Mesoporous Silica-Supported Ionic Liquids as Catalysts for Styrene Carbonate Synthesis from CO2

Abstract

Various types of mesoporous silica were used as carriers to synthesize a series of immobilized imidazolium-based ionic liquids. Their activity was tested in the synthesis of styrene carbonate from CO2 and styrene. This is one-pot process, whereby two stages are carried out in one reactor and there is no need to isolate the intermediate product, epoxide. A systematic study on the influence of parameters such as temperature, the reaction time, CO2 pressure, as well as the amount and type of catalyst used was carried out. A strong synergistic catalytic effect of ionic liquid and Lewis acid was observed in promoting this reaction. The addition sequence of regents and amount of immobilized catalyst were considered crucial for the synthesis of styrene carbonate from CO2 and styrene. The tested silica-supported ionic liquids gave an easily-recyclable system which under the most favorable conditions ([mtespim]Cl/@SiO2; ZnBr2, 0.1 mol%; 110 °C, 4 h, 1 MPa) can be reused without a significant loss of catalytic activity nor selectivity.

Recent developments in state-of-the-art silica-modified catalysts for the fixation of CO2 in epoxides to form organic carbonates

“…This catalyst maintained its activity and selectivity for two cycles, but the loss in catalytic activity in the fourth cycle was observed due to the partial release of the catalyst and the deposition of side-products on the catalyst. 198 In another work, Pescarmona et al prepared a multi-layered covalently supported ionic liquid phase (mlc-SILP) using different bis-vinyl imidazolium salts on thiol-functionalized silica for the synthesis of cyclic carbonates via the conversion of CO 2 with epoxide. This reaction progressed via the supported imidazolium-based ionic liquids with Br − and I − as halides, which acted as a nucleophile.…”

Mixed Manganese Dioxide on Magnetite Core MnO2@Fe3O4 as a Filler in a High-Performance Magnetic Alginate Membrane

“…In the case of the Alg-MnO 2 membrane with 5 wt.% filler loading, fine sponge-like structures with numerous channels formed (Figure 2). This kind of structure is frequently observed in mesoporous silica [39]. The unbroken agglomerates of MnO 2 in 5 wt.% loaded membranes were rare and the typical size of filler grains was about 2-4 µm.…”

Deep Eutectic Solvents as Catalysts for Cyclic Carbonates Synthesis from CO2 and Epoxides

“…As the reaction of carbon dioxide and epoxide can only occur in the presence of a catalyst [11], many different catalytic systems have been developed for this synthesis. The most common catalysts are quaternary onium salts (including ammonium, phosphonium and imidazolium halides [10,[12][13][14]), Lewis bases [10,15,16], N-heterocyclic carbenes [17], ionic liquids (ILs) [18][19][20][21], deep eutectic solvents (DES) [22][23][24], metal oxides (e.g., MgO, Nb 2 O 5 ) [10,25], metal halides [10] and metal-organic complexes [10,26], including metal-organic frameworks [27].…”