Novel complex-oxide and complex-boride catalysts bearing
rare-earth and alkali-earth metals was obtained under conditions of Self-Propagating
High-Temperature Synthesis (SHS). The SHS catalysts were used for methane
oxidative dehydrodimerization to ethylene and showed stable high activity
at 700-800 C (methane conversion up to 20 %) and C2-selectivity (up to
60%) for a long time
(several hundreds of hours). Oxygen atoms of the crystalline
lattice of complex-oxide SHS ceramics was shown by the method of thermoprogrammed
desorption (TPD) with mass spectrometric analysis to take part in the sorption-desorption
processes. It provides high stability of the catalyst operating in time.
The relay-race mechanism was proposed for the process of oxygen transport.