SO_4^(2-)/TiO_2及S_2O_8^(2-)/TiO_2催化剂的制备及表征  

Preparation and Characterization of SO_4^(2-)/TiO_2 and S_2O_8^(2-)/TiO_2 Catalysts

作　　者：马雪旦[1] 郭岱石[1] 蒋淇忠[1] 马紫峰[1] 马正飞[2] 叶伟东[3] 李春波[3] 

机构地区：[1]上海交通大学化学工程系,上海200240 [2]南京工业大学化学化工学院,江苏南京210009 [3]浙江医药股份有限公司新昌制药厂,浙江新昌312500

出　　处：《高校化学工程学报》2006年第2期239-244,共6页Journal of Chemical Engineering of Chinese Universities

基　　金：国家自然科学基金(50236010.20476055);国家863计划(2002AA323040);国家973计划(2003CB214504);教育部留学回国人员科研启动基金。

摘　　要：制备了纳米级固体超强酸SO42?/TiO2、S2O82-/TiO2,以及MCM-41负载的SO42-/ZrO2。利用X射线衍射、氮吸附-脱附和原位吡啶吸附红外等表征方法,并通过对假性紫罗兰酮催化环化反应的初步考察,从结构、酸性和催化活性等方面对三种催化剂进行了比较分析。结果表明,所制备的SO42-/TiO2和S2O82-/TiO2催化剂不但具有小于7.0nm的纳米级晶粒、高于140cm2-g-1的比表面积、以及约4nm的相对规整的介孔结构,还保持了单纯而完善的锐钛晶型和较强的酸活性。与SO42-/ZrO2/MCM-41主要表现为Lewis酸性不同,SO42-/TiO2和S2O82-/TiO2主要以Brφnsted酸性为主,其中采用硫酸为促进剂制备的SO42-/TiO2具有最强的Br-nsted酸性,而采用过硫酸根作为促进剂则使S2O82-/TiO2产生较SO42-/ZrO2/MCM-41更强的Lewis酸中心。研究发现,SO42-/TiO2和S2O82-/TiO2对假性紫罗兰酮催化环化反应具有远高于SO42-/ZrO2/MCM-41的酸催化活性,其活性差异源于不同的酸性本质,而催化剂中较多强Brφnsted酸中心的存在有利于需要质子参与的环化反应的进行。Nano-sized solid superacids SO4^2-/TiO2 and S2O8^2-/TiO2, as well as MCM-41 supported SO4^2-/ZrO2 were prepared. Their structures, acidities were investigated and compared through characterization methods of XRD, N2 adsorption-desorption, and in situ pyridine adsorption FTiR, and catalytic activities were evaluated by the cyclization reaction of pseudoionone cyclization. The results show that SO4^2-/TiO2 and S2O8^2-/TiO2 particles possess not only nanosize with diameters less than 7.0 nm, large BET surface larger than 140 cm^2·g^-1, and relatively regular mesostructures with pores size about 4.0 nm, but also pure anatase phase and strong acidity. Different from the Lewis acidity nature of SO4^2-/ZrO2/MCM-41, SO4^2-/TiO2 and S2O8^2-/TiO2 behave mainly Brgnsted acidities. The strongest Brgnsted acid sites are formed on SO4^2-/TiO2 promoted with H2SO4, while Lewis acid sites on S2O8^2-/TiO2 are even stronger than those on SO4^2-/ZrOE/MCM-41, and the former which are generated when persulfate solution is used as sulfating agent. The catalytic activities of SO4^2-/TiO2 and S2O8^2-/TiO2 for cyclization of pseudoionone are much higher than that of SO4^2-/ZrOE/MCM-41 due to their distinct acid natures, and it can be concluded that existence of more Bronsted acid sites is favorable for the proton participating cyclization reaction.

关 键 词：固体超强酸 SO4^2-/TIO2 S2O8^2-/TriO2 紫罗兰酮 环化 

分 类 号：TQ426.81[化学工程] TQ426.6