Reaction Performance of CaSO4/Ben Oxygen Carrier Modified by Fe2O3 in Chemical Looping Combustion
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摘要: 分别采用间歇式流化床反应器和热重分析仪进行多次循环实验及反应性能测试，研究了Fe2O3在化学链燃烧过程中对CaSO4/Ben（膨润土）载氧体的催化作用，并对比Fe2O3不同添加量（质量分数）时CaSO4/Ben载氧体与CO的反应活化能。结果表明，添加Fe2O3后CaSO4/Ben载氧体的比表面积和孔容增加，还原反应速率提高，并使系统内维持较高浓度的CO2；添加Fe2O3可抑制CaSO4生成CaO和含硫气体的反应，提高CaSO4/Ben载氧体循环反应的稳定性；Fe2O3的最佳添加量为w =15.0%，该添加量下CaSO4/Ben载氧体与CO反应的活化能由88.72 kJ/mol降低至43.08 kJ/mol，反应活性显著提高。Abstract: Multiple cycles of experiments and reaction performance tests respectively were conducted using a batch fluidized bed reactor and a thermogravimetric analyzer. The catalytic effect of Fe2O3 on CaSO4/Ben oxygen carriers (OCs) during chemical looping combustion (CLC) was analyzed and the reaction activation energy of CaSO4/Ben OCs with different Fe2O3 contents and CO were compared to verify. The experimental results showed that the specific surface area and pore volume of CaSO4/Ben OCs increased with the addition of Fe2O3, which improved the reduction reaction rate and maintained the high CO2 concentration in the system. Fe2O3 could inhibit CaSO4 reaction to generate CaO and sulfur-containing gases, and improve the stability of CaSO4/Ben OCs circulation reaction. w=15.0% Fe2O3 addition was the best choice. The addition of w=15.0% Fe2O3 reduced the activation energy of CaSO4/Ben OCs reacting with CO from 88.72 kJ/ mol to 43.08 kJ/mol, and the reactivity of CaSO4/Ben OCs were significantly improved.
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Key words:
- chemical looping combustion /
- Ca-based oxygen carrier /
- Fe2O3 modifier /
- catalysis
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图 3 反应器出口气体浓度与反应时间的关系曲线
Figure 3. Variation of reactor outlet gas concentration with reaction time
图 4 载氧体化学链燃烧反应物及产物浓度曲线
Figure 4. Concentration curves of reactants and products in CLC of oxygen carriers
图 5 CO平均转化率随循环次数的变化
Figure 5. CO average conversion rate varies with the cycles numbers
图 6 CaSO4/Ben-15.0%Fe载氧体12次循环反应前后的SEM分析
Figure 6. SEM analysis of CaSO4/Ben-15.0%Fe oxygen carriers before and after the 12 th cycles
图 7 CaSO4/Ben-15%Fe载氧体颗粒在12次循环反应前后孔径分布情况
Figure 7. Pore size distribution of CaSO4/Ben-15%Fe oxygen carrier particles before and after the 12th cycles
图 9 不同载氧体在800 °C下的TG和DTG曲线
Figure 9. TG and DTG curves of different oxygen carriers at 800 °C
图 10 不同反应条件下CaSO4/Ben载氧体转化率的实验数据和模型数据比较
Figure 10. Comparison of experimental and model data of conversion of CaSO4/Ben oxygen carrier with different reaction conditions
图 12 活化能随Fe2O3负载量的变化曲线
Figure 12. Change curve of activation energy with Fe2O3 contont
表 1 CaSO4/Ben和CaSO4/Ben-15.0%Fe载氧体颗粒孔径特性
Table 1. Pore size characteristics of CaSO4/Ben and CaSO4/Ben-15.0%Fe oxygen carriers
Sample SBET/(m2·g−1) Vp /(cm3·g−1) D/nm CaSO4/Ben 2.4548 0.014772 30.4082 CaSO4/Ben-15.0%Fe 3.1795 0.022442 32.6607 
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表 2 CaSO4/Ben-15.0%Fe载氧体颗粒在12次循环反应前后孔径特性
Table 2. Pore size characteristics of CaSO4/Ben-15.0%Fe oxygen carriers before and after the 12th cycles
Sample SBET/(m2·g−1) Vp/(cm3·g−1) D/nm CaSO4/Ben-15.0%Fe 3.18 0.022 32.66 CaSO4/Ben-15.0%Fe after
the 12th cycle2.67 0.013 27.71
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表 3 不同反应温度对应的最佳拟合值m
Table 3. Best fitting value m corresponding to different reaction temperatures
t/°C Best fitting
value of mLinear correlation
coefficientStandard deviation 800 1.711 0.946 0.027 850 1.719 0.953 0.030 900 1.750 0.976 0.027 950 1.756 0.991 0.019
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