Mn基脱硝催化剂抗水抗硫改性的模拟与实验研究

doi:10.11949/0438-1157.20190690

摘要/Abstract

摘要：

为考察ZSM-5分子筛作载体和Ce掺杂对催化剂低温脱硝活性及抗水抗硫性的影响，通过分子动力学模拟和实验研究的手段研究了载体类型、掺杂Ce对催化剂性能的影响。分子动力学模拟发现，ZSM-5分子筛作载体较γ-Al₂O₃明显抑制H₂O在其表面的吸附，在活性组分中添加Ce既抑制H₂O在其表面的吸附，又减轻SO₂对催化剂的毒化作用。实验研究发现，Mn-Fe-Ce/ZSM-5催化剂性能更优，Ce的添加对提高催化剂的低温脱硝活性和抗水抗硫性能具有明显的积极作用，ZSM-5分子筛作为载体也对提高催化剂抗水性能起到重要作用。通过SEM、XRD、BET、TG-DTG等表征手段和BaCl₂鼓泡实验对Mn-Fe-Ce/ZSM-5催化剂抗硫性提高的原因分析发现，添加Ce使催化剂储氧释氧能力提高，将烟气中的SO₂氧化为SO₃并被烟气携带，避免了SO₂与催化剂活性组分的反应，则催化剂表面的活性组分不被破坏，保证了催化剂的催化反应性能。

关键词: 低温脱硝, 锰基催化剂, 选择催化还原, 分子模拟, 抗水抗硫性

Abstract:

To investigate the effect of ZSM-5 zeolite as carrier and Ce doping on the low temperature denitrification activity and water/sulfur resistance of the catalyst, the effects of carrier type and Ce doping on the performance of the catalyst were studied by molecular dynamics simulation and experimental research. Molecular dynamics simulations showed that ZSM-5 zeolite as a carrier significantly inhibited the adsorption of H₂O on its surface compared with γ-Al₂O₃. Adding Ce to the active component not only inhibited the adsorption of H₂O on its surface, but also mitigated the poisoning effect of SO₂ on the catalyst. The experimental study found that Mn-Fe-Ce/ZSM-5 has better denitration activity under low temperature and water/sulfur resistance. The addition of Ce has a positive effect on improving the low temperature activity and water/sulfur resistance of the catalyst. ZSM-5 zeolite as carriers also play an important role in improving the water resistance of the catalyst. The SEM, XRD, BET, TG-DTG and other characterization methods and BaCl₂ bubbling experiments were carried out to analyze the mechanisms for the improvement of sulfur resistance of Mn-Fe-Ce/ZSM-5 catalyst. It was found that the addition of Ce increased the oxygen storage and oxygen release capacity of the catalyst. Oxidation of SO₂ in the flue gas to SO₃ avoids the reaction of SO₂ with the active component, so that the active component on the surface of the catalyst is not destroyed, and the catalytic reaction performance of the catalyst is ensured.

Key words: low temperature denitration, Mn-based catalyst, selective catalytic reduction, molecular simulation, water/sulfur resistance

中图分类号:

TQ 534.9

王金玉, 朱怀志, 安泽文, 巩建, 王翠苹. Mn基脱硝催化剂抗水抗硫改性的模拟与实验研究[J]. 化工学报, 2019, 70(12): 4635-4644.

Jinyu WANG, Huaizhi ZHU, Zewen AN, Jian GONG, Cuiping WANG. Simulation and experimental study on modification of water and sulfur resistance by Mn-based denitration catalyst[J]. CIESC Journal, 2019, 70(12): 4635-4644.

