Masahide Tanaka

Hydrogenation of carbon monoxide in the presence of homogeneous ruthenium catalysts: effects of onium halides as promoters

Abstract The direct formation of ethylene glycol and ethanol from synthesis gas in the presence of a homogeneous ruthenium carbonyl catalyst is promoted by onium halides, such as ammonium, phosphonium and iminium halides. The catalytic activities for ethylene glycol and ethanol formation are dependent on the nature of the halides, and increase in the order I − − − and Cl − − ≤ Br − , respectively. The ruthenium catalyst in conjunction with (Ph 3 P) 2 NCl shows the highest activity for ethylene glycol formation. The catalytic activities are dependent on the electron-accepting abilities of the solvents. A moderate electron-accepting ability of the solvent is important for oxygenate formation.

1-Alkylbenzimidazoles as unique promoters for a homogeneous ruthenium catalyst for direct ethylene glycol formation from synthesis gas

Abstract 1-Alkylbenzimidazoles such as 1-methylbenzimidazole and 1,5,6-trimethylbenzimidazole have been found to be excellent promoters for direct ethylene glycol formation from hydrogen and carbon monoxide in the presence of a homogeneous ruthenium catalyst. High pressure IR analyses revealed that three Ru species, [HRu 3 (CO) 11 ] − (I), Ru(CO) 5 (II) and Ru(CO) 4 (1-alkylbenzimidazole) (III) had formed. An analysis of the relationship between activity and identity of Ru species showed that ruthenium species III plays an important role in ethylene glycol formation, and that the high coordination ability of benzimidazoles is essential to the promoting effect on ethylene glycol formation.

Hydrogenation of carbon monoxide by homogeneous ruthenium-rhenium bimetallic catalysts: effects of rhenium carbonyl as a promoter for ethylene glycol formation

Abstract The activity of the ruthenium-halide catalyst for ethylene glycol formation from CO/H 2 is enhanced by a rhenium carbonyl compound. The activity of the Ru-Re bimetallic catalyst is dependent upon the ratio of Re/Ru atoms and the ratio of moles of halide to atoms of Re. The activities of Ru-Re-alkali metal iodide catalysts increased with increasing ionic radius of alkali metal.

A new homogeneous rhodium catalyst for formation of ethylene glycol from synthesis gas: novel effect of imidazole promoters

Abstract A homogeneous rhodium catalyst, when treated with large excess of an imidazole compound has been found to show high activity for formation of ethylene glycol from synthesis gas. Solvent effect and IR analyses suggest that HRh(CO) 3 (imidazole) plays an important role in formation of ethylene glycol.