| Popis: |
The thermal desorption of methanol and its decompostion products from magnesium oxide powder was recorded over the temperature range 300–1123 K. The formation of formaldehyde was observed in small quantities above 438 K. Large quantities of CO and H 2 were evolved at 723–900 K, accompanied by smaller amounts of CH 4 . No ether formation was detected. Methanol desorption was observed below 773 K, with structure in the spectrum revealing at least two different phases of the desorption process. The variation of this structure with initial coverage serves to confirm and clarify previous models for methoxyl on MgO, based on infrared absorption studies. The ease of adsorption, desorption, and migration of methanol species on MgO are also studied, and these features are compared with the corresponding properties of the methanol/Al 2 O 3 system. The differences between them are correlated with the differences in proposed models for surface species in the two cases. |
