Solid-State MAS NMR Study of Hydrated/Dehydrated Phosphorus-modified ZSM-5 Zeolite

摘要

The chemical changes of the phosphorus-modified ZSM-5 zeolites in hydration/dehydration processes have been studied by using the solid-state MAS NMR spectroscopy. The identification of the chemical species of the steamed or washed zeolite could be done by analyzing the spectral changes on the solid-state multinuclear MAS NMR spectroscopy when the zeolite was hydrated and dehydrated. It was reconfirmed that the steaming process effectively remove Al-attached polyphosphates from the zeolite framework even though the zeolite was modified with phosphorus but the washing process did not. Dehydration process led to a dramatic change of aluminum species by breaking the aluminum-oxygen bond in the zeolite framework and to a formation of polyphosphate attached to aluminum.