School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China.
Phys Chem Chem Phys. 2018 Sep 12;20(35):22744-22752. doi: 10.1039/c8cp02270d.
In this paper, black TiO2 without adding active components was developed for NH3-SCR-DeNOx. The catalytic activity tests showed that the NO removal efficiency of black TiO2 was always greater than 90% at 330-390 °C, which almost reached that of the commercial NH3-SCR-DeNOx catalyst. XRD, UV-vis, TG, EPR, XPS, H2-TPR, DFT and NH3-TPD analyses were carried out to study the structure-effectiveness relationship. We found that a large number of oxygen vacancies were formed over the black TiO2 surface. It was not only promoted the adsorption of NH3via direct (oxygen vacancies as Lewis acid sites for NH3 adsorption) and indirect (oxygen vacancies promote the formation of surface hydroxyl groups, which are Brønsted acid sites for NH3 adsorption) forms, but also improved the redox properties by promoting the reduction of Ti4+ to Ti3+. These changes lead to the superior catalytic activity of black TiO2 for NH3-SCR-DeNOx. Additionally, an in situ DRIFT study demonstrated that the NH3-SCR-DeNOx reaction over black TiO2 occurred via the Eley-Rideal (E-R) mechanism. Finally, the catalytic stability and resistance to H2O and SO2 of the black TiO2 catalyst were studied, and it showed good performances. This study offered new and important insights into the understanding of the role of oxygen vacancies in determining the physical and chemical properties of catalysts.
本文开发了一种无需添加活性组分的黑色 TiO2 用于 NH3-SCR-DeNOx。催化活性测试表明，在 330-390°C 下，黑色 TiO2 的 NO 去除效率始终大于 90%，几乎达到了商业 NH3-SCR-DeNOx 催化剂的水平。通过 XRD、UV-vis、TG、EPR、XPS、H2-TPR、DFT 和 NH3-TPD 分析研究了结构-性能关系。我们发现黑色 TiO2 表面形成了大量的氧空位。这不仅促进了 NH3 的吸附（氧空位作为 NH3 吸附的路易斯酸位）和间接吸附（氧空位促进表面羟基的形成，这是 NH3 吸附的布朗斯台德酸位），还通过促进 Ti4+ 还原为 Ti3+ 提高了氧化还原性能。这些变化导致了黑色 TiO2 在 NH3-SCR-DeNOx 中具有优异的催化活性。此外，原位 DRIFT 研究表明，黑色 TiO2 上的 NH3-SCR-DeNOx 反应通过 Eley-Rideal (E-R) 机制进行。最后，研究了黑色 TiO2 催化剂的催化稳定性以及对 H2O 和 SO2 的抗干扰性，结果表明其具有良好的性能。本研究为理解氧空位在决定催化剂物理化学性质方面的作用提供了新的重要见解。
