Catalytic Production of Glycerol Carbonate from Glycerol Using Sunflower Stalk-Derived Biochars: Fabrication, Characterization, and Performance Evaluation

Abstract

This study investigates the fabrication, characterization, and catalytic performance of innovative biochars derived from sunflower stalk cellulose, emphasizing their potential as sustainable catalysts in green chemistry applications. Biochars were produced via pyrolysis at 450, 550, and 650 °C, yielding samples labeled SSB1, SSB2, and SSB3, respectively. The production of glycerol carbonate through the transesterification of glycerol and dimethyl carbonate (DMC) was selected as a model reaction to evaluate the catalytic efficacy of these biochars. This approach aligns with the principles of green chemistry, addressing the effective utilization of biomass waste and excess glycerol while contributing to a circular economy. Characterization using FTIR, XRD, TGA, N₂ adsorption, and SEM-EDX analyses revealed significant effects of pyrolysis temperature on the physicochemical properties of the biochars, including yield, pH, surface area, and mineral content. Higher pyrolysis temperatures led to increased porosity, surface area, and mineral content, which enhanced catalytic performance. Under optimized conditions, the catalytic activity of SSB1, SSB2, and SSB3 was evaluated at a reaction temperature of 110 °C, a catalyst loading of 5 wt%, a reaction period of 20 min, and a DMC-to-glycerol molar ratio of 5:1. Among the biochars, SSB3 demonstrated the highest catalytic activity, achieving a glycerol conversion rate of 65.3% and glycerol carbonate selectivity of 53.4%. By linking the structure-performance relationship, this paper highlights the innovation and logic of utilizing biochars as effective catalysts in heterogeneous processes. The findings demonstrate the potential of biochars derived from sunflower stalk residues as sustainable alternatives to conventional catalysts, offering valuable insights into the development of functional materials for environmentally friendly chemical processes.