Preparation And Catalytic Activities Of Sulfonic Acid Group Functionalized Solid Acid

Compared to the traditional liquid acid catalysts,solid acid catalysts owned the advantages of easy separation,reusability and simple post-treatment.The solid acids fit the development requirements of green chemistry,which had a broad potential application areas.At present,many solid acids were studied such as solid superacid,metal oxides,heteropolyacids,cation exchangable resin,clay ore and zeolites,but these solid acids suffered from the following problems such as less acid,poor thermal stability,weak acidic sites,etc.Carbon based solid acids received wide attention due to their high acidity and thermal stability.However,traditional carbon based solid acids have some drawbacks,such as low BET surface area,amorphous structure and so on,which added the separation difficulty and inactivities for the reactions involving hydrophobic reactants,thus limiting their application.In order to solve the above problems,the novel carbon microtube based solid acid catalysts were prepared from the biomass raw materials.By changing the biomass raw materials and the preparation conditions,the structure and surface area of the carbon microtube based solid acids can be well adjusted.These solid acids showed excellent catalytic performance in the preparation of biodiesel from waste oil.The main research contents include:?1?Using catkins as raw material,carbon microtubule intermediate was formed after carbonization,then the carbon intermediate sulfonate to introduce the sulfonic acid groups.The influence of carbonization temperature on the solid acids was studied.The structure of the solid acids was characterized by FT-IR,TG,SEM and BET.The results showed that the microtubule structure was well preserved when the catkin was carbonized at 400?.The solid acid owned the high surface area of278m²/g and the acidity of 3.5mmol/g.The catalyst showed very high catalytic activity for the preparation of biodiesel from waste oil.When the molar ratio of alcohol to oil was 15:1,the reaction temperature was 70?,and the amount of catalyst was 0.05g,the total yield of biodiesel reached 99.1%,and it has high reusability.?2?In order to solve the problem of catkin collection and seeds removal,sulfonic acid functionalized solid acids were prepared from pampas grass sticks which were easy to obtain.The effects of maturity and carbonization temperature on the structure and properties of solid acids were studied.The structure of the catalyst was characterized by FT-IR,TG,SEM and BET.The novel solid acid catalyst owned better microtubule structure,with a specific surface area of 224m²/g and an acidity of2.5mmol/g.The specific microtubule structure and high specific surface endow the material with high catalytic activity.In the process of catalytic synthesis of biodiesel from waste oil,when the molar ratio of alcohol to oil was 15:1,the reaction temperature was 70?,and the amount of catalyst was 0.05g,both the free fatty acid and triglyceride could be converted into biodiesel at the same time,with a total yield of 99.1%,and good reusability.?3?In order to simplify the reuse of catalyst,magnetic microtubule solid acid was prepared by introducing magnetic core onto the catkins based solid acid.The catkins were treated with the solution of Fe Cl₃.6H₂O and ethanol to form the Fe Cl₃.6H₂O doped raw material,which was carbonized to form the intermediate of magnetic carbon microtubule,and then reacted with diazotized benzene sulfonic acid to introduce sulfonic acid group to prepare magnetic microtubule solid acid.The structure of the catalyst was characterized by FT-IR,XRD,SEM and BET.The novel sulfonic acid functionalized solid acid catalyst owned the microtubule structure,with the surface area of 215m²/g and acidity of 2.3mmol/g.The reaction condition was optimized as following:the molar ratio of alcohol to oil 15:1,the reaction temperature70?,the amount of diazotized benzene sulfonic acid 6g and the amount of catalyst0.05g.The total yield of biodiesel from waste oil can reach 99%.The magnetic property greatly simplified the catalyst recovery process.After reused for 10 times,the catalyst still had high catalytic activity.