Robust and Coke-free Ni Catalyst Stabilized by 1-2 nm-Thick Multielement Oxide for Methane Dry Reforming
Robust and Coke-free Ni Catalyst Stabilized by 1-2 nm-Thick Multielement Oxide for Methane Dry Reforming
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用于甲烷干重整的坚固且无焦镍催化剂，由 1-2 纳米厚的多元氧化物稳定
DOI：
10.1021/acscatal.1c02995
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发表时间：
2021-09-23
期刊：
影响因子：
12.9
通讯作者：
Lu, An-Hui
中科院分区：
文献类型：
--
作者：
He, Lei;Li, Mingrun;Lu, An-Hui
甲烷干重整将温室气体 CH4 和 CO2 共同转化为化学活性合成气 (H-2/CO2)，为利用碳资源生产化学品和燃料提供了一条有前景的途径。镍催化剂对于该反应是最活跃的，但由于金属在较高温度（>973 K）下烧结或在相对较低温度（673-973 K）下焦炭积累而导致快速失活的困境。在这里，我们报告了一种催化剂结构——Ni颗粒（15 nm）被1-2 nm厚的多元素氧化物（MEO）层限制——允许在873-1073 K下稳定运行，化学计量CH4/CO2比率为1.0，即催化剂失活的严酷条件，但对于工艺效率和原子经济性具有工业意义。原位演化的 MEO 层类似于高熵氧化物的特性，即使在 1173 K 下也能稳定具有适当尺寸和高折射率面的 Ni 颗粒。同时，近大气压下的原位 TEM 结合智能重力分析 (IGA)-质谱 (MS) 表征证明这种独特的结构平衡了 CH4 和 CO2 的活化。因此，即使在最严重的结焦温度 873 K 下，催化剂的寿命也得到了有效延长，几乎无焦操作。这种高熵设计和稳定效应提供了一种简便的策略，可以精确制造活性和坚固的金属催化剂，其具有广泛的操作温度，适用于许多具有挑战性的反应。
Methane dry reforming, co-converting greenhouse gases CH4 and CO2 into chemically active syngas (H-2/CO2), 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.