Title page for ETD etd-08252005-144859


Type of Document Master's Thesis
Author Ma, Qiang
Author's Email Address qma@vt.edu
URN etd-08252005-144859
Title HALOETHANE REACTIONS OVER THE CHROMIA Cr2O3(1012) SURFACE
Degree Master of Science
Department Chemical Engineering
Advisory Committee
Advisor Name Title
Cox, David F. Committee Chair
Davis, Richey M. Committee Member
Oyama, Shigeo Ted Committee Member
Keywords
  • dissociation
  • ethyl chloride
  • metal oxide
  • hydrogenation
  • chromium (III) oxide
  • dehydrogenation
  • haloethane
  • ethyl iodide
Date of Defense 2005-08-11
Availability unrestricted
Abstract

Ethyl iodide and ethyl chloride have been used as reactants to produce ethyl fragments on the stoichiometric α-Cr2O3(1012) surface by means of thermal dissociation. Ethyl iodide is dissociated giving iodine adatoms and ethyl fragments bound to surface Cr cation sites, while ethyl chloride is dissociated giving chlorine adatoms and ethyl fragments. No oxygenated products are observed in thermal desorption, suggesting the 3-coordinate lattice oxygen on the stoichiometric α-Cr2O3(1012) surface is very stable, and no nucleophilic attack occurs at the carbon atoms on surface ethyl fragments.

For both reactants, the only reaction products observed are ethylene gas (CH2=CH2), ethane gas (CH3-CH3), hydrogen gas (H2) and halogen adatoms (Clads or Iads). In thermal desorption experiments, all the gas phase products from ethyl chloride are produced in a reaction-limited, high temperature desorption feature attributed to a rate limiting Β-hydride elimination from surface ethyl fragments. Similar product desorption features are observed for the reaction of ethyl iodide. However, the reaction of ethyl iodide also produces ethylene and ethane via a low temperature, desorption-limited reaction channel. It is postulated that I adatoms produced in the reaction of ethyl iodide thermal desorption might somehow promote a low temperature route to products that Cl adatoms do not.

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