Yoshiyuki Nishiyama

Bio: Yoshiyuki Nishiyama is an academic researcher from Tohoku University. The author has contributed to research in topics: Catalysis & Nickel. The author has an hindex of 25, co-authored 104 publications receiving 1668 citations. Previous affiliations of Yoshiyuki Nishiyama include Monash University, Clayton campus.

Catalytic electroreduction of molecular oxygen using iron or cobalt 4,4',4",4'"-tetracarboxyphthalocyanine

Abstract: Etudes de l'electroreduction de l'oxygene dans une solution aqueuse contenant des tetracarboxyphtalocyanines de Fe et de Co

Gas-phase hydrogenation of nitriles by nickel on various supports

Abstract: Gas-phase hydrogenation of benzonitrile and acetonitrile was investigated using 5% nickel on various supports at normal pressure and in a temperature range of 170–230°C. The only products obtained were the corresponding primary amines; however, the catalytic activity was strongly influenced by the support used, being in the order of alumina>titania>silica-alumina>silica. The activity was higher for the catalyst having a smaller degree of nickel dispersion measured by temperature programmed desorption of hydrogen.

Effects of metal particle size in gas-phase hydrogenation of acetonitrile over silica-supported platinum catalysts

Abstract: The gas-phase hydrogenation of acetonitrile was studied with silica-supported platinum catalysts of which the degrees of metal dispersion were widely changed by reduction conditions. The activities were found to decrease gradually during the course of reaction for all the catalysts examined. The initial rate of reaction increased with an increase in the degree of platinum dispersion, D. Triethylamine was the only main product irrespective of D and period of reaction time. The initial turnover frequency, TOF0, was shown to be smaller for larger D values. This dependence of TOF0 on D was explained by the electronic state of the surface of the platinum particles and the state of acetonitrile molecules adsorbed on them on the basis of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy measurements. The surface layer of smaller particles is more favorable for the adsorption of acetonitrile. The acetonitrile is adsorbed by platinum with the electron lone pair of nitrogen in the antibon...

Gold-catalysed oxidation of carbon monoxide

Abstract: Of the many important reactions that are known to be catalysed by gold particles supported on transition metal oxides, the oxidation of carbon monoxide is of outstanding significance: the current state of understanding of its mechanism is reviewed, and discordant observations reported in the literature are noted and analysed. A general mechanism involving reaction at the edge of a particle containing both gold atoms and ions, and involving the support, is suggested, although not all features of it are necessarily always operative. Possible practical uses for gold in catalysing this reaction include pollution control, fuel cells, and gas sensing.

Selective Hydrogenation of α,β-Unsaturated Aldehydes

Abstract: The synthesis of a large number of fine chemicals, particularly in the field of flavor and fragrance chemistry [1,2] and pharmaceuticals [3], involves the selective hydrogenation of unsaturated carbonyl intermediates as a critical step. The hydrogenation of α,β-unsaturated carbonyls into saturated carbonyls is comparatively easy to achieve because thermodynamics favor the hydro-genation of the C═C bonds; therefore, research efforts were more directed at improving the selectivity to unsaturated alcohols. When a substituent is present on the carbon atom of the carbonyl group (i.e. with ketones), there is no chance to hydrogenate selectively the C═O bond, and saturated ketones are obtained with a high yield. This review is thus mostly restricted to the hydrogenation of α, β-unsaturated aldehydes into the corresponding unsaturated alcohols.

A review of catalytically grown carbon nanofibers

Abstract: Carbon nanofibers (sometimes known as carbon filaments) can be produced in a relative large scale by the catalytic decomposition of certain hydrocarbons on small metal particles. The diameter of the nanofibers is governed by that of the catalyst particles responsible for their growth. By careful manipulation of various parameters it is possible to generate carbon nanofibers in assorted conformations and at the same time also control the degree of their crystalline order. This paper is a review of the recent advances made in the development of these nanostructures, with emphasis both on the fundamental aspects surrounding the growth of the material and a discussion of the key factors which enable one to control their chemical and physical properties. Attention is also given to some of the possible applications of the nanostructures which center around the unique blend of properties exhibited by the material.

Carbon Deposition in Steam Reforming and Methanation

Abstract: Deactivation of supported metal catalysts by carbon or coke formation is a problem of serious magnitude in steam reforming, methanation, and other important catalytic processes. Its causes are generally threefold: (1) fouling of the metal surface, (2) blockage of catalysts pores and voids, and/or (3) actual physical disintegration of the catalyst support. Since loss of catalytic activity and physical destruction of the catalyst by carbon deposits can occur rapidly (within hours or days) under unfavorable conditions, understanding and control of these effects are of major technological and economical importance.