Magnesium Oxide‐catalyzed Oxidative Depolymerization of EFB Lignin

Abstract

Empty fruit bunch (EFB) lignin, which had been isolated by the previous sulfuric acid treatment of EFB, was oxidized in the presence of a base and air to depolymerize the solvent‐insoluble lignin into smaller solvent‐soluble molecules. Depending on the types of base and solvent, the yield of solvent‐soluble lignin (SSL) varied, and the highest yield of 54% was obtained when MgO and ethanol were used at 150 °C with an air pressure of 500 psig for 3 h. Gel permeation chromatography analysis of the oxidized lignin showed that SSL had decreased molecular weight compared to native EFB lignin. 31P NMR experiments revealed that concentrations of hydroxy group and acid group were increased by the oxidation. 2D 1H‐13C HSQC NMR was performed, and it was found that the area intensities related to methoxy group and β‐O‐4′ unit as well as guaiacyl, oxidized syringyl, and p‐hydroxybenzoate group were decreased by the oxidation.

Zirconium-Incorporated Mesoporous Silicates Show Remarkable Lignin Depolymerization Activity

“…15−17 Several lignin deconstruction strategies have also been reported recently, using catalytic hydrodeoxygenation. 18 Oxidative lignin depolymerization has also been receiving increased interest, using either H 2 O 2 or O 2 as an oxidant over various catalysts, viz., methyltrioxorhenium, 19 Pd/γ-Al 2 O 3 , 20 ionic liquids (butylimidazolium hydrogen sulfate and triethylammonium hydrogen sulfate), 21 MgO, 22 perovskite-type oxide, 23 and CuO/Fe 2 (SO 4 ) 3 /NaOH. 24 Homogeneous metal complexes and salts of Ru and Mn have been reported to depolymerize lignin model compounds and lignin.…”

“…Ni/C and Pt/C catalysts in conjunction with hydrogen donor solvents, such as methanol and formic acid, have been shown to depolymerize lignin. − Several lignin deconstruction strategies have also been reported recently, using catalytic hydrodeoxygenation . Oxidative lignin depolymerization has also been receiving increased interest, using either H 2 O 2 or O 2 as an oxidant over various catalysts, viz., methyltrioxorhenium, Pd/γ-Al 2 O 3 , ionic liquids (butylimidazolium hydrogen sulfate and triethylammonium hydrogen sulfate), MgO, perovskite-type oxide, and CuO/Fe 2 (SO 4 ) 3 /NaOH …”

Microwave-assisted phenolation of acid-insoluble Klason lignin and its application in adhesion

“…Klason lignin was prepared as previously reported in the literature. 36 More specifically, raw empty fruit bunch (EFB) powder (1.00 kg) was hydrolyzed using 70 wt% H 2 SO 4 (2.37 kg) at 30 °C for 30 min. Subsequently, deionized (DI) water was added to the reaction mixture to dilute the acid concentration to 30 wt%, and stirring was continued at 80 °C for 5 h. After this time, the powder was washed with DI water until the pH of the filtrate became neutral.…”

Depolymerization and Activation of Lignin: Current State of Knowledge and Perspectives

“…In turn, Widyay et al studied the impact of different catalysts (magnesium and calcium oxides, potassium acetate, and potassium hydroxide) on the depolymerization of lignin in ethanol [42]. In spite of the very good results obtained for the potassium catalysts, in view of their high solubility in the reaction medium, further tests were carried out using magnesium oxide.…”

“…Also noted was the degradation of some of the carbon-carbon bonds and the structural units of lignin. The authors further drew attention to the possibility of reusing the catalyst without detriment to its activity or structure [42].…”