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Heterogeneous photocatalytic oxidation of atmospheric trace contaminants (Document No: 19970015392)
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Ollis, David F. |
| Copyright Year | 1996 |
| Description | Heterogeneous photocatalysis involves the use of a light-activated catalyst at room temperature in order to carry out a desired reaction. In the presence of molecular oxygen, illumination of the n-type semiconductor oxide titanium dioxide (TiO2) provides for production of highly active forms of oxygen, such as hydroxyl radicals, which are able to carry out the complete oxidative destruction of simple hydrocarbons such as methane, ethane, ethylene, propylene, and carbon monoxide. This broad oxidation potential, coupled with the ability with sufficient residence time to achieve complete oxidation of simple hydrocarbon contaminants to carbon dioxide and water, indicated that heterogeneous photocatalysis should be examined for its potential for purification of spacecraft air. If a successful catalyst and photoreactor could be demonstrated at the laboratory level, such results would allow consideration of photocatalysts as a partial or complete replacement of adsorption systems, thereby allowing for reduction in lift-off weight of a portion of the life support system for the spacecraft, or other related application such as a space station or a conventional commercial aircraft. The present research was undertaken to explore this potential through achievement of the following plan of work: (a) ascertain the intrinsic kinetics of conversion of pollutants of interest in spacecraft, (b) ascertain the expected lifetime of catalysts through examination of most likely routes of catalyst deactivation and regeneration (c) model and explore experimentally the low pressure drop catalytic monolith, a commercial configuration for automotive exhaust control (d) examine the kinetics of multicomponent conversions. In the recent course of this work, we have also discovered how to increase catalyst activity via halide promotion which has allowed us to achieve approximately 100% conversion of an aromatic contaminant (toluene) in a very short residence time of 5-6 milliseconds. |
| File Size | 1241512 |
| Page Count | 34 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19970015392 |
| Archival Resource Key | ark:/13960/t5z65g16z |
| Language | English |
| Publisher Date | 1996-09-30 |
| Access Restriction | Open |
| Subject Keyword | Environment Pollution Methane Catalysts Carbon Dioxide Automobiles Space Stations Titanium Oxides Propylene Heterogeneity Air Purification Adsorption Contaminants N-type Semiconductors Carbon Monoxide Exhaust Emission Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
