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  • 1
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    The effect of H2O and pretreatment on the activity of a Pt/SnO2 catalyst (1990)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: CO oxidation catalysts with high activity at 25 C to 100 C are important for long-life, closed-cycle operation of pulsed CO2 lasers. A reductive pretreatment with either CO or H2 has been shown to significantly enhance the activity of a commercially available platinum on tin (IV) oxide (Pt/SnO2) catalyst relative to an oxidative or inert pretreatment or no pretreatment. Pretreatment at temperatures of 175 C and above causes an initial dip in the observed CO2 yield before the steady-state yield is attained. This dip has been found to be caused by dehydration of the catalyst during pretreatment and is readily eliminated by humidifying the catalyst or the reaction gas mixture. It is hypothesized that the effect of humidification is to increase the concentration of OH groups on the catalyst surface which play a role in the reaction mechanism.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: Low-Temperature CO-Oxidation Catalysts for Long-Life CO2 Lasers; p 181-191
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  • 2
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    Pt/SnO2-based CO-oxidation catalysts for long-life closed-cycle CO2 lasers (1990)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Noble-metal/tin-oxide based catalysts such as Pt/SnO2 have been shown to be good catalysts for the efficient oxidation of CO at or near room temperature. These catalysts require a reductive pretreatment and traces of hydrogen or water to exhibit their full activity. Addition of Palladium enhances the activity of these catalysts with about 15 to 20 percent Pt, 4 percent Pd, and the balance SnO2 being an optimum composition. Unfortunately, these catalysts presently exhibit significant decay due in part to CO2 retention, probably as a bicarbonate. Research on minimizing the decay in activity of these catalysts is currently in progress. A proposed mechanism of CO oxidation on Pt/SnO2-based catalysts has been developed and is discussed.
    Keywords: LASERS AND MASERS
    Type: Low-Temperature CO-Oxidation Catalysts for Long-Life CO2 Lasers; p 41-53
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  • 3
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    Studies of long-life pulsed CO2 laser with Pt/SnO2 catalyst (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Closed-cycle CO2 laser testing with and without a catalyst and with and without CO addition indicate that a catalyst is necessary for long-term operation. Initial results indicate that CO addition with a catalyst may prove optimal, but a precise gas mix has not yet been determined. A long-term run of 10 to the 6th power pulses using 1.3% added CO and a 2% Pt on SnO2 catalyst yields an efficiency of about 95% of open-cycle steady-state power. A simple mathematical analysis yields results which may be sufficient for determining optimum running conditions. Future plans call for testing various catalysts in the laser and longer tests, 10 to the 7th power pulses. A Gas Chromatograph will be installed to measure gas species concentration and the analysis will be slightly modified to include neglected but possibly important parameters.
    Keywords: LASERS AND MASERS
    Type: Closed-Cycle, Frequency-Stable CO2 Laser Technology; p 211-218
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  • 4
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    Catalysts for long-life closed-cycle CO2 lasers (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Long-life, closed-cycle operation of pulsed CO2 lasers requires catalytic CO-O2 recombination both to remove O2, which is formed by discharge-induced CO2 decomposition, and to regenerate CO2. Platinum metal on a tin (IV) oxide substrate (Pt/SnO2) has been found to be an effective catalyst for such recombination in the desired temperature range of 25 to 100 C. This paper presents a description of ongoing research at NASA-LaRC on Pt/SnO2 catalyzed CO-O2 recombination. Included are studies with rare-isotope gases since rare-isotope CO2 is desirable as a laser gas for enhanced atmospheric transmission. Results presented include: (1) achievement of 98% to 100% conversion of a stoichiometric mixture of CO and O2 to CO2 for 318 hours (greater than 1 x 10 to the 6th power seconds), continuous, at a catalyst temperature of 60 C, and (2) development of a technique verified in a 30-hour test, to prevent isotopic scrambling when CO-18 and O-18(2) are reacted in the presence of a common-isotope Pt/Sn O-16(2) catalyst.
