Surface modifications during Y zeolite dealumination

The external shell formed on a Y zeolite during steaming is shown by XPS to contain both Al and Si extracted from the framework. The progressive formation of SiOH defect groups during steaming and subsequent acid leaching may be followed by binding energy changes and by peak decomposition. The usefulness of the latter for characterization of the chemical environment in silica aluminas is, in this case, limited to suggesting a coherent framework for interpretation of binding energy shifts.