Self-hydrating of a ceria-based catalyst enables efficient operation of solid oxide fuel cells on liquid fuels

Kang Xu; Hua Zhang; Wanqing Deng; Ying Liu; Yong Ding; Yucun Zhou; Meilin Liu; Yu Chen

doi:10.1016/j.scib.2023.09.012

Self-hydrating of a ceria-based catalyst enables efficient operation of solid oxide fuel cells on liquid fuels

Sci Bull (Beijing). 2023 Nov 15;68(21):2574-2582. doi: 10.1016/j.scib.2023.09.012. Epub 2023 Sep 12.

Authors

Kang Xu¹, Hua Zhang¹, Wanqing Deng¹, Ying Liu², Yong Ding³, Yucun Zhou³, Meilin Liu³, Yu Chen⁴

Affiliations

¹ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
² Research Institute of Renewable Energy and Advanced Materials, Zijin Mining Group Co., Ltd., Xiamen 361101, China.
³ School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta GA 30309, USA.
⁴ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China. Electronic address: eschenyu@scut.edu.cn.

PMID: 37730510
DOI: 10.1016/j.scib.2023.09.012

Abstract

The commercialization of solid oxide fuel cells (SOFCs) that run on liquid hydrocarbon fuels is hindered by the poor coking tolerance of the state-of-the-art anode. Among the strategies developed, modulating the reforming reaction site's local steam/carbon ratios to enhance the coking tolerance is efficient but challenging. Here we report our rational design of a ceria-based catalyst (with a nominal composition of Ce_0.95Ru_0.05O_2-_δ, CR₅O) that demonstrates remarkable tolerance to coking while maintaining excellent activity for direct utilization of liquid fuels in SOFCs. Under operating conditions, the catalyst is transformed to a partially reduced oxide frame covered with Ru nanoparticles (Ru/Ce_0.95Ru_0.05-_xO_2-_δ, Ru/CR_5-_xO), as confirmed by experimental analyses. The Ru/CR_5-_xO demonstrates excellent self-hydration capability to remove the coke. When applied to the Ni-yttria-stabilized zirconia (Ni-YSZ) anode of an SOFC with liquid fuels, the catalyst enables excellent performance, achieving a peak power density of 1.010 W cm^-2 without coking for ∼200 h operation (on methanol) at 750 °C. Furthermore, density functional theory calculations reveal that the high activity and coking tolerance of the Ru/CR_5-_xO catalyst-coated Ni-YSZ anode is attributed to the reduced energy barrier for the rate-limiting step and the formation of a COH intermediate for rapid carbon removal.

Keywords: Anode; Carbon removal; Catalyst; Liquid fuels; Nanoparticles.