The Study of Reverse Water Gas Shift Reaction Activity over Different Interfaces: The Design of Cu-Plate ZnO Model Catalysts
The Study of Reverse Water Gas Shift Reaction Activity over Different Interfaces: The Design of Cu-Plate ZnO Model Catalysts
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DOI：
10.3390/catal10050533
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发表时间：
2020-05
期刊：
影响因子：
3.9
通讯作者：
Jinjun Wen;Chunlei Huang;Yuhai Sun;L. Liang;Yudong Zhang;Yujun Zhang;Mingli Fu;Junliang Wu;Limin Chen;D. Ye
中科院分区：
文献类型：
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作者：
Jinjun Wen;Chunlei Huang;Yuhai Sun;L. Liang;Yudong Zhang;Yujun Zhang;Mingli Fu;Junliang Wu;Limin Chen;D. Ye
CO2加氢制甲醇是Cu/ZnO基催化剂上应用最广泛的催化反应之一，Zn从ZnO载体上迁移到Cu纳米粒子表面（ZnOx-Cu NP-ZnO）形成的界面是CO2加氢制甲醇的主要原因。然而，伴随的逆水煤气变换（RWGS）反应显着降低甲醇的选择性和失活催化剂很快。因此，抑制RWGS对于提供高产率的甲醇是非常重要的。了解直接接触Cu-ZnO界面和ZnOx-Cu NP-ZnO界面上的RWGS反应活性，对于揭示CO2加氢制甲醇的低甲醇选择性和寻找RWGS反应的高效催化剂具有重要意义。采用水热法制备了Cu掺杂的片状ZnO（ZnO：XCu）模型催化剂，模拟Cu-ZnO直接接触界面，并与湿法浸渍法制备的片状ZnO负载1wt%Cu（1Cu/ZnO）催化剂进行RWGS反应对比。采用电子顺磁共振（EPR）、X射线衍射（XRD）、扫描电镜（SEM）、拉曼、氢程序升温还原（H2-TPR）和CO2程序升温脱附（CO2-TPD）等手段对催化剂进行了表征。表征结果表明，H2还原后，Cu进入ZnO晶格，最终形成直接接触的Cu-ZnO界面。结果表明，与ZnOx-Cu NP-ZnO界面相比，直接接触Cu-ZnO界面在反应温度低于500 °C时表现出较差的RWGS反应活性;而在反应温度高于500 °C时，直接接触Cu-ZnO界面更稳定，使得ZnO：XCu模型催化剂的催化活性上级于1Cu/ZnO。这一发现将有助于设计用于CO2加氢制甲醇和RWGS反应的稳健且高效的催化剂。
CO2 hydrogenation to methanol is one of the main and valuable catalytic reactions applied on Cu/ZnO-based catalysts; the interface formed through Zn migration from ZnO support to the surface of Cu nanoparticle (ZnOx-Cu NP-ZnO) has been reported to account for methanol synthesis from CO2 hydrogenation. However, the accompanied reverse water gas shift (RWGS) reaction significantly decreases methanol selectivity and deactivates catalysts soon. Inhibition of RWGS is thus of great importance to afford high yield of methanol. The clear understanding of the reactivity of RWGS reaction on both the direct contact Cu-ZnO interface and ZnOx-Cu NP-ZnO interface is essential to reveal the low methanol selectivity in CO2 hydrogenation to methanol and look for efficient catalysts for RWGS reaction. Cu doped plate ZnO (ZnO:XCu) model catalysts were prepared through a hydrothermal method to simulate direct contact Cu-ZnO interface and plate ZnO supported 1 wt % Cu (1Cu/ZnO) catalyst was prepared by wet impregnation for comparison in RWGS reaction. Electron paramagnetic resonance (EPR), XRD, SEM, Raman, hydrogen temperature-programmed reduction (H2-TPR) and CO2 temperature-programmed desorption (CO2-TPD) were employed to characterize these catalysts. The characterization results confirmed that Cu incorporated into ZnO lattice and finally formed direct contact Cu-ZnO interface after H2 reduction. The catalytic performance revealed that direct contact Cu-ZnO interface displays inferior RWGS reaction reactivity at reaction temperature lower than 500 °C, compared with the ZnOx-Cu NP-ZnO interface; however, it is more stable at reaction temperature higher than 500 °C, enables ZnO:XCu model catalysts superior catalytic activity to that of 1Cu/ZnO. This finding will facilitate the designing of robust and efficient catalysts for both CO2 hydrogenation to methanol and RWGS reactions.