Mechanistic studies of heterogeneously catalyzed reactions of ammonia and acetic acid on platinum surfaces

Thesis/Dissertation · Thu Jan 01 00:00:00 EST 1987

OSTI ID:7050801

Vajo, J J

The design and operation of a versatile microreactor capable of studying the rates of both steady-state and batch heterogeneous reactions on a wire, a foil or a single crystalline surface at pressures between 10/sup -7/ and 1000 Torr are described. The residence time distribution of the microreactor was characterized in order to evaluate the validity of using the continuous stirred tank reactor approximation to calculate reaction rates. Absolute reaction rates have been measured for both the catalytic decomposition of NH/sub 3/ and ND/sub 3/ and the NH/sub 3/ + D/sub 2/ exchange reaction over a polycrystalline platinum wire. The measured kinetics of the NH/sub 3/ + D/sub 2/ exchange reaction were employed together with adsorption-desorption parameters of NH/sub 3/, N/sub 2/ and H/sub 2/ to develop a mechanistic model that describes the reaction rate over the entire (wide) range of conditions studied. Steady-state absolute reaction rates are reported also for the catalytic decomposition of NH/sub 3/ on the Pt(110)-(1 x 2) single crystalline surface at pressures between 1 x 10/sup -6/ and 2.6 x 10/sup -6/ Torr and at temperatures between 400 and 1000 K. The decomposition of CH/sub 3/ /sup 13/COOH at 7 x 10/sup -4/ Torr on a polycrystalline platinum wire at temperatures between 300 and 900 K was examined in the microreactor. The major reaction products on the initially clean surface are /sup 13/CO, CO, /sup 13/CO/sub 2/, H/sub 2/ and adsorbed carbon-12. The catalytic dehydration of acetic acid to ketene was investigated over a graphitized polycrystalline platinum surface at pressures between 8 x 10/sup -7/ and 7 x 10/sup -4/ Torr and temperatures between 500 and 800 K. Reaction kinetics are reported for the determinations.

• Research Organization: California Inst. of Tech., Pasadena (USA)
• OSTI ID: 7050801
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

10 SYNTHETIC FUELS
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ACETIC ACID
CHEMICAL REACTIONS
AMMONIA
CRYSTALS
CATALYTIC EFFECTS
FOILS
PLATINUM
WIRES
DEUTERIUM
ISOTOPE EFFECTS
PRESSURE EFFECTS
REACTION KINETICS
TEMPERATURE EFFECTS
CARBOXYLIC ACIDS
ELEMENTS
HYDRIDES
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
ISOTOPES
KINETICS
LIGHT NUCLEI
METALS
MONOCARBOXYLIC ACIDS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PLATINUM METALS
STABLE ISOTOPES
TRANSITION ELEMENTS
090310* - Inorganic Hydrogen Compound Fuels- Properties- (1976-1989)
400201 - Chemical & Physicochemical Properties
400202 - Isotope Effects
Isotope Exchange
& Isotope Separation