Efficient removal of the carbon deposits formed during the mixed methane reforming over Ni/Al_2O_3

摘要

This work investigates the process of elimination of carbon deposits formed during the mixed reforming of methane mixture. The mixed reforming of methane to synthesis gas was studied over Ni/Al2O3 catalyst in the 650-750 degrees C. The amount of carbon deposit on the surface of catalyst varied from 2.8 to 5.9%, depending on the reaction temperature. The reactivity of carbon species was evaluated in the oxygen, hydrogen, carbon dioxide, and water mixtures. The obtained results revealed the presence of highly active carbon form (etched at a temperature below 200 degrees C) and inactive form (gasification at a temperature above 500 degrees C). The SEM and Raman analyses confirmed the presence of carbon in the form of filaments. Among all investigated gasification agents, water vapor was found to be the most efficient in removing the carbon deposit due to better adsorption of water on the surface of aluminum oxide. The overall mechanism of mixed methane reforming along with carbon gasification was shown.