    Keywords: LASERS AND MASERS
    Type: Closed-Cycle, Frequency-Stable CO2 Laser Technology; p 113-119
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  • 5
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    A proposed mechanism for Pt/SnO(x)-catalyzed CO oxidation (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A mechanism for Pt/SnO(x)-catalyzed CO oxidation is proposed, which is consistent with a broad range of experimental observations. CO oxidation catalysts with high activity at or near room temperature are used in closed-cycle CO2 lasers and air purification.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: Journal of Catalysis (ISSN 0021-9517); 130; 314-317
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  • 6
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    Research on catalysts for long-life closed-cycle CO2 laser oaperation (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: Long-life, closed-cycle operation of pulsed CO2 lasers requires catalytic CO-O2 recombination both to remove O2, which is formed by discharge-induced CO2 decomposition, and to regenerate CO2. Platinum metal on a tin-oxide substrate (Pt/SnO2) has been found to be an effective catalyst for such recombination in the desired temperature range of 25 to 100 C. This paper presents a description of ongoing research at NASA-Langley on Pt/SnO2 catalyzed CO-O2 recombination. Included are studies with rare-isotope gases since rare-isotope CO2 is desirable as a laser gas for enhanced atmospheric transmission. Results presented include: (1) the effects of various catalyst pretreatment techniques on catalyst efficiency; (2) development of a technique, verified in a 30-hour test, to prevent isotopic scrambling when C(O-18) and (O-18)2 are reacted in the presence of a common-isotope Pt/Sn(O-16)2 catalyst; and (3) development of a mathematical model of a laser discharge prior to catalyst introduction.
    Keywords: LASERS AND MASERS
    Type: Laser radar II; May 19, 20, 1987; Orlando, FL; United States
    Format: text
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  • 7
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    Isotope exchange in oxide-containing catalyst (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A method of exchanging rare-isotope oxygen for common-isotope oxygen in the top several layers of an oxide-containing catalyst is disclosed. A sample of an oxide-containing catalyst is exposed to a flowing stream of reducing gas in an inert carrier gas at a temperature suitable for the removal of the reactive common-isotope oxygen atoms from the surface layer or layers of the catalyst without damaging the catalyst structure. The reduction temperature must be higher than any at which the catalyst will subsequently operate. Sufficient reducing gas is used to allow removal of all the reactive common-isotope oxygen atoms in the top several layers of the catalyst. The catalyst is then reoxidized with the desired rare-isotope oxygen in sufficient quantity to replace all of the common-isotope oxygen that was removed.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
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  • 8
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    Reactivation of a tin oxide-containing catalyst (1989)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A method for the reactivation of a tin oxide-containing catalyst of a CO.sub.2 laser is provided. First, the catalyst is pretreated by a standard procedure. When the catalyst experiences diminished activity during usage, the heated zone surrounding the catalyst is raised to a temperature which is the operating temperature of the laser and 400.degree. C. for approximately one hour. The catalyst is exposed to the same laser gas mixture during this period. The temperature of the heated zone is then lowered to the operating temperature of the CO.sub.2 laser.
    Keywords: Inorganic, Organic and Physical Chemistry
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  • 9
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    Enhancement of Pt/SnO2 Catalysts by Addition of H2O (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Water vapor in pretreatment gas restores essential hydroxyl groups. Platinum on tin oxide (Pt/SnO2) is good catalyst for oxidation of carbon monoxide (CO) at temperatures from about 25 degrees C to 100 degress C. Activity of Pt/SnO2 for CO oxidation significantly enhanced by pretreating it at approximately 225 degrees C with reducing gas such as CO. Technique useful in manufacture of high-power CO2 lasers for industrial and scientific uses.
    Keywords: MATERIALS
    Type: LAR-14084 , NASA Tech Briefs (ISSN 0145-319X); 14; 7; P. 54
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  • 10
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    Isotope Exchange in Oxide Catalyst (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Replacement technique maintains level of CO2/18 in closed-cycle CO2 lasers. High-energy, pulsed CO2 lasers using rare chemical isotopes must be operated in closed cycles to conserve gas. Rare isotopes operated in closed cycles to conserve gas. Rare isotopes as CO2/18 used for improved transmission of laser beam in atmosphere. To maintain laser power, CO2 must be regenerated, and O2 concentration kept below few tenths of percent. Conditions achieved by recombining CO and O2.
    Keywords: MATERIALS
    Type: LAR-13542 , NASA Tech Briefs (ISSN 0145-319X); 11; 6; P. 40
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