133Cs and 23Na MAS NMR studies of zeolite X containing cesium

Abstract The local structures around cesium and sodium in the zeolites X containing cesium in excess of the ion-exchange capacity (cesium-added zeolite X ) were examined by 133 Cs and 23 Na MAS NMR to elucidate the location of the added cesium and the formation of the basic sites caused by addition of the excess cesium. The cesium species located in the intracrystalline cavities of zeolite and those on the outer surface of zeolite crystallites were distinguished by a combination of 133 Cs and 23 Na MAS NMR data. The excess cesium species are located in the supercages for the samples containing an excess of 1.1 and 2.9 cesium atoms per supercage, whereas for the samples containing 5.1 and 9.8 cesium atoms per supercage, parts of the cesium species are on the outer surface of the zeolite crystallites. The cesium-added zeolites which contain cesium species in the supercages and possess a high surface area exhibit high activities for 1-butene isomerization.