图/表 19

图1 载体模型

Fig.1 Carrier models

表1 H2O分子在不同载体模型上的吸附能、键长和原子间距

Table 1 Adsorption energy, bond length and atomic spacing of H2O molecules on different carrier models

载体	吸附能/(kcal/mol)	吸附后H—O键长/nm	吸附后原子间距/nm
ZSM-5分子筛	-9.743	0.1076	0.3789
γ-Al₂O₃	-11.610	0.1022	0.3026

图2 活性组分β-MnO2模型

Fig.2 Active component β-MnO2 models

表2 H2O分子在不同活性组分表面上不同吸附构型的吸附能

Table 2 Adsorption energy of different adsorption configurations of H2O molecules on surface of different active components

吸附构型	H₂O分子在β-MnO₂（0 0 1）上的吸附能/(kcal/mol)	H₂O分子在β-MnO₂（+Ce）上的吸附能/(kcal/mol)
H₂O分子中H吸附到β-MnO₂的Mn	-6.577	-3.857
H₂O分子中H吸附到β-MnO₂的O	-7.943	-5.335
H₂O分子中O吸附到β-MnO₂的Mn	-10.982	-7.396
H₂O分子中O吸附到β-MnO₂的O	-6.044	-4.769

图3 反应物与生成物模型

Fig.3 Reactant and product models

表3 SO2分子与不同活性组分的反应活化能

Table 3 Reaction activation energy of SO2 molecule and different active components

活性组分类型	反应活化能/（kcal/mol）
β-MnO₂（0 0 1）	15.473
β-MnO₂（+Ce）	33.581

图4 烟气脱硝实验装置 1—氮气气瓶；2—二氧化硫气瓶；3—一氧化氮气瓶；4—氨气气瓶；5—氧气气瓶；6—蒸汽发生器；7—减压阀；8—质量流量计；9—气体缓冲瓶；10—温控箱；11—管式炉；12—阀门；13—三通；14—烟气分析仪

Fig.4 Schematic diagram of flue gas denitration experimental device

图5 不同温度下Mn-Fe-Ce/ZSM-5和Mn-Fe/γ-Al2O3催化剂的脱硝效率

Fig.5 Denitration efficiency of Mn-Fe-Ce/ZSM-5 and Mn-Fe/γ-Al2O3 catalysts at different temperatures

图6 不同Ce负载量下Mn-Fe-Ce/ZSM-5催化剂的脱硝效率

Fig.6 Denitration efficiency of Mn-Fe-Ce/ZSM-5 catalyst under different Ce loadings

图7 不同H2O体积分数下Mn-Fe-Ce/ZSM-5和Mn-Fe/γ-Al2O3催化剂的脱硝效率

Fig.7 Denitration efficiency of Mn-Fe-Ce/ZSM-5 and Mn-Fe/γ-Al2O3 catalysts with different H2O volume fractions

图8 不同SO2浓度下Mn-Fe-Ce/ZSM-5和Mn-Fe/γ-Al2O3催化剂的脱硝效率

Fig.8 Denitration efficiency of Mn-Fe-Ce/ZSM-5 and Mn-Fe/γ-Al2O3 catalysts at different SO2 concentrations

图9 反应前后Mn-Fe-Ce/ZSM-5和Mn-Fe/γ-Al2O3催化剂的SEM图

Fig.9 SEM images of Mn-Fe-Ce/ZSM-5 and Mn-Fe/γ-Al2O3 catalysts before and after reaction

图10 反应前后Mn-Fe-Ce/ZSM-5和Mn-Fe/γ-Al2O3催化剂的XRD谱图

Fig.10 XRD patterns of Mn-Fe-Ce/ZSM-5 and Mn-Fe/γ-Al2O3 catalysts before and after reaction

图11 反应前Mn-Fe/γ-Al2O3催化剂的TG和DTG曲线

Fig.11 TG and DTG curves of Mn-Fe/γ-Al2O3 catalyst before reaction

图12 反应后Mn-Fe/γ-Al2O3催化剂的TG和DTG曲线

Fig.12 TG and DTG curves of Mn-Fe/γ-Al2O3 catalyst after reaction

表4 反应前后Mn-Fe-Ce/ZSM-5和Mn-Fe/γ-Al2O3催化剂物理性质变化

Table 4 Physical properties of Mn-Fe-Ce/ZSM-5 and Mn-Fe/γ-Al2O3 catalysts before and after reaction

催化剂类型	比表面积/ (m²/g)	孔容×10²/ (cm³/g)	平均孔径 /nm
Mn-Fe/γ-Al₂O₃（反应前）	129	20	6.9
Mn-Fe/γ-Al₂O₃（反应后）	115	18.1	5.8
Mn-Fe-Ce/ZSM-5（反应前）	308	10	5
Mn-Fe-Ce/ZSM-5（反应后）	303	9.4	4.7

