Systematic Review of Hydrogen Production via Co-Pyrolysis of Lignocellulosic Biomass and Plastic Waste

Abstract

This systematic review examines hydrogen production via co-pyrolysis of lignocellulosic biomass and plastic waste, a promising technology for mitigating the environmental impact of these residues. Using the PRISMA methodology, 50 articles published between 2015 and 2025 were selected and analyzed to identify synergistic effects, reactor configurations, and optimal operating parameters. Co-pyrolysis exploits synergistic interactions in which plastics act as hydrogen donors, increasing the effective hydrogen index (H/C_eff) of biomass, which is inherently deficient in this element. The results indicate that hydrogen yield is maximized within a temperature range of 600 °C to 850 °C, promoting secondary cracking and reforming reactions. The use of catalysts, primarily nickel-based (Ni), zeolites (HZSM-5), and calcium oxide (CaO), is crucial for reducing activation energy and minimizing tar formation. Hydrogen yields of up to 115.33 mmol H2/g and gas-phase concentrations of up to 86% v/v have been reported, depending on the biomass-to-plastic ratio (commonly 1:1 or 3:1). The most commonly employed reactor types are fixed-bed and fluidized-bed systems. Critical gaps are identified in studies on agro-industrial fruit seeds (such as avocado and mango) and on the behavior of real, contaminated plastic mixtures. It is concluded that co-pyrolysis represents a viable pathway for the circular economy; however, further research is required on predictive modeling and industrial-scale implementation to enable global deployment.