Highly selective synthesis of single-walled carbon nanotubes from methane in a coupled Downer-turbulent fluidized-bed reactor

(整期优先)网络出版时间:2013-04-14
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Forthesynthesisofsingle-walledcarbonnanotubes(SWCNTs)fromCH4overaFe/MgOcatalyst,weproposedacoupledDowner-turbulentfluidized-bed(TFB)reactortoenhancetheselectivityandyield(orproductionrate)ofSWCNTs.Bycontrollingaveryshortcatalystresidencetime(1-3s)intheDowner,onlypartofFeoxidescanbereducedtoformFenanoparticles(NPs)availableforthegrowthofSWCNTs.ThepercentageofunreducedFeoxidesincreasedandtheyieldofSWCNTsdecreasedaccordinglywiththeincreaseofcatalystfeedingrateinDowner.SWCNTswerepreferentiallygrownonthecatalystsurfaceandinhibitedthesinteringoftheFecrystalliteswhichwouldbeformedthereafterinthedownstreamTFB,evidencedbyTEM,RamanandTGA.ThecoupledDowner-turbulentfluidized-bedreactortechnologyallowedhigherselectivityandhigherproductionrateofSWCNTsascomparedtoTFBalone.