Thermochemical Conversion of Lignocellulosic Biomass into Mass-Producible Fuels: Emerging Technology Progress and Environmental Sustainability Evaluation

Lignocellulosic biomassis increasingly recognized as a carbon-neutralresource rather than an organic solid waste nowadays. It can be usedfor the production of various value-added chemicals and biofuels likebio-oil. However, the undesirable properties of bio-oil such as chemicalinstability, low heating value, high corrosivity, and high viscosityare greatly restricting the utilization of bio-oil as a drop-in fuel.As a consequence, bio-oil should be upgraded. Recently, several emergingmethods, such as electrocatalytic hydrogenation, atmospheric distillation,and plasma-assisted catalysis, have been developed for improving thebio-oil quality under mild conditions. Here, we overview the new knowledgeon the molecular structure of lignocellulosic biomass gained overthe past years and discuss the future challenges and opportunitiesfor further advances of the bio-oil production and upgrading fromlignocellulosic biomass. The development of sustainable biomass resourcerecycle systems with improved efficiency and minimized environmentalimpacts is analyzed in details. Also, their environmental impactsand sustainability are evaluated. Lastly, the remaining knowledgegaps are identified, and the future research needs that may lead tomassive production of biofuels from lignocellulosic biomass are highlighted.