Effect of iron minerals during coaling on the transformation of NO in the presence of NH 3: Take pyrite as an example
Effect of iron minerals during coaling on the transformation of NO in the presence of NH 3: Take pyrite as an example
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NH 3 存在下成煤过程中铁矿物对NO转化的影响——以黄铁矿为例
DOI：
10.1016/j.scitotenv.2020.138951
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发表时间：
2020-08-20
影响因子：
9.8
通讯作者：
Liu, Haibo
中科院分区：
文献类型：
--
作者：
Shu, Daobing;Chen, Tianhu;Liu, Haibo
黄铁矿是一种天然矿物，广泛存在于煤中。本文研究了在催化剂床前NH_3存在下黄铁矿结构的变化、黄铁矿衍生的α-Fe_2O_3转化NO的能力以及动力学。通过500、600、700、800 ℃煅烧得到黄铁矿型α-Fe 2 O3，并采用X射线衍射（XRD）、N2物理吸附、X射线光电子能谱（XPS）、扫描电镜（SEM）、紫外-可见近红外光谱（UV-vis-near-infrared spectroscopy（UV-vis DRS）、氨的程序升温脱附（NH3-TPD）和原位漫反射红外傅里叶变换光谱（原位DRIFTS）。结果表明，在NH3存在的条件下，在200-450 ℃的反应温度范围内，天然黄铁矿α-Fe 2 O3对NO的转化率有一定的促进作用，尤其是在350 ℃时，黄铁矿α-Fe 2 O3对NO的转化率最高。此外，黄铁矿氧化生成的硫酸盐在300-450 ℃时促进了NO的转化，而在200-275 ℃时阻碍了NO的转化。原位DRIFTS和动力学研究表明，当反应温度超过200 ℃时，NO的选择性催化还原（SCR）反应符合Eley-Rideal和Langmuir-Hinshelwood机理，而当反应温度超过300 ℃时，NO的选择性催化氧化（C-O）反应发生。该研究有助于了解烟气管道中NH3蔓延后NO的行为以及NO在催化剂床层前的转化机理。
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 alpha-Fe2O3 to convert NO in the presence of NH3 before catalyst bed and the kinetic study were investigated in this work. The pyrite-derived alpha-Fe2O3 was obtained by calcining at 500, 600, 700, 800 degrees C and was characterized by the X-ray diffraction (XRD), N-2 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 (NH3-TPD) and the in situ diffuse reflectance infrared Fourier transform spectroscopy (in-situ DRIFTS). The results indicated that the alpha-Fe2O3 derived from natural pyrite exhibited an affirmative effect on NO conversion in the presence of NH3 at reaction temperatures of 200-450 degrees C, particularly at 350 degrees C, the pyrite-derived alpha-Fe2O3 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 degrees C, while hinder the NO conversion at 200-275 degrees 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 degrees C, while selective catalytic oxidization (C-O) happened over 300 degrees C. This study favored the understanding of the NO behavior in flue gas pipeline after sprawling NH3 and the mechanism of NO conversion before the catalyst bed.