来源:Frontiers of Environmental Science & Engineering 发布时间:2021/10/21 11:23:52
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FESE | 前沿研究:整体式蜂窝状赤泥催化剂上的活性炭对氮氧化物选择性催化还原的促进机制见解

论文标题:Insight into the promotion mechanism of activated carbon on the monolithic honeycomb red mud catalyst forselective catalytic reduction of NOx(整体式蜂窝状赤泥催化剂上的活性炭对氮氧化物选择性催化还原的促进机制见解)

期刊: Frontiers of Environmental Science & Engineering

作者:Qiuzhun Chen(陈邱谆), Xiang Zhang(张翔), Bing Li(李兵), Shengli Niu(牛胜利), Gaiju Zhao(赵改菊), Dong Wang (王栋), Yue Peng(彭悦), Junhua Li(李俊华), Chunmei Lu(路春美), John Crittenden

发表时间:17 Dec 2020

DOI:10.1007/s11783-020-1337-7

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编者荐语:

《前沿》系列之《环境科学与工程前沿》最新发表

原文链接:

https://journal.hep.com.cn/fese/EN/PDF/10.1007/s11783-020-1337-7

文章出版:Front. Environ. Sci. Eng. 2021, 15(5): 92

原文信息

题目:

Insight into the promotion mechanism of activated carbon on the monolithic honeycomb red mud catalyst forselective catalytic reduction of NOx

作者:

Qiuzhun Chen(陈邱谆)1, Xiang Zhang(张翔)1, Bing Li(李兵)3, Shengli Niu(牛胜利)1, Gaiju Zhao(赵改菊)4, Dong Wang (王栋)2(), Yue Peng(彭悦)3, Junhua Li(李俊华)3, Chunmei Lu(路春美)1, John Crittenden2

