Microwave Pyrolysis Combined with CO<sub>2</sub> and Steam as Potential Approach for Waste Valorization

Abstract

Microwave pyrolysis combined with CO2 and steam environment is investigated for its feasibility as an alternative method for waste disposal. The combined use of CO2 and steam under microwave radiation created a synergistic effect in enhancing the thermal cracking of waste material during pyrolysis. The motivation of using CO2 is to replace N2 as carrier gas during pyrolysis as an effort to reduce the production of potent greenhouse gas. In this study, different types of microwave pyrolysis are performed including conventional, CO2 and CO2+steam on waste particleboard. It was found that the utilization of steam and CO2 affect the final pyrolytic products yield and composition. Incorporating CO2 and steam in microwave pyrolysis decreased the yield of char by 33% but increased the yield of bio-oil by 108%. Biochar obtained under CO2 showed well-developed and cleaner pore structure compared to biochar produced under N2. Our results demonstrate that the utilization of CO2 and steam in microwave pyrolysis shows great potential to convert wastes into value-added char and bio-oil with desirable properties.