Author: William Clark HeckerPublisher:
ISBN:
Category :
Languages : en
Pages : 618
Book Description
Reduction of Nitric Oxide by Carbon Monoxide and Hydrogen Over a Silica-supported Rhodium Catalyst
Author: William Clark HeckerPublisher:
ISBN:
Category :
Languages : en
Pages : 618
Book Description
Reduction of Nitric Oxide by Carbon Monoxide Over a Silica Supported Platinum Catalyst
Author: D'Arcy Harold LorimerPublisher:
ISBN:
Category :
Languages : en
Pages : 330
Book Description
Reduction of Nitric Oxide by Carbon Monoxide Over a Silica Supported Platinum Catalyst
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 151
Book Description
The reduction of nitric oxide by carbon monoxide over a 4.5 weight precent platinum catalyst supported on silica was studied at 300 C. Reaction rate data was obtained together with in situ infrared spectra of species on the catalyst surface. The kinetics of the system were found to exhibit two distinct trends, depending on the molar ratio of CO/NO in the reactor. For net reducing conditions (CO/NO> 1) the catalyst underwent a transient deactivation, the extent of which was dependent on the specific CO/NO ratio during reaction. Reactivation of the catalyst was obtained with both oxidizing and reducing pretreatments. For molar feed ratios of CO/NO less than one, carbon monoxide conversion was typically 95 to 100%, resulting in strongly oxidizing conditions over the catalyst. Under these conditions no deactivation was apparent. Infrared spectra recorded under reaction conditions revealed intense bands at 2075 and 2300 cm−1, which were identified as carbon monoxide adsorbed on Pt and Si-NCO, respectively. Isocyanate bands formed under reducing conditions were more intense and exhibited greater stability than those formed under oxidizing conditions. A reaction mechanism based on the dissociation of nitric oxide as the rate-limiting step was used to correlate nitric oxide reaction rates and nitrous oxide selectivities observed under reducing conditions. As part of this mechanism it is assumed that nitrous bxide is formed via a Langmuir-Hinshelwood process in which an adsorbed nitrogen atom reacts with an adsorbed nitric oxide molecule. The nitric oxide reaction rate was found to be first order in nitric oxide partial pressure, and inverse second order in carbon monoxide partial pressure. A mechanism is proposed to qualitatively explain the deactivation process observed under reducing conditions. The essential part of this mechanism is the formation of an isocyanate species on the Pt crystallites of the catalyst and the subsequent transient diffusion of these species to the silica support. The deactivation is believed to result from the build-up of NCO on vacant sites necessary for the dissociation of nitric oxide.
Catalytic Reduction of Nitric Oxide by Carbon Monoxide Or Hydrogen Over a Monel Metal Catalyst
Author: Ian Stewart CrawfordPublisher:
ISBN:
Category : Automobiles
Languages : en
Pages : 754
Book Description
Rhodium-Molybdenum Catalysts for Nitric Oxide Reduction by Carbon Monoxide
Author: Michael David WardinskyPublisher:
ISBN:
Category : Carbon monoxide
Languages : en
Pages : 260
Book Description
Oxidation Catalysis in Environmental Applications
Author: Matthew Maurice YungPublisher:
ISBN:
Category : Carbon monoxide
Languages : en
Pages : 228
Book Description
Abstract: The environmental applications of oxidation catalysis were examined as part of a two-stage strategy for the reduction of nitrogen oxides (NOx) and also for the removal of carbon monoxide from hydrogen streams. Cobalt-based catalysts were examined. Reduction of NOx, Co/TiO2 and Co/ZrO2 were studied for the oxidation of NO to NO2 in excess oxygen. NO oxidation was studied as the first step in a two-step catalytic scheme where NO is oxidized to NO2 and, in turn, NO2 is reduced with CH4 to N2 under lean conditions. Catalysts were prepared by sol-gel and incipient-wetness impregnation techniques. It was found that increasing the calcination temperature had an adverse effect on the activity of the IWI catalysts. Catalyst characterization showed higher activity for NO oxidation on Co/ZrO2 than on Co/TiO2 which was observed to correlate with the formation of the Co3O4 phase. For the preferential oxidation of CO, cobalt on several metal oxide supports were investigated and showed the highest activity on Co/ZrO2. A variety of reaction experiments were performed to examine the effects of reactant concentrations, residence time, and temperature on the CO conversion and O2 selectivity to CO2.
Influence of Metal-support Interactions on the Reduction of Nitric Oxide Over Rhodium Catalysts
Author: Nutan Kumari PandeA Kinetic Study of the Reduction of Nitric Oxide by Carbon Monoxide Over an Alumina Supported Platinum Catalyst
Author: S. Tariq HussainCatalytic Reduction of Nitric Oxide with Carbon Monoxide
Author: Yu Sim NgUrea-SCR Technology for deNOx After Treatment of Diesel Exhausts
Author: Isabella NovaPublisher: Springer Science & Business Media
ISBN: 1489980717
Category : Science
Languages : en
Pages : 715
Book Description
Urea-SCR Technology for deNOx After Treatment of Diesel Exhausts presents a complete overview of the selective catalytic reduction of NOx by ammonia/urea. The book starts with an illustration of the technology in the framework of the current context (legislation, market, system configurations), covers the fundamental aspects of the SCR process (catalysts, chemistry, mechanism, kinetics) and analyzes its application to useful topics such as modeling of full scale monolith catalysts, control aspects, ammonia injections systems and integration with other devices for combined removal of pollutants.