Evaluating sustainability of CO2-mediated pyrolysis of lignocellulose

Abstract

Despite the growing interest in biomass as a carbon–neutral resource, technical challenges have limited its comprehensive utilization. Pyrolysis has emerged as a promising method for reducing the carbon footprint by more effectively valorizing carbon in biomass. This study investigated the use of carbon dioxide (CO2) in the pyrolysis of pine cone (PC), a lignocellulosic biomass. Thermogravimetric analysis confirmed that lignin was the primary component of the PC. Characterization and quantification of the three pyrolytic products (syngas, biocrude, and biochar) revealed that CO2 enhanced CO production and the surface area of the biochar, thereby improving its CO2 adsorption capacity. Additional heat and a Ni catalyst further amplified CO2′s functionality. The sustainability of the proposed pyrolysis system was evaluated by calculating energy requirements of the pyrolysis processes and the net CO2 emissions. Catalytic pyrolysis under CO2 was the most effective, achieving a reduction of 3.34 g of CO2 per gram of PC.