| Popis: |
The adsorption behavior of propylene and oxygen on CuO, a catalyst for total oxidation of propylene, and on Cu2O, a catalyst for partial oxidation, has been investigated. As well as adsorption from pure gases, adsorption from rm{C 3 H 6 O 2 } mixtures has been measured. These adsorptions accordingly refer to precatalysis conditions, and have been studied both volumetrically and by infrared spectroscopy. Differences between the catalysts are related to differences in the composition and structure of chemisorbed intermediate surface complexes (ISC). ISC formed from propylene and oxygen on CuO are considered to contain more oxygen than that corresponding to a 1:1 C3H6:O2 ratio and to be chemisorbed as formate-, acetate-, and oxalate-like compounds. On Cu2O, however, there is mostly reversible chemisorption of propylene and the formation of ISC without excess oxygen. In this case the complexes are weakly bonded to the catalyst, and the strengths of their CC and CH (CH3 group) bonds are weakened as compared to propylene. |
