Reactions of carbon monoxide, nitric oxide, oxygen, and water vapor on commercial Pt/. gamma. Al/sub 2/O/sub 3/ and three-way catalysts

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1984

OSTI ID:5711337

Subramaniam, B

The CO-NO-O/sub 2/-H/sub 2/O reaction is of import in the catalytic cleanup of automotive exhaust gas. This thesis deals with several aspects of this reaction system, both on Pt/..gamma..Al/sub 2/O/sub 3/ and commercial three-way catalysts. Three-way catalysts (TWCs) are multimetallic and are currently used in automobiles in the US. They are capable of simultaneously controlling the emissions of the three major pollutants viz., CO, hydrocarbons and NO/sub x/. When CO, NO, O/sub 2/ and H/sub 2/O are passed over a TWC, depending upon oxidizing potential (S = (2(O/sub 2/) + NO)/CO) and temperature, some NH/sub 3/ may be formed. A reliable method to continuously monitor this NH/sub 3/ formation has been developed. The method is based on a quantitative oxidation of NH/sub 3/ (formed over the TWC) to NO on a Pt/..gamma..Al/sub 2/O/sub 3/ catalyst (housed in an auxiliary reactor) and measuring the NO using a continuous chemiluminescent analyzer. Complex dynamic behavior was discovered in a new catalytic system: CO-NO-O/sub 2/-H/sub 2/O system on Pt/..gamma..Al/sub 2/O/sub 3/ catalyst. Self-sustained, a periodic oscillations in outlet species concentrations were observed under certain steady inlet conditions. The oscillatory behavior always occurred in a rather narrow window of inlet O/sub 2/ concentrations near the stoichiometric point for the CO-O/sub 2/ reaction. The effects of catalyst aging, temperature and inlet gas concentrations on these oscillations are reported. The oscillations are explained qualitatively in terms of the competition among the various species for adsorption and subsequent reaction on the catalyst surface.

• OSTI ID: 5711337
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
500200* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ADSORPTION
AIR POLLUTION CONTROL
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
AMMONIA
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYSIS
CATALYSTS
CATALYTIC CONVERTERS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CONTROL
DATA
DIFFUSION
ELEMENTS
EQUIPMENT
EXHAUST GASES
EXPERIMENTAL DATA
FLUIDS
GASEOUS WASTES
GASES
HYDRIDES
HYDROGEN COMPOUNDS
INFORMATION
KINETICS
MASS TRANSFER
MATHEMATICAL MODELS
METALS
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NITROGEN OXIDES
NONMETALS
NUMERICAL DATA
OXIDATION
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
POLLUTION CONTROL
POLLUTION CONTROL EQUIPMENT
QUANTITY RATIO
REACTION KINETICS
SORPTION
TEMPERATURE DEPENDENCE
TIME DEPENDENCE
TRANSITION ELEMENTS
WASTES
WATER
YIELDS