Catalytic steam reforming of ethanol over high surface area CeO2: The role of CeO2 as an internal pre-reforming catalyst

Abstract

In the present work, it was found that high surface area ceria (CeO2 (HSA)), synthesized by a surfactant-assisted approach, have useful ethanol steam reforming activity under solid oxide fuel cells (SOFCs) temperatures. The catalyst provides good reforming reactivity and high resistance toward carbon deposition compared to Ni/Al2O3 and conventional low surface area ceria (CeO2 (LSA)). Although the hydrogen selectivity at steady state from the ethanol steam reforming over CeO2 (HSA) was lower than Rh/Al2O3, the resistance toward carbon deposition of CeO2 (HSA) was considerably higher.At temperature 900°C, the main products from the steam reforming of ethanol over CeO2 (HSA) (with inlet C2H5OH/H2O molar ratio of 1.0/3.0) were H2 (with the selectivity of 67.5%), CH4, CO, and CO2. In contrast, the formations of C2H4 and C2H6 were also observed from the steam reforming of ethanol over Ni/Al2O3 and CeO2 (LSA). The combination use of CeO2 and Ni/Al2O3 was studied in an annular ceramic reactor by applying CeO2 as an internal pre-reforming catalyst. The main purpose of CeO2 is to convert all ethanol and other high hydrocarbon compounds (e.g. C2H4 and C2H6) forming CH4, CO, CO2, and H2, while Ni/Al2O3 is applied to reform all CH4 left from the pre-reforming section and maximize the yield of hydrogen production. After operated at 900°C for 100h, this combination pattern offers high hydrogen selectivity (87.0–91.4%) and good resistance toward carbon deposition. This successful development eliminates the requirement of expensive noble metal catalysts or the installation of an external pre-reformer in order to reform ethanol internally (IIR-SOFC).