New synthetic approaches to efficient Ti–SiO2 epoxidation catalysts
(2019)
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- The epoxidation of olefins is a subject of considerable fundamental and industrial interest. This reaction is catalyzed by heterogeneous Ti–SiO2 titanosilicates, which first emerged in the 1970s. Among these catalysts, TS-1 zeolite is industrially used for the production of propylene oxide. Despite its attractive performance, this microporous catalyst is restrained to lower substrates. Intensive efforts were therefore made in the past decades to develop new Ti–SiO2 catalysts with improved catalytic performance and expanded reaction scope. This thesis tackles challenges that are omnipresent in the current research on titanosilicate catalysts. On the one hand, the intricate relation between the physico-chemical properties and the catalytic performance is highlighted. New Ti–SiO2 prepared by atypical sol-gel techniques are investigated, with a particular focus on selected properties, namely the surface functionality, the texture, and the macroscopic morphology. Each catalyst is characterized in details and its catalytic performance is evaluated and compared to the benchmark TS-1 catalyst. Even though hydrogen peroxide is an attractive oxidant for the green epoxidation of olefins, its current industrial production raises some questions. Therefore, on the second hand, the chemo-enzymatic formation of epoxides with in situ production of H2O2 is investigated. Exploiting the spray-drying technique, TS-1 crystals are assembled into hollow microstructures that can accommodate large amounts of enzymes on a single solid. This controlled design is shown to be effective for chemo-enzymatic epoxidation and appears as a promising way to develop new multifunctional materials.
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Smeets, V. (2019). New synthetic approaches to efficient Ti–SiO2 epoxidation catalysts. https://hdl.handle.net/2078.5/124648