DRIFTS Study of Surface of γ-Alumina and Its Dehydroxylation
Citations Over TimeTop 18% of 2008 papers
Abstract
γ-Alumina surfaces pretreated at different temperatures (25 to 450 °C) and their rehydration after pyridine adsorption were studied using the conventional pyridine adsorption/DRIFTS technique. The results show that hydration at ambient temperature cannot convert all of the surface-coordinatived unsaturated Al sites to six-coordination, and weak and medium strong Lewis acid sites can still be observed for the fully hydrated γ-alumina. Dehydration at above 200 °C starts to generate strong Lewis acid sites. The number of weak, medium strong, and strong Lewis acid sites changes with dehydration temperature and all types of Lewis acid sites have adjacent OH groups. A good correlation between the number of Lewis acid sites and the intensity of perturbed OH groups is observed. Rehydration of the pyridine-adsorbed 450 °C pre-dehydrated alumina leads to removal of the pyridine adsorbed on the strong and medium strong Lewis acid sites and recovery of the surface of the original alumina. Water cannot replace the pyridine adsorbed on the weak Lewis acid sites.
Related Papers
- → Effect of leaf dehydration duration and dehydration degree on PSII photochemical activity of papaya leaves(2014)13 cited
- → Effects of dehydration processes on colour and rehydration of fruits(1967)4 cited
- → Acetylene studies. IV. Dehydration of dialkylethynylcarbinols(1953)1 cited
- Analysis of influence factors on ultra heavy oil dehydration rate(2007)
- Experimental Research of Demulsification and Dehydration for Aging Heavy Oil(2010)