Thanaphon Palikanon, Navadol Laosiripojana, Suttichai Assabumrungrat, and Sumittra Charojrochkul

pp. 1237 - 1249

Abstract

Methane steam reforming performances of Ni on high surface area (HSA) CeO₂ and CeO₂-ZrO₂ supports have been studied under solid oxide fuel cell (SOFC) operating conditions. Their performances were compared to general Ni/CeO₂ , Ni/CeO₂-ZrO₂, and Ni/Al₂O₃. It was firstly observed that Ni/CeO₂-ZrO₂ (HSA) with the Ce/Zr ratio of 3/1 showed the best performance in terms of activity and stability toward the methane steam reforming among those with the Ce/Zr ratios of 1/1, 1/3, and 3/1. Both Ni/CeO₂-ZrO₂ (HSA) and Ni/CeO₂ (HSA) presented better resistance toward carbon formation than the general Ni/CeO₂ , Ni/CeO₂-ZrO₂, and Ni/Al₂O₃ at the same operating conditions. These benefits are related to the high oxygen storage capacity (OSC) of CeO₂-ZrO₂. During the steam reforming process, in addition to the reactions on Ni surface (*), the redox reactions between the gaseous components presented in the system and the lattice oxygen (O_x) on CeO₂-ZrO₂ surface also take place. Among these reactions, the redox reactions between the high carbon formation potential compounds (CH₄, CH_x-*n and CO) and the lattice oxygen (O_x) can prevent the formation of carbon species from the methane decomposition and Boudard reactions at the inlet H₂O/CH₄ ratio of 3.0/1.0.