Abstract
This study investigates the production of hydrogen-rich syngas from the co-pyrolysis of lignocellulosic biomass and plastic solid waste through a comparative analysis of conventional pyrolysis and microwave-assisted pyrolysis (MAP). The primary objective is to assess the effectiveness of these thermochemical conversion routes in terms of product distribution, syngas composition, and hydrogen yield, with particular attention to the influence of feedstock composition and heating mechanisms. Laboratory-scale experiments were performed using different biomass-to-plastic ratios under inert conditions, ensuring controlled and comparable operating environments. The results demonstrate that MAP significantly enhances process performance compared to conventional pyrolysis. In particular, MAP promotes higher gas yields and improved syngas quality, with hydrogen concentrations increasing by up to 35% and carbon dioxide emissions decreasing by nearly 40%. The H2/CO ratio obtained under microwave conditions is notably higher, making the resulting syngas more suitable for downstream applications such as synthetic fuel and chemical production. These improvements are primarily attributed to the unique heating characteristics of MAP, including rapid and volumetric heat transfer, reduced temperature gradients, and the formation of localized high-temperature zones that intensify cracking, reforming, and water–gas shift reactions. Furthermore, the study highlights the presence of significant synergistic interactions during the co-pyrolysis of biomass and plastics. Hydrogen-rich volatiles released from plastics enhance the deoxygenation of biomass-derived compounds, while biomass contributes to improved heat distribution and reaction stability. These interactions result in non-linear increases in gas yield and hydrogen production, exceeding the expected additive behavior of individual feedstocks. In contrast, conventional pyrolysis exhibits slower heat transfer and less uniform temperature profiles, limiting both reaction efficiency and synergy between components. In addition to gas production, notable differences were observed in liquid and solid product distributions. MAP favors the formation of lighter hydrocarbons and reduces the generation of heavy wax fractions, improving the quality and usability of liquid products. Overall, the findings confirm that microwave-assisted pyrolysis is a promising and sustainable technology for the valorization of heterogeneous waste streams. By enhancing hydrogen production and improving syngas quality, MAP offers a viable pathway to support circular economy strategies and the transition toward low-carbon energy sy
