Solketal Production Using Eco-Friendly Reduced Graphene Oxide as the Catalyst

Abstract

In this study, two materials based on reduced graphene oxide (rGOH or rGOE) were synthesized through the Hummers methodology and a more sustainable electrochemical method. These materials were extensively characterized and tested as catalysts in solketal production. Both rGOH and rGOE demonstrated significant catalytic activity, achieving 66.18% and 63.97% conversion rates, respectively. The catalytic activity of the synthesized materials was 30 times more efficient than the homogeneous catalyst p-Toluenesulfonic acid. Pseudo-homogeneous and heterogeneous kinetic models were employed to gain further insights into the glycerol ketalization reaction with acetone. The pseudo-homogeneous model suggested that the direct rate constant was lower than the reverse rate constant. In this sense, a reversible bimolecular reaction was proposed. The heterogeneous kinetic models revealed that in the Langmuir-Hinshelwood-Hougen-Watson mechanism, the controlling step of the reaction was the glycerol-acetone surface reaction on the catalyst. In contrast, in the Eley-Rideal mechanism, the reaction was controlled by the adsorbed glycerol on the reaction surface reacting with the available acetone in the bulk fluid. In the reusability tests, the rGOE catalyst demonstrated superior performance over five consecutive cycles, maintaining the highest activity without needing post-reaction washing or treatment.