Abstract:
The development of nanoporous gas separation membranes to extract H2
from a mixed fuel stream of CH4/H2O/CO2/CO is desirable for use in methane
steam reforming reactions. Ni-containing cordierite glass-ceramics are candidate
materials for this application. The final microstructure of these glass-ceramics
includes two sieving mechanisms: (1) a 5 Å channel inherent to the cordierite
crystal structure which grows normal to the surface of the glass, and (2) a
nanoporous non-stoichiometric spinel in the bulk with theoretical pore diameters
ranging from 4-8 Å.
Through reaction with hydrogen we demonstrate the ability to form
nanopores in NixMg1-xAl2O4 spinel. The stability limit for the non-stoichiometric
spinel formed during the H2 reaction lies between 0.5_x_0.75. The formation of
an equal number of nickel and oxygen vacancies in spinel is determined using
Rietveld refinement of X-ray diffraction data and thermogravimetric analysis.
These vacant sites form the nanopores in the defect spinel structure.
Description:
Advisory committee members: William Carty, Doreen Edwards, William Lacourse. Dissertation completed in partial fulfillment of the requirements for the degree of Doctorate of Philosophy in Materials Science and Engineering at the Kazuo Inamori School of Engineering, New York State College of Ceramics at Alfred University
