Vovchok Dimitriy, Guild Curtis J, Llorca Jordi, Xu Wenqian, Jafari Tahereh, Toloueinia Panteha, Kriz David, Waluyo Iradwikanari, Palomino Robert M, Rodriguez José A, Suib Steven L, Senanayake Sanjaya D
Department of Chemistry, Stony Brook University, Stony Brook, NY 11794, USA and Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
Department of Chemistry, University of Connecticut, Storrs, CT 06269, USA.
Phys Chem Chem Phys. 2017 Jul 21;19(27):17708-17717. doi: 10.1039/c7cp02378b. Epub 2017 Jun 27.
We have synthesized and tested a highly active Cu doped mesoporous CeO catalyst system for the low temperature water-gas shift (WGS) reaction. While typical oxide-supported copper WGS catalysts are characterized by high copper loadings (30-40%), the morphological properties of the mesoporous CeO material enable high catalytic activity at copper loadings as low as 1%. Operando X-ray diffraction, in situ X-ray absorption near-edge structure spectroscopy (XANES), and operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) methods were used to probe the interactions between the metal and mesoporous oxide components under reaction conditions. Copper was observed to undergo reduction from oxide to metal under WGS conditions at 150 °C, while the CeO lattice was observed to expand upon heating, indicating Ce formation correlated with CO production. The active state of the catalysts was confirmed by in situ XANES to contain Cu and partially reduced CeO. DRIFTS analysis revealed carboxyl species bound to copper during reduction, as well as formate and carbonate surface species on ceria. Lower concentrations of copper were observed to foster enhanced metal-support interactions.
我们合成并测试了一种用于低温水煤气变换（WGS）反应的高活性铜掺杂介孔CeO催化剂体系。典型的氧化物负载型铜WGS催化剂的特点是铜负载量高（30 - 40%），而介孔CeO材料的形态特性使得在低至1%的铜负载量下仍具有高催化活性。采用原位X射线衍射、原位X射线吸收近边结构光谱（XANES）和原位漫反射红外傅里叶变换光谱（DRIFTS）方法来探究反应条件下金属与介孔氧化物组分之间的相互作用。观察到在150℃的WGS条件下，铜从氧化物还原为金属，同时观察到CeO晶格在加热时膨胀，表明Ce的形成与CO生成相关。原位XANES证实催化剂的活性状态包含Cu和部分还原的CeO。DRIFTS分析揭示了还原过程中与铜结合的羧基物种，以及氧化铈上的甲酸盐和碳酸盐表面物种。观察到较低浓度的铜会促进增强的金属 - 载体相互作用。