图13 反应前后Mn-Fe/γ-Al2O3催化剂孔径、孔容分布变化

Fig.13 Variation of pore size and pore volume distribution of Mn-Fe/γ-Al2O3 catalyst

图14 反应前后Mn-Fe-Ce/ZSM-5催化剂孔径、孔容分布变化

Fig.14 Changes in pore size and pore volume distribution of Mn-Fe-Ce/ZSM-5 catalyst before and after reaction

图15 有无氧气条件下出口SO2浓度的变化

Fig.15 Changes in outlet SO2 concentration with or without oxygen

参考文献 30

1	Miroslav R . Reduction of nitrogen oxides in flue gases[J]. Environmental Pollution, 1998, 102(1): 685-689.
2	张楚莹, 王书肖, 邢佳, 等 . 中国能源相关的氮氧化物排放现状与发展趋势分析[J]. 环境科学学报, 2015, 28(12): 2470-2479.
	Zhang C Y , Wang S X , Xing J , et al . Current status and future projections of NO _x emissions from energy related in dustries in China[J]. Acta Scientiae Circumstantiae, 2015, 28(12): 2470-2479.
3	Xue Y , Tian H , Yan J , et al . Temporal trends and spatial variation characteristics of primary air pollutants emissions from coal-fired industrial boilers in Beijing, China[J]. Environmental Pollution, 2016, 213: 717-726.
4	Chiu C H , Hsi, H C, Lin H P , et al . Effects of properties of manganese oxide-impregnated catalysts and flue gas condition on multipollutant control of HgO and NO[J]. Journal of Hazardous Materials, 2015, 291: 1-8.
5	Wang X , Li Y J , Shi J W , et al . Simultaneous SO₂/NO removal performance of carbide slag pellets by bagasse templating in a bubbling fluidized bed reactor[J]. Fuel Processing Technology, 2018, 180: 75-86.
6	Liu Z , Woo S I . Recent advances in catalytic DeNO _x science and technology[J]. Catalysis Reviews, 2006, 48(1): 43-89.
7	黄海凤, 张峰, 卢晗锋, 等 . 制备方法对低温NH₃-SCR脱硝催化剂MnO _x /TiO₂结构与性能的影响[J]. 化工学报, 2010, 61(1): 80-85.
	Huang H F , Zhang F , Lu H F , et al . Effect of preparation methods on structures and performance of MnO _x /TiO₂ catalyst for low-temperature NH₃-SCR[J]. CIESC Journal, 2010, 61(1): 80-85.
8	Qi G , Yang R T . Performance and kinetics study for low-temperature SCR of NO with NH₃ over MnO _x -CeO₂ catalyst[J]. Journal of Catalysis, 2003, 217(2): 434-441.
9	Muniz J , Marban G , Fuertes A B . Low temperature selective catalytic reduction of NO over modified activated carbon fibers[J]. Applied Catalysis B: Environmental, 2000, 27: 27-36.
10	Lei Z , Liu X , Jia M . Modeling of selective catalytic reduction (SCR) for NO removal using monolithic honeycomb catalys[J]. Energy & Fuels, 2009, 23: 6146-6151.
11	Shi J , Zhang Z H , Chen M X , et al . Promotion effect of tungsten and iron co-addition on the catalytic performance of MnO _x /TiO₂ for NH₃-SCR of NO _x [J]. Fuel, 2017, 210(15): 783-789.
12	Nam K B , Kwon D W , Hong S C . DRIFT study on promotion effects of tungsten-modified Mn/Ce/Ti catalysts for the SCR reaction at low-temperature[J]. Applied Catalysis A: General, 2017, 542: 55-62.
13	廖永进, 张亚平, 余岳溪, 等 . MnO _x /WO₃/TiO₂低温选择性催化还原NO _x 机理的原位红外研究[J]. 化工学报, 2016, 67(12): 5031-5039.
	Liao Y J , Zhang Y P , Yu Y X , et al . In situ FT-IR studies on low temperature NH₃-SCR mechanism of NO _x over MnO _x /WO₃/TiO₂catalyst[J]. CIESC Journal, 2016, 67(12): 5031-5039.
14	Wu Z B , Jiang B Q , Liu Y , et al . Experimental study on a low-temperature SCR catalyst based on MnO _x /TiO₂ prepared by sol-gel method[J]. Journal of Hazardous Materials, 2007, 145: 488-94.
15	Jiang S Y , Zhou R X . Ce doping effect on performance of the Fe/β catalyst for NO _x , reduction by NH₃ [J]. Fuel Processing Technology, 2015, 133: 220-226.
