Converting Lignin And Its Model Compounds With Transition Metal Based Catalysts

With the depletion of the fossil fuels,biomass as a renewable resource of fuels and chemicals draws worldwide attention.Among the components of biomass,lignin is a promising resource of aromatic chemicals.Kraft lignin has been produced in a great amount as the byproduct of pulping process.It is left in the black liquor as a pollution waste or used as a low heating value boiler fuel.Here,different catalysts were used to convert lignin and its model compounds to value-added chemicals.?1?The complete conversion of Kraft lignin is examined over a MoC_1-x/Cu-MgAlO_z catalyst in pure ethanol to give value-added chemicals with small molecular weight,including C₆ alcohols,C₈-C₁₀ esters,benzyl alcohols,phenols and arenes,without the formation of char or tar.MoC_1-x/Cu-MgAlO_z achieved the highest yield of aromatic compounds,575 mg/g lignin,at 330 ^oC.Furthermore,the MoC_1-x/Cu-MgAlO_z catalyst is reusable with a 22.4%loss of the yield of aromatic compounds after 5 cyclic runs.?2?When V₂O₅ is reduced in a mixture of guaiacol and methanol,Haggite structured V₄O₆?OH?₄ is obtained,which possesses a semiconductor-insulator transition.Methanol is a strong reductant for V₂O₅ and it over-reduces V₂O₅ to V₂O₃.However,Haggite is directly obtained by reducing V₂O₅ in mixture of guaiacol and methanol.In this solution,guaiacol delays the over-reduction of Haggite to V₂O₃.?3?V₂O₅ is used for the conversion of guaiacol in methanol but is in-situ reduced to Haggite.Haggite catalyzes the deoxygenation of guaiacol following the reverse Mars-van Krevelen mechanism and the alkylation of guaiacol.The conversion of guaiacol produces 6 main products among which 5 are alkylphenols.When the reaction is carried out at 300 ^oC for 6 h,an 83.5%total selectivity to alkylphenols was achieved with a 99.0%conversion.?4?Re₂O₇ is used for the conversion of lignin and its model compounds in ethanol.The reaction rate of guaiacol is high,reaching 93.1%conversion at 1.5 h.The conversion of guaiacol and catechol mainly produces alkylphenols.The major product of phenol conversion is 2-ethylphenol.The major product of anisole conversion is phenol.EHL is depolymerized with a 15.80%yield of monomers.The main products are alkylphenols.