NiMo-calcium-doped ceria catalysts for inert-substrate-supported tubular solid oxide fuel cells running on isooctane

Abstract

A calcium-doped ceria (Ce1-xCaxO2−δ, 0 ≤ x ≤ 0.3) has been applied as a ceramic support in NiMo-based catalysts for an internal reforming tubular solid oxide fuel cell running on isooctane. Introducing calcium into the CeO2-based ceramic was found to improve conductivity of Ce1-xCaxO2−δ. The Ce0.9Ca0.1O2−δ (x = 0.10) sample exhibited an optimum conductivity of 0.045 S cm−1 at 750 °C. The transport of oxygen ions in Ce1-xCaxO2−δ promoted the catalytic partial oxidation of isooctane in the NiMo–Ce1-xCaxO2−δ catalyst, which increased the fuel conversion as well as H2 and CO yields. As a result, the NiMo–Ce0.9Ca0.1O2−δ (x = 0.10) catalyst exhibited a high isooctane conversion of 98%, and the H2 and CO yields achieved 74% and 83%, respectively, for reforming of isooctane and air at the O/C ratio of 1.0 at 750 °C. Furthermore, the NiMo–Ce0.9Ca0.1O2−δ catalyst has been applied as an internal reforming layer for an inert-substrate-supported tubular solid oxide fuel cell running on isooctane/air. Due to its high reforming activity, the single cell presented an initial maximum power density of 355 mW cm−2 in isooctane/air at 750 °C and displayed stable electrochemical performance during ~30 h operation. These results demonstrated the application feasibility of the NiMo–Ce0.9Ca0.1O2−δ catalyst for direct internal reforming solid oxide fuel cells running on isooctane/air.