Robust and Coke-free Ni Catalyst Stabilized by 1–2 nm-Thick Multielement Oxide for Methane Dry Reforming
Lei He, Mingrun Li, Wen‐Cui Li, Wei Xu, Yang Wang, Yan‐Bo Wang, Wenjie Shen, An‐Hui Lu
Abstract
Methane dry reforming, co-converting greenhouse gases CH4 and CO2 into chemically active syngas (H2/CO), affords a promising route for producing chemicals and fuels from carbon resources. Ni catalysts are the most active for this reaction but suffer from the dilemma of rapid deactivation caused by metal sintering at higher temperatures (>973 K) or coke accumulation at relatively lower temperatures (673–973 K). Here, we report a catalyst configuration—Ni particles (15 nm) confined by a 1–2 nm-thick multielement-oxide (MEO) layer—allows a stable operation at 873–1073 K with a stoichiometric CH4/CO2 ratio of 1.0, that is, the severe conditions for catalyst deactivation but of industrial interest for process efficiency and atomic economy. The in situ-evolved MEO layer resembles the property of high-entropy oxide, which stabilizes the Ni particles with appropriate size and high-index facets, even at 1173 K. Meanwhile, in situ TEM under near atmospheric pressure combining intelligent gravity analysis (IGA)-mass spectrometry (MS) characterizations prove that this unique structure balanced the activation of CH4 and CO2. Thus, the lifetime of the catalyst has been efficiently prolonged with nearly coke-free operations, even at 873 K, the most severe coking temperature. This high-entropy design and stabilization effect offers a facile strategy to precisely fabricate active and robust metal catalysts with wide operation temperatures for many challenging reactions.