溶剂效应对介孔SiO_2负载磷钨酸催化剂的影响  

Effect of Solvents on the Structure and Properties of Mesoporous SiO_2 Supported Phosphotungstic Acid

作　　者：戴群和[1] 孙继红[1] 任博[1] 陈东[1] 武霞[1] 

机构地区：[1]北京工业大学环境与能源工程学院,北京100124

出　　处：《无机材料学报》2013年第5期537-544,共8页Journal of Inorganic Materials

基　　金：国家自然科学基金(21076003);北京市属市管高等学校人才强教计划(PHR200907105005;PHR201107104;005000543111517;005000541211019/20)~~

摘　　要：以具有两种不同介孔结构的多孔SiO2(BMMs)为载体,采用浸渍法负载磷钨酸(HPW)得到负载型磷钨酸催化剂(HPW/BMMs),通过XRD、FTIR、N2吸附-脱附,TG和SEM等表征手段,重点考察了水、乙醇以及丙酮和乙腈等溶剂对HPW/BMMs催化剂结构和性能的影响。结果表明:在不同溶剂中所制备的负载型HPW/BMMs催化剂样品均保持了BMMs介孔结构,但随着HPW负载量的增大,样品的介孔有序度逐渐降低,比表面积和孔体积逐渐减小;低负载量时,样品表面出现新的HPW物种,通过提高HPW的负载量,可抑制该物种的产生。水溶剂对HPW的Keggin结构影响较大,但HPW的晶型保持完好,分散性能较好,负载量为40%的样品(40HPW/BMMs-WA)总酸密度最高,达到1.381μmol/m2;乙腈溶剂虽更有利于保持HPW的Keggin结构,但晶型破坏较严重,且分散性较差;相比较而言,乙醇和丙酮溶剂的影响则不明显。此外,初步考察了HPW/BMMs样品对废油脂与甲醇催化酯化的降酸效果。HPW/BMMs catalyst was prepared by supported phosphotungstic acid on mesoporous SiO2 with two different mesoporous structures v/a impregnation method, and characterized by means of XRD, FTIR, nitrogen adsorption- desorption, TG and SEM. The effects of solvents, such as water, ethanol, acetone and acetonitrile, on the structure and properties of supported phosphotungstic acid were systematically investigated. The results showed that the mesoporous structures of BMMs were maintained in the catalysts synthesis process, however, the mesopores order degree, surface area and pore volume of the catalysts （HPW/BMMs） decreased as the increase of HPW loading. A new HPW species in HPW/BMMs appeared at lower loadings and disappeared as the increasing of HPW amount. In addition, the influence of aqueous solution on the Keggin structure of HPW in HPW/BMMs was remarkable, al- though the HPW crystal remained intact with the uniform dispersion. The acid density of the catalyst synthesis in water with 40% HPW loading （40HPW/BMMs-WA） was up to 1.381 gmol/m^2. In contrast, when acetonitrile was used as solvent, the Keggin structure of HPW was more likely to be maintained, but the HPW crystal phase was severely destroyed with a low dispersing inside the mesoporous channels. In comparison, the effects of ethanol and acetone as solvent were not obvious. Furthermore, the acid reduced performances of the HPW/BMMs catalysts in etherification reaction between waste oils and methanol were preliminarily investigated.

关 键 词：磷钨酸 双模型介孔SiO2 废油脂 酯化 

分 类 号：O643[理学—物理化学]