CO2-mediated pyrolysis for syngas generation from wood-plastic composite waste

Abstract

Wood-plastic composites (WPCs) are extensively utilized in construction, furniture, and outdoor applications due to their superior physicochemical properties. However, their low biodegradability presents a critical challenge for waste management. This study explores upcycling WPC waste into syngas via CO2-mediated pyrolysis. CO2 serves as reaction medium, enhancing thermal decomposition and partial oxidation of volatile matters (VMs) generated from pyrolysis of WPCs to form carbon monoxide (CO) through homogeneous reactions. To further optimize the role of CO2, a multi-stage pyrolysis operating isothermally at 700 °C was employed. In this configuration, the reactivity of CO2 was more pronounced at lower temperatures than that during single-stage pyrolysis, indicating that the additional thermal energy accelerated CO2-induced reactions. The introduction of a nickel-based catalyst accelerated the CO2-induced homogeneous reactions by facilitating the adsorption and reaction of CO2 with VMs during pyrolysis. Thus, utilizing CO2 as a reaction medium in the catalytic pyrolysis process represents a strategic pathway for the upcycling of WPC waste.