Influence of Density on Microwave Pyrolysis of Cellulose

Herein we present the influence of sample density on the microwave induced pyrolysis of crystalline cellulose, with heating rate, biochar and bio-oil yields investigated. This Letter demonstrates that sample density is a fundamental parameter influencing microwave-assisted biomass pyrolysis, with a direct impact on heating rate, the speed of volatiles diffusion through the sample matrix and distribution of products. Of significant interest was that the maximum heating rate and bio-oil yield corresponded to an optimum sample density as a result of heat and mass transfer effects. Increase in density above this value stimulated a rise in biochar yield. The increased understanding of the mechanisms influenced by sample density in a microwave field gives increased ability for users to produce bio-oil or biochar, giving rise to improved microwave-based biorefineries for future energy and chemical needs.This work is financially supported by EPSRC for research grant no. EP/K014773/1, the Industrial Biotechnology Catalyst (Innovate UK, BBSRC, EPSRC) to support the translation, development and commercialization of innovative industrial Biotechnology processes (EP/N013522/1). P.S.S. also gratefully acknowledges the Spanish Ministry Economy and Competitivity (MINECO) for a Ramón y Cajal senior research fellowship (RYC-2014-16759) and a proyecto de I+D+I para jóvenes investigadores (MAT2014-59674-JIN)Peer Reviewe