Article Abstract:
A method for acidity adjustment of HZSM-5 zeolites with steaming and citric acid treatments, is described and the realumination effects of citric acid on HZSM-5 zeolites dealuminated by steaming is studied. The realumination effect of the citric acid treatment on the streamed HZSM-5 zeolite, can nearly recover the pore structure of the steamed zeolite to that of parent HZSM-5 zeolite and appropriately tailor the amount and strength of different acid sites.
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Article Abstract:
The crystallization process of colloidal (nanosized) molecular sieves stabilized in water with Raman and (super 13)C NMR spectroscopic methods was investigated by using the encapsulation of small quaternary ammonium ions in zeolite framework. The molecular packing effect and restricted mobility resulted in the shifts and substantial broadening of the (super 13)C NMR signals and, position changes and relative intensities of the Raman peaks.
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Article Abstract:
Solid-state nuclear magnetic resonance spectroscopy (NMR) and density functional theory (DFT) calculations are used to investigate the covalent linkages formed in organically functionalized MCM-41mesoporous silica materials. The results have shown that state-of-art spectroscopic and theoretical methods can be used together to refine the complex structures of inorganic-organic hybrid materials.
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