A review on role of process parameters on pyrolysis of biomass and plastics: Present scope and future opportunities in conventional and microwave-assisted pyrolysis technologies

Pyrolysis is one of the thermochemical conversion platforms for biomass and plastics into value-added product resources. The products formation significantly varied with feedstock composition, pyrolysis parameters, and heating source. Hence, the objectives of this review article are to understand the role of type of feedstock, heating rate, reaction temperature, residence time, feedstock particle size, and type of pyrolysis reactor. In addition, the upgradation of bio-oil using physical and catalytic approaches has been analyzed. Co-pyrolysis and catalytic co-pyrolysis which promote the product properties through synergy are also investigated. The role of microwave heating with the help of a susceptor to promote product synthesis is discussed. The metal oxide and zeolite catalysts' role in the formation mechanism of hydrocarbons and oxygenates are studied. For the future scope, the studies related to pyrolysis-combustion combination, microwave hybrid heating, and continuous catalytic co-pyrolysis are promising approaches. To this end, this review bridges the research gap in the domain of pyrolysis process parameters, and waste valorization using microwave-assisted pyrolysis, co-pyrolysis, and catalytic co-pyrolysis technologies. Moreover, this review would further provide the way for the current issues related to effective biomass and plastic waste utilization.