Catalytic deoxygenation of carboxyl compounds in the hydrothermal liquefaction crude bio-oil via in-situ hydrogen supply by CuO-CeO2/γ-Al2O3 catalyst

Hydrothermal liquefaction (HTL) has drawn great attention as a potential method to produce bio-oil from biomass waste. However, bio-crude from HTL shows undesired high-oxygen content and needs further deoxygenation upgrading. Herein, stearic acids as a model carboxylic compounds in HTL bio-crude was...

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Bibliographic Details
Published in:Fuel (Guildford) 2022-06, Vol.317, p.123367, Article 123367
Main Authors: Du, Hongbiao, Yu, Qi, Liu, Guohua, Li, Jie, Zhang, Jinglai, Wang, Wenjia, Duan, Guoyi, Meng, Yanghao, Xie, Haijiao
Format: Article
Language:English
Subjects:
Catalytic deoxygenation
CuO-CeO2/γ-Al2O3
In-situ hydrogen supply
Stearic acid
Subcritical water
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Summary:Hydrothermal liquefaction (HTL) has drawn great attention as a potential method to produce bio-oil from biomass waste. However, bio-crude from HTL shows undesired high-oxygen content and needs further deoxygenation upgrading. Herein, stearic acids as a model carboxylic compounds in HTL bio-crude was employed to investigate catalytic deoxygenation performance. Results showed that (CuO)10-CeO2/γ-Al2O3 had the most superior catalytic deoxygenation performance for the stearic acids. The maximum stearic acid conversion rate (96.36%) and total hydrocarbon yield (88.79%) were obtained at 300°C, 12h, ratio of stearic acid to water 1:4. The main catalytic deoxygenation pathways were proposed: carbon monoxide generation (decarbonylation) – in-situ hydrogen generation (water–gas shift) – short-chain fatty acid generation (hydrogenolysis) – n-alkanes generation (decarboxylation, hydrodeoxygenation and hydrogenation). DFT calculation elucidated that CuO-CeO2 reduced the activation energy from 24.8kcalmol−1 (vacuum) to 15.0kcalmol−1 (catalytic). Thus, deoxygenation via CuO-CeO2/γ-Al2O3 would be an effective method for upgrading HTL bio-crude. [Display omitted] •Preparing CuO-CeO2/γ-Al2O3 catalysts and applying in bio-oil deoxygenation.•Obtaining stearic acid conversion rate of 96.36% total hydrocarbon yield of 88.79%.•Proposing a pathway of catalytic deoxygenation via CuO-CeO2/γ-Al2O3 catalyst.•Verifying the mechanism of CO generation reaction over CuO-CeO2 catalyst by DFT.
ISSN:0016-2361
1873-7153
DOI:10.1016/j.fuel.2022.123367