The Preparation Of Rare Earth Ce Modification Y Zeolite

The Ce modified NaY zeolite was prepared by liquid-phase ion ex-change method,the preparation process was optimized by single-factor ex-periment.A series of CeY zeolites with different Ce content were prepared by the optimized process,the location and migration of Ce in NaY molecular sieves got by Rietveld structure refined.Ce(NO3)3.6H2O was choosed as rare earth precursor,the CeY prepar-ation process optimized as follows:5.000g NaY zeolite added 50mL distilled water,and the mixture solution was uniformly stirred and adjusted the pH about 6?7 with 1 mol/L and 0.1 mo1/L dilute nitric acid solution,cerium nitrate hexahydrate was added to the solution and the concentration of ce-rium nitrate hexahydrate in the solution is 30g/L,then the pH of the solution is adjusted to 4 with dilute nitric acid,stirred for 2h on 90?,filtered,washed,dried,and calcined 3h at 550?,this is a preparation process of first exchange and first calcination,and the exchange is performed again,only the concentration of cerium nitrate hexahydrate in the exchange solu-tion was changed to 20 g/L,the second calcination condition is to roasted at 550? for 1 hour.A series of Ce-modified NaY zeolites with different Ce contents were prepared by liquid-phase ion exchange that had been optimized before.The samples were characterized by XRD combined Rietveld structure refinement to study the localization and migration of Ce in NaY zeolite during the ex-change and calcination progress.The results showed that after the first ex-change,Ce is only located in the supercage of molecular sieve,after the first calcination,about 74.67%Ce migrate to the sodalite cage and coordinates with the structure O3.The migration of Ce in zeolite second exchange and the second calcination were similar to the first exchange and the first calci-nation,except that the migration of Ce content is decreased to 43.61%.NaY zeolite and four typical samples were selected to did other char-acterization,XPS and XRF characterization data showed that most of Ce entered the cage and only tiny part of Ce was located on the surface.It is similar to Raman results.XPS analysis showed that the valence of Ce located molecular sieve surface is 4.NH3-TPD and Py-IR showed that after the in-troduction of Ce in zeolite,the weak acid content was decreased,at the same time,the proportion of medium strong acid was increased,It has changed the acid type distribution on surface,that is the distribution of B acid was increased and L acid was decreased.N2 physisorption-desorption show that the specific surface area and pore volume of the sample were decreased with the increase of cerium content in the zeolite.