Hydro-deoxygenation of pyrolytic oil derived from pyrolysis of lignocellulosic biomass: A review

The rapid depletion of fossil fuels and environmental concerns have led researchers to explore alternative sources of energy. Pyrolytic oil derived from biomass is considered to be a potential alternative to fossil fuels, but it lacks certain physicochemical properties that make it unsuitable to be used as fuel. For instance, the high oxygen content in the pyrolytic oil exhibits chemical instability, the tendency to polymerize, and low energy density compared to traditional fuels. The hydrodeoxygenation (HDO) method is a viable technique to enhance the desirable characteristics of pyrolytic oil for commercial applications. This method has the disadvantage of catalyst deactivation owed due to coking, and its extent depends on the nature of oxy-compounds, catalyst type, and experimental conditions. However, by varying the experimental parameters such as catalyst acidity, temperature, pressure, solvent, and reaction time, the HDO product characteristics may be tailored to meet the specific requirements and applications. In this work, we have presented a comprehensive review of multiple alternatives to produce pyrolytic oil with essential fuel characteristics. The techno-economic analysis (TEA) and kinetic analysis of the pyrolytic oil were also elaborated. Overall, the review paper highlights the influence of process variables, kinetics investigation, reactor types and techno-economic analysis of HDO.