Study On Catalytic Conversion Of Lignin With Nano-euronium Oxide

Lignin is an important part of plant cell wall,whose storage is only less than cellulose,is the renewable biological resources which contain rich aromatic monomer in nature.Lignin production reaches 50 billion tons around the globe every year,but due to the stability and complex of its structure,it was not far reaching the large-scale application.Most of lignin is processed in low value-added ways such as heat generation and power generation or is discharged at will which caused the waste of resources.It will realize the one of the effective path of lignin resource and high value to obtain aromatic compound through the method of catalytic depolymerization.Lignin mainly has microbial degradation,oxidative degradation,acid-base catalytic degradation,reductive degradation in the directional depolymerization and others.Due to Rare earth element has the unique electronic transition characteristics,it shows very strong ability to transfer electrons in catalytic reaction.In recent years,the lignin also has been emphasized in catalytic oxidation research.This essay uses hydrothermal method and template method to prepare for four different morphologies of nano europium oxide catalysts:spherical,fusiform,flake,and rod and enhance the catalyst activity and stability.The selective catalytic oxidation of lignin model molecules(dp-ol)and lignin in the autoclave,X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),hydrogen desorption adsorption(H2-TPR)and X-ray photoelectron spectroscopy(XPS)analysis of the crystal form,morphology,and oxidation ability characterize to analyze the composition of the obtained liquid product by gas chromatography mass spectrometry(GC-MS)and evaluate high performance liquid chromatography(HPLC),and the regeneration performance of the catalyst.The study result shows:different shapes of europium oxide have different catalytic capabilities for lignin model molecules,among which the conversion rate of rod-shaped europium oxide to the lignin model compound was 91.2%under 220?,1 MPa O2,8 h,and study the catalytic oxidation process of real lignin by using rod-shaped nano-European oxide as a catalyst.Through catalytic oxidation of cotton lignin,the yield of several monomeric aromatic compounds was quantified using GC-MS.Finally,vanillin,methyl vanillate and methyl syringate were obtained and their corresponding monomer yields were 2.12 wt%,0.73 wt%and 0.74 wt%.This essay further enriched the study of heterogeneous catalytic depolymerization of lignin and also provided new ideas in solving the bottleneck problem of the resource utilization of cotton stalks in Xinjiang.