Effect of microwave pretreatment on pyrolysis of crude glycerol–olive kernel alternative fuels

• Microwave activation investigated as pretreatment of glycerol–biomass mixtures.
• Microwave irradiation was performed for a 25 wt% crude glycerol–olive kernel fuel.
• Pyrolysis of microwave-activated fuel showed increased liquids at 500 °C.
• Pyrolysis at 720 °C gave a high yield of syngas (84.9 wt%).
• Microwave activation had no significant effect on char yields and characteristics.

Pyrolysis is considered to be a sustainable energy technology and is practiced widely in waste management. In this study, three issues were explored: (a) the implication of crude glycerol addition to lignocellulosic biomass in pyrolysis, (b) the effect of microwave pretreatment on the pyrolysis product yields and (c) study of pyrolysis parameters and assessment of products quality. Characterization of the above glycerol–biomass mixtures along with pyrolysis products was performed by ICP–OES, SEM, EDX and GC techniques. It was resulted that higher liquid yield (max 59.53% v/v) obtained by pyrolysis of pretreated mixtures at 500 °C, compared to pyrolysis yields of non-pretreated mixtures, due to the prevalence of recombination reactions in pyrolysis of the microwave-pretreated mixtures. The gas produced from the microwave pretreated feedstock-based pyrolysis showed an enriched syngas (H2 + CO) concentration (84.9% v/v), compared to the non-microwave pretreated samples (79.1% v/v), at 720 °C. No significant effect, either on the char yields or on the char structural characteristics were observed. Consequently, microwave pretreatment before pyrolysis, can serve as a potential pretreatment for enhanced production of fuels via post-pyrolysis.

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