Showing papers by "Atsushi Takahashi published in 2005"
TL;DR: In this paper, the effect of particle size on ethylene and propylene epoxidation was studied on a series of silver catalysts supported on CaCO 3 with loading levels of 0.5-56 wt%.
162 citations
TL;DR: A kinetic model for the disappearance of phenol was proposed and explained well the fact that a higher amount of TiO2 and dissolved oxygen concentration gave faster disappearance rate.
111 citations
TL;DR: Adsorption and reactions of NO on clean and CO-precovered Ir(111) were investigated by means of X-ray photoelectron spectroscopy, high-resolution electron energy lossSpectroscopy (HR-EELS), infrared reflection absorption spectroscopic (IRAS), and temperature-programmed desorption (TPD).
Abstract: Adsorption and reactions of NO on clean and CO-precovered Ir(111) were investigated by means of X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HR-EELS), infrared reflection absorption spectroscopy (IRAS), and temperature-programmed desorption (TPD). Two NO adsorption states, indicative of fcc-hollow sites and atop sites, were present on the Ir(111) surface at saturation coverage. NO adsorbed on hollow sites dissociated to Na and Oa at temperatures above 283 K. The dissociated Na desorbed to form N2 by recombination of Na at 574 K and by a disproportionation reaction between atop-NO and Na at 471 K. Preadsorbed CO inhibited the adsorption of NO on atop sites, whereas adsorption on hollow sites was not affected by the coexistence of CO. The adsorbed CO reacted with dissociated Oa and desorbed as CO2 at 574 K.
46 citations
TL;DR: In this article, a direct epoxidation of propylene by oxygen was investigated over Ag-based catalysts containing an added 3D transition-metal species (Mn, Fe, Co, or Ni).
Abstract: Direct epoxidation of propylene by oxygen was investigated over Ag-based catalysts containing an added 3d transition-metal species (Mn, Fe, Co, or Ni). The oxidation of propylene occurred at lower temperatures over Ag-based catalysts containing small amounts of added metal species than over a Ag single catalyst. The yield of propylene oxide (PO) depended strongly on the type of metal: the addition of Ni afforded the highest yield of PO at similar values for the conversion of propylene (4–6%). The highest PO selectivity, four times that obtained with the Ag single catalyst, was obtained at 33 mol% Ni. X-ray diffraction analysis and transmission electron microscopy results showed that the dispersion of Ag particles in the Ag–Ni catalysts increased with increasing Ni content, which suggests that Ni atoms controlled the Ag particle size by suppressing the sintering of Ag particles. The turnover frequency for propylene epoxidation was highest at a Ag particle size of approximately 80 nm.
40 citations
Patent•
29 Sep 2005
TL;DR: In this article, the authors proposed a method for producing alcohols by a one-step reaction from a hydrocarbon and oxygen, to provide a catalyst suitable for the reaction and to provide an appropriate reaction apparatus.
Abstract: PROBLEM TO BE SOLVED: To provide a method for producing alcohols by a one-step reaction from a hydrocarbon and oxygen, to provide a catalyst suitable for the reaction and to provide a reaction apparatus suitable for the reaction. SOLUTION: The method for producing the alcohols comprises bringing the hydrocarbon and molecular oxygen into contact with an inorganic complex catalyst containing a titanium compound. The reaction apparatus is a flow type reaction apparatus equipped with a packed bed of the inorganic complex catalyst containing the titanium compound and a space layer for making a gas after contact with the catalyst stay for a long time. A reaction tube or a reaction vessel kept at the reaction temperature or a temperature in the vicinity thereof is used as the space layer. COPYRIGHT: (C)2005,JPO&NCIPI
1 citations