TiO2 grafted silica MCM-41 catalyst with and without sulfate treatment were prepared. The structural and acid properties of these materials were investigated by XRD, N2 adsorption-desorption, element analysis, thermal analysis, Raman and FTIR measurements. Their acid-catalytic activities were evaluated using the cyclization reaction of pseudoionone. It was found that the obtained materials possess well-ordered mesostructure, and the grafted TiO2 components were in highly dispersed amorphous form. T/MCM41 without sulfation contained only Lewis acid sites, while Bronsted and Lewis acidities were remarkably improved for the sulfated materials ST/MCM41 and d-ST/MCM41. T/MCM-41 was not active for the cyclization reaction of pseudoionone, but ST/MCM-41 and d-ST/MCM-41 possessed favorable catalytic activities. The catalytic performance of ST/MCM-41 was comparable with that of the commercial solid acid catalyst of Amberlyst-15, and better than that of d-ST/MCM-41, although the latter underwent a second TiO2 grafting process and accordingly had higher Ti and S content. The specific surface structure of Si-O-Ti-O-S=O in ST/MCM-41 and the bilateral induction effect of Si and S=O on Si-O-Ti bonds were speculated to account for its higher acid catalytic activity.

中文翻译：

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硫酸盐处理的TiO2接枝二氧化硅MCM-41的制备及酸催化活性

制备了经过硫酸盐处理和未经硫酸盐处理的TiO2接枝二氧化硅MCM-41催化剂。通过XRD，N2吸附-脱附，元素分析，热分析，拉曼和FTIR测量研究了这些材料的结构和酸性质。使用假紫罗兰酮的环化反应评估了它们的酸催化活性。发现所获得的材料具有良好的介观结构，并且接枝的TiO 2组分为高度分散的无定形形式。没有硫酸化的T / MCM41仅包含路易斯酸位，而硫酸化材料ST / MCM41和d-ST / MCM41的布朗斯台德和路易斯酸度显着提高。T / MCM-41对假紫酮的环化反应没有活性，但是ST / MCM-41和d-ST / MCM-41具有良好的催化活性。ST / MCM-41的催化性能与Amberlyst-15的市售固体酸催化剂相当，并且优于d-ST / MCM-41，尽管后者经过了第二次TiO2接枝过程，因此具有更高的催化性能。钛和硫含量。据推测，ST / MCM-41中Si-O-Ti-OS = O的比表面结构以及Si和S = O对Si-O-Ti键的双边诱导作用是由于其较高的酸催化活性。