Insights into the Nature of the Active Sites of TināMontmorillonite for the Synthesis of Polyoxymethylene Dimethyl Ethers (OME)
In this study,we reportthat intercalationof tin into montmor-illoniteclay (Sn-MMT)boostscatalyticactivityfor the synthesisof polyoxymethylenedimethylethers,a promisingdieselfueladditive.This increasein activityis attributedto the formationof a hierarchicalcatalystdisplayinghighsurfaceareawithaccessibleBrĆønstedand Lewisacid sites.Extensivecharacter-izationsuchas MAS-NMR,XRD and in-situDRIFTSconfirmedthat tin insertioninducedreorganizationof the clay layersintoa disorganizedhouse-of-cardsstructure.It also revealedthat tinresidedbetweenthe clay layersas defectiveSnO2nanocrystalsstabilizedby the negativechargeof MMT.The sourceof acidityin Sn-MMTwas studiedby comparingit withtwo similarmaterials,namelySn(OH)4, and thermallytreatedSn-MMT.Lowactivitymeasuredfor isolatedhydroxylatedSnO2nanoparticlesillustratesthe importanceof havingclayand tin in closeproximity.Meanwhile,deactivationuponthermaltreatmentoccurredvia sinteringof the tin phaseand diffusionof theprotonsinsidethe layers.Sn-MMTacidityis attributedto thecombinationof SiOHAl groups,formedas a by-productofSnO2crystallization,and undercoordinatedSn surfacesites,stabilizedby the negativechargeof MMT.
ChemCatChem - 2019 - Baranowski - Insights into the Nature of the Active Sites of TināMontmorillonite for the Synthesis of.pdf
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