Insights into the synergetic effect for co-pyrolysis of oil sands and biomass using microwave irradiation

Microwave-assisted co-pyrolysis of oil sands and biomass (sawdust) was carried out for the first time to investigate the synergistic effect under microwave irradiation. In the co-pyrolysis process, the pyrolysis residues of sawdust serve as the effective microwave absorber to enable the improved thermal decomposition of oil sands compared with the case by the conventional thermal treatment. Effects of co-pyrolysis temperature, blending ratio, and feedstock-to-microwave absorber ratio on the product distribution were examined. Compared with conventional (CV) co-pyrolysis, a synergetic effect, in terms of 10.9 wt % higher gas yield and 8.3 wt % lower liquid yield, was manifested during microwave (MW) co-pyrolysis. Biomass added to the feedstock promoted the generation of compounds with molecular weight > 800 Da in the liquid products. MW radiation promoted 24.5 % higher aromatic hydrocarbons on average, but 19.2 % fewer phenols in MW-generated oils, which are more desirable as value-added chemicals. Furthermore, chars produced by MW performed more porotic, contributing to positive recycling as absorbing materials. The thermochemical conversion of biomass with oil sand revealed that MW heating is a simple, effective, and alternative solution to increase the energy efficiency of co-pyrolysis process, maximizing the use of resources.