16	Huang T J , Zhang Y P , Zhuang K , et al . Preparation of honeycombed holmium-modified Fe-Mn/TiO₂ catalyst and its performance in the low temperature selective catalytic reduction of NO _x [J]. Journal of Fuel Chemistry & Technology, 2018, 46(3): 319-327.
17	Chen X , Wang P , Fang P , et al . Tuning the property of Mn-Ce composite oxides by titanate nanotubes to improve the activity selectivity and SO₂/H₂O tolerance in middle temperature NH₃-SCR reaction[J]. Fuel Processing Technology, 2017, 167: 221-228.
18	Jiang B Q , Wu Z B , Liu Y , et al . DRIFT Study of the SO₂ effect on low-temperature SCR reaction over Fe-Mn/TiO₂ [J]. Journal of Physical Chemistry C, 2010, 114(11): 4961-4965.
19	Shen B X , Liu T . Deactivation of MnO _x -CeO _x /ACF catalysts for low temperature NH₃-SCR in the presence of SO₂ [J]. Acta Physico-Chimica Sinica, 2010, 26(11): 3009-3016.
20	Phil H H , Reddy M P , Kumar P A , et al . SO₂ resistant antimony promoted V₂O₅/TiO₂ catalyst for NH₃-SCR of NO _x at low temperatures[J]. Applied Catalysis B: Environmental, 2008, 78(3): 301-308.
21	Li Y , Han X , et al . Role of CTAB in the improved H₂O resistance for selective catalytic reduction of NO with NH₃ over iron titanium catalyst[J]. Chemical Engineering Journal, 2018, 347(1): 313-321.
22	Park T S , Jeong S K , Hong S H , et al . Selective catalytic reduction of nitrogen oxides with NH₃ over natural manganese ore at low temperature[J]. Ind. Eng. Chem. Res., 2001, 40(21): 4491-4495.
23	刘亭 . 锰铈基低温选择性催化还原(SCR)脱硝催化剂的研究[D]. 天津: 南开大学, 2011.
	Liu T . Study on manganese sulfhydryl group low temperature selective catalytic reduction (SCR) denitration catalyst[D]. Tianjin: Nankai University, 2011.
24	Kijlstra W S , Biervliet M , Poels E K , et al . Deactivation by SO₂ of MnO _x /Al₂O₃ catalysts used for the selective catalytic reduction of NO with NH₃ at low temperatures[J]. Applied Catalysis B: Environmental, 1998, 16(4): 327-337.
25	孙克勤, 钟秦, 黄丽娜 . SCR钒基催化剂吸附氨和水的密度泛函研究[J]. 环境化学, 2008, 27(1): 33-38.
	Sun K Q , Zhong Q , Huang L N . DFT Study of ammonia and water adsorption on vanadia-based catalysts catalysts for SCR reaction[J]. Environmental Chemistry, 2008, 27(1): 33-38.
26	程浩 . 铈掺杂对铜基氧载体释氧性能以及CO化学链燃烧影响的研究[D]. 武汉: 华中科技大学, 2016.
	Cheng H . Study of the influence of Ce-doping on the oxygen releasing properties of copper based oxygen carrier and CO chemical looping combustion[D].Wuhan: Huazhong University of Science and Technology, 2016.
27	王雪冲 . 碱土金属对Ce基催化剂SCR烟气脱硝性能的影响研究[D]. 北京: 中国石油大学, 2016.
	Wang X C . The effect of alkaline earth metals on Ce based catalyst for selective catalytic reduction of NO[D]. Beijing: China University of Petroleum, 2016.
28	Reddy B M , Lakshmanan P , Khan A , et al . Structural characterization of CeO₂-ZrO₂/TiO₂ and V₂O₅/CeO₂-ZrO₂/TiO₂ mixed oxide catalysts by XRD, Raman spectroscopy, HREM, and other techniques[J]. Journal of Physical Chemistry B, 2005, 109(5): 1781.
29	Luo M , Chen J , Chen L , et al . Structure and redox properties of Ce _x Ti_1- _x O₂ solid solution[J]. Chem. Mater., 2001, 13(1): 197-202.
30	Chen L , Weng D , Wang J , et al . Low-temperature activity and mechanism of WO₃-modified CeO₂-TiO₂ catalyst under NH₃-NO/NO₂ SCR conditions[J]. Chinese Journal of Catalysis, 2018, 39(11): 1804-1813.

