 3 , KOH, HCl, H 2 SO 4 , HNO 3 ) on the quality of cotton stalk bio-oil under moderate hydrothermal conditions (220 °C, 4 h) were investigated. Characterization techniques including infrared spectroscopy, thermogravimetric analysis, elemental analysis, and GC-MS were employed. The results revealed that CeO 2 and NaOH achieved the highest bio-oil yield due to Ce 3+ /Ce 4+ redox reactions, OH-LCC disruption, and ionic swelling effects. Nano-oxides enhanced the formation of compounds like N-ethyl formamide and aliphatic aldehydes while suppressing nitrogen-containing aromatics. The total pore volume and average pore width of oxides negatively correlated with their catalytic efficiency. CeO 2 with low pore volume and width exhibited the highest energy recovery. The energy recovery of cotton stalk bio-oil was influenced by both acid and base sites on the oxide surface, with a higher weak base content favoring higher yields and a higher weak acid content inhibiting them. The findings of this research are expected to provide valuable insights into the energy utilization of agricultural solid waste, such as cotton stalks, as well as to inform the design and development of highly efficient catalysts.

Keywords: nanometer oxide; catalytic hydrothermal liquefaction; cotton stalk; bio-oil; energy recovery rate (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2024
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