Engineering oxygen vacancy-rich CeOx overcoating onto Ni/Al2O3 by atomic layer deposition for bi-reforming of methane
Engineering oxygen vacancy-rich CeOx overcoating onto Ni/Al2O3 by atomic layer deposition for bi-reforming of methane
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DOI：
10.1016/j.cej.2023.141611
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发表时间：
2023-02-03
影响因子：
15.1
通讯作者：
Liang, Xinhua
中科院分区：
文献类型：
--
作者：
Jin, Baitang;Wang, Kaiying;Liang, Xinhua
采用原子层沉积法（ALD）制备了CeOx/Ni/Al 2 O3甲烷二重整催化剂，作为甲烷干重整（DRM）和甲烷水蒸气重整（SRM）的组合。采用原子层沉积法在Ni/Al 2 O3催化剂上成功制备了非化学计量比的CeOx薄膜，形成了良好的Ni-CeOx界面，改善了催化剂的性能。归因于独特的ALD生长模式，在ALD沉积的CeOx外涂层中存在大量的Ce（III）和氧空位。在BRM反应之前的还原过程有助于Ce（IV）进一步还原为Ce（III），导致更多的氧空位。在Ni-CeOx界面处的氧空位使得能够实现高速率的CO2活化，并且使得能够实现用于BRM的CO2和H2O的活化之间的平衡。由于其氧空位作为CO2和H2O的活化位点，CeOx ALD外涂层显著提高了Ni/Al 2 O3催化剂的活性，并且在合适的H2O/CO2/CH 4进料比下实现了对H2/CO比的更好控制。CeOx外涂层增强了Ni（II）位点的还原性，并有助于防止Ni在BRM反应期间氧化。具有CeOx外涂层的Ni/Al_2O_3催化剂由于其更好的反应物活化能力而实现了更少的积碳。
Atomic layer deposition (ALD) was applied to develop CeOx-overcoated Ni/Al2O3 catalyst for bi-reforming of methane (BRM), as the combination of dry reforming of methane (DRM) and steam reforming of methane (SRM). Non-stoichiometric CeOx thin films were successfully deposited on Ni/Al2O3 particles by ALD, which constructed a beneficial Ni-CeOx interface and modified the catalyst property. Ascribed to the unique ALD growth mode, a high amount of Ce(III) and oxygen vacancies existed in the ALD-deposited CeOx overcoating. A reduction process before the BRM reaction contributed to the further reduction of Ce(IV) to Ce(III), resulting in more oxygen vacancies. The oxygen vacancies at the Ni-CeOx interface enabled a high rate of CO2 activation and enabled the balance between the activation of CO2 and H2O for BRM. Due to its oxygen vacancies as activation sites for CO2 and H2O, CeOx ALD overcoating significantly improved the activity of Ni/Al2O3 catalyst and achieved a better control in the H2/CO ratio with a suitable ratio of H2O/CO2/CH4 feed. CeOx overcoatings enhanced the reducibility of Ni(II) sites and assisted in preventing Ni from oxidation during the BRM reaction. Less carbon deposition was achieved by the Ni/Al2O3 catalyst with CeOx overcoating as ascribed to its better reactant activation capacity.