探讨 ReOx/CeO2 催化剂对 CO2 加氢反应的形态影响,Catalysis Science & Technology

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探讨 ReOx/CeO2 催化剂对 CO2 加氢反应的形态影响
Catalysis Science & Technology ( IF 4.4 ) Pub Date : 2022-01-06 , DOI: 10.1039/d1cy02096j
Bin Yang _{1,

2,

3} , Yifu Wang ₃ , Longtai Li ₃ , Biao Gao ₃ , Lingxia Zhang _{1,

2} , Limin Guo ₃

Affiliation

可以通过控制晶体形态来优化二氧化铈（CeO _{2 ）负载催化剂在非均相反应中的性能。}然而，仍然缺乏关于CeO ₂形态如何影响CO ₂加氢性能的见解。在这里，原位漫反射红外傅里叶变换光谱和程序升温表面反应技术用于识别和表征 CeO ₂负载铼 (Re) 催化剂的形态效应，包括 CeO ₂纳米立方体负载 Re (ReO _x /CeO ₂ -C ), CeO ₂纳米棒负载的 Re (ReO _x /CeO₂ -R)和CeO₂纳米多面体负载的Re(ReO_x /CeO₂ -P)。在 2 MPa 和 613 K 下，_{与 ReO x} /CeO₂ -C (1.5%) 和 ReO_x /CeO₂ -P (1.3% ) 相比，ReO x /CeO 2 -R 表现出增强的 CO 2 转化率₍ 14.7_% )_{。 ReO}_x /CeO_{2 -R (40.9%) 的}₄选择性也远远超过 ReO_x /CeO₂ -C 和 ReO_x /CeO₂ -P (~5%)。_{Re和CeO 2}之间的电子金属-载体相互作用发现很大程度上取决于CeO ₂的形态并且与H ₂活化和CO ₂吸附密切相关。_{在CO 2}加氢过程中，强吸附碳酸盐(CO ₃^2- ) 被确定为覆盖ReO _x /CeO ₂ -P 和ReO _x /CeO ₂ -C的表面，但在ReO _x /CeO ₂ -R 上不存在。这种稳定且不可逆的中间体局部改变了催化性能。ReO _x /CeO ₂ -R 中的金属 Re ⁰有利于 H ₂解离产生氧空位并因此促进CO 2 化学吸附_为CO ₂^δ^-而不是CO ₃^2-。此外，在 ReO _x /CeO ₂ -R中轻松消除 CO ₃^2-是实现高催化性能的关键步骤。这项工作揭示了在 CO ₂加氢中起重要作用的 CeO _{2形态效应。}这些发现提供了对形态依赖性催化机理的新认识，并开辟了控制CeO ₂负载的金属催化剂用于CO ₂加氢反应的新途径。

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Probing the morphological effects of ReOx/CeO2 catalysts on the CO2 hydrogenation reaction

The performance optimization of ceria (CeO₂)-supported catalysts in heterogeneous reactions can be enabled by the control of crystal morphology. However, insights into how the CeO₂ morphology affects the CO₂ hydrogenation performance are still lacking. Here, in situ diffuse reflectance infrared Fourier transform spectroscopy and temperature-programmed surface reaction techniques are utilized to identify and characterize the morphological effect of CeO₂ supported rhenium (Re) catalysts, including CeO₂ nanocube supported Re (ReO_x/CeO₂-C), CeO₂ nanorod supported Re (ReO_x/CeO₂-R), and CeO₂ nanopolyhedron supported Re (ReO_x/CeO₂-P). ReO_x/CeO₂-R exhibits enhanced CO₂ conversion (14.7%) compared to ReO_x/CeO₂-C (1.5%) and ReO_x/CeO₂-P (1.3%) at 2 MPa and 613 K. The CH₄ selectivity on ReO_x/CeO₂-R (40.9%) also far exceeds those on ReO_x/CeO₂-C and ReO_x/CeO₂-P (∼5%). The electronic metal–support interaction between Re and CeO₂ is found to be largely dependent on the CeO₂ morphology and closely linked with H₂ activation and CO₂ adsorption. The strongly adsorbed carbonate (CO₃²⁻) is identified to cover the surface of ReO_x/CeO₂-P and ReO_x/CeO₂-C during CO₂ hydrogenation but is absent over ReO_x/CeO₂-R. This stable and irreversible intermediate locally modifies the catalytic performance. The metallic Re⁰ in ReO_x/CeO₂-R favors H₂ dissociation to generate oxygen vacancies and thus promotes chemisorption of CO₂ as CO₂^δ− rather than CO₃²⁻. Moreover, the facile elimination of CO₃²⁻ in ReO_x/CeO₂-R is a key step for highly catalytic performance. This work uncovers the CeO₂ morphological effects which play a significant role in CO₂ hydrogenation. These findings offer a new understanding of the morphology-dependent catalytic mechanism and open a new avenue to control the reactivity of CeO₂-supported metal catalysts for CO₂ hydrogenation.

更新日期：2022-01-06

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