The Study On Preparation Of Aromatic Aldehyde From Degradation Of Lignin By The Catalystic Oxidative

Lignin, is an important biomass resource, the content is only after cellulose. The previous developments and utilizations of lignin belonging to extensive, but not value maximum. With the petroleum shortage, study on making high added-value from lignin has become a focus of current research.The catalytic oxidative degradation of lignin to prepare aromatic aldehydes in NaOH condition was studied in this paper. The effects of different conditions were investigated and the optimum conditions were suggested. Under the optimum conditions, the yield of aromatic aldehydes was24.4%. During the experiment, the solvent cannot be reused, more acid was used for neutralization and the salt solution from post-processing polluted environment, at last the aromatic aldehydes were hard to depart.In addition, the oxidative degradation reaction of lignin for the production of aromatic aldehydes was investigated in the presence of mixed phosphate solution, and applied the dissociation extraction to separate the target products. Under this system, the yield of aromatic aldehydes was25.3%. Compared with the traditional solvent NaOH aqueous solution, this solution promoted the oxidative degradation reaction, and gave some advantages to the reaction include higher yield of the target products, easily post processing, recyclability of solvent finitely. But there was a lot salt precipitated from the mixed phosphate solution which was reused several times, it was potential threat of pollution to environment.Aiming at these problems, a novel approach has been developed in order to use lignin as a renewable resource for the production of high added-value aromatic aldehyde. The concept is based on the use of ionic liquid such as [mmin][Me2PO4]、[mmo][Me2PO4]、[mpy][Me2PO4] and [mtetn][Me2PO4]. The ILs above were prepared and identified by NMR and IR. These ILs were applied to the oxidative degradation of lignin. The total yield of aromatic aldehydes was28.6%, which was higher than the result of alkaline condition. In addition, the IL system possesses has following advantages:green productive environment and process, energy saving, the mixture of products and IL phase was easily separated, and IL phase demonstrated good reusability.