Novel Silica Gel Supported Polyether Ionic Liquids:Efficient Catalysts Applied in Transformation of Carbon Dioxide

(整期优先)网络出版时间:2018-04-14
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Threenewcatalystsbasedonthesilicagelsupportedpolyetherionicliquids(ILs),i.e.,[HO-PECH-MIM]Cl-Si,[H2N-PECH-MIM]Cl-Si,and[HOOC-PECH-MIM]Cl-Si,wereprepared,andtheirchemicalstructureswerecharacterizedbyinfrared(IR)spectroscopyandnuclearmagneticresonance(NMR)spectroscopy.Thermogravimetricanalyzer(TG),X-raydiffractometer(XRD)andscanningelectronmicroscope(SEM)wereusedtoevaluatetheirthermalstability,crystallinestructureandapparentmorphology,respectively.SurfaceareasofthepreparedcatalystswerecalculatedbytheBrunauer-Emmett-Teller(BET)method.Thecatalyticreactionforthesynthesisofpropylenecarbonate(PC)usingCO2andpropyleneoxide(PO)inthepresenceofthepreparedcatalystswasstudied.Theinfluencesoftimesofrecyclingandcatalyststructureoncatalyticperformancewerealsoinvestigated.TheexperimentalresultsshowedthatthesilicagelsupportedpolyetherILscatalystssuccessfullypreparedundermildconditioncouldpossesstheadvantagesofhighactivity,excellentthermalstability,goodselectivityandeasyrecycling,whilethephasetransitionoftheliquidpolyetherILscatalystswasalsoachieved.Whenthereactiontemperaturewas90°C,theCO2pressurewas2.0MPaandthedosageofthecatalystwas2.5%,[HOOC-PECH-MIM]Cl-Siwasfoundtohavethebestcatalyticperformanceinthecatalyticprocess,withtheconversionratereaching100%andtheselectivityequatingto98.2%.Theconversionrateandselectivitystillcouldreachmorethan90%evenafterthecatalystwasreusedfor15times.