Silica-supported Ti chloride tetrahydrofuranates, precursors of Ziegler-Natta catalysts
Silica-supported Ti chloride tetrahydrofuranates, precursors of Ziegler-Natta catalysts
复制标题
DOI：
10.1039/c3dt50603g
复制
发表时间：
2013-01-01
影响因子：
4
通讯作者：
Groppo, Elena
中科院分区：
文献类型：
--
作者：
Seenivasan, Kalaivani;Gallo, Erik;Groppo, Elena
用TiCl4(thf)(2)和TiCl3(thf)(3)配合物（Ziegler-Natta催化剂的前驱体）浸渍聚合物级脱羟基二氧化硅得到氯化四氢呋喃酸钛样品，并用FT-IR、XAS、XES和漫反射紫外-可见光谱结合DFT计算研究了样品的结构和电子性能。无论起始前驱体是什么，两种二氧化硅负载样品的性质都非常相似。在这两种情况下，大多数原本围绕在钛位点周围的氯配体在二氧化硅上接枝后被氧配体取代。因此，二氧化硅负载的钛位的电子性质与相应的前驱体有很大的不同，在这两种情况下，大多数接枝的钛位都具有+4的形式氧化态。整套实验数据表明，单核钛主要存在于二氧化硅表面。
The structural and electronic properties of silica-supported titanium chloride tetrahydrofuranates samples, obtained by impregnating a polymer-grade dehydroxylated silica with TiCl4(thf)(2) and TiCl3(thf)(3) complexes, precursors of Ziegler-Natta catalysts, are investigated by means of FT-IR, XAS, XES and diffuse reflectance UV-Vis spectroscopy, coupled with DFT calculations. The properties of the two silica-supported samples are very similar, irrespective of the starting precursor. In both cases, most of the chlorine ligands originally surrounding the Ti sites are substituted by oxygen ligands upon grafting on silica. As a consequence, the electronic properties of silica-supported Ti sites are largely different from those of the corresponding precursors, and in both cases most of the grafted Ti sites have a formal oxidation state of +4. The whole set of experimental data provide evidence that mono-nuclear Ti species are mainly present at the silica surface.