氧化钨改性的氧化钛固体超强酸催化剂的研究  

Studies on Tungsten Oxide Modified Titania Solid Superacid Catalysts

作　　者：任立国[1] 张晓丽[1] 

机构地区：[1]辽宁石油化工大学材料科学与工程系,辽宁抚顺113001

出　　处：《高校化学工程学报》2008年第1期71-76,共6页Journal of Chemical Engineering of Chinese Universities

摘　　要：通过偏钨酸铵水溶液浸渍TiO2·xH2O粉末和空气中高温焙烧制备了氧化钨改性的TiO2固体超强酸催化剂,用N2-吸附、Hammett指示剂法、NH3-TPD、吡啶吸附-FT-IR、XRD和LRS进行了表征。WO3含量低于15%(wt)之前,氧化钨物种和TiO2之间的强相互作用稳定了氧化钨物种以及氧化钨物种在TiO2的表面上高度分散,氧化钨抑制了TiO2的锐钛矿晶相向金红石晶相的转变,催化剂的表面积、孔容、孔径和酸量随着WO3含量的增加而增大。WO3含量超过15%(wt),500℃焙烧催化剂中出现WO3晶相。加入少量的WO3,催化剂的酸强度和酸量明显增加,其表面上同时存在L酸中心和B酸中心以及L酸中心和B酸中心可以相互转化。氧化钨改性的TiO2固体超强酸在草酸和异戊醇的酯化反应中具有良好的催化性能。Tungsten oxide modified titania solid superacid catalysts were prepared by impregnation of TiO2·xH2O powder in ammonium metatungstate aqueous solution and calcination in air with high temperature. The modified catalysts prepared were characterized by NH3-TPD, FT-IR of pyridine adsorption, XRD and LRS. The results show that the small amount addition of tungsten oxide can remarkably increase the acidity and the acid strength of the modified catalysts prepared, both the Lewis and Bronsted acid sites exist on the surface of the modified catalysts and these two species of acid sites are interchangeable. It was also found that, when the addition amount of tungsten oxide is less than 15% of the weight of modified catalyst, the interaction between tungsten oxide and TiO2 stabilizes the tungsten oxide species, forms good dispersion of tungsten oxide on the surface of TiO2 support and hinders the transition of TiO2 from anatase to rutile phase. The surface area, pore volume, pore diameter and acidity of the catalyst increase with the content of the tungsten oxide. The tungsten oxide modified titania solid superacid catalyst has good catalytic performance for the esterification of ethane diacid and isopentyl alcohol. However when the content of tungsten oxide is over 15%（wt） with the calcination temperature over 500℃, the crystal phase of WO3 will appear and the specific surface area, acidity and the acid strength of the modified catalysts decrease.

关 键 词：固体超强酸 酸性 表征 酸催化 酯化 

分 类 号：O643.361[理学—物理化学] TQ426.82[理学—化学]