CENTRO DE INVESTIGACION Y DESARROLLO EN CIENCIAS APLICADAS "DR. JORGE J. RONCO"
Unidad Ejecutora - UE
Structural and morphological evolutions of spent FCC catalyst pellets toward NaA zeolite
MAXIMILIANO R. GONZALEZ; GEOLAR FETTER; ANDREA M. PEREYRA; VICTOR H. LARA; PEDRO BOSCH; ELENA I. BASALDELLA
JOURNAL OF MATERIALS SCIENCE
Lugar: Berlin; Año: 2016 vol. 51 p. 5061 - 5061
Sphericallyshaped pellets, usually discarded after use in fluidized-bed catalytic crackingunits (FCCs), were converted to zeolite A-surface-enriched pellets. The finalpellets were obtained through a two-step treatment consisting of: (1) alkalinethermal activation followed by (2) a hydrothermal crystallization inselectedreaction conditions. The alkaline thermal activation provided pellets mainlyconstituted by silico-aluminate compounds. When the pellets are heated at 800 ºC incontact with sodium carbonate, a structural rearrangement occurs which includesnepheline, crystalline aluminosilicate, and an amorphous fraction expected tobe silicon-enriched, preserving the pellet original geometry. Afterward,reaction mixtures were prepared by adding sodium hydroxide solution to theheat-treated product. Then, commercial sodium aluminate was added. During thehydrothermal synthesis at 85 ± 3 _C, zeolite A was formed from thecalcined product and NaAlSiO4 turned out to bean intermediary crystalline compound. The LTA crystals were already observedfor a reaction time of 0.5 h, but the highest conversion to pure zeolite A wasreached after 6 h. Those final round solid pellets showed an external surface fullycovered by well anchored zeolite A cubic crystals about 1?2 lm in size. Such materials may be very useful in ionexchange, molecular sieving, and adsorption processes. The crystalline orderingwas followed by XRD, SEM, NMR, and water adsorption.