Critical Analysis of Process Parameters for Bio-oil Production via Pyrolysis of Biomass: A Review

A.   P. Singh   Chouhan; A.   K.   Sarma

Abstract

Pyrolysis is the destructive distillation of the biomass at high temperature in absence of oxygen. Depending upon the heating rate and residence time of vapors during the pyrolysis process, it is classified into slow and fast pyrolysis. Slow pyrolysis generally produces less amount of bio-oil and higher amount of charcoal than fast pyrolysis. This is attributed to the longer residence time for slow pyrolysis. A critical review on this subject has been elucidated in this article. It implies that the different constituents of biomass i.e. cellulose, hemicellulose and lignin are degraded at different temperature ranges. Moreover, the elemental composition of the initial biomass found to govern the bio-oil production such as C, H, N and O which are primarily dependent upon the types of waste materials. Thus, actual bio-oil production potential depends on feed materials, type of reactor, operating temperature, heating rate, volatile matter, carbon content, sweep gas flow rate and residence time. Bio-oil chemical compositions are also affected by the operating temperatures during the pyrolysis of biomass. The kinetic study of different biomass materials and methods applied to evaluate activation energy, accordingly, are also reviewed and listed. In this review article, a critical analysis of the factors upon which bio-oil production depends are emphasized with appropriate citation. It also covers an extensive literature review to ascertain the effect of operating parameters on pyrolysis of biomass. This article also focuses about the estimated waste biomass potential in India. Efforts are also made to highlight the estimated potential of biomass sources for bio-oil production in Indian perspective. An estimate shows that approximately 7% of petroleum crude oil can be compensated with the bio-oil if all the waste biomasses available in the country were properly used.

Keywords: Waste biomass, bio-oil, pyrolysis, cellulose, hemicellulose, lignin, sweep gas, heating rate, India’s potential.