[1]	宋明昊, 赵霏, 刘淑晴, 李国选, 杨声, 雷志刚. 离子液体脱除模拟油中挥发酚的多尺度模拟与研究[J]. 化工学报, 2023, 74(9): 3654-3664.
[2]	胡建波, 刘洪超, 胡齐, 黄美英, 宋先雨, 赵双良. 有机笼跨细胞膜易位行为的分子动力学模拟研究[J]. 化工学报, 2023, 74(9): 3756-3765.
[3]	赵佳佳, 田世祥, 李鹏, 谢洪高. SiO₂-H₂O纳米流体强化煤尘润湿性的微观机理研究[J]. 化工学报, 2023, 74(9): 3931-3945.
[4]	汪林正, 陆俞冰, 张睿智, 罗永浩. 基于分子动力学模拟的VOCs热氧化特性分析[J]. 化工学报, 2023, 74(8): 3242-3255.
[5]	陈吉, 洪泽, 雷昭, 凌强, 赵志刚, 彭陈辉, 崔平. 基于分子动力学的焦炭溶损反应及其机理研究[J]. 化工学报, 2023, 74(7): 2935-2946.
[6]	董明, 徐进良, 刘广林. 超临界水非均质特性分子动力学研究[J]. 化工学报, 2023, 74(7): 2836-2847.
[7]	刘远超, 蒋旭浩, 邵钶, 徐一帆, 钟建斌, 李耑. 几何尺寸及缺陷对石墨炔纳米带热输运特性的影响[J]. 化工学报, 2023, 74(6): 2708-2716.
[8]	顾浩, 张福建, 刘珍, 周文轩, 张鹏, 张忠强. 力电耦合作用下多孔石墨烯膜时间维度的脱盐性能及机理研究[J]. 化工学报, 2023, 74(5): 2067-2074.
[9]	李辰鑫, 潘艳秋, 何流, 牛亚宾, 俞路. 基于碳微晶结构的炭膜模型及其气体分离模拟[J]. 化工学报, 2023, 74(5): 2057-2066.
[10]	杨松涛, 李东洋, 牛玉清, 李鑫钢, 康绍辉, 李洪, 叶开凯, 周志全, 高鑫. 氟化物势能函数和热力学性质的分子模拟研究进展[J]. 化工学报, 2022, 73(9): 3828-3840.
[11]	廖艺, 牛亚宾, 潘艳秋, 俞路. 复配表面活性剂对油水界面行为和性质影响的模拟研究[J]. 化工学报, 2022, 73(9): 4003-4014.
[12]	郑默, 李晓霞. ReaxFF MD模拟揭示的煤热解挥发分自由基反应的竞争与协调[J]. 化工学报, 2022, 73(6): 2732-2741.
[13]	李春晖, 何辉, 何明键, 张萌, 高杨, 矫彩山. 离子液体萃取硝酸中Ce（Ⅳ）的动力学研究[J]. 化工学报, 2022, 73(4): 1606-1614.
[14]	王瑞, 任瑛, 陈卫, 韩永生. 冰水界面动态结构的分子动力学模拟研究[J]. 化工学报, 2022, 73(3): 1315-1323.
[15]	张瑾渊, 徐娜, 贺文云, 吕耀东, 刘子璐, 张兴芳. 消防用PEO/OTAC/NaSal减阻体系的介观分子动力学分析[J]. 化工学报, 2022, 73(3): 1157-1165.