Catalytic studies of nitric oxide: A. Reduction of nitric oxide with methane over alumina supported rhidium. B. Characterization of alumina supported cobalt molybdate for olefin metathesis
Kinetic studies at 300/sup 0/-400/sup 0/C in a gradientless recirculating reactor showed that nitric oxide reduction was first order in methane and -0.63 order in nitric oxide, with an activation energy of 18.4 kcal/mole, and a deuterium kinetic isotope effect of 1.9, suggesting that dissociative methane adsorption is the rate-determining step. Nitrogen-15 tracer studies showed that the reaction involves N/sub 2/O as a surface intermediate, and a mechanism is proposed involving two-step dissociation of adsorbed NO to adsorbed N/sub 2/O and N/sub 2/ and surface oxygen atoms, which rapidly poison the catalyst unless removed by methane. Propylene metathesis to ethylene and 2-butene over cobalt molybdate was studied by nitric oxide poisoning and shown to follow Langmuir-Hinshelwood kinetics. Two different dual-site mechanisms, one involving propylene adsorption on adjacent molybdenum atoms and the other involving adsorption of two propylene molecules on one molybdenum atom, fit the data equally well. An upper limit to the active site density was determined as 2.5 x 10/sup 13//sq cm at 27/sup 0/C, i.e., only 9Vertical Bar3< of the surface molybdenum atom density.
- OSTI ID:
- 6319229
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201 -- Chemical & Physicochemical Properties
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ACTIVATION ENERGY
ALKANES
ALKENES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COBALT
CONVERSION
DATA
ELEMENTS
ENERGY
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
ISOTOPE APPLICATIONS
KINETICS
METALS
METHANE
MOLYBDATES
MOLYBDENUM COMPOUNDS
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REACTION KINETICS
REDUCTION
REFRACTORY METAL COMPOUNDS
RHODIUM
TRACER TECHNIQUES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS