Yoshihisa Watanabe

Reduction of Nox in Combustion Flue Gases on Tungsten Based Catalysts

We report the results of our search for highly efficient catalysts for reduction of nitrogen oxides in combustion flue gases at higher temperatures (over ca. 40O°C) by ammonia. Ti-W oxide and Fe-W oxide catalysts were investigated for the composition, the calcination temperature, and the life in combustion flue gases. The Ti-W oxide catalyst was proved to be excellent for industrial use at higher reaction temperature. A mechanism of NO-NH 3 reaction on the Ti-W oxide catalyst was investigated. It was suggested that the acidic property of the catalyst was closely related to the activity of the Ti-W oxide catalyst.

Hydrogenation of carbon monoxide by ruthenium catalysts: a synergistic effect of chloride salts and weak acids

Abstract Hydrogenation of carbon monoxide by a Ru—PPNCl—acid system was examined. A synergistic effect was observed for a combination of halide salts and weak acids. Ethylene glycol, methanol and ethanol are the major products. Mechanistic studies suggest that a single catalytic species, presumably the hydroxymethyl-metal intermediate, is responsible for a major part of the ethylene glycol and methanol. Positive effects of moderately polar solvents and weak acids indicate the ion-paired nature of the catalytic species.

Electronic and steric effects of phosphine ligands in the formation of ethylene glycolfrom synthesis gas catalyzed by rhodium

Abstract The catalytic activity of the rhodium/phosphine system in the formation of ethylene glycol from synthesis gas is determined by the electronic and steric effects of the phosphine ligands, including alkyl-substituted phosphorinane and alkyl diisopropylphosphine. Tafts substitution constant of the alkyl substituent and the 31 P NMR chemical shifts for the coordinated phosphine are used as the electronic and steric parameters, respectively. For both types of phosphine, the rate of ethylene glycol formation increases with an increase in the electron-donating effect of the alkyl substituent. The steric hindrance of the substituents in alkyl diisopropylphosphine inhibits the electronic effect for glycol formation.

Promoting effect of acids on the formation of ethylene glycol from synthesis gas catalyzed by the rhodium-tricyclohexylphosphine system

Abstract Carboxylic acids, pentafluorophenol and phosphoric acid (HX) facilitate the formation of ethylene glycol from synthesis gas catalyzed by the rhodium-tricyclohexylphosphine (TCP) system. Complexes recovered from the resultant solutions were identified as RhX(CO)(TCP) 2 , which are stable to repeated use. The catalytically active species or its immediate precursor is proposed to be HRh(CO) 2 (TCP) 2 from IR spectroscopic analysis under synthesis gas pressure of 280 bar.