Title page for ETD etd-082199-084653


Type of Document Dissertation
Author York, Steven C.
Author's Email Address syork@swva.net
URN etd-082199-084653
Title Halocarbon Reactions on the Chromium (III) Oxide (1012) Surface
Degree PhD
Department Chemical Engineering
Advisory Committee
Advisor Name Title
Cox, David F. Committee Chair
Dillard, John G. Committee Member
Hanson, Brian E. Committee Member
Marand, Eva Committee Member
Oyama, Shigeo Ted Committee Member
Keywords
  • halocarbon
  • AES
  • XPS
  • acetylene
  • oxygen adsorption
  • chromium oxide
  • dehalogenation
  • single crystal
  • Cr2O3
  • haloalkene
  • haloalkane
Date of Defense 1999-08-13
Availability restricted
Abstract
A nearly stoichiometric, (1x1) Cr2O3 (1012) surface

was prepared from a single crystal of alpha-Cr2O3.

The five-coordinate cations exposed at the stoichiometric

surface dissociatively adsorb molecular oxygen to

form a (1x1), terminating chromyl (Cr=O) layer

that is stable to >1100 K. TDS and AES were used

to investigate the reactivity of the halo-alkanes

CFCl2CH2Cl, CF2ClCH2Cl, CF3CH2Cl, and CF2CH2F, in

addition to the halo-alkenes CFCl=CH2 and CF2=CH2.

The halo-alkanes CFCl2CH2Cl, CF2ClCH2Cl, and CF3CH2Cl

undergo 1,2-dihalo elimination similar to the Zn-catalyzed

dehalogenation of vicinal dihalides to form alkenes.

Some acetylene is also formed. The halo-alkenes

CFCl=CH2 and CF2=CH2 decompose to yield acetylene.

Halogen removed from the molecules remains bound

to the surface following TDS experiments and

eventually terminates the surface chemistry due

to site blocking of the cations. Reactivity is

directly related to the chlorine content of the

molecules investigated. Only CFCl2CH2Cl was

reactive on a chromyl-terminated surface.

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