STUDY ON ACTIVE-SITES FOR SPLITTING C-H B OND OF CH4 ON SURFACE OF LA2O3

A series of La2O3 samples were prepared under different conditions. Th e hydrogen exchange reaction between CH4 and CD4 was chosen as test re action to measure the activity of splitting C-H bond on La2O3. The NH3 -TPD, CO2-TPD and poisoning experiments were carried out to study the acidic sites and the active sites on La2O3. The surface structure comp osition (O / La ratio) was measured by XPS. It was found that although being minor component of active sites, the acidic sites are also esse ntial for the cleavage of C-H bond of CH4. The acidic sites and basic sites composing the active sites are probably a part of lattice La3+ a nd O2- ions, which show enough strength of acidity and basicity, respe ctively. The formation of vacancies in La2O3 crystal can make more lat tice ions become active sites.