Methane dehydrogenation and aromatization over 4 wt% Mn/HZSM-5 in the absence of an oxidant

Methane dehydrogenation and aromatization over 4 wt% Mn/HZSM-5 in the absence of an oxidant (GHSV = 1600 mL h(-1) g(-1)) was investigated. Mn/HZSM-5 was prepared by impregnation of HZSM-5 with manganese acetate tetrahydrate solution; Mn3O4 formed was the precursor of active phase for methane activation. The induction period over Mn/HZSM-5 catalyst before aromatic products appear was long at 700 degrees C. This period shortened with a rise of the reaction temperature to 800 degrees C. XPS and TPO results showed that the partly carburized or carburized Mn species formed are probably responsible for methane activation.