Microwave assisted fast pyrolysis of corn cob, corn stover, saw dust and rice straw: Experimental investigation on bio-oil yield and high heating values

In the present research, microwave assisted pyrolysis of biomass feed stocks such as corn cob, corn stover, saw dust and rice straw were carried out at constant microwave experimental conditions. GC-MS and bomb calorimeter analyses were carried out to identify the compounds present in bio-oil and higher heating values (HHV), respectively. Amongst all, corn cob gave the highest bio-oil yield up to 42.1% (wt) with a higher bio-oil HHV of 22.38 MJ/kg at the given experimental conditions. GC-MS analysis of corn cob based bio-oil showed the presence of ethyl ether, phenol, aliphatic hydrocarbons, furfural, furan derivatives and acids in major proportions. Higher HHV of bio-oil from corn cob was due to the presence of ethyl ether and 2-bromo-butane with a relative proportion of 15.63% and 4.60%, respectively. Addition of MgCl2 compound as a catalyst during corn cob pyrolysis yielded only in selective formation of furfural compound, and bio-oil yield in this case was found to be similar (40%, wt) to that of pyrolysis of corn cob in absence of catalyst. The results suggested that the corn cob can be used a potential biomass feed stock to produce bio-oil in major quantity, which can be further distilled to produce fuel oils.