The Acidity and Catalytic Activity of Supported Acidic Cesium Dodecatungstophosphates Studied by MAS NMR, FTIR, and Catalytic Test Reactions
作者:Á Molnár、T Beregszászi、Á Fudala、P Lentz、J.B Nagy、Z Kónya、I Kiricsi
DOI:10.1006/jcat.2001.3285
日期:2001.9
(Cs1.7H1.3[PW12O40]-on-SiO2 and Cs1.8H1.2[PW12O40]-on-MCM41) are active, selective, and recyclable catalysts in Friedel–Crafts alkylations (isopropylation, transalkylation), the aromatic ortho-Claisen rearrangement, and the dehydration of pinacol. The specific activity of these catalyst preparations are comparable with that of neat Cs2.6H0.4[PW12O40]. This indicates that the active species are in a
通过多核MAS NMR,FTIR和催化测试反应对负载在二氧化硅和MCM-41上的十二碳三磷酸(H 3 PW)的酸性铯盐进行了表征。31 P-NMR数据表明,负载的样品含有各种化学计量的盐(Cs 3 PW和Cs 2 HPW),甚至还有H 3 PO 4。根据29 Si-NMR数据,在二氧化硅载体的情况下,Cs盐的沉积不会改变各种SiOH基团的相对量。相反,当载体为MCM-41时,SiOH基团的相对数量显着增加,表明硅氧烷键与H 3相互作用而破坏了硅氧烷键。PW。的133 Cs的MAS-NMR谱还表明,CsPW盐相互作用更强与MCM-41载体比的SiO 2。催化研究的结果表明,具有低Cs含量的十二碳四烯磷酸磷酸铯盐负载在二氧化硅或MCM-41上(Cs 1.7 H 1.3 [PW 12 O 40 ] -SiO- 2和Cs 1.8 H 1.2 [PW 12 O 40 ] -on-MCM41)在Fri