Nitric Oxide Reduction by Hydrogen over Rhodium Using Transient Response Techniques

Savatsky, Bruce J.; Bell, Alexis T.

doi:10.1021/bk-1982-0178.ch005

Cited by 10 publications

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“…Whereas reactions such as the NO dissociation − and recombination of atomic nitrogen to N 2 , have been studied extensively, the microscopic mechanisms of N 2 O and NH 3 formation are still unknown. NH 3 formation is commonly described by the stepwise hydrogenation of atomic nitrogen …”

Section: Introductionmentioning

confidence: 99%

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Kinetics and Mechanism of NH₃ Formation by the Hydrogenation of Atomic Nitrogen on Rh(111)

1997

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The reaction between atomic nitrogen and H 2 has been studied in order to elucidate the mechanism of NH 3 formation on Rh(111). Atomic nitrogen layers of 0.10 monolayer (ML) coverage were obtained by adsorbing NO at 120 K and selectively removing the atomic oxygen from dissociated NO by reaction with H 2 at 375 K. The rate of NH 3 formation is first order in the atomic nitrogen coverage and linearly proportional to the H 2 pressure below 5 × 10 -7 mbar. Static secondary ion mass spectrometry (SSIMS) indicates that N and NH 2 are the predominant reaction intermediates, while small amounts of NH 3 are also detected. The NH 2 surface coverage increases with increasing H 2 pressure. The presence of NH 2 is also indicated by the appearance of a reaction-limited H 2 desorption state in temperature-programmed desorption (TPD) spectra. The hydrogenation of NH 2 to NH 3 is expected to be the rate-determining step in the NH 3 formation. From the temperature dependence of the NH 3 formation rate an effective activation energy of 40 kJ/mol was determined, which could be translated into an activation energy of 76 kJ/mol for the hydrogenation from NH 2 to NH 3 .

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Section: Introductionmentioning

confidence: 99%

“…NH 3 formation is commonly described by the stepwise hydrogenation of atomic nitrogen. 14 Indeed, many reports on NH and NH x species exist. On Rh(100) 15 and Pt/Rh(100) 6,16 evidence was found by electron energy loss spectroscopy (EELS) for an NH intermediate that was reversibly formed when a c(2 × 2)-N adlayer was exposed to H 2 .…”

Section: Introductionmentioning

confidence: 99%

Kinetics and Mechanism of NH₃ Formation by the Hydrogenation of Atomic Nitrogen on Rh(111)

1997

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“…This allowed Alex to refine the reaction mechanisms proposed in his earlier work. e.g., 27,28,[58][59][60][61][62][63][64] When coupled with in situ IR, Raman and NMR spectroscopy, he was able to elucidate the key rate-determining steps occurring on the surface of the metal catalysts, and to distinguish between the active and the spectator adsorbates ( Figure 4). 29,31,61,65 This combination of experimental techniques -developed and advanced by Alex, his students and collaborators -contributed to our current molecular-level understanding of relationship between catalyst structure and its function.…”

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A Career in Catalysis: Alexis T. Bell

et al. 2017

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On the occasion of Alexis T. Bell's fiftieth year at Berkeley, we are honored to discuss a few aspects of his extensive contributions to catalysis, reaction engineering, and understanding of molecular scale structure in catalytic processes. The illustrations provided here help reveal some of his traits most valued by our community: a drive to employ the best methods of instrumentational and computational analysis available; the instinct to search for the essence of the most important problems at hand, and the skill to write about them with exceptional clarity; and the formation and nurturing of collaborative teams to focus on the most essential questions.

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“…Dent and Kokes used the transient method in IR studies in 1970 (18). Since then the method has been applied to kinetic studies in particular by Ueno et al (19,20) and most recently by Savatsky and Bell (21).…”

Section: Some Experimental Methodsmentioning

confidence: 99%

“…With a dispersion instrument the experiment can be run at several constant wave numbers in repeated experiments. At the signal levels often obtained in studies of the bands of adsorbed species, a Fourier transform instrument may require about 20 scans of Is each to obtain an adequate interferogram, which of course repre sents only an average spectrum (21) . Software has been developed to resolve this problem through multiplexing in time and mirror position (55,56).…”

Section: Some Experimental Methodsmentioning

confidence: 99%

Understanding Heterogeneous Catalysis Through the Transient Method

Bennett

1982

ACS Symposium Series

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Although catalysis can be understood through steady-state ex periments, it seems clear that transient experiments will usually furnish much additional information. Often steady-state data can be explained by a number of different models, but the results of transient experiments are usually so rich that only a detailed, complex model will come close to explaining the results. These ideas have long been applied in other fields, but in heterogeneous catalysis they have come into acceptance only during the last 15 years or so. Pioneering experiments were done by Wagner (1) in 1938, and Tamaru (2)

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Nitric Oxide Reduction by Hydrogen over Rhodium Using Transient Response Techniques

Cited by 10 publications

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Kinetics and Mechanism of NH₃ Formation by the Hydrogenation of Atomic Nitrogen on Rh(111)

Kinetics and Mechanism of NH₃ Formation by the Hydrogenation of Atomic Nitrogen on Rh(111)

A Career in Catalysis: Alexis T. Bell

Understanding Heterogeneous Catalysis Through the Transient Method

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Nitric Oxide Reduction by Hydrogen over Rhodium Using Transient Response Techniques

Cited by 10 publications

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Kinetics and Mechanism of NH3 Formation by the Hydrogenation of Atomic Nitrogen on Rh(111)

Kinetics and Mechanism of NH3 Formation by the Hydrogenation of Atomic Nitrogen on Rh(111)

A Career in Catalysis: Alexis T. Bell

Understanding Heterogeneous Catalysis Through the Transient Method

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Kinetics and Mechanism of NH₃ Formation by the Hydrogenation of Atomic Nitrogen on Rh(111)

Kinetics and Mechanism of NH₃ Formation by the Hydrogenation of Atomic Nitrogen on Rh(111)