碱金属赋存形态对水稻秸秆热解过程的影响机制

张玉洁; 王焦飞; 卫俊涛; 白永辉; 宋旭东; 苏暐光; 于广锁

doi:10.1016/S1872-5813(21)60025-7

碱金属赋存形态对水稻秸秆热解过程的影响机制

doi: 10.1016/S1872-5813(21)60025-7

张玉洁^1,,
王焦飞^1, ,,
卫俊涛^{2, 3},
白永辉¹,
宋旭东¹,
苏暐光¹,
于广锁^{1, 3, ,}

1.
宁夏大学化学化工学院省部共建煤炭高效利用与绿色化工国家重点实验室，宁夏银川 750021
2.
南京林业大学材料科学与工程学院生物质能源与材料国际合作实验室，江苏南京 210037
3.
华东理工大学洁净煤技术研究所，上海 200237

基金项目: 国家自然科学基金(21968024)，宁夏回族自治区重点研发计划重大项目(2019BCH01001)和宁夏重点研发项目(引才专项) (2019BEB04037, 2019BEB04001)资助

详细信息

作者简介:
张玉洁：zyj19972080@163.com

通讯作者:
Tel：0951-2062008，E-mail：wjfdafei@nxu.edu.cn

gsyu@nxu.edu.cn

中图分类号: TQ536.9
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- 被引次数: 0
出版历程
- 收稿日期: 2020-11-10
- 修回日期: 2021-01-04
- 网络出版日期: 2021-03-30
- 刊出日期: 2021-06-30

Effect of alkali metal occurrence on the pyrolysis behavior of rice straw

1.
State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering, Schoolof Chemistry and Chemical Engineering, Ningxia University, Yinchuan 750021, China
2.
Joint International Research Laboratory of Biomass Energy and Materials, Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Materials Science and Engineering, Nanjing Forestry University, Nanjing 210037, China
3.
Institute of Clean Coal Technology, East China University of Science and Technology, Shanghai 200237, China

Funds: The project was supported by National Natural Science Foundation of China (21968024), Project of Key Research Plan of Ningxia (2019BCH01001) and Project of Key Research Plan of Ningxia (Special Talent Introduction Project) (2019BEB04037, 2019BEB04001)

摘要

摘要: 碱金属是生物质热解过程的重要影响因素。本研究以含不同赋存形态碱金属的水稻秸秆(RS)为研究对象，采用热重-质谱联用仪(TG-MS)和热裂解-气质联用仪(Py-GC/MS)研究其热解特性、小分子气体的释放规律及原位热解焦油组成变化规律，以揭示不同赋存形态碱金属在热解过程中的作用机理。结果表明，随水稻秸秆碱金属脱除程度的提高，热解过程中小分子释放温度向高温区域偏移，碱金属对小分子逸出过程存在催化作用。而不同赋存形态的碱金属对焦油组分的影响不同。水溶性碱金属抑制了醇类物质的产生而促进酮类和醛类的生成。离子交换态碱金属在不同温度下对油品组成的影响不同，在300 ℃热解时抑制了醛类和醚类的产生，促进了酯类和酮类的生成，而热解温度高于400 ℃后则相反。动力学分析表明，水溶性碱金属离子和交换态碱金属均会降低生物质热解活化能。
- 秸秆 /
- 热解 /
- 碱金属 /
- 赋存形态 /
- 焦油
Abstract: Alkali metals are important factors affecting the process of biomass pyrolysis. In this paper, rice straw (RS) with different occurrence forms of alkali metals was used as the research object. The heat decomposition characteristics, the release law of small molecule gases and the change law of in-situ pyrolysis tar composition were investigated by the thermal mass spectrometer (TG-MS) and thermal pyrolysis-GC/MS (Py-GC/MS) to reveal the action mechanism of different occurrence forms of alkali metals in the pyrolysis process. The results showed that with the increase of the removal degree of alkali metal from rice straw, the release temperature of small molecules during the pyrolysis shifted to the high temperature region, due to the catalytic effect of alkali metals on the escape of small molecules. The different occurrence forms of alkali metals had different influences on the tar components. Water-soluble alkali metals inhibited the production of alcohols and promoted the production of ketones and aldehydes. Ion-exchanged alkali metals had different effects on oil composition at different temperatures. At the pyrolysis of 300 ℃, the presence of ion-exchanged alkali metals inhibited the production of aldehydes and ethers, and promoted the production of esters and ketones, but opposite effect was obtained at the temperature higher than 400 ℃. Kinetic analysis showed that both water-soluble alkali metal ions and exchanged alkali metal could reduce the activation energy of biomass pyrolysis.
- straw /
- pyrolysis /
- alkali metal /
- occurrence form /
- tar

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FIG. 717. FIG. 717.

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图 1 样品制备过程示意图

Figure 1 Samples preparation process

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图 2 洗涤处理前后水稻秸秆在15 ℃/min的升温速率下热解的失重和失重速率曲线

Figure 2 TG and DTG curves of RS before and after washing at heating rate of 15 °C/min

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图 3 热解过程小分子气体逸出特性

Figure 3 Escape characteristics of small molecule gases during pyrolysis

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图 4 RS在不同温度下热解所得焦油组分的面积百分比

Figure 4 Area percentage of tar component produced from pyrolysis of RS at different temperatures

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图 5 RS在不同温度下热解所得焦油中各含氧化合物组分的面积百分比

Figure 5 Area percentage of tar oxygen-containing component produced from pyrolysis of RS at different temperatures

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图 6 水稻秸秆热解的活化能

Figure 6 Activation energy of rice straw pyrolysis

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表 1 水稻秸秆的工业分析和元素分析

Table 1 Proximate and ultimate analyses of RS

Sample	Proximate analysis w_ad /%				Ultimate analysis w_daf /%
Sample	M	A	V	FC	C	H	O	N	S
RS1	6.76	9.22	69.16	14.87	44.50	6.24	45.66	1.46	2.15
RS2	7.32	8.33	70.68	13.68	45.31	6.25	43.29	1.62	3.54
RS3	8.38	6.55	74.54	10.53	45.29	6.14	43.61	1.56	3.40
RS4	5.96	9.48	72.90	11.67	46.10	6.23	43.71	1.11	2.85

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表 2 水稻秸秆的灰化学组成

Table 2 Ash compositions of rice straw

Compositions w/%
SiO₂	Al₂O₃	Fe₂O₃	CaO	Na₂O	K₂O	MgO	others
52.42	0.55	0.47	3.42	0.67	24.56	3.27	14.64

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表 3 样品的碱金属及碱土金属元素组成

Table 3 Element composition of main alkali and alkaline earth metals in samples

Sample	Content w_ad /%
Sample	K	Na	Ca	Mg	Fe
RS1	2.10	0.65	0.37	0.18	0.05
RS2	0.61	0.03	0.40	0.08	0.04
RS3	0.02	0.01	0.34	0.02	0.03
RS4	< 0.01	< 0.01	< 0.01	0.01	0.02

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表 4 水稻秸秆热解的活化能

Table 4 Activation energy of rice straw pyrolysis

Sample	Linear equations	E_α/(kJ·mol⁻¹)	R²
RS1	y = −21.84x + 26.62	181.57776	0.990
RS2	y = −22.57x + 26.99	187.64698	0.996
RS3	y = −23.22x + 26.64	193.05108	0.984
RS4	y = −26.15x + 31.16	217.41110	0.982

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