Pakrieva Ekaterina, Kolobova Ekaterina, Kotolevich Yulia, Pascual Laura, Carabineiro Sónia A C, Kharlanov Andrey N, Pichugina Daria, Nikitina Nadezhda, German Dmitrii, Partida Trino A Zepeda, Vazquez Hugo J Tiznado, Farías Mario H, Bogdanchikova Nina, Cortés Corberán Vicente, Pestryakov Alexey
Research School of Chemistry & Applied Biomedical Sciences, National Research Tomsk Polytechnic University, Lenin Av. 30, 634050 Tomsk, Russia.
Instituto de Catálisis y Petroleoquímica, Consejo Superior de InvestigacionesCientíficas, Marie Curie 2, 28049 Madrid, Spain.
Nanomaterials (Basel). 2020 May 2;10(5):880. doi: 10.3390/nano10050880.
This study aims to identify the role of the various electronic states of gold in the catalytic behavior of Au/MO/TiO (where MO are FeO or MgO) for the liquid phase oxidation of -octanol, under mild conditions. For this purpose, Au/MO/TiO catalysts were prepared by deposition-precipitation with urea, varying the gold content (0.5 or 4 wt.%) and pretreatment conditions (H or O), and characterized by low temperature nitrogen adsorption-desorption, X-ray powder diffraction (XRD), energy dispersive spectroscopy (EDX), scanning transmission electron microscopy-high angle annular dark field (STEM HAADF), diffuse reflectance Fourier transform infrared (DRIFT) spectroscopy of CO adsorption, temperature-programmable desorption (TPD) of ammonia and carbon dioxide, and X-ray photoelectron spectroscopy (XPS). Three states of gold were identified on the surface of the catalysts, Au, Au and Au, and their ratio determined the catalysts performance. Based on a comparison of catalytic and spectroscopic results, it may be concluded that Au was the active site state, while Au had negative effect, due to a partial blocking of Au by solvent. Au also inhibited the oxidation process, due to the strong adsorption of the solvent and/or water formed during the reaction. Density functional theory (DFT) simulations confirmed these suggestions. The dependence of selectivity on the ratio of Brønsted acid centers to Brønsted basic centers was revealed.
本研究旨在确定金的各种电子态在Au/MO/TiO（其中MO为FeO或MgO）对辛醇液相氧化反应的催化行为中的作用，反应条件温和。为此，采用尿素沉积沉淀法制备了Au/MO/TiO催化剂，改变金含量（0.5或4 wt.%）和预处理条件（H或O），并通过低温氮吸附-脱附、X射线粉末衍射（XRD）、能量色散光谱（EDX）、扫描透射电子显微镜-高角度环形暗场（STEM HAADF）、CO吸附的漫反射傅里叶变换红外（DRIFT）光谱、氨和二氧化碳的程序升温脱附（TPD）以及X射线光电子能谱（XPS）对其进行表征。在催化剂表面鉴定出三种金的状态，即Au⁰、Au⁺和Au³⁺，它们的比例决定了催化剂的性能。基于催化和光谱结果的比较，可以得出结论，Au⁰是活性位点状态，而Au⁺由于被溶剂部分覆盖而具有负面影响。Au³⁺也抑制了氧化过程，这是由于反应过程中溶剂和/或水的强烈吸附。密度泛函理论（DFT）模拟证实了这些观点。揭示了选择性对布朗斯特酸中心与布朗斯特碱中心比例的依赖性。
