Kinetic analysis of CO2 gasification of biochar and anthracite based on integral isoconversional nonlinear method
The nonisothermal thermogravimetric analysis was implemented for gasification of sawdust char (SD-char), wheat straw char (WS-char), rice husk char (RH-char), bamboo char (BB-char) and anthracite coal (AC) in the presence of CO2. The dependence of activation energy upon conversion for different bioc...
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| Format: | Article |
| Language: | English |
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De Gruyter
2020-10-01
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| Series: | High Temperature Materials and Processes |
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| Online Access: | https://doi.org/10.1515/htmp-2020-0086 |
| _version_ | 1819131535911026688 |
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| author | Dai Bing Qiu Jia-Yong Ren Shan Su Bu-Xin Ding Xiang Ju Dian-Chun Bai Ni Long Hong-Ming |
| author_facet | Dai Bing Qiu Jia-Yong Ren Shan Su Bu-Xin Ding Xiang Ju Dian-Chun Bai Ni Long Hong-Ming |
| author_sort | Dai Bing |
| collection | DOAJ |
| description | The nonisothermal thermogravimetric analysis was implemented for gasification of sawdust char (SD-char), wheat straw char (WS-char), rice husk char (RH-char), bamboo char (BB-char) and anthracite coal (AC) in the presence of CO2. The dependence of activation energy upon conversion for different biochars and AC was obtained by the integral isoconversional nonlinear (NL-INT) method which is a model-free method. Based on the activation energy values from the NL-INT method, a model-fitting method called random pore model (RPM) was used to estimate the kinetic parameters including the preexponential factor and pore structure parameter from the experimental data. The results are shown that the gasification reactivity of different samples from high to low can be sorted as that of WS-char, SD-char, BB-char, RH-char and AC. In the early stage of gasification, the activation energy values of biochars increase generally with an increase in the conversion degree, whereas the value of AC decreases. Thereafter, the activation energy values remain almost unchanged when the conversion is up to some extent. When the conversion degree varies between about 0.3 and 0.9, these carbon materials can be sorted in the order of average activation energy from low to high as WS-char, SD-char, AC, RH-char and BB-char, respectively, 134.3, 143.8, 168.5, 184.8 and 193.0 kJ/mol. It is shown that a complex multistep mechanism occurs in the initial stage of gasification, while a single-step gasification mechanism exists in the rest of the gasification process. The RPM is suitable for describing the gasification of biomass chars and AC except the initial gasification. Additionally, it is found that the kinetic compensation effect (KCE) still exists in the gasification reactions of biochars and AC. However, the AC deviates markedly from the KCE curve. This may be caused by the similarity of carbonaceous structure of biochars and the difference in reactivity between biochars and AC. |
| first_indexed | 2024-12-22T09:17:03Z |
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| id | doaj.art-11242c092727464786f7d7824df38d12 |
| institution | Directory Open Access Journal |
| issn | 0334-6455 2191-0324 |
| language | English |
| last_indexed | 2024-12-22T09:17:03Z |
| publishDate | 2020-10-01 |
| publisher | De Gruyter |
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| series | High Temperature Materials and Processes |
| spelling | doaj.art-11242c092727464786f7d7824df38d122022-12-21T18:31:17ZengDe GruyterHigh Temperature Materials and Processes0334-64552191-03242020-10-0139152753810.1515/htmp-2020-0086htmp-2020-0086Kinetic analysis of CO2 gasification of biochar and anthracite based on integral isoconversional nonlinear methodDai Bing0Qiu Jia-Yong1Ren Shan2Su Bu-Xin3Ding Xiang4Ju Dian-Chun5Bai Ni6Long Hong-Ming7Anhui Province Key Laboratory of Metallurgical Engineering & Resources Recycling, Anhui University of Technology, Maanshan, 243002, Anhui, ChinaSchool of Metallurgical and Materials Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212003, Jiangsu, ChinaCollege of Materials Science and Engineering, Chongqing University, Chongqing, 400044, ChinaDepartment of General Planning and Research, China Metallurgical Industry Planning and Research Institute, Beijing, 100013, ChinaAnhui Province Key Laboratory of Metallurgical Engineering & Resources Recycling, Anhui University of Technology, Maanshan, 243002, Anhui, ChinaSchool of Metallurgical and Materials Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212003, Jiangsu, ChinaSchool of Metallurgical and Materials Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212003, Jiangsu, ChinaAnhui Province Key Laboratory of Metallurgical Engineering & Resources Recycling, Anhui University of Technology, Maanshan, 243002, Anhui, ChinaThe nonisothermal thermogravimetric analysis was implemented for gasification of sawdust char (SD-char), wheat straw char (WS-char), rice husk char (RH-char), bamboo char (BB-char) and anthracite coal (AC) in the presence of CO2. The dependence of activation energy upon conversion for different biochars and AC was obtained by the integral isoconversional nonlinear (NL-INT) method which is a model-free method. Based on the activation energy values from the NL-INT method, a model-fitting method called random pore model (RPM) was used to estimate the kinetic parameters including the preexponential factor and pore structure parameter from the experimental data. The results are shown that the gasification reactivity of different samples from high to low can be sorted as that of WS-char, SD-char, BB-char, RH-char and AC. In the early stage of gasification, the activation energy values of biochars increase generally with an increase in the conversion degree, whereas the value of AC decreases. Thereafter, the activation energy values remain almost unchanged when the conversion is up to some extent. When the conversion degree varies between about 0.3 and 0.9, these carbon materials can be sorted in the order of average activation energy from low to high as WS-char, SD-char, AC, RH-char and BB-char, respectively, 134.3, 143.8, 168.5, 184.8 and 193.0 kJ/mol. It is shown that a complex multistep mechanism occurs in the initial stage of gasification, while a single-step gasification mechanism exists in the rest of the gasification process. The RPM is suitable for describing the gasification of biomass chars and AC except the initial gasification. Additionally, it is found that the kinetic compensation effect (KCE) still exists in the gasification reactions of biochars and AC. However, the AC deviates markedly from the KCE curve. This may be caused by the similarity of carbonaceous structure of biochars and the difference in reactivity between biochars and AC.https://doi.org/10.1515/htmp-2020-0086biochargasificationintegral isoconversional nonlinear methodrandom pore modelkinetic compensation effect |
| spellingShingle | Dai Bing Qiu Jia-Yong Ren Shan Su Bu-Xin Ding Xiang Ju Dian-Chun Bai Ni Long Hong-Ming Kinetic analysis of CO2 gasification of biochar and anthracite based on integral isoconversional nonlinear method High Temperature Materials and Processes biochar gasification integral isoconversional nonlinear method random pore model kinetic compensation effect |
| title | Kinetic analysis of CO2 gasification of biochar and anthracite based on integral isoconversional nonlinear method |
| title_full | Kinetic analysis of CO2 gasification of biochar and anthracite based on integral isoconversional nonlinear method |
| title_fullStr | Kinetic analysis of CO2 gasification of biochar and anthracite based on integral isoconversional nonlinear method |
| title_full_unstemmed | Kinetic analysis of CO2 gasification of biochar and anthracite based on integral isoconversional nonlinear method |
| title_short | Kinetic analysis of CO2 gasification of biochar and anthracite based on integral isoconversional nonlinear method |
| title_sort | kinetic analysis of co2 gasification of biochar and anthracite based on integral isoconversional nonlinear method |
| topic | biochar gasification integral isoconversional nonlinear method random pore model kinetic compensation effect |
| url | https://doi.org/10.1515/htmp-2020-0086 |
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