Ammonia intermediacy as a basis for catalyst selection for nitric oxide reduction

Klimisch, Richard L.; Taylor, Kathleen C.

doi:10.1021/es60074a006

Cited by 57 publications

(24 citation statements)

References 10 publications

(18 reference statements)

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“…Shelef and Gandhi (1972) reported that the selectivity for NH3 formation over ruthenium reached a maximum of 35% at 220 "C and declined to 10% at 400 O C . Klimisch and Taylor (1973) also found low NH3 selectivity with ruthenium, but selectivity differed for reduced and oxygen-treated catalysts. Since ruthenium is a good catalyst for NH3 decomposition, these authors suggested that the low NH3 selectivity at high temperatures might be attributed to NH3 decomposition, with reduction of NO to N2 proceeding through a gas-phase 0019-7890/78/1217-0322$01,00/0 NH3 intermediate.…”

Section: Introductionmentioning

confidence: 91%

“…The importance of catalyst history and of adhering to a strict experimental procedure is underscored by the "dual state" nature of ruthenium catalysts (Voorhoeve and Trimble, 1975;Klimisch and Taylor, 1973). Each charge was exposed to flowing hydrogen at 375 "C for 12 h before making kinetic tests, and between runs the reactor was swept with 2.5% H2 in N2.…”

Section: Apparatus and Proceduresmentioning

confidence: 99%

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Kinetics of the Ruthenium-Catalyzed Reduction of Nitric Oxide by Hydrogen

Matson¹,

Harriott²

1978

Ind. Eng. Chem. Prod. Res. Dev.

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typical oxide films. Also, we do not have the problem of electronic conduction which can complicate the metal oxide film growth kinetics. Despite these differences between the formation of organic coatings and metal oxide layers the same kinetic treatment applies to both processes.The kinetics of reduction of NO by H, over a supported ruthenium catalyst were explored in integral and differential reactor tests at atmospheric pressure and 100 to 350 O C with reactant concentrations of 60-3200 ppm of NO and 0.15-2.5% H, . The reduction of nitric oxide is half order to hydrogen and zero or negative order to nitric oxide, indicating a surface reaction between dissociatively adsorbed hydrogen and strongly chemisorbed nitric oxide or a surface species derived from it. Selectivity for ammonia formation depends only weakly on nitric oxide concentration; it increases with temperature from 100 to 200 O C , reaching a maximum of about 50% and then declining at higher temperatures. The decline is caused by the reaction of nitric oxide with ammonia or ammonia precursors rather than by the decomposition of ammonia.

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Section: Introductionmentioning

confidence: 91%

Section: Apparatus and Proceduresmentioning

confidence: 99%

Kinetics of the Ruthenium-Catalyzed Reduction of Nitric Oxide by Hydrogen

Matson¹,

Harriott²

1978

Ind. Eng. Chem. Prod. Res. Dev.

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“…It is favored not only for its high activity but also because under exhaust conditions it has been shown to be more selective to the formation of Ng over ammonia (2)(3)(4)(5)(6)(7)(8) than platinum or rhodium.…”

Section: Kinetic Procedures 4lmentioning

confidence: 99%

Interaction and reactivity of nitric oxide and carbon monoxide on ruthenium surfaces

Quick

1980

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Quick, Edward Edwards, "The interaction and reactivity of nitric oxide and carbon monoxide on ruthenium surfaces " (1979 INFORMATION TO USERSThis was produced from a copy of a document sent to us for microfilming. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the material submitted.The following explanation of techniques is provided to help you understand markings or notations which may appear on this reproduction. 1. The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting through an image and duplicating adjacent pages to assure you of complete continuity. When an image on the film is obliterated with a round black mark it is anindication that the film inspector noticed either blurred copy because of movement during exposure, or duplicate copy. Unless we meant to delete copyrighted materials that should not have been filmed, you will find a good image of the page in the adjacent frame,.3. When a map, drawing or chart, etc., is part of the material being photo graphed the photographer has followed a definite method in "sectioning" the material. It is customary to begin filming at the upper left hand comer of a large sheet and to continue from left to right in equal sections with small overlaps. If necessary, sectioning is continued agaun-beginning below the first row and continuing on until complete.

