Defect modification in MFI zeolite membranes: Cyclodextrin deposition
by Gibbons, William, M.S., UNIVERSITY OF COLORADO AT BOULDER, 2009, 70 pages; 1473631

Abstract:

β-Cyclodextrin (CD), which is too large to fit into MFI pores, was deposited in the defects of MFI zeolite membranes in an effort to decrease flow through the defects and increase separation selectivity. The permeation behavior of molecules that swell MFI crystals (SF6, n-butane, i-butane) and those that do not (He, H2), plus the permeation of i-octane, which only diffuses through membrane defects, were used to show that CD lodged in the defects, inhibited MFI crystal expansion due to adsorption, and limited how much the defects decreased in size. This unexpected result provides direct evidence that defect sizes decrease when some molecules adsorb in MFI pores, and demonstrates the difficulty of characterizing MFI membranes because defect sizes change in the presence of many adsorbates. Most of the CD could be removed by calcination, but it was not possible to completely remove CD, and membranes did not return to pre-CD behavior.
 
AdvisersJohn L. Falconer; Richard D. Noble
SchoolUNIVERSITY OF COLORADO AT BOULDER
SourceMAI/ 48-03, p. , Feb 2010
Source TypeThesis
SubjectsChemical engineering
Publication Number1473631
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