Zwitterionic Imidazole‐Urea Derivative Framework Bridged Mesoporous Hybrid Silica: A Highly Efficient Heterogeneous Nanocatalyst for Carbon Dioxide Conversion

Abstract

The use of supported zwitterionic nanoparticles is an interesting and important strategy for the development of new CO2 conversion catalysts with enhanced activity and selectivity. Several zwitterionic imidazole‐urea derivative frameworks bridged mesoporous hybrid silica materials were prepared and characterized by using FTIR spectroscopy, solid‐state NMR spectroscopy, X‐ray photoelectron spectroscopy, XRD, TEM, and thermogravimetric analysis. The new Im‐Si‐X‐ϕ materials possess a high surface area, hydrogen‐bond donor ability, and nucleophilicity. The material that contains iodine and is protonated by an inorganic acid shows an excellent catalytic activity for CO2 conversion into cyclic carbonates with good recyclability. Reaction parameters for the cycloaddition of CO2 with propylene oxide to propylene carbonate were optimized. The one‐component material is an efficient heterogeneous catalyst for CO2 cycloaddition reactions and is a greener alternative to conventional supported transition‐metal catalysts. Its catalytic features were also compared to those of the unsupported free ionic compound and other supported catalysts reported previously.

Recent developments in organocatalysed transformations of epoxides and carbon dioxide into cyclic carbonates

“…In 2018, zwitterionic mesoporous silica-supported catalysts were created by Arai et al, containing imdizaole-urea frameworks attached onto silica. 141 By changing the anions coordinating to the imidazole component, the efficiency of these catalysts to form cyclic carbonate varied in line with the nucleophilicity of the anions tested (I -> Br -> Cl -> NO 3 -). Under the optimum reaction conditions (110 o C, 25 bar carbon dioxide, 7.5 wt% of catalyst relative to epoxide after 4 h) conversions of 82-98% and ≥98% selectivity were obtained for four terminal epoxides.…”

Cycloaddition of Carbon Dioxide to Epoxides for the Synthesis of Cyclic Carbonates with a Mixed Catalyst of Layered Double Hydroxide and Tetrabutylammonium Bromide at Ambient Temperature

“…[8] At present, however, these heterogeneous catalysts require harsh reaction conditions, which limits their practical application. [9] Therefore, the development of more effective heterogeneous catalysts with high catalytic activity and selectivity under mild reaction conditions is still a hot and significant issue. and SO 4 2À , and x is normally between 0.2-0.4.…”

“…Considering these drawbacks of homogeneous catalysts, a number of heterogeneous ones have been developed for the CO 2 fixation to cyclic carbonates, such as metal‐organic frameworks (MOFs), porous organic polymers (POPs), metal‐oxides and carbon‐based material . At present, however, these heterogeneous catalysts require harsh reaction conditions, which limits their practical application . Therefore, the development of more effective heterogeneous catalysts with high catalytic activity and selectivity under mild reaction conditions is still a hot and significant issue.…”

Heterogeneous catalysts for cyclic carbonate synthesis from carbon dioxide and epoxides

“…In the same year, Liu and co-workers developed zwitterionic nanocatalysts with imidazole-urea derived frameworks [12]. The imidazole-urea components were attached to mesoporous hybrid silica materials, and different versions of the catalyst with various nucleophilic anions were prepared (Figure 4).…”