Oscillations in Pt-catalyzed reactions: H sub 2 oxidation; pressure variations in CO oxidation; and coupled catalytic oscillators

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:7010221

Tsai, P K

Oscillations in the oxidation of H{sub 2} were systematically studied at atmospheric pressure. The behavior of the oscillations as a function of time, gas flow rate, and gas temperature was characterized for different ranges of P{sub H{sub 2}}/P{sub O{sub 2}}. Unusual oscillations in the oxidation of CO were observed at atmospheric pressure at transitions between states of low, intermediate and high activity. Oscillations were simple at high gas temperatures, and became complex as the temperature was lowered. Oscillations in the rate of CO oxidation over polycrystalline Pt have been measured at total pressures of 760 Torr and 10 Torr. Despite the pressure change of two orders of magnitude, oscillations occurred between similar values of high and low reactivity, and over roughly the same experimental parameters (T{sub g}, P{sub CO}/P{sub O{sub 2}}). This behavior is not predicted by standard Langmuir-Hinshelwood kinetics, and the author suggests alternate adsorption geometries involving inhomogeneous adsorbate distributions. In addition consideration of changes in the gas transport properties resulting from the pressure variations yielded information about the effect of coupling through gas phase diffusion on the oscillations.

• Research Organization: California Univ., San Diego, CA (USA)
• OSTI ID: 7010221
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
330702* -- Emission Control-- Carbon Monoxide
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800 -- Combustion
Pyrolysis
& High-Temperature Chemistry
54 ENVIRONMENTAL SCIENCES
540120 -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
ATMOSPHERIC PRESSURE
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMICAL REACTORS
DIFFUSION
ELECTRONIC EQUIPMENT
ELEMENTS
EQUIPMENT
FLOW RATE
FLUID FLOW
GAS FLOW
HYDROGEN
KINETICS
MEASURING INSTRUMENTS
METALS
MONITORING
NONMETALS
OSCILLATIONS
OSCILLATORS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PARTIAL PRESSURE
PLATINUM
PLATINUM METALS
PRESSURE DEPENDENCE
REACTION KINETICS
TEMPERATURE DEPENDENCE
TEMPERATURE MEASUREMENT
THERMOCOUPLES
TIME DEPENDENCE
TRANSITION ELEMENTS