LA-CONTAINING SBA-15/H2O2 SYSTEMS FOR THE MICROWAVE ASSISTED OXIDATION OF A LIGNIN MODEL PHENOLIC MONOMER

Xiaoli Gu, Ming He, Yijun Shi, Zhongzheng Li

Abstract


A convenient and efficient application of heterogeneous Lanthanum-containing SBA-15systems for the microwave assisted oxidation of a lignin model phenolic monomer, 3-methoxy-4-hydroxybenzyl alcohol, is reported. Environmental friendly and low-cost H2O2 was used as theoxygen atom donor. The catalyst was prepared by immobilizing Lanthanum species on to the periodicmesoporous channels of siliceous SBA-15. Powder X-ray diffraction data and Inductively CoupledPlasma-Atomic Emission Spectroscopy (ICP-AES) revealed that the host retains its hexagonalmesoporous structure after immobilization and most of the lanthanum species are better dispersedin the calcined materials. The surface area and pore size of La/SBA-15 was considerably decreasedindicating the intrapore confinement of the Lanthanum species. The activity of the La/SBA-15 wasinvestigated in the oxidation of 3-methoxy-4-hydroxybenzyl alcohol in the presence of hydrogenperoxide as oxidant. 68% conversion of 3-methoxy-4-hydroxybenzyl alcohol to vanillin or otherundetectable by-products was obtained after 30 min of reaction under 200W microwave irradiation,compared to a poor 25% degradation after 24 h under conventional heating. The possibility ofrecycling the catalyst was studied.

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