Conversion and Selectivity in Hydroformylation of Hex‐1‐en with Silica‐Gel‐, Silica‐Alumina‐Gel and Alumina‐Oxide‐ Supported Dicobalt Octacarbonyl and Cyclopentadienylcobalt DicarbonylThe catalytic influence of silica‐gel‐, silica‐alumina‐gel‐ and alumina‐oxide‐supported Co2(CO)8and CpCo(CO)2on the conversion and selectivity in hydroformylation of hex‐1‐en has been studied at 353 K under 120 bar syngas pressure in acetonitrile. The support systems were prepared by impregnation of SiO2(Grace), SiO2/4% Al2O3(Kali Chemie), SiO2/11% Al2O3(Kali Chemie) and Al2O3(Kali Chemie) using Co2(CO)8and CpCo(CO)2solutions in pentane, dichlormethane and 2‐chlorpropane.The results are discussed with regard to some measured relevant support characteristics. The turn over numbers especially those of silica‐gel‐ and silica‐alumina‐gel supported Co2(CO)8and CpCo(CO)2show positive effects in relation to a heterogeneo