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Waste Disposal & Sustainable Energy
Waste Disposal & Sustainable Energy  2021, Vol. 3 Issue (1): 63-71    DOI: 10.1007/s42768-020-00064-7
    
Enhanced catalytic activity for simultaneous removal of PCDD/Fs and NO over carbon nanotubes modified MnOx-CeO2/TiO2?catalyst at low temperature
Enhanced catalytic activity for simultaneous removal of PCDD/Fs and NO over carbon nanotubes modified MnOx-CeO2/TiO2?catalyst at low temperature
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摘要： 碳纳米管改性MnOx-CeO2/TiO2 催化剂协同低温催化降解 PCDD/Fs 和 NO 摘要：低温同时催化脱除多氯二苯并对二恶英和二苯并呋喃（PCDD/Fs）和氮氧化物（NOx）排放对于解决垃圾焚烧过程中造成的多重空气污染问题具有重要意义。迫切需要一种对 PCDD/Fs 催化分解具有优异低温活性以及 NO 与 NH3 选择性催化还原 (SCR) 的新型催化剂，以同时控制 PCDD/Fs 和 NO 排放。本研究使用溶胶-凝胶法制备了负载在二氧化钛上的锰-铈复合氧化物(MnOx-CeO2/TiO2)和碳纳米管 (CNTs) 复合载体 (MnOx-CeO2/TiO2-CNTs) 。研究了同时降解邻二氯苯（o-DCBz，模拟 PCDD/Fs 的模型分子）和 NO。研究发现，在 150 °C 和 15,000 h-1 的空速 (GHSV) 下，o-DCBz 和 NO 在 MnOx-CeO2/TiO2 催化剂上的同时去除效率分别降低到 27.9% 和 51.3%，由于反应物之间竞争有限的表面酸性位点和表面活性氧，添加碳纳米管提高了催化活性。当MnOx-CeO2/TiO2 负载在20 wt.% CNT 上时，实现了70% 以上的 o-DCBz 和 NO脱除效率。表征结果表明，具有适当CNTs含量的MnOx-CeO2/TiO2-CNTs催化剂具有更大的Brunauer-Emmet-Teller表面积和大大改善的表面酸性性能，有利于o-DCBz和NO的吸附。此外，Mn4+相对较高的表面原子浓度以及丰富的表面Ce3+原子的存在加速了催化剂的氧化还原循环并富集了表面活性氧。以上因素均减轻了o-DCBz催化氧化与NH3-SCR反应之间的竞争效应，有利于o-DCBz和NO的同时降解。然而，过量的 CNTs 对增强 Mn 原子和 Ce 原子之间的相互作用的贡献较小，从而导致催化活性的提高较小。
Abstract: Simultaneous catalytic removal of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and nitrogen oxides (NOx) emission at low temperature is of great significance to solve the multiple air pollution problem caused during waste incineration. A novel catalyst with excellent low-temperature activity towards PCDD/Fs catalytic decomposition, as well as selective catalytic reduction (SCR) of NO with NH3?is urgently needed to simultaneously control PCDD/Fs and NO emissions. Manganese-cerium composite oxides supported on titanium dioxide (MnOx-CeO2/TiO2) or TiO2?and carbon nanotubes (CNTs) composite carrier (MnOx-CeO2/TiO2-CNTs) were prepared using sol–gel method, and their catalytic activity towards simultaneous abatement of ortho-dichlorobenzene (o-DCBz, model molecular to simulate PCDD/Fs) and NO was investigated. In comparison with their removal, the simultaneous removal efficiencies of o-DCBz and NO over MnOx-CeO2/TiO2?catalyst are lowered to 27.9% and 51.3% at 150?°C under the gas hourly space velocity (GHSV) of 15,000?h?1, due to the competition between the reactants for the limited surface acid sites and surface reactive oxygen species. CNTs addition improves the catalytic activity for their simultaneous removal. The optimum condition occurs on MnOx-CeO2/TiO2?combined with 20 wt.% CNTs that above 70% of o-DCBz and NO are removed simultaneously. Characterization results reveal that MnOx-CeO2/TiO2-CNTs catalyst with proper CNTs content has larger Brunauer–Emmet–Teller surface area and greatly improved surface acidity property, which are beneficial to both o-DCBz and NO adsorption. Moreover, the?relatively higher surface atomic concentration of Mn4+?as well as the existence of abundant surface Ce3+?atom accelerates the redox cycle of the catalyst and enriches the surface reactive oxygen species. All the above factors alleviate the competition effect between o-DCBz catalytic oxidation and NH3-SCR reaction and are conducive to the simultaneous abatement of o-DCBz and NO. However, excess CNTs make less contribution on enhancing the interaction between Mn atom and Ce atom, thereby resulting in less improvement in the catalytic activity.
出版日期: 2021-06-27
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Qiulin Wang
Zhuping Jiang
Jianjian Zhou & Jin Jing

引用本文:

Qiulin Wang, Zhuping Jiang, Jianjian Zhou & Jin Jing. Enhanced catalytic activity for simultaneous removal of PCDD/Fs and NO over carbon nanotubes modified MnOx-CeO2/TiO2?catalyst at low temperature. Waste Disposal & Sustainable Energy, 2021, 3(1): 63-71.

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https://www.zjujournals.com/wdse/CN/10.1007/s42768-020-00064-7    或    https://www.zjujournals.com/wdse/CN/Y2021/V3/I1/63

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