Reduction of NO by CO over a silica-supported platinum catalyst: infrared and kinetic studies

Journal Article · Sat Sep 01 04:00:00 EDT 1979 · J. Catal.; (United States)

DOI:https://doi.org/10.1016/S0021-9517(79)80027-5· OSTI ID:5804519

Lorimer, D; Bell, A T

The reduction of NO by CO was studied over a Pt/SiO/sub 2/ catalyst at 300/sup 0/C. Reaction rate data were obtained together with in situ infrared spectra of species adsorbed on the catalyst surface. The performance of the catalyst depended strongly on the ratio of CO/NO in the reactor. For net reducing conditions (CO/NO > 1) the catalyst deactivated with time. Measurements of kinetics taken during a period of slow deactivation showed that the rate of NO reduction was first order in NO and inverse second order in CO. Reactivation of the catalyst was obtained with both oxidizing and reducing pretreatments. Under net oxidizing conditions (CO/NO < 1) the catalyst was much more active than under reducing conditions and did not deactivate. In situ infrared spectra showed bands corresponding to CO chemisorbed on Pt and NCO and CN groups attached to the support as Si-NCO and Si-CN, respectively. Both the CO and NCO bands were more intense under reducing than oxidizing conditions. The kinetics and product selectivities observed under reducing conditions were found to be in good agreement with a mechanism based upon the dissociation of NO as the rate-limiting step. This mechanism further assumes that N/sub 2/O is formed by reaction of adsorbed NO with an adsorbed nitrogen atom. It is proposed that the loss in catalyst activity is associated with a change in the electronic properties of the supported Pt crystallites, caused by the accumulation of large concentrations of NCO and CN groups on the support in areas adjacent to the crystallites.

• Research Organization: Univ. of California, Berkeley
• OSTI ID: 5804519
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 59:2; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
330701 -- Emission Control-- Nitrogen Oxides
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical &amp; Physicochemical Properties
500200 -- Environment
Atmospheric-- Chemicals Monitoring &amp; Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
DATA
DATA FORMS
ELEMENTS
EXPERIMENTAL DATA
INFORMATION
ISOLATED VALUES
METALS
NITROGEN COMPOUNDS
NITROGEN OXIDES
NITROUS OXIDE
NUMERICAL DATA
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
REDUCTION
SILICON COMPOUNDS
SILICON OXIDES
TRANSITION ELEMENTS