Mechanistic elucidation of chloromethane transformation over SAPO-34 using deuterated probe molecule: A FTIR study on the surface evolution of catalyst

Adsorption and transformation of chloromethane over SAPO-34 catalyst were studied using deuterated CD3Cl as probe by in situ FTIR spectroscopy and compared with CH3Cl. The detection of the deuterated hydroxyls Si(OD)Al indicated the existence of the H and D exchange reaction due to the interaction of Si(OH)Al and DCl molecules produced by CD3Cl conversion. The reversible breaking of Al–O–P bonds as a result of the interaction of Al–O–P with the produced DCl molecules has been clearly evidenced by the observation of P–OD and P–OD–Al species. Increasing CD3Cl loading favors CC generation and higher hydrocarbons formation. A possible surface species evolution and formation during CD3Cl transformation over SAPO-34 catalyst is proposed.