A comprehensive understanding of synergetic effect and volatile interaction mechanisms during co-pyrolysis of rice husk and different rank coals

The techniques of co-utilization of biomass and coal are of wide concern due to the benefit of CO2 reduction. Although the co-pyrolysis process was extensively studied over the past few years, the effects of different rank coals on synergetic effect and volatile interaction mechanisms remained unclear. In this work, co-pyrolysis of rice husk (RH) and three different rank coals was comprehensively investigated to reveal the volatile release, gas product formation, changes of pore structure, pyrolysis kinetics and the synergetic effect. Co-pyrolysis of RH and coals always showed positive synergetic effect and could release more volatile species compared with individual pyrolysis. The extent of the synergetic effect in terms of volatile release and gas production was profoundly affected by different rank coals and increased remarkably as the blending changed from lignite to bituminous coal. A novel step-wise volatile release and interaction mechanism was proposed to explain the existence of synergetic effect and changes of pore structure in chars on the basis of the research results. In addition, kinetic studies showed that co-pyrolysis reactions of RH and coals were essentially controlled by chemical reaction mechanism from first to third order.