Application Of Yttrium-based Catalytic System In Biomass Conversion

Cellulose is the most abundant renewable resource on Earth,and the catalytic conversion of cellulose into fine chemicals is two important ways for the efficient utilization of biomass resources.As important fine chemicals,lactic acid and polyols have many applications in different fields such as food industry,pharmaceuticals and plastics.The synthesis of lactic acid and polyols through the biomass route is of great significance for promoting the utilization and development of biomass and achieving carbon neutrality.Rare earth elements,especially yttrium,have a wide range of applications in the field of optics due to their relatively stable structure and unique 4f electronic layer structure,but they are used in catalysis,especially in the field of biomass catalysis.In this thesis,a variety of yttrium-based catalysts were synthesized using yttrium,a rare earth metal as the research object,and used for the catalytic conversion of cellulose to lactic acid and polyols.The main research contents are as follows:（1）Five Y（OH）₃ catalysts with different morphologies were synthesized by simple hydrothermal method.Catalysts with different morphologies are calcined to form five Y₂O₃ with different morphologies and structures.Under certain reaction conditions,the catalytic activity of Y（OH）₃ with different morphologies has the following order:polygonal Y（OH）₃>platelet Y（OH）₃>flower-like Y（OH）₃>tube-like Y（OH）₃>microspindles Y（OH）₃.The catalytic performance of Y₂O₃with different morphologies and structures to catalyze the conversion of cellulose to lactic acid is not much different.（2）Various Y-Beta catalysts with different yttrium loadings were prepared by solid-state ion exchange method and applied in the reaction of cellulose catalytic conversion to lactic acid.The prepared Y-Beta catalystssynthesized in this work were characterized by using N₂physical adsorption,XRD,TEM,XPS,FT-IR and NH₃-TPD and other characterization methods.Additionally,The effects of reaction conditions such as reaction temperature,reaction time,catalytic dose and cellulose amount on the yield of lactic acid were investigated.Lactic acid yields as high as 49.2%and 100%conversion of cellulose were abtained when reacting 0.1 g of 10%Y-Beta catalyst,0.3 g cellulose and 30 m L water at 220°C under 2 MPa N₂ for 30 min.Due to the loss of Y and carbon deposition during the reaction,the yield of lactic acid was reduced to 37.3%after three cycles of recycling.Under the optimal reaction conditions,the reaction substrate was also extended to other protobiomass materials such as rice husk,pine wood and corn stalks.（3）By combining the prepared Y（OH）₃ with 1%Ru/C catalyst in the hydrogenation reaction of cellulose,the effects of reaction conditions,such as reaction temperature,reaction time,catalytic dose and reaction pressure,on the yields of ethylene glycol and 1,2-propanediol were investigated.The results show that when 0.1804 g 1%Ru/C and0.0282 g Y（OH）₃ are used as catalysts,the reaction temperature is 245 ^oC,the H₂ pressure is 6 MPa,and the cellulose is completely converted after 30 minutes of reaction,ethylene glycol and 1,2-propanediol The yields were 20.4%and 12.9%,respectively.By combining Y（OH）₃with 1%Ru/C catalyst for hydrogenation of cellulose,the effects of reaction conditions,such as reaction temperature,reaction time,catalytic dose and reaction pressure,on the yields of ethylene glycol and 1,2-propanediol were investigated.