Microwave-assisted depolymerization of lignin with synergic alkali catalysts and a transition metal catalyst in the aqueous system. Issue 8 (12th May 2022)

• Record Type: Journal Article
• Authors: Li, Heyu; Huang, Yingfang; Lin, Xiuhua; Liu, Yifan; Lv, Yuancai; Liu, Minghua; Zhang, Yuming
• Is Part Of: Reaction chemistry & engineering. Volume 7:Issue 8(2022)
• Page Start: 1750
• Page End: 1761
• Publication Date: 2022-05-12
• Subjects: Reaction mechanisms (Chemistry) -- Periodicals; Chemical engineering -- Periodicals; Chemical engineering; Reaction mechanisms (Chemistry); Periodicals; 547.705
• DOI: 10.1039/d2re00091a
• Languages: English
• ISSNs: 2058-9883

Abstract

Abstract : In this study, synergic alkali catalysts (NaOH + NaAlO2 ) and Ni/ZrO2 were used for microwave-assisted lignin depolymerization. Abstract : In this study, synergic alkali catalysts (NaOH + NaAlO2 ) and Ni/ZrO2 were used for microwave-assisted lignin depolymerization. The effect of temperature, alkali dosage, Ni/ZrO2 dosage, and solid-to-liquid mass ratio was studied to improve the catalytic degradation efficiency and the yield of phenolic compounds. The results showed that more than 87.7% of lignin was converted and more than 0.582 mmol g −1 total phenolic hydroxyl concentration was obtained at 180 °C. Furthermore, the characterization results of FT-IR, UV-VIS, TG-DSC, GPC and 1 H-NMR clearly demonstrated that the synergistic system of an alkali and Ni/ZrO2 effectively improved the degradation efficiency and inhibited the formation of char, and resulted in a series of compounds with low molecular weight (<1000). In addition, the GC-MS results showed that the selectivity of the phenolic monomer product (68.2%) significantly improved after degradation. The lignin depolymerization mechanisms involved demethoxylation, dealkylation and decarbonylation.