TY - JOUR
T1 - The effect of decomposition atmosphere on the activity and selectivity of the carbonyl cluster derived Co/SiO2 and Rh/SiO2 catalysts
AU - Kiviaho, Jari
AU - Niemelä, Marita
AU - Reinikainen, Matti
AU - Vaara, T.
AU - Pakkanen, Tapani
PY - 1997
Y1 - 1997
N2 - The effect of pretreatment atmosphere, hydrogen or carbon monoxide, on the activity and selectivity of the Rh4(CO)12/SiO2 and Co4(CO)12/SiO2
catalysts in CO hydrogenation was determined. The catalysts pretreated
under hydrogen exhibited a higher degree of decomposition of the
original cluster, higher hydrogen uptake and lower carbon content than
those decomposed under CO. Therefore, some of the active sites of the
catalysts were encapsulated by carbon, and in the case of Co4(CO)12 poorly reducible cobalt silicates were probably also formed. The activity of the hydrogen-treated Rh4(CO)12/SiO2
was fairly similar to that of the CO-treated catalyst, but
significantly fewer oxygenates were formed. Thus, the carbon monoxide
treatment appeared to facilitate the formation of oxygenates. Probably
the original structure of rhodium carbonyl was better retained, and
thereby some of the rhodium particles remained more dispersed under CO
than under hydrogen. In the case of Co4(CO)12/SiO2
catalysts, however, no benefit was observed in conjunction with CO
pretreatment either in activity or selectivity. Most likely the CO
treatment resulted in the formation of unreactive carbonaceous species
which permanently blocked most of the active sites.
AB - The effect of pretreatment atmosphere, hydrogen or carbon monoxide, on the activity and selectivity of the Rh4(CO)12/SiO2 and Co4(CO)12/SiO2
catalysts in CO hydrogenation was determined. The catalysts pretreated
under hydrogen exhibited a higher degree of decomposition of the
original cluster, higher hydrogen uptake and lower carbon content than
those decomposed under CO. Therefore, some of the active sites of the
catalysts were encapsulated by carbon, and in the case of Co4(CO)12 poorly reducible cobalt silicates were probably also formed. The activity of the hydrogen-treated Rh4(CO)12/SiO2
was fairly similar to that of the CO-treated catalyst, but
significantly fewer oxygenates were formed. Thus, the carbon monoxide
treatment appeared to facilitate the formation of oxygenates. Probably
the original structure of rhodium carbonyl was better retained, and
thereby some of the rhodium particles remained more dispersed under CO
than under hydrogen. In the case of Co4(CO)12/SiO2
catalysts, however, no benefit was observed in conjunction with CO
pretreatment either in activity or selectivity. Most likely the CO
treatment resulted in the formation of unreactive carbonaceous species
which permanently blocked most of the active sites.
U2 - 10.1016/S1381-1169(96)00451-7
DO - 10.1016/S1381-1169(96)00451-7
M3 - Article
SN - 1381-1169
VL - 121
SP - 1
EP - 8
JO - Journal of Molecular Catalysis A: Chemical
JF - Journal of Molecular Catalysis A: Chemical
IS - 1
ER -