Progress and challenges in sustainable pyrolysis technology: Reactors, feedstocks and products

Abstract

Pyrolysis is a thermo-chemical decomposition process that converts organic or inorganic materials into solid, liquid and gaseous products. The pyrolysis process involves multiple complex chemical reactions, and the derived products are highly dependent on the pyrolysis operating parameters and type of feedstock. In the present review, progress on the state-of-the-art pyrolysis technology, feedstock and properties of the end products are thoroughly reviewed. The potential application of the pyrolysis products in the industries is discussed: solid leftover can be upgraded and used as a bio-adsorbant, soil amendment, fertilizer or solid fuel, pyrolysis liquid can be used as a bio-chemical source or upgraded into liquid fuel, gaseous products can be used as recirculating gas for the pyrolysis environment or burnt as fuel for heat and power generation. Despite the potential of pyrolysis in processing agricultural or industrial wastes, studies regarding the economic feasibility and environment sustainability of scaled-up pyrolysis plant are scarce. A comprehensive overview on the type of pyrolysis reactor technology, potential feedstock and the properties of the derived products is presented. Further, the sustainability of the technology is assessed from the aspects of energy balance, environment and economics. In spite of the potential benefits to the environment and recovery of valuable products, there are several challenges that need to be addressed to ensure the sustainability and commercialibility of the pyrolysis technologies.