Study On Lignin Degradation Via Catalytic Hydrogenation In Transition Metal Composite Ionic Liquid [BMIm] Cl

Alkali lignin as the main component of black liquor can be used as materials of many chemicals because of its unique rich benzene ring structure, but it was not utilized widely so far. It not only caused serious environmental pollution, but also caused a resource a lot of waste. The transformation and use of alkali lignin has been a top problem in today’s scientific research workers.In this paper,[BMIm]Cl ionic liquids which can be used in subsequent was firstly synthesized in the laboratory experiments. The as-synthesized [BMIm]Cl were characterized by1H NMR, FT-IR and GC-MS. The results show that the impurity of as-synthesized [BMIm]Cl ionic liquids is extremely low.The heterogeneous catalysts Fe2O3/HZSM-5, CO3O4/HZSM-5and NiO/HZSM-5were prepared by a precipitation method with the HZSM-5zeolite as the support.4,7-dimethyl-indan,5-methyl indole,1-methyl indene and tetralin alcohol were the relatively high percentage of degradation products of alkali lignin hydrogenolysis in a heterogeneous catalytic system. The degradation of the typical decomposition a-methyl cinnamaldehyde reached the highest4.42%over Fe2O3/HZSM-5catalyst at210℃. Comparative blank test, the yield was improved by more than50%. FT-IR analysis showed that the absorption peaks after alkali lignin degradation has greatly diminished,-OH outside plane bending vibration significantly strengthened to achieve the alkali lignin degradation.The homogeneous catalyst [BMIm][FeCl4],[BMIm][NiCl3] and [BMIm][CrCl4] were composited with [BMIm]Cl and the transition metal salt.4,7-dimethyl-indan,5-methyl indole,1-methyl-4-(1-methyl-oxiranyl)-heptane,1-methyl indene and a-tetrahydronaphthalene alcohol were the relatively high percentage of degradation products of alkali lignin hydrogenolysis in a heterogeneous catalytic system. The degradation of the typical decomposition a-methyl cinnamaldehyde reached the highest5.70%over [BMIm][FeCl4] catalyst at180℃. Comparative blank test, the yield was improved by more than300%. FT-IR showed that the benzene ring substituents ortho disubstituted enhanced to achieve a partial degradation of alkali lignin. ANOVA showed that the effect of temperature on the relative percentage of alkali lignin decomposition products of hydrogen by catalytic hydrogenation of the degradation of the system extremely significant, even if all the transition metal degradation reaction system, the relative percentage hydrogenolysis product also has a great the difference. Under different reaction system, the relative content of the hydrogenolysis product with change of temperature is different even opposite.