Effect of zeolite geometry for propane selective oxidation on cation electrostatic field of Ca2+ exchanged zeolites

The effects of zeolite geometry on propane selective oxidation were studied by in situ infrared spectrometry on Ca2+ exchanged Y, MOR and ZSM5 zeolites. Oxygen and propane adsorption at room temperature, revealed that the electrostatic field of Ca2+ increased in the order CaY < CaMOR < CaZSM5. The electrostatic field of Ca2+ cations in CaY and CaZSM5 was observed to correlate with propane selective oxidation activity and selectivity. At 353 K, low activity but high selectivity to acetone was observed for propane oxidation on CaY zeolite, while high activity and a 2:1 mixture of 2-propanol and acetone was observed on CaZSM5. CaMOR showed the lowest activity for oxygenates formation of propane oxidation, but deep oxidation to CO and CO2 was found. The results convincingly show that the geometrical structure of a zeolite determines activity and selectivity of propane partial oxidation on Ca2+ exchanged zeolites to a large extent.