High Resolution Electron Microscopy and Catalytic studies of Pure and Copper Interchanged Y Faujasites
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HIGH RESOLUTION ELECTRON MICROSCOPY AND CATALYTIC STUDIES OF PURE AND COPPER INTERCHANGED Y FAUJASITES DWIGHT R. ACOSTA*,
JOSE OROZCO, MAURO BRICERO** AND MITSUO OGUNacional Aut6noma de Mfxico, SUniverisdad IFUNAM, A.P. 20-264 01000 Mexico, D.F. MEXICO ** Universidad de Los Andes, Facuttad de Ciencias, Mltrida, VeRA***
nezuela
*** Univerzidad Central de Venezuela,
Caracas,
Venezuela
ABSTRACT Commercial pute Y Faujasites wete intetchanged with sevetat metatlic ions, in order to improve catalytic properties. The resulting .samptes were studied using a series o6 physicochemical techniques and catalytic tests were realized some 4esults are reported in this work. THEORY Synthetic zeotites improve their catalytic properties when the original structural sodium ions ate interchanged with another metallic ions. Improved chemical properties usually are connected with vatiation oD6physical properties with &ezpect the non inte4changed zeotites. In order to check poszible changes, surfjace area measurements, differential thetmal analyzis, magnetic susceptibility studies, structural crystatlogrcaphic observations and catalytic standard test werte realized; a•t o4 them, give independente o6 simultaneousty infotmation about phy.ico-chemicat changes in the sample.6. In 6igure I fourPL dtfferent cationic sites o6 Y zeolitez ate showed. EXPERIMENTAL Interchange was realized using salts like Cu(NO3 ) 6 H2 0 for instance, and fottowing standard techniques (1). Smattl quantities o6 each interchanged zeolite were studied using specific atea measurements, differential thermal analysis in order to check thetmat instabilities, magnetic susceptibility using the Faraday method o6 constant force to test the magnetic state o6 interchanged metattic ions; X rays difftaction and selected a-tea electton microscopy were used to check structutal altetations; high tezotution electron microscopy was used to detect in projected potencial images, the pte4ence and density oj fautlted zones in the material; in this stage azso degradation process were followed fot each different interchanged zeotite. At last severat catalytic test were perfotmed in an integrtal fux system and resulting prtoducts wete detected using gas cromatohraphy techniques. RESULTS The Y faujazitez interchanged with Pt, Ni, Co and Cu were analyzed with atomic absorption techniques and azso the corresponding interchange isothetms got each one, were obtained. In 6igure 2 some results are showed and from this it can be appreMat. Res. Soc. Symp. Proc. Vol. 139. @1989 Materials Research Society
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ciated that: 1. The sodium ions interchange with transition metal ions is not a quantitative one. This means that for the tatio Eq Met/Eq Na=1, the masimum of intetchange does not teach in each case the 50% rtespectively. 2. The maximum of intetchange teached follows the sequence: Y + Co>Y + Ni>Y + Cu>VY + Pt
this sequence could be telated with ionic tadii oj intetchanged metals. Structural Results.
X rLays diffraction obsetvations and selected atea electron difftactions pattetns teveal
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