Catalysis Letters, Vol.33, No.3-4, 331-339, 1995
Hydrogenative Ring-Opening of Propylcyclopropane over Silica-Supported Pt and Pd Catalysts
The effects of temperature and hydrogen pressure on the hydrogenative ring opening of propylcyclopropane over Pt/SiO2 and Pd/SiO2 catalysts were studied. Temperature dependence in the 323-373 K temperature range in a pulse system was investigated, while a static recirculation reactor was used for hydrogen pressure dependence measurements. The ring-opening reactions took place exclusively at all temperatures and hydrogen pressures studied. Monotonous increase was observed for the reactivity of propylcyclopropane as a function of temperature. At constant temperature, the reaction rate vs. hydrogen pressure dependence curves passed through a maximum indicating dissociative adsorption over both Pt and Pd catalysts. The scission of the sterically less hindered direction (producing 2-methylpentane) was the major reaction pathway on both catalysts with practically identical regioselectivity values. On the basis of these results a selective mechanism was proposed for the ring-opening reaction.
Keywords:ALKYL-SUBSTITUTED CYCLOPROPANES;OXYGEN-MODIFIED MO(111);METHYLCYCLOPROPANE HYDROGENOLYSIS;PRESSURE-DEPENDENCE;PT/SIO2 CATALYST;ISOMERIZATION;HYDROCARBONS;MECHANISMS;RUTHENIUM;EXCHANGE