Study On Preparation Technology Of Ce Modified Y Zeolite

The Ce modified NaY zeolite was prepared by liquid-phase ion exchange method,Through the systematic research on the technological parameters of the first exchange,the first calcination,the second exchange and the second calcination,The CeY molecular sieve samples were prepared by"two exchange one calcination" pro cess which can meet the requirement of technical index.The location and migration of Ce in NaY molecular sieves got by Rietveld structure refinement.Ce(NO3)3.6H2O was choosed as rare earth precursor,the CeY prepar-ation process optimized as follows:Add a moderate amount of distilled water in NaY zeolite and cerium nitrate solution,the content of Ce species(measured on a scale of Ce2O3)is 12wt%,The concentration of Ce species(measured on a scale of Ce2O3)is 11g/L,adjust the solution pH value about 4.00 with 0.5mol/L and 0.1mol/L nitric acid solution,adjust the exchange temperature about 90?,and the exchange time is 2h.After filter and washed with distilled water about 40 ?,stoving 2h under 105 ?,this is the "one exchange" CeY zeolite samples.then calcined the"one exchange"CeY zeolite samples 3h at 550? obtained the"one exchange one calcinati-on" CeY zeolite sample.The second exchange process and the first exchange process did not change except adding amount of rare earths change into 1 2.28 wt%.In this way," two exchange one calcination" CeY zeolite samples were prepared.And calcined the"two exchange one calcination" CeY zeolite samples 3h at 550? obtained the”two exchange two calcination" CeY zeolite samples.ICP-AES,XRD characterization analysis and Rietveld structure re-finement were used to analyze the difference between " two exchange one calcination"and the" two exchange two calcination”CeY zeolite sa-mples.Found rare earth can only enter into the supercage after the e-xchange,and cann't enter into sodalite cage until calcined,Ce in super cage to gradually migrated to the sodalite cage,and the migration m-ount of rare earth increased with time,and reached a certain valueaft-er 3h which is the maximum value of Ce content.The results of refi-nement and ICP-AES characterization showed that CeY zeolite sampl-es prepared by the optimized process "two exchange one calcination" c-an meet the requirements of the existing process indexes and can re-place the "two exchange two calcination" process.