https://orcid.org/0000-0002-0176-4358
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ABSTRACT
Selenium in flue gas from coal combustion, released into the atmosphere, will affect the environment and human health greatly. The adsorption method can achieve good control of selenium emission, by using CaO as adsorbent, but CaO is easy to sinter at high temperature, resulting in the decrease of adsorption capacity. Therefore, thermostability ZSM-5 molecular sieve was added to prepare composite adsorbent to improve the adsorption performance for selenium at high temperature. CaO/ZSM-5 composite adsorbent was prepared by impregnation method, and its adsorption performance and mechanism were studied. The results show that the composite adsorbent shows stronger adsorption capacity at high temperatures. The mixing ratio has a great influence on the microstructure of the composite adsorbent influencing the adsorption capacity. When the ratio is 1:1, the adsorption efficiency of the composite adsorbent shows a good performance. At 900°C, the adsorption efficiency of Z1C1(ZSM-5/CaO = 1:1 wt%) can still maintain 67%, which is 32% higher than that of CaO. Si and Al in the composite adsorbent have different effects on the improvement of microstructure. The existence of Si is conducive to maintaining the stable skeleton of the composite adsorbent, improving anti-sintering, while the addition of Al tends to improve the porosity, furtherly ameliorating the structure of the composite adsorbent for high-temperature adsorption.
Nomenclature
| ABET | = | specific surface area, m2·g−1 |
| B.E. | = | binding energy |
| BET | = | specific surface area testing method (Brunauer, Emmett, Teller) |
| dave | = | average pore diameter, nm |
| DSC | = | differential scanning calorimetry |
| DTG | = | thermogravimetric differential curve |
| E | = | adsorption efficiency |
| HMS | = | hexagonal mesoporous silica |
| HZSM | = | hydrogen type ZSM molecular sieve |
| ICP | = | inductively coupled plasma emission spectrometer |
| M | = | mass of SeO2 volatilized in the crucible, mg |
| mr | = | mass of SeO2 adsorbed by the sorbents, mg |
| p/p0 | = | relative pressure |
| PEG | = | polyethylene glycol |
| SBA-15 | = | well-ordered hexagonal mesoporous silica structures |
| SEM | = | scanning electron microscope |
| Temp | = | temperature |
| TG | = | thermogravimetric curve |
| Va | = | cm3(STP)g−1 |
| VT | = | total pore volume, cm3·g−1 |
| XPS | = | X-ray photoelectron spectroscopy |
| XRD | = | diffraction of x-rays |
| Z0C1 | = | calcium oxide |
| Z1C0 | = | ZSM-5 molecular sieve |
| Z1C1 | = | composite molecular sieve (ZSM-5/CaO = 1:1 wt%) |
| Z1C2 | = | composite molecular sieve (ZSM-5/CaO = 1:2 wt%) |
| Z2C1 | = | composite molecular sieve (ZSM-5/CaO = 2:1 wt%) |
| ZSM | = | zeolite socony mobil |
| θ | = | diffraction angle |
Acknowledgements
The financial supports of this work was provided by National Natural Science Foundation of China (51976036) and National Key R&D Program of China (2018YFB0605102).
Disclosure statement
No potential conflict of interest was reported by the authors.
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Notes on contributors
Jinlei Li
Jinlei Li is a master student in the Department of Power Engineering and Engineering Thermophysics, School of Energy and Environment, Southeast University. His research field is pollution prevention and control.
Mengzhu Yu
Mengzhu Yu is a doctoral student in the School of Energy and Environment of Southeast University. Her research field is pollution prevention and control.
Yaji Huang
Yaji Huang is a professor in the Department of Power Engineering and Engineering Thermophysics, School of Energy and Environment, Southeast University. He received his doctorate in engineering from Southeast University in 2004. His research interests include biomass energy utilization, combustion optimization, combustion pollutant control, and solid waste resource utilization.
Zhicheng Zhu
Zhicheng Zhu is a doctoral student in the School of Energy and Environment of Southeast University. His research field is solid waste treatment and resource utilization.
Zhiyuan Li
Zhiyuan Li is a doctoral student in the School of Energy and Environment of Southeast University. His research field is solid waste treatment and resource utilization.
Xueyu Ding
Xueyu Ding is a master student in the Department of Power Engineering and Engineering Thermophysics at the School of Energy and Environment, Southeast University. Her research field is solid waste recycling.
Yuxin Li
Yuxin Li is a master student in the Department of Power Engineering and Engineering Thermophysics, School of Energy and Environment, Southeast University. Her research area is boiler combustion performance optimization.
Xuewei Zhang
Xuewei Zhang is a master student in the School of Energy and Environment of Southeast University. His research field is combustion pollutant control.
Zekun Wei
Zekun Wei is a master student in the Department of Power Engineering and Engineering Thermophysics, School of Energy and Environment, Southeast University. His research field is acoustic agglomeration and dust removal.