Production and Optimization of Hydroxy and Methyl Phenolic Compounds Through Microwave-Assisted Catalytic Hydrogenolysis from Lignin Valorization

Abstract

The phenol-based antioxidants as free radical scavengers are expected to continue increasing as additives in industries. As an antioxidant, lignin has low oxidative stability in pure solid form, so stabilization is needed to produce lignin-based antioxidants. This research focuses on the valorization of alkaline lignin by hydrogenolysis using a Pt/C catalyst and formic acid as a hydrogen donor. Three treatment variables, namely the amount of formic acid (FA), the amount of ethanol (EtOH), and radiation time (T), were observed for their contribution to the three responses, namely the total phenol content (TPC), the degree of depolymerization (DD), and the IC₅₀ value of DPPH as an antioxidants activity. This study found that the best results were obtained at operating conditions FA, EtOH, and T 5 mL, 100 mL, 3 min in sequence, producing TPC, DD, and IC₅₀ worth 4792,055 mg/ L, 23.650%, and 35.860 mg/L, respectively. The results were optimized using the response surface methodology with the Design Expert 11 program with the optimized result being FA, EtOH, and T 10 mL, 100 mL, 3 min consecutively and resulted in TPC, DD, and IC₅₀ of 4987.12 mg/L, 26.451%, and 33.865 mg/L, respectively. The results of this study indicate that OPFEB is a source of lignin that has the potential to produce phenolic compounds, which are sources of renewable fine chemicals based on biomass.