Investigation of silica particle structure containing metallocene immobilized by a sol–gel method

The Power of Non-Hydrolytic Sol-Gel Chemistry: A Review

“…Moreover, access to the active centers encapsulated inside an almost non-porous silica support is strongly hindered. An increase in catalytic activity was achieved by increasing metallocene concentration in these materials [222]. The same group also described alizarin incorporated silica materials with potential application as pH sensors [223].…”

“…vs. Si-OH) and therefore their reactivities differ significantly. Silica-based materials containing catalytic centers, such as metallocenes or methylaluminoxanes (MAO), were reported by the group of Dos Santos [221,222]. The preparation of their silica supports is based on the reaction between SiCl 4 and Si(OEt) 4 in toluene with the addition of a catalytic amount of FeCl 3 .…”

Direct production of ultra-high molecular weight polyethylene with oriented crystalline microstructures

“…In addition, previous studies [9] on the characterization of the present catalyst by small angle X-ray scattering (SAXS) have shown that the obtained silica particle is formed by aggregation of primary particles of average diameter of approximately 16 nm. The metallocene complex is entrapped within this environment, that is, it is surrounded by the network structures made from the primary particles.…”

“…Therefore, the choice of the support type and immobilization methodology plays an important role on the performance of metallocenes during the polymerization. In a previous study, we have proposed a methodology for the immobilization of zirconocenes into a silica matrix concomitantly with the SiO 2 synthesis by a non-hydrolytic sol-gel method [8,9]. In this method, the metallocene catalyst is entrapped within the amorphous SiO 2 network formed around the metallocene complex.…”

The Role of the Support in the Performance of Grafted Metallocene Catalysts

“…We have been studying the heterogenization of metallocenes for ca. fifteen years in terms of the influence of experimental parameters (grafting time and temperature, contact time, solvent, etc) on the grafting reaction;14, 15 the effect of alternative immobilization techniques, such as the synthesis of supported metallocenes on hybrid silicas,16 in situ immobilization17 or metallocene encapsulation;18 the nature of the surface species;19, 20 and the effect of surface modification with compounds such as organosilanes21 or tin chloride 22. More recently, we have investigated the effect of the textural properties of silicas produced by different techniques (aerogel, xerogel, precipitated silicas, etc),23, 24 as well as the effect of the support surface's chemical composition (alumino‐silicates, silica‐zirconia, magnesium silica supports) and its crystallinity (amorphous, lamellar and crystalline materials)25 on the catalysts' performance.…”