燃机脱硝催化剂制备与性能研究

论文总字数：32560字

摘 要

近年来，燃气轮机及其联合循环机组已成为主力发电机组之一，氮氧化物（NOx）为燃气轮机的主要排放污染物。氮氧化物对大气环境造成严重的影响，主要表现为酸雨、光化学烟雾、臭氧层破坏和温室效应等问题。目前， NH₃-SCR技术是最常见的脱硝技术，它的核心是催化剂。铁分子催化剂催化剂具有较宽的活性温度窗口，优异的中期脱氮性能和较高的N2选择性，在SCR研究中备受关注。

本文对Ce和Ni改性的Fe/ZSM-5催化剂进行了脱硝性能测试，同时通过比表面积及孔容孔径测试（BET）、程序升温还原（TPR）、程序升温脱附（TPD）、原位漫反射傅里叶变换红外光谱（in situ DRIFTS）等表征技术对催化剂的微观结构、理化性质和脱硝机理进行研究和分析，筛选出满足燃机烟气应用环境的高温脱硝催化剂配方。在此基础上，对优选出的催化剂进行了烟气工况对催化剂脱硝性能的影响和水热稳定性的研究。

采用浸渍法制备了Ce改性的Fe/ZSM-5催化剂和Ni改性的Fe/ZSM-5催化剂，经过脱硝活性测试和表征测试发现，CeO₂的掺杂可以提升Fe/ZSM-5催化剂的高温脱硝活性并且拓宽反应温度窗口。在550℃时，Ce₁Fe₄/ZSM-5催化剂的脱硝效率高达97%，在350-600℃的温度区间内脱硝效率保持在80%以上。改性后的催化剂具有高比表面积、强氧化还原能力、丰富的表面酸位点、NH₃的吸附活化能力和NO向NO₂氧化的能力得到增强，从而脱硝性能提升。通过改变烟气工况条件来测试脱硝活性，发现Ce₁Fe₄/ZSM-5催化剂对空速、氧含量以及NO₂的浓度有很强的适应性，且烟气中NO₂浓度的增加，进一步提高了脱硝效率。同时发现催化剂经水热老化处理后，仍有较高的高温脱硝活性。

关键词：燃机烟气，脱硝催化剂，选择性催化还原，ZSM-5，水热老化

Abstract

Gas turbines and their combined cycle units have become one of the main generator sets, and nitrogen oxides (NOx) are the main pollutants emitted by gas turbines. Therefore, NOx treatment of gas turbines is imminent. At present, selective catalytic reduction (NH₃-SCR) is the dominant NO_x control technology, and the key of the NH₃-SCR system is the catalyst with excellent performance, which will determine the success or failure of the entire catalytic reaction system. Fe-based molecular sieve catalysts have attracted extensive attention in the field of SCR research because of their wide active temperature window, excellent medium-temperature activity and N₂ selectivity, and have been considered as the most practical application of denitration catalysts.

In this paper, the denitration performance of Ce and Ni modified Fe/ZSM-5 catalysts were tested. At the same time, the specific surface area (BET)，temperature programmed reduction (TPR), temperature programmed desorption (TPD), in situ DRIFTS and other characterization techniques were used to study and analyze the microstructure, physicochemical properties and denitrification mechanism of the catalyst. The high temperature denitration catalyst that met the application environment of the gas turbine was selected. On this basis, the effect of flue gas conditions on the denitrification performance and the hydrothermal stability of the catalysts were studied over the preferred catalysts.

Ce modified Fe/ZSM-5 catalyst and Ni modified Fe/ZSM-5 catalyst was prepared by impregnation method. The results of activity test and characterization show that the doping of CeO₂ could enhance the high temperature denitration activity of the Fe/ZSM-5 catalyst and broaden the reaction temperature window. At 550 ℃, the denitration efficiency of the Ce₁Fe₄/ZSM-5 catalyst was as high as 97%, and maintained above 80% in the temperature range of 350-600 ℃. The modified catalyst had high specific surface area, strong redox capacity, and abundant surface acid sites. It was also found that the adsorption activation ability of NH₃ and the ability of NO to oxidize to NO₂ were enhanced, thus the denitration performance of the catalyst was improved. Furthermore, the denitrification activity was tested by changing the flue gas conditions. The results showed that the Ce₁Fe₄/ZSM-5 catalyst had strong adaptability to space velocity, oxygen content and NO₂ concentration, and the increase of NO₂ concentration in flue gas further improved the denitration efficiency. At the same time, it was found that the catalyst still had high high-temperature denitration activity after hydrothermal aging treatment.

Key words: Gas turbine flue gas；Denitrification catalysts; NH₃-SCR； ZSM-5； Hydrothermal deactivation

目录

第一章 绪论 1

1.1研究背景及意义 1

1.2国内外研究现状 2

1.2.1脱硝催化剂组分研究 2

1.2.2脱硝催化剂制备方法的研究 4

1.3研究内容 5

1.4技术路线 5

第二章 实验装置与实验试剂 7

2.1实验试剂与仪器 7

2.1.1实验试剂 7

2.1.2实验仪器设备 7

2.2催化剂的制备与性能测试 8

2.2.1催化剂的制备 8

2.2.2催化剂活性评价 8

2.3催化剂水热老化实验 9

2.4催化剂表征 9

2.4.1比表面积及孔容孔径测试（BET） 9

2.4.2 X射线衍射（XRD） 10

2.4.3程序升温还原（H₂-TPR） 10

2.4.4程序升温脱附（NH3-TPD） 11

2.4.5原位漫反射傅里叶变换红外光谱（in situ DRIFTS） 11

第三章 Ce和Ni改性Fe基分子筛催化剂表征和脱硝性能评价 13

3.1 Ce改性Fe基分子筛催化剂NH₃-SCR脱硝性能研究 13

3.1.1不同Fe含量催化剂脱硝性能 13

3.1.2 Ce改性Fe/ZSM-5催化剂脱硝活性的影响 13

3.1.3催化剂的表征 14

3.2 Ni改性Fe基分子筛催化剂的NH₃-SCR脱硝性能研究 18

3.2.1 Ni改性Fe/ZSM-5催化剂脱硝活性的影响 18

3.2.2催化剂的表征 18

3.3 本章小结 21

第四章 燃机烟气工况对催化剂脱硝性能的影响 23

4.1烟气条件对催化剂脱硝性能的影响 23

4.1.1 烟气空速的影响 23

4.1.2 NO/NO₂的影响 24

4.1.3 O₂含量的影响 24

4.2水热老化对催化剂脱硝性能的影响 25

4.2.1 Ce₁Fe₄/ZSM-5催化剂的水热稳定性测试 25

4.2.2老化后Ce₁Fe₄/ZSM-5催化剂的NH₃-TPD图谱 25

4.2.3老化后Ce₁Fe₄/ZSM-5催化剂的H₂-TPR图谱 26

4.3 本章小结 26

第五章 总结与建议 28

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