Catalytic hydrothermal carbonization of wet organic solid waste: A review

Oraléou Sangué Djandja; Rock Keey Liew; Chang Liu; Jianhao Liang; Haojun Yuan; Weixin He; Yifei Feng; Bachirou Guene Lougou; Pei-Gao Duan; Xuebin Lu; Shimin Kang

doi:10.1016/j.scitotenv.2023.162119

Catalytic hydrothermal carbonization of wet organic solid waste: A review

Sci Total Environ. 2023 May 15:873:162119. doi: 10.1016/j.scitotenv.2023.162119. Epub 2023 Feb 10.

Authors

Affiliations

¹ Engineering Research Center of None-food Biomass Efficient Pyrolysis and Utilization Technology of Guangdong Higher Education Institutes, Guangdong Provincial Key Laboratory of Distributed Energy Systems, Dongguan University of Technology, Dongguan, Guangdong, 523808, China; School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, PR China; Organization of African Academic Doctors (OAAD), Off Kamiti Road, P. O. Box 25305000100, Nairobi, Kenya.
² Pyrolysis Technology Research Group, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia; NV WESTERN PLT, No. 208B, Second Floor, Macalister Road, 10400 Georgetown, Penang, Malaysia.
³ Shaanxi Key Laboratory of Energy Chemical Process Intensification, School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, PR China.
⁴ Engineering Research Center of None-food Biomass Efficient Pyrolysis and Utilization Technology of Guangdong Higher Education Institutes, Guangdong Provincial Key Laboratory of Distributed Energy Systems, Dongguan University of Technology, Dongguan, Guangdong, 523808, China.
⁵ School of Energy Science and Engineering, Harbin Institute of Technology, 92 West Dazhi Street, Harbin 150001, China.
⁶ School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, PR China.
⁷ Engineering Research Center of None-food Biomass Efficient Pyrolysis and Utilization Technology of Guangdong Higher Education Institutes, Guangdong Provincial Key Laboratory of Distributed Energy Systems, Dongguan University of Technology, Dongguan, Guangdong, 523808, China. Electronic address: kangshimin@dgut.edu.cn.

PMID: 36773913
DOI: 10.1016/j.scitotenv.2023.162119

Abstract

Hydrothermal carbonization has gained attention in converting wet organic solid waste into hydrochar with many applications such as solid fuel, energy storage material precursor, fertilizer or soil conditioner. Recently, various catalysts such as organic and inorganic catalysts are employed to guide the properties of the hydrochar. This review presents a summarize and a critical discussion on types of catalysts, process parameters and catalytic mechanisms. The catalytic impact of carboxylic acids is related to their acidity level and the number of carboxylic groups. The catalysis level with strong mineral acids is likely related to the number of hydronium ions liberated from their hydrolysis. The impact of inorganic salts is determined by the Lewis acidity of the cation. The metallic ions in metallic salts may incorporate into the hydrochar and increase the ash of the hydrochar. The selection of catalysts for various applications of hydrochars and the environmental and the techno-economic aspects of the process are also presented. Although some catalysts might enhance the characteristics of hydrochar for various applications, these catalysts may also result in considerable carbon loss, particularly in the case of organic acid catalysts, which may potentially ruin the overall advantage of the process. Overall, depending on the expected application of the hydrochar, the type of catalyst and the amount of catalyst loading requires careful consideration. Some recommendations are made for future investigations to improve laboratory-scale process comprehension and understanding of pathways as well as to encourage widespread industrial adoption.

Keywords: Biomass; Energy; Hydrochar; Reaction mechanism; Thermochemical treatment; Waste-to-resources.

Publication types

Review