Hydrogenation of propylene and hydrogenolysis of cyclopropane on activated Mo(CO)6/Alumina catalysts

The hydrogenation of propylene and the hydrogenolysis of cyclopropane has been studied on Mo(CO) 6 Al 2 O 3 activated in flowing He or H2. The γ-alumina was either partially dehydroxylated in flowing He at 475 °C (PDA) or nearly completely dehydroxylated at 950 °C (DA). In a pulse reactor with hydrogen carrier, Mo(CO) 3 PDA converted propylene both to ethylene + 2-butene (metathesis) and to propane (hydrogenation). Activation in He or in H2 to 300 °C (average ON ∼- +2 and +3, respectively) greatly enhanced the activity of Mo(CO) 3 PDA for hydrogenation which had to be measured in a flow reactor at −46 °C. Mo(CO) 6 DA activated to 300–500 °C in He or in H2 (average ON near zero) was an even more active catalyst and heating DA;He,300 ° in H2 to 500 °C led to a still more active catalyst. Hydrogenation was approximately zero order in propylene and first order in hydrogen. The same materials catalyzed the hydrogenolysis of cyclopropane at 0–100 °C. DA;He,300 ° and PDA;He,300 ° were the most active catalysts. Both single and double hydrogenolysis occurred as initial reactions to form propane and methane + ethane, respectively. Double hydrogenolysis was favored by molybdenum in lower ON.