Key Laboratory of Nano-minerals and Pollution Control of Anhui Higher Education Institutes, Hefei University of Technology, Hefei 230009, China; Institute of Environmental Minerals and Materials, School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China.
Key Laboratory of Nano-minerals and Pollution Control of Anhui Higher Education Institutes, Hefei University of Technology, Hefei 230009, China; Institute of Environmental Minerals and Materials, School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China.
Sci Total Environ. 2020 Aug 20;731:138951. doi: 10.1016/j.scitotenv.2020.138951. Epub 2020 May 1.
Pyrite, a naturally occurring mineral, can be found extensively in coal. The change in the pyrite structure that occurs during coaling process, the ability of the pyrite-derived α-FeO to convert NO in the presence of NH before catalyst bed and the kinetic study were investigated in this work. The pyrite-derived α-FeO was obtained by calcining at 500, 600, 700, 800 °C and was characterized by the X-ray diffraction (XRD), N physisorption, the X-ray photoelectron spectrometer (XPS), the scanning electron microscope (SEM), UV-visible near-infrared spectroscopy (UV-vis DRS), the temperature-programmed desorption of ammonia (NH-TPD) and the in situ diffuse reflectance infrared Fourier transform spectroscopy (in-situ DRIFTS). The results indicated that the α-FeO derived from natural pyrite exhibited an affirmative effect on NO conversion in the presence of NH at reaction temperatures of 200-450 °C, particularly at 350 °C, the pyrite-derived α-FeO displayed the best efficiency for the NO conversion. In addition, the formed sulfate derived from the oxidation of pyrite enhanced the NO conversion at the temperature of 300-450 °C, while hinder the NO conversion at 200-275 °C. The in-situ DRIFTS and kinetic studies demonstrated that both the Eley-Rideal and Langmuir-Hinshelwood mechanism contributed to the selective catalytic reduction (SCR) of NO when the reaction temperature was over 200 °C, while selective catalytic oxidization (CO) happened over 300 °C. This study favored the understanding of the NO behavior in flue gas pipeline after sprawling NH and the mechanism of NO conversion before the catalyst bed.
黄铁矿是一种天然存在的矿物，广泛存在于煤炭中。本工作研究了在成煤过程中黄铁矿结构的变化、黄铁矿衍生的α-FeO 在催化剂床层前存在 NH 时转化 NO 的能力以及动力学研究。黄铁矿衍生的α-FeO 通过在 500、600、700、800°C 下煅烧获得，并通过 X 射线衍射（XRD）、N 物理吸附、X 射线光电子能谱（XPS）、扫描电子显微镜（SEM）、紫外可见近红外光谱（UV-vis DRS）、氨程序升温脱附（NH-TPD）和原位漫反射红外傅里叶变换光谱（in-situ DRIFTS）进行了表征。结果表明，在 200-450°C 的反应温度下，天然黄铁矿衍生的α-FeO 对 NH 存在下的 NO 转化具有肯定的效果，特别是在 350°C 时，黄铁矿衍生的α-FeO 对 NO 转化的效率最高。此外，黄铁矿氧化生成的硫酸盐在 300-450°C 的温度下增强了 NO 的转化，而在 200-275°C 的温度下则阻碍了 NO 的转化。原位 DRIFTS 和动力学研究表明，当反应温度高于 200°C 时，Eley-Rideal 和 Langmuir-Hinshelwood 两种机制都有助于选择性催化还原（SCR）NO，而当反应温度高于 300°C 时，则发生选择性催化氧化（CO）。本研究有助于理解 NH 扩散后烟道气中 NO 的行为以及催化剂床前 NO 转化的机制。
