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Ionic Liquids 英超联赛直播液体

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The direct production of methyl, ethyl and n-butyl carbamates (MC, EC and BC) from NH3, CO2 and alcohols could efficiently be catalyzed by V2O5, and ca. 11–25% yields with 98% selectivity for alkyl carbamates could be obtained. The catalyst could be recycled six times without obvious decrease in catalytic activity. XRD and XPS analysis showed that in-situ produced (NH4)2V3O8 was the catalytically active species.

Keywords: Carbon dioxide; Vanadium(V)-oxide catalyst; Fixation; Alkyl carbamates

★★★☆☆ Catalysis Communications 12 (2011) 1224–1227

One kind of novel ionic liquids (ILs) with a tertiary amino moiety and a quaternary ammonium group were synthesized and identified by FT-IR, 1H and 13C NMR. The elemental chemical state and basicity of ILs were determined by XPS and Hammett indicator method, respectively. Then the catalytic performance of these bifunctional catalysts was investigated in one-step synthesis of dimethyl carbonate (DMC) from ethylene oxide (EO), carbon dioxide and methanol. The best catalytic performance with 99% EO conversion and a maximum of 74% DMC selectivity was obtained using [N111,6N11]I as catalyst under optimized reaction conditions. And the catalyst could be reused for several times. Normally, stronger basicity could be obtained by altering the anions with different nucleophilicity in ILs and a better catalytic activity could be achieved correspondingly. A mechanism that both the ring opening of epoxide through nucleophilic attacks and the transesterification play an important role in the reaction was proposed based on experimental results.

Keywords Ionic liquid  Bi-functional  One-step synthesis  Dimethyl carbonate  Carbon dioxide

★★★☆☆ Catal Lett (2011) 141:339–346

One kind of novel heterogenous bifunctional catalyst, MCM-41 grafted quaternary ammonium salts with terminal amino group, was prepared. These catalysts exhibited excellent catalytic performance and good reusability in the sequential synthesis of dimethyl carbonate from epoxides, CO2, and methanol.

★★★☆☆ Li J,Wang LG,Liu SM,et al. Mcm-41 Grafted Quaternary Ammonium Salts As Recyclable Catalysts For The Sequential Synthesis Of Dimethyl Carbonate From Epoxides, Co2, And Methanol[J]. Chem. Lett.,2010,39:1277-1278.