Reaction-Controlled Phase-Transfer Catalysis for Propylene Epoxidation to Propylene Oxide

Abstract

The epoxidation of olefins with H2O2 was performed with a tungsten-containing catalyst. This insoluble catalyst forms soluble active species by the action of H2O2, and when the H2O2 is used up, the catalyst precipitates for easy recycling. Thus, the advantages of both homogeneous and heterogeneous catalysts are combined in one system through reaction-controlled phase transfer of the catalyst. When coupled with the 2-ethylanthraquinone/2-ethylanthrahydroquinone redox process for H2O2 production, O2 can be used for the epoxidation of propylene to propylene oxide with 85% yield based on 2-ethylanthrahydroquinone without any co-products. This approach avoids the problematic co-products normally associated with the industrial production of propylene oxide.

Construction of Amphiphilic Polyoxometalate Mesostructures as a Highly Efficient Desulfurization Catalyst

“…[ 18,19 ] To overcome this obstacle, a number of amphiphilic POM catalytic systems, both homogeneous and heterogeneous, have been reported. Common systems include phase transformation, [ 20 ] encapsulation by dendritic cations, [ 21 ] microemulsion formation, [22][23][24] and immobilization into a polymer or silica matrix. [ 19 , 25,26 ] However, generally both homogeneous and heterogeneous systems suffer from limitations.…”

NaCl-Promoted CuO–RuO2/SiO2 Catalysts for Propylene Epoxidation with O2 at Atmospheric Pressures: A Combinatorial Micro-reactor Study

“…Then, metal precursors were added into the mixture and the mixture was stirred for 1 h under these conditions. In order to obtain the gel, NH 4 OH was added to the synthesis mixture. After aging the gel for 24 h under ambient conditions, catalysts were dried at 120°C and further calcined at 550°C for 5 h. Pure s-SiO 2 material was prepared by skipping metal addition steps for wet impregnation method.…”

“…Thus, they are not preferable due to their environmental and economical drawbacks [2]. Because of the deficiencies of the aforementioned PO production processes, novel methods of producing PO have been explored which included direct oxidation of propylene using various catalytic systems and proper oxidants, such as H 2 O 2 [3][4][5] O 2 -H 2 gas mixture [6][7][8][9] and N 2 O [10,11]. However, high costs of these oxidants restrict the commercialization of these processes.…”

Transition Metal‐Catalyzed Epoxidation of Alkenes

“…The low tungsten leaching (<2%) using these catalysts is certainly advantageous. A particularly interesting system for the epoxidation of propylene to propylene oxide, working under pseudo-heterogeneous conditions, was reported by Zuwei and coworkers [35]. The catalyst, which was based on the Venturello anion combined with long-chain alkylpyridinium cations, showed unique solubility properties.…”