Catalytic Degradation Of Lignin Based On Hydrogen Transfer Reaction

In the last century,due to the rapid development of steel,automobile industries and the continuous consumption of fossil fuels,some problems have gradually become serious around the world.Those problems include energy problems because of non-renewable fossil fuels,as well as air pollution problems due to the effects of large amounts of emissions.In order to solve these problems,biomass energy has gradually become the object of study.One of the most important ways to solve the energy crisis in the world is to use biomass energy to produce high value-added chemicals that people need.In the biomass resource,lignin is concerned by most people due to the huge productivity but low utilization rate.A large number of lignin can't be effectively used every year,resulting in a huge loss.Therefore,how to effectively catalyze the degradation of lignin to be available products is a very important issue.In the process of catalyzing the degradation of lignin,using hydrogen transfer reaction to carry out degradation have been more and more noticeable because of its mild conditions and green,clean,environmentally friendly characteristics.Based on the above background,this paper is divided into the following aspects:In the first chapter,the structure and properties of lignin,the background of hydrogen transfer reaction and the research progress are introduced.The types of hydrogen transfer reaction catalysts and hydrogen donors,including noble metal catalysis and metal supported catalysts are also described.In the second chapter,we introduce a two-step method for converting lignin into valuable low molecular weight compound based on the hydrogen transfer reaction.In this part,two different types of lignin were analyzed first,and then the catalytic effect of different hydrogen transfer reaction catalysts on lignin was analyzed.The optimum reaction was in follows:firstly,the lignin was catalyzed under the hydrogen transfer reaction using Raney nicker catalyst.The reaction was carried out at 180? for 18h.In this step,lignin was liquefied into the primary products with large molecular weight in more than 90%conversion rate.The liquefied product of lignin was then degraded using palladium-carbon catalyst under hydrogen transfer reaction.The reaction were reaction at 80? for 12h.Finally,high selectivity products with high conversion were obtained.The products we're calibrated by gas chromatography-mass spectrometry,and the total yield was over 30%.In the third chapter,a method of catalyzing the lignin and its model compounds by hydrogen transfer reaction using copper catalyst supported on graphene is introduced.And the results were analyzed.By using this catalyst to catalyze the degradation of the lignin model compound,we have found that this catalyst can well break the?-O-4 bond in lignin.This catalyst is applied to the catalysis of lignin,and two kinds of monomers can be detected.The yield of these two monomers and the conversion rate of the reaction are analyzed.