Accession Number : AD0712856

Title :   ELECTRONIC EFFECTS OF CHEMISORPTION ON A POWDERED ZINC OXIDE CATALYST.

Descriptive Note : Technical rept. Sep 68-Sep 70,

Corporate Author : PRINCETON UNIV N J

Personal Author(s) : Chong,Victor M. ; Mark,Peter

Report Date : SEP 1970

Pagination or Media Count : 110

Abstract : The report presents a general discussion of electronic surface states and their possible electronic and catalytic effects. It also presents a method by which the temperature-dependence of the catalyst's conductivity can be used to elicit information on the disposition of the surface states relative to the bulk band structure. The catalyst was ZnO in powder form and an impedance technique was used to measure its conductivity under single gas (CO and O2) and differential reaction (2CO + 02 yields 2CO2) ambients. Oxygen acceptor surface states appear to have a dominant influence over the catalyst's conductivity even at O2 pressures as low as 0.00001 torr and in reaction mixture containing greater than 4 parts CO to one part O2. The apparent donor effect of adsorbed CO appears to result from the interaction with adsorbed or lattice oxygen rather than from the formation of a donor-like CO adsorption state. The experimental measurements tend to confirm the energy band structure model of this semiconductor catalyst and reveal certain features of interest for the electronic theory of catalysis. However, it does appear that powder systems may be too complex to deal with quantitatively at the present stage of development of electronic surface state theories. (Author)

Descriptors :   (*ZINC COMPOUNDS, *ADSORPTION), (*CARBON MONOXIDE, *OXIDATION), BAND THEORY OF SOLIDS, MOLECULAR ENERGY LEVELS, SURFACES, CHEMISORPTION, CATALYSTS, CARBON DIOXIDES, OXYGEN, THESES

Subject Categories : Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE