Study on copper-based oxygen carrier catalytic power plant flue gas deoxidation
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摘要: 电厂烟气主要成分为N2、CO2和部分O2，将电厂烟气注入矿井采空区可实现CO2封存，并替代注氮气防治遗煤自燃，但是烟气中的O2是造成遗煤自燃的因素之一。因此，亟待开发一种经济有效的催化剂来脱除电厂烟气中的O2。本研究采用共沉淀法，通过调变载体和负载量可控制备了铜基催化剂和系列xCuO/CeO2催化剂，利用BET、XRD、ICP、TEM、H2-TPR和XPS等手段对催化剂进行了表征，并建立催化剂结构与催化电厂烟气脱氧性能之间的构效关系。结果表明，CeO2的加入提高了CuO的分散性、增加了催化剂的氧空位，提高了催化剂的活性和还原氧化性能，Cu-Ce界面结构的协同效应促进了还原氧化过程，表现出良好的活性和循环稳定性。30CuO/CeO2由于其CuO颗粒尺寸最小、分散性最高、氧空位浓度最高，表现出较优的催化电厂烟气脱氧性能。本研究为开发低成本可循环使用、高活性和高稳定性的脱氧催化剂提供了参考。Abstract: The main components of power plant flue gas are N2, CO2 and part O2. Injecting power plant flue gas into mine goaf can achieve CO2 storage and replace nitrogen injection to prevent spontaneous combustion of left coal. However, O2 in flue gas is one of the factors causing spontaneous combustion of left coal. Therefore, it is urgent to develop an economical and effective catalyst to remove O2 from power plant flue gas. In this study, four types of copper-based catalysts were prepared using a controllable modulating carrier and loading capacity through co-precipitation method. Additionally, a series of xCuO/CeO2 catalystswere synthesized. The catalysts were characterized using BET analysis, XRD analysis, ICP analysis, TEM analysis, H2-TPR and XPS analysis to establish a structure-activity relationship between catalyst structure and deoxidation performance for catalytic power plant flue gases. The results showed that the addition of CeO2 improved the dispersion of CuO, increased the oxygen vacancy of the catalyst, and improved the activity and reduction oxidation performance of the catalyst. Moreover, the synergistic effect of Cu-Ce interface structure promoted the reduction oxidation process, showing good activity and cycle stability. Among xCuO/CeO2 catalysts, 30CuO/CeO2 showed the best catalytic deoxidation performance due to its smallest CuO particle size, highest dispersion and highest oxygen vacancy concentration. The results of this study provide a reference for the development of low cost, recyclable, high activity and high stability deoxidation catalysts.
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Key words:
- chemical-looping combustion /
- CuO/CeO2 /
- redox /
- interface structure /
- oxygen vacancies
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图 1 Cu基催化剂的XRD谱图（a）和xCuO/CeO2催化剂的XRD谱图（b）
Figure 1 XRD patterns of Cu-based catalysts (a) and XRD patterns of xCuO/CeO2 catalysts (b)
图 3 40CuO/CeO2催化剂反应前后的XRD谱图
Figure 3 XRD patterns of 40CuO/CeO2 catalyst before and after the reaction
图 5 xCuO/CeO2催化剂的XPS谱图
Figure 5 XPS spectra of xCuO/CeO2 catalysts O 1s (a) ; Cu 2p (b) ; Ce 3d (c)
图 6 40CuO/CeO2、40CuO/MgO、40CuO/Al2O3、40CuO/SiO2催化剂在250 ℃下的还原性能（a）和氧化性能（b）
Figure 6 Reduction performance (a) and oxidation performance (b) curves of 40CuO/CeO2, 40CuO/MgO, 40CuO/Al2O3 and 40CuO/SiO2 catalysts at 250 ℃
图 7 40CuO/CeO2催化剂在不同温度下的还原性能（a）和氧化性能（b）
Figure 7 Reduction performance (a) and oxidation performance (b) curves of 40CuO/CeO2 catalysts at different temperatures
图 8 xCuO/CeO2催化剂在250 ℃下的还原性能（a）和氧化性能（b）
Figure 8 Reduction performance (a) and oxidation performance (b) curves of xCuO/CeO2 catalysts at 250 ℃
图 9 30CuO/CeO2催化剂在不同氧浓度下的氧化性能
（反应条件：GHSV=420 mL/(g·h)，O2:N2:CO2=x:21:79-x，其中x分别为4、5、7、10）
Figure 9 Oxidation performance of 30CuO/CeO2 catalyst at different oxygen concentrations
Reaction conditions: GHSV=420 mL/(g·h), O2∶N2∶CO2=x∶21∶79−x, where x is 4, 5, 7, 10.
图 10 30CuO/CeO2催化剂在不同气体流量下的氧化性能
Figure 10 Oxidation performance of 30CuO/CeO2 catalysts at different gas flow rates
图 11 30CuO/CeO2催化剂CLC循环实验的热重曲线
（反应条件：H2:N2=10:90，N2，O2:N2:CO2=5:15:80，流速50 mL/min）
Figure 11 Thermogravimetric curve of 30CuO/CeO2 catalyst for CLC cycling experiments
Reaction condition: H2∶N2=10∶90, N2, O2∶N2∶CO2=5∶15∶80, flow rate 50 mL/min.
图 12 30CuO/CeO2、40CuO/Al2O3、40CuO/MgO、40CuO/SiO2催化剂在250 ℃的H2-TPR谱图
Figure 12 H2-TPR of 30CuO/CeO2, 40CuO/Al2O3, 40CuO/MgO, 40CuO/SiO2 catalysts at 250 ℃
表 1 催化剂的物理参数
Table 1 Physical parameters of the catalyst
Catalyst dCuO/nm Abefore/（m2·g−1） Aafter/（m2·g−1） vbefore/（cm3·g−1） vafter/（cm3·g−1） Cu w/% CuO 40 1.929 1.897 0.005 0.005 − 40CuO/MgO 23 10.393 10.048 0.047 0.044 40.493 40CuO/Al2O3 11 21.790 21.304 0.110 0.062 41.508 40CuO/SiO2 13 18.155 18.096 0.103 0.098 40.464 40CuO/CeO2 17 15.796 8.477 0.101 0.060 39.112 30CuO/CeO2 15 21.380 17.451 0.140 0.109 30.412 20CuO/CeO2 16 19.159 15.374 0.052 0.112 20.019 10CuO/CeO2 19 18.439 14.877 0.123 0.096 9.984 
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表 2 xCuO/CeO2的XPS表征
Table 2 XPS results of xCuO/CeO2 catalyst
Catalyst Ce3+/(Ce3++Ce4+)/% 10CuO/CeO2 13.54 20CuO/CeO2 16.78 30CuO/CeO2 23.19 40CuO/CeO2 15.02
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