The reaction kinetics of the oxidative dehydrogenation of propane was studied at 475-550°C over a VMgO catalyst. Vanadium-magnesium-oxides are among the most selective and active catalysts for the dehydrogenation...The reaction kinetics of the oxidative dehydrogenation of propane was studied at 475-550°C over a VMgO catalyst. Vanadium-magnesium-oxides are among the most selective and active catalysts for the dehydrogenation of propane to propylene. Selectivity to propylene up to about 60% was obtained at 10% conversion, but the selectivity decreased with increasing conversion. No oxygenates were detected, the only by-products were CO and CO2. The reaction rate of propane was found to be first order in propane and close to zero order in oxygen, which is in agreement with a Mars van Krevelen mechanism with the activation of the hydrocarbon as the rate determining step. The activation energy of the conversion of propane was found to be 122±6 kJ/mol.展开更多
THE oxidative dehydrogenation of propane （ODP） to propene is one of the potentially important catalytic processes for the effective utilization of light alkanes. The VMgO catalysts which have better catalytic perfor...THE oxidative dehydrogenation of propane （ODP） to propene is one of the potentially important catalytic processes for the effective utilization of light alkanes. The VMgO catalysts which have better catalytic performances for the reaction have aroused much interest and argument.Kung et al. proposed that the active phase was magnesium orthovanadate （Mg<sub>3</sub>V<sub>2</sub>O<sub>8</sub>）, but Volta et al. suggested that magnesium pyrovanadate （α-Mg<sub>2</sub>V<sub>2</sub>O<sub>7</sub>） was the active phase; in this phase, V<sup>4+</sup> ions which are associated to the formation of oxygen vacancies could stably exist, and Mg<sub>3</sub>V<sub>2</sub>O<sub>8</sub> is responsible for the total oxidation due to nonexistence of V<sup>4+</sup> ions.展开更多
文摘The reaction kinetics of the oxidative dehydrogenation of propane was studied at 475-550°C over a VMgO catalyst. Vanadium-magnesium-oxides are among the most selective and active catalysts for the dehydrogenation of propane to propylene. Selectivity to propylene up to about 60% was obtained at 10% conversion, but the selectivity decreased with increasing conversion. No oxygenates were detected, the only by-products were CO and CO2. The reaction rate of propane was found to be first order in propane and close to zero order in oxygen, which is in agreement with a Mars van Krevelen mechanism with the activation of the hydrocarbon as the rate determining step. The activation energy of the conversion of propane was found to be 122±6 kJ/mol.
文摘THE oxidative dehydrogenation of propane （ODP） to propene is one of the potentially important catalytic processes for the effective utilization of light alkanes. The VMgO catalysts which have better catalytic performances for the reaction have aroused much interest and argument.Kung et al. proposed that the active phase was magnesium orthovanadate （Mg<sub>3</sub>V<sub>2</sub>O<sub>8</sub>）, but Volta et al. suggested that magnesium pyrovanadate （α-Mg<sub>2</sub>V<sub>2</sub>O<sub>7</sub>） was the active phase; in this phase, V<sup>4+</sup> ions which are associated to the formation of oxygen vacancies could stably exist, and Mg<sub>3</sub>V<sub>2</sub>O<sub>8</sub> is responsible for the total oxidation due to nonexistence of V<sup>4+</sup> ions.
