Formation of active sites in titanium-containing zeolites with MFI structure in propylene epoxidation with hydrogen peroxide

Abstract

Propylene epoxidation with hydrogen peroxide on titanosilicates with different Si/Ti ratios and various states of titanium in the catalysts, prepared by hydrothermal crystallization according to two different procedures, has been investigated. It has been demonstrated that a change in the pH of the crystallizing gel leads to a change in the sequence of titanium insertion in the zeolite structure at a hydrothermal synthesis temperature of 170°C. It was shown that titanium incorporated in the zeolite framework in the tetrahedral positions is an active site in the epoxidation reaction, whereas titanium in the form of titanium dioxide leads to unproductive degradation of hydrogen peroxide.

Liquid-Phase Epoxidation of Light Olefins over W and Nb Nanocatalysts

“…105 Therefore, a mechanism involving Lewis acid sites of moderate strength during epoxidation of alkenes with H 2 O 2 is proposed 207,230 while strong Lewis acidity activates the H 2 O 2 decomposition reaction. 231,232 The low selectivity has been attributed to the presence of strong Brønsted acid sites, which enhance the reaction of ring epoxide opening by hydrolysis.…”

Mesoporous Methyl-Functionalized Titanosilicate Produced by Aerosol Process for the Catalytic Epoxidation of Olefins

“…The Ti 2p spectrum is composed of two spin-orbit components (Ti 2p 3/2 and Ti 2p 1/2 ) which are separated by 5.7 eV [82]. While the Ti 2p 3/2 binding energy of pure TiO 2 is 458.5 eV (octahedral coordination) [82,83], it is known that Ti in titanosilicate displays peak broadening and shift to higher binding energy (BE) [29,62,80,84,85]. In fact, the Ti 2p 3/2 peak can be decomposed considering two kinds of Ti species: FW-Ti (460.0 eV) [83,[86][87][88] and EFW-Ti (458.5 eV) [82,83].…”

Liquid-Phase Epoxidation of Propylene with H2O2 over TS-1 Zeolite: Impurity Formation and Inhibition Study

“…10 The HPPO route is a new PO production process based on the liquid-phase epoxidation of propylene with dilute H 2 O 2 in the methanol solvent over the titanium hybridized MFI-type zeolite, titanium silicalite-1 (TS-1). 11 TS-1 zeolite was discovered by Taramasso et al in 1983. 12 Soon later, the pioneering way of olefins epoxidation with dilute H 2 O 2 over the TS-1 zeolite catalyst was claimed by Neri et al 13 The commercialization of the HPPO process was realized in 2008.…”

“…The HPPO route is a new PO production process based on the liquid-phase epoxidation of propylene with dilute H 2 O 2 in the methanol solvent over the titanium hybridized MFI-type zeolite, titanium silicalite-1 (TS-1) . TS-1 zeolite was discovered by Taramasso et al in 1983 .…”