Catalysis Surveys From Asia 

About: Catalysis Surveys From Asia is an academic journal published by Springer Science+Business Media. The journal publishes majorly in the area(s): Catalysis & Chemistry. It has an ISSN identifier of 1571-1013. Over the lifetime, 497 publications have been published receiving 14011 citations.

Oxide semiconductor gas sensors

Abstract: Semiconductor gas sensors utilize porous polycrystalline resistors made of semiconducting oxides. The working principle involves the receptor function played by the surface of each oxide grain and the transducer function played by each grain boundary. In addition, the utility factor of the sensing body also takes part in determining the gas response. Therefore, the concepts of sensor design are determined by considering each of these three key factors. The requirements are selection of a base oxide with high mobility of conduction electrons and satisfactory stability (transducer function), selection of a foreign receptor which enhances surface reactions or adsorption of target gas (receptor function), and fabrication of a highly porous, thin sensing body (utility factor). Recent progress in sensor design based on these factors is described.

Photocatalyst Materials for Water Splitting

Abstract: Various photocatalyst materials developed by the group of the present author are described. Alkali and alkaline earth tantalates have arisen as a new group of photocatalyst materials for splitting of water into H2 and O2 under ultraviolet irradiation. They showed activities even without co-catalysts such as Pt, being different from titanate photocatalysts. When NiO co-catalysts were loaded on the tantalate photocatalysts, the photocatalytic activities were markedly increased. Among the tantalates, NiO/NaTaO3 doped with La showed the highest activity. BiVO4, AgNO3, and TiO2 co-doped with Cr and Sb photocatalysts showed high activities for O2 evolution in the presence of a sacrificial reagent (Ag+) under visible light irradiation (λ > 420 nm). Pt/SrTiO3 co-doped with Cr and Sb or Ta, Pt/NaInS2, and Pt/AgInZn7S9 photocatalysts showed high activities for H2 evolution from aqueous solutions containing reducing reagents under visible light irradiation. Furthermore, Cu- or Ni-doped ZnS photocatalysts showed H2 evolution activities even without co-catalysts such as Pt.

Photocatalysis on titanium oxide catalysts: Approaches in achieving highly efficient reactions and realizing the use of visible light

Abstract: The photocatalytic reactivities of various Ti-based photocatalysts have been investigated for various different types of reactions in order to achieve as highly efficient photocatalytic reactivities as possible. The reactivity of powdered TiO2 is dramatically enhanced by the addition of small amounts of Pt which initiates an effective charge separation of the photo-formed electrons and holes. The highly dispersed titanium oxide species prepared and encapsulated within the zeolite cavities as well as into the SiO 2 matrices exhibit high photocatalytic reactivities due to the high reactivities of their charge transfer excited states. With regard to the use of visible light, ion implantation of metal ions such as Cr or V into powdered TiO2 catalysts has been found to modify the electronic state of TiO 2 , resulting in the shift of the absorption band to longer wavelength regions, i.e., into the visible light region. The extent of the shift strongly depends on the type and concentration of the implanted metal. The present study focuses on the preparation of the photocatalysts, a detailed characterization of the active sites and their dynamics, the direct detection of the reaction intermediate species, as well as a clarification of the mechanisms behind the observed photocatalytic reactions at the molecular level. This work significantly contributes to advances in the design of photocatalysts which will be able to operate efficiently and effectively not only under UV irradiation but, most ideally, under visible light.

Novel catalysis of gold deposited on metal oxides

Abstract: Gold exhibits a unique catalytic nature and action when it is deposited as nanoparticles on a variety of metal oxides. Most reactions are noticeably structure sensitive over such supported gold catalysts. Typical examples obtained in Japan of the low-temperature catalytic combustion, partial oxidation of hydrocarbons, hydrogenation of carbon oxides and unsaturated hydrocarbons, reduction of nitrogen oxides, and so forth, are presented. Another line of advance is also introduced in the thin films of gold metal oxide composites, which are applicable to electrical and optical gassensing.

Dry Reforming of Methane Over Cobalt Catalysts: A Literature Review of Catalyst Development

Abstract: Dry reforming of methane produces syngas with desirable H2/CO ratio. Besides noble metal catalysts, the cobalt catalyst performs good activity in this reaction. However, carbon deposition and catalyst deactivation are becoming the main problems inhibiting the scale up of this process into industrial application. Recently, many scientists were trying to increase the activity as well as the stability toward coking by using variants of support, promoter, and combination of metal series catalyst. This paper presents a recent technology of methane dry reforming over cobalt metal-base catalyst, covering the catalyst activity and their resistance of catalyst deactivation.