Synergistic enhancement of product quality through fast co-pyrolysis of acid pretreated biomass and waste plastic

With the increasing global production of plastics, co-pyrolyzing biomass and waste plastics has emerged as a promising way to improve the quality of pyrolysis products. In the present study, the possibility of enhancing the synergistic interactions between biomass and plastics was explored by co-pyrolyzing acid pretreated corn stover (CS) and polyethylene (PE) in the presence or absence of zeolite catalyst. During non-catalytic co-pyrolysis, the use of acid-pretreated CS was found to synergistically reduce char yield and increase both the yield and quality of CS-derived pyrolysis oil. When acid-pretreated CS was catalytically co-pyrolyzed with PE, the yields of aromatic hydrocarbons and alkene increased whereas the yields of solid residue and carbon oxides decreased to a much greater extent than co-pyrolyzing raw CS and PE. The synergistic effect was least significant with raw CS and PE, suggesting the presence of alkali and alkaline earth metals (AAEMs) in the biomass hinder the occurrence of synergy. The positive synergy was strongest with acid-infused CS and PE. When acid-infused CS was co-pyrolyzed with PE, not only did the yield of phenolic monomers increase, but levoglucosan yield also increased significantly. During catalytic co-pyrolysis, acid-infused CS and PE also produced the highest yield of aromatic hydrocarbon and lowest yield of solid residue. This study also showed that co-pyrolysis with PE mitigates char agglomeration associated with pyrolyzing CS alone.