Pretreatment effect on the catalyst activity fand on the enthalpy changes during exposure of Pd/SnO{sub 2} and Pd metal to CO, O{sub 2}, and CO + O{sub 2}

Journal Article · Mon May 01 04:00:00 EDT 1995 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1995.1123· OSTI ID:96281

Tripathi, A K; Gupta, N M ^[1]

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1. Bhabha Atomic Research Centre, Bombay (India)

The paper reports on the adsorption and the enthalpy changes observed during exposure of a Pd(2%)/SnO{sub 2} catalyst and poly-crystalline Pd powder to CO, O{sub 2} and CO + O{sub 2} (2:1) at different temperatures in the 300-470 K range and as a function of an oxidizing (ox) or a reducing (red) pretreatment given to the samples. A larger fraction of CO was adsorbed/reacted as compared to that of O{sub 2} when a Pd/SnO{sub 2}(ox) sample was exposed to successive CO + O{sub 2} (2:1) pulses. The fraction of adsorbed O{sub 2} and the yield of CO{sub 2} increased progressively with the rise in sample temperature. On the other hand, a negligible amount of CO and mainly O{sub 2} was adsorbed/reacted on a Pd/SnO{sub 2}(red) at the respective temperatures of 300, 370, 420, and 470 K, the corresponding values in the case of the Pd/SnO{sub 2}(ox) sample being around 75, 125, 150, and 170 kJ mol{sup {minus}1}. In the case of Pd metal, the adsorption behaviour was almost independent of pretreatment and the fraction of CO or O{sub 2} adsorbed from a CO + O{sub 2} pulse depended on the catalyst temperature. The effect of H{sub 2} pretreatment on the adsorption characteristics and also on the observed CO oxidation activity of Pd/SnO{sub 2} is attributed to the formation of Pd-O-Sn moieties at the catalyst surface. 22 refs., 12 figs., 2 tabs.

• OSTI ID: 96281
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 153; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
40 CHEMISTRY
ADSORPTION
CARBON MONOXIDE
CATALYTIC EFFECTS
CHEMICAL PREPARATION
ENTHALPY
OXYGEN
PALLADIUM
PALLADIUM OXIDES
SORPTIVE PROPERTIES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TIN OXIDES