铁镍复合助剂对煤热解过程中氮迁移规律的影响

doi:10.16085/j.issn.1000-6613.2020-0478

摘要/Abstract

摘要：

为了减少煤炭燃烧过程中NO_x的排放，在管式炉中进行了煤与金属助剂（FeCl₃、NiCl₂）的热解实验，研究了助剂负载量、热解温度、助剂添加方式对氮迁移及N₂产率的影响并且对复合助剂作用机理进行了探讨。结果表明：随着助剂负载量的增加，氮脱除率及N₂产率呈现先增加后趋于稳定的趋势，且负载量以0.8%Fe复合1.0%Ni为最佳。在700~1000℃的热解温度范围内氮脱除率及N₂产率随热解温度的增加而增加。对煤进行溶胀处理添加复合助剂后，氮脱除率及N₂产率要优于未经处理的煤样。铁基助剂与镍基助剂在催化煤热解氮迁移过程中形成互补，铁基助剂的添加增加了镍基助剂的活性，弥补了单助剂的劣势，且复合助剂相比于单助剂有更强的氮脱除效果并且N₂产率达到最高39%。铁镍复合助剂对煤中N-5转化为N₂的催化效果更加明显，因为复合助剂对吡咯的内氢转移和开环有更强的催化作用。本研究能够为煤炭洁净化利用提供理论和实验依据。

关键词: 铁镍复合助剂, 煤热解, 氮迁移, 氮氧化物

Abstract:

In order to reduce NO_x emissions in the coal combustion process, the pyrolysis experiments of coal and metal additives (FeCl₃, NiCl₂) were carried out in a tube furnace. The effects of additive loading, pyrolysis temperature, and adding method of additives on nitrogen migration and N₂ yield were investigated, and the mechanism of compound additives was discussed. The results indicate that as the loading of the additive increases, the nitrogen removal rate and N₂ yield tend to stabilize after increasing, and the loading is preferably 0.8% Fe and 1.0% Ni. In the pyrolysis temperature of 700—1000℃, the nitrogen removal rate and N₂ yield increase with the increase of pyrolysis temperature. By swelling treatment of coal and the addition of composite additives, the nitrogen removal rate and N₂ yield are higher than untreated coal samples. In the process of nitrogen migration during the coal pyrolysis, iron-based additives and nickel-based additives complement each other. The addition of iron-based additives increases the activity of nickel-based additives to make up for the disadvantages of single additives. Compared with the single additive, the compound additive has a stronger nitrogen removal effect and the N₂ yield reaches a maximum of 39%. The Fe-Ni composite additive has a better catalytic effect on the conversion of N-5 to N₂ in raw coal, as the composite additive has a stronger catalytic effect on the internal hydrogen transfer and ring opening of pyrrole. This research can provide theoretical and experimental basis for the clean utilization of coal.

Key words: iron and nickel composite additive, coal pyrolysis, nitrogen migration, nitrogen oxide

中图分类号:

TQ53

刘月华, 上官炬, 刘守军, 杨颂, 杜文广. 铁镍复合助剂对煤热解过程中氮迁移规律的影响[J]. 化工进展, 2021, 40(1): 164-172.

Yuehua LIU, Ju SHANGGUAN, Shoujun LIU, Song YANG, Wenguang DU. Nitrogen migration regarding the addition of iron-Ni composite additives during coal pyrolysis[J]. Chemical Industry and Engineering Progress, 2021, 40(1): 164-172.

图/表 14

表1 肥煤的工业分析和元素分析（质量分数）

工业分析/%				元素分析/%
M_ad	A_ad	V_ad		C_ad	H_ad	N_ad	S_t,ad
0.82	10.6	29.50		71.80	4.70	1.33	2.82

图1 热解实验装置流程示意图

图2 氮质量平衡

图3 氮脱除率及N2产率随Fe负载量的变化

图4 氮脱除率及N2产率随Ni负载量的变化

图5 不同负载方法下氮脱除率及N2产率

表2 原煤及其溶胀处理孔结构分布

样品	S_BET/m²·g^-1	孔径/nm	孔体积/mL·g^-1
肥煤	1.1140	20.84	0.0104
乙醇处理肥煤	1.4480	31.19	0.0162

图6 不同热解温度下氮脱除率及氮含量变化

图7 不同热解温度下N2产率

图8 不同热解温度下焦炭的XRD分析图

图9 铁镍复合助剂反应机理

图10 肥煤和焦炭的N1S元素XPS光谱图

表3 肥煤和焦炭中的氮含量（质量分数）

名称	总氮/%	N-5/%	N-6/%	N-Q/%	N-X/%
肥煤	1.34	0.75	0.31	0.20	0.09
肥煤焦炭-1000℃	0.68	0.49	0.06	0.13	0
肥煤+FeNi焦炭-1000℃	0.54	0	0.12	0.28	0.14

图11 肥煤和肥煤添加Fe-Ni复合助剂热解氮的迁移路径

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