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“…Since the NH3 formed is thermodynamically unstable at 540°C, it would be expected to decompose readily on a suitable catalyst. Nickel has been reported to have such activity (Klimisch and Taylor, 1973). A run was made in the 9.5-mm reactor in which the bed consisted of two sections.…”

Section: Ni and Cu Cotalystsmentioning

confidence: 99%

Reduction and removal of SO₂ and NO_x from simulated flue gas using iron oxide as catalyst/absorbent

Clay

Lynn

1975

AIChE Journal

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Iron oxide supported on alumina is a promising catalyst/absorbent for use in the simultaneous removal of NO, and SO, from power plant stack gases. A dry-contacting process is under development which would operate under net reducing conditions at temperatures of 370° to 540OC. Iron oxide is converted to the ferrous state, NO is reduced to Nz or NH3, and SOz is removed as ferrous sulfide or sulfate. Regeneration with air produces SO2 and reforms Fe20s.The reduction of SOz by CO and H2 was studied in fixed-bed reactors to determine the effects of temperature and of the other reactive components of flue gas (excepting fly ash) on the rate of reaction and the products formed. H2S and COS react with FeO to form FeS. Under readily attainable conditions, virtually complete removal of sulfur compounds was achieved for gas-phase residence times of about 1 to 10 ms. NO and Oz were also reduced. Conditions under which oxygen poisons the catalyst were determined. DAVID T. CLAY and SCOTT LYNN Department of Chemical EngineeringUniversity of California Berkeley, Colifornia 94720 SCOPESulfur dioxide and nitric oxide are major air pollutants in the United States. Fossil-fueled power plants are major sources of both. Wet processes for SO2 removal are currently being developed commercially, but to date no process for simultaneous SO2 and NO removal has passed the laboratory scale. A dry removal process would be preferred, since this would avoid flue-gas reheating, the problems of contacting the gas with a liquid or slurry, and the crystallization phenomena usually encountered in flue-gas scrubbing. The objective of this study was to develop a dry process which not only achieves high NO and SO2 removals, but also converts NO to innocuous materials and SO2 to a salable product and is potentially economical to operate.The process flow sheet is shown in Figure 1. Iron oxide, supported on alumina, acts as a catalyst for the reduction of both SOz and NO by CO and H2. Simultaneously, it acts as an absorbent for sulfur compounds, converting them to FeS. The catalyst/absorbent is in the form of fine pellets (0.05 to 0.10 mm) and contacts the gas as a falling bed in concurrent flow at 370° to 540OC. The solid is regenerated with air at 675OC to produce a rich stream of SO2, suitable for conversion to H2SO4 or elemental sulfur. Fez03 is reformed in the particles. Experiments in fixed-bed reactors using mixtures of helium and one or more reactant gases were run to demonstrate the basic process chemistry, to estimate rates for preliminary design purposes, and to look for interfering reactions. A preliminary estimation of the capital and operating costs of the process was made on the basis of the results obtained. CONCLUSIONS AND SIGNIFICANCEThe overall reactions listed in Table 1 were shown to proceed rapidly at 370" to 540°C in fixed-bed reactors using pellets of supported iron oxide 3.2 mm x 3.2 mm or particles 0.25 to 0.50 mm diameter. Iron oxide was reduced to the ferrous state, SO2 was reduced by both CO and H2, and the sulfur was absorbed ...

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Ammonia intermediacy as a basis for catalyst selection for nitric oxide reduction

Cited by 57 publications

References 10 publications

Kinetics of the Ruthenium-Catalyzed Reduction of Nitric Oxide by Hydrogen

Kinetics of the Ruthenium-Catalyzed Reduction of Nitric Oxide by Hydrogen

Interaction and reactivity of nitric oxide and carbon monoxide on ruthenium surfaces

Reduction and removal of SO₂ and NO_x from simulated flue gas using iron oxide as catalyst/absorbent

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Ammonia intermediacy as a basis for catalyst selection for nitric oxide reduction

Cited by 57 publications

References 10 publications

Kinetics of the Ruthenium-Catalyzed Reduction of Nitric Oxide by Hydrogen

Kinetics of the Ruthenium-Catalyzed Reduction of Nitric Oxide by Hydrogen

Interaction and reactivity of nitric oxide and carbon monoxide on ruthenium surfaces

Reduction and removal of SO2 and NOx from simulated flue gas using iron oxide as catalyst/absorbent

Contact Info

Product

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Reduction and removal of SO₂ and NO_x from simulated flue gas using iron oxide as catalyst/absorbent