LA-MODIFIED SBA-15/H2O2 SYSTEMS FOR THE MICROWAVE ASSISTED OXIDATION OF ORGANOSOLV BEECH WOOD LIGNIN

Kanghua Cheng, Ming He, Yijun Shi, Zhongzheng Li

Abstract


In this manuscript, the in uence of organosolv beech wood lignin (LOB) on its oxidative conversionto high added-value phenolic aldehydes is discussed. Environmental friendly and low-cost H2O2was used as the oxygen atom donor. e catalyst was prepared by immobilizing Lanthanum compoundsonto the periodic mesoporous channels of siliceous SBA-15. e activity of the La/SBA-15 wasinvestigated towards oxidation of LOB in the presence of hydrogen peroxide as oxidant with microwaveirradiation. Considering the characteristics of LOB, an unexpected low syringaldehyde concentrationat 10min of reaction time (1.47 g/L, corresponding to 15.66% yield) was obtained; the other majorproduct was vanillin at 25min (0.78 g/L, i.e., 9.94% yield). e high reactivity of syringyl nuclei may bepointed out as the main reason for the faster production and degradation of syringaldehyde in oxidation.Other low molecular weight phenolic products were found: vanillic acid, syringic acid and minorquantities of aceto-derivatives. e pro le of products concentration with the reaction time of catalyticoxidation with microwave irradiation are shown and discussed with reference to the investigated ligninfeatures. e mechanism of the microwave catalytic oxidation for LOB under alkaline conditions wasproposed.

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