Preparation Of Fe₃O₄@PAA-PPD/H₃PW₁₂O₄₀Composite Catalyst And Study On Its Catalytic Performance

Based on the fact that the pollution of human living environment is getting worse and worse,in recent years,"environmentally-friendly catalyst"has gradually attracted extensive attention.People not just use a single active component to catalyze a chemical reaction,they pay more attention to the non-toxic,harmless,pollution-free and efficient chemical reaction process.Traditional catalysts,such as liquid acids and metal salts,generally cause a series of problems in chemical reactions,such as corrosion equipment,cumbersome post-treatment,non-renewable catalysts,environmental pollution and so on.If solid acid is used as catalyst and immobilized on the carrier with excellent magnetic recovery property,the problems mentioned above can be overcomed one by one by using this material to catalyze chemical reaction.In this paper,a composite material based on Fe₃O₄,magnetic nanoparticles was designed.Fe₃O₄@?CH₂-CH?_nCOOH–NH₂-C₆H₄-NH₂/H₃PW₁₂O₄₀0 was prepared with magnetic Fe₃O₄ nanoparticles as carriers,surface modification and polymerization of acrylic acid were used,p-phenylenediamine was introduced through acid-base interaction,and loaded Keggin-type polyoxometalates(H₃PW₁₂O₄₀).Its chemical composition was abbreviated as Fe₃O₄@PAA-PPD/H₃PW₁₂O₄₀,which could easily separated from the system of reaction by an external magnetic field and can be recycled.Catalytic hydrolysis of glucose and cellulose was used to investigate their catalytic performance,and the recycling of magnetic nanocomposites was evaluated.The specific contents were as follows:1.Firstly,synthesize the Fe₃O₄ nanoparticles by coprecipitation method.Then,acrylic acid was modified,initiator and acrylic acid were added to polymerize with acrylic acid that adhering to the carrier's surface.Then,aniline was modified by acid-base interaction.Finally,material Fe₃O₄@PAA-PPD/H₃PW₁₂O₄₀0 was obtained by doping a certain amount of Keggin-type polyoxometalates.Its structure,morphology and properties were characterized by infrared spectroscopy?FT-IR?,thermogravimetric analysis?TGA?,transmission electron microscopy?TEM?,vibration sample magnetometer?VSM?,Inductively Coupled Plasma Emission Spectrometry?ICP?and so on.2.Glucose hydrolysis was used as a probe reaction to investigate of the catalytic properties of Fe₃O₄@PAA-PPD/H₃PW₁₂O₄₀.It was found that the main product of glucose dehydration was 5-hydroxymethyl furfural?5-HMF?,and the corresponding explanations were given for the different results of each change of conditions.The optimum reaction conditions were determined by single factor experiments,the yield of 5-HMF was 97%when the mass ratio of glucose to catalyst was 1:1,the solvent was 5 mL distilled water+ethanol?1:1?,the temperature was 200?and the reaction time was 2 h.Finally,the recycling of Fe₃O₄@PAA-PPD/H₃PW₁₂O₄₀0 was investigated,after it recycled five times,the yield of 5-HMF was 95%.3.Cellulose hydrolysis was used as probe reaction for further investigate of the catalytic properties of Fe₃O₄@PAA-PPD/H₃PW₁₂O₄₀.It was found that the main product of cellulose dehydration reaction was glucose,and the different results of each condition change were explained accordingly.The optimum reaction conditions were determined by single factor experiments,the yield of glucose can be 97%when the mass ratio of cellulose to catalyst was 2:1,the solvent was 5 mL distilled water,the temperature was 200?and the reaction time was 1 h.Finally,the recycling of Fe₃O₄@PAA-PPD/H₃PW₁₂O₄₀0 was investigated,after it recycled five times,the yield of glucose was 96%.