A review on lignocellulosic biomass waste into biochar-derived catalyst: Current conversion techniques, sustainable applications and challenges

Biochar, is one of the thermo-chemical conversion products generated from lignocellulosic biomass via conversion techniques including gasification, pyrolysis, torrefaction, hydrothermal liquefaction, and carbonization. Modified biochar has received great attention in the catalytic process due to the great physicochemical properties and catalytic activities. Hence, this work presents a review on the current conversion techniques in transforming lignocellulosic biomass waste into biochar, which mainly focuses on gasification and pyrolysis. Additionally, comparison on the conversion techniques in terms of benefits, drawbacks, and limitations such as environmental factor, costing and safety aspect are discussed. Moreover, this review highlights the modification techniques of biochar and compares the physical properties of the pristine and modified biochar. Likewise, the biochar characterization techniques such as FT-IR, XRD, TGA, and TPD are reviewed. Subsequently, the applications of biochar-derived catalyst are studied in the production of biodiesel, syngas, and biogas, as well as NOx reduction. Besides that, the performance of biochar-derived catalyst and conventional catalyst are compared. The analysis showed that both catalysts give comparable catalytic activities. Hence, the biochar-derived catalyst generated from lignocellulosic biomass waste can be an alternative heterogeneous catalyst to replace conventional catalyst if more in-depth researches are performed. Lastly, the current challenges and limitations are discussed, and the impacts of the fourth industrial revolution on the biomass industry are highlighted.