Effects of microwave and plastic content on the sulfur migration during co–pyrolysis of biomass and plastic

Abstract

In order to reduce the risks of sulfur-containing contaminants present in biofuels, the effects of microwave and content of hydrogen donor on the cracking of C–S bonds and the migration of sulfur were studied by co–pyrolysis of biomass and plastic. The synergistic mechanism of microwave and hydrogen donor was explored from the perspective of deducing the evolution of sulfur–containing compounds based on microwave thermogravimetric analysis. By combining temperature–weight curves, it was found that microwaves and hydrogen radicals promoted the cracking of sulfur–containing compounds and increased the mass loss of biomass during pyrolysis. The mixing ratio of hydrogen donor (plastic) was the key parameter resulting in the removal of sulfur from oil. By adjusting the mixing ratio, the yield of co–pyrolyzed oil was three times higher than that of cow dung pyrolysis alone and the relative removal rate of sulfur reached 73.67%. The relative content of sulfur in the oil was reduced by 73.77% due to the escape of sulfur–containing gases (H2S, COS and C2H5SH) and the formation of sulfate crystals in the char. Microwave selectively heated sulfur–containing organics and hydrogen radicals stimulated the breaking of C–S bonds, which improved the cracking efficiency of the oil. This breaking will provide a theoretical and technological reference for the environmentally friendly treatment of biomass and biofuels.