TAP study on CO oxidation on a highly active Au/Ti (OH)4* catalyst

Olea, Maria; Kunitake, Maki; Shido, Takafumi; Iwasawa, Yasuhiro

doi:10.1039/b007121h

Cited by 37 publications

(32 citation statements)

References 29 publications

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“…It has been argued that the fact that CO oxidation on small gold particles occurs at low temperatures with very low activation energies implies that it cannot proceed through a mechanism involving a highly energetic process such as oxygen dissociation (220,474). Schubert et al (226) and Iwasawa and co-workers (375,377,494) O with no double labeled CO2 of either type. These results indicate that lattice oxygen was not participating in the reaction in any fashion and suggest that oxygen did not dissociate readily on the surface.…”

Section: 2mentioning

confidence: 99%

Surface chemistry of catalysis by gold

et al. 2004

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IntroductionGold has long been regarded as an "inert" surface and bulk gold surfaces do not chemisorb many molecules easily. However, in the last decade, largely through the efforts of Masatake Haruta, gold particles, particularly those below 5 nm in size, have begun to garner attention for unique catalytic properties (1-8). In recent years, supported gold particles have been shown to be effective as catalysts for low temperature CO oxidation (9), selective oxidation of propene to propene oxide (10), water gas shift (11), NO reduction (12), selective hydrogenation of acetylene (or butadiene) (13)

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Section: 2mentioning

confidence: 99%

Surface chemistry of catalysis by gold

et al. 2004

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“…All experiments were conducted using the TAP reactor system which has been described in detail elsewhere [21,22]. Briefly, the TAP system consists of a fast-pulse gas delivery system, a fixed-bed micro-reactor, and a computer-controlled real-time quadrupole mass spectrometer (Spectra Co.).…”

Section: Methodsmentioning

confidence: 99%

“…Our previous TAP studies on Au/Ti(OH) 4 * proved that oxygen at high pulse intensities and carbon dioxide exhibited very strong (reversible) adsorption on this catalyst [21,22]. But for low pulse intensities, the oxygen adsorption was weak and reversible.…”

Section: Single-pulse Experimentsmentioning

confidence: 99%

“…It has been proved [18,22,23] the particles is proportional to the pore length. But, the pore length strongly depends on the particle size.…”

Section: R E V I E W C O P Ymentioning

confidence: 99%

“…We have reported TAP studies [21,22] on diffusion and on carbon monoxide, oxygen, and carbon dioxide adsorption as well as catalytic carbon monoxide oxidation over a newlydeveloped titania-supported gold catalyst (denoted as Au/Ti(OH) 4 * ), which was tremendously active for low-temperature carbon monoxide oxidation. The followings were shown: carbon monoxide molecules reversibly and weakly adsorbed on the catalyst surface; oxygen adsorbed molecularly and strongly for high pulse intensities, with a lifetime of 4500-6900 ms at 373-423 K; reaction occurred between adsorbed carbon monoxide and adsorbed molecular oxygen; lattice oxygen atoms were active in oxygen exchange only with carbon dioxide.…”

Section: Introductionmentioning

confidence: 99%

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Transient studies on carbon monoxide oxidation over supported gold catalysts: support effects

Olea

Iwasawa

2004

Applied Catalysis A: General

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Transient Catalytic Studies

Hinrichsen

2008

Handbook of Heterogeneous Catalysis

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The Importance of Transient Catalytic StudiesThe concept of using transient operations dates back to the late 1930s and the preliminary investigations conducted by Wagner and Hauffe [1,2]. Later, during the 1960s, Tamaru contributed substantially to this field in heterogeneous catalysis, in particular, by the use of the method of transient response [3] and by introducing the isotopic labeling technique [4]. Since then, transient methods have become standard tools for unraveling heterogeneously catalyzed reactions; for details, see the reviews in Refs. [5][6][7][8][9][10], monographs [11,12], and a special edition of Applied Catalysis [13]. The reasons for the wide application of transient methods are manifold. In chemical reactions, generally speaking, if the rate (rate equation, rate constant, and activation energy) of each of the elementary steps which comprise the overall reaction is known, the (micro)kinetics of the overall reaction may be understood. To take a simple example, in the reaction between hydrogen and bromine, the kinetics of the overall reaction follows a rather complicated rate law:However, if all the elementary reactions in the overall reaction are known, the kinetic behavior of the overall reaction may be explained on the basis of the rate constants, and the activation energies of the forward and backward reactions of the following elementary steps:In the case of such gas-phase reactions, the rate constants and activation energies of each of the elementary steps are independent of the concentration of reactants, reaction products, and reaction intermediates. This approximately also holds for reactions in solution.In the case of heterogeneously catalyzed reactions, the properties of the catalyst depend upon the concentrations of reactants, reaction intermediates, reaction products and, in some cases, spectator species that do not participate in the reaction path but which are chemisorbed on the catalyst surface. Furthermore, in many cases surface restructuring may occur along with the adsorption, and this results in marked changes in the reactivity of the surface. Consequently, even if the catalyst surface is kept in a well-defined state at the outset, as examined ex situ using a variety of spectroscopic techniques, it can be markedly different during the progress of reaction, and especially under industrially relevant reaction conditions. For example, in the case of oxide catalysts the extent of oxidation of the catalyst surface during the redox reaction is also influenced by the relative ratio of the rates of reduction and oxidation. This results in prominent changes in the properties of catalyst surfaces, depending upon the relative concentration of the reactants and the reaction temperature. In the case of acid catalysts, the acidity of the working catalyst surface (which should be associated with the catalytic activity) is that under the reaction conditions, and not that under the conditions far from those prevailing in the actual reaction.In the case of heterogeneous catalysis the rate co...

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TAP study on CO oxidation on a highly active Au/Ti (OH)4* catalyst

Cited by 37 publications

References 29 publications

Surface chemistry of catalysis by gold

Surface chemistry of catalysis by gold

Transient studies on carbon monoxide oxidation over supported gold catalysts: support effects

Transient Catalytic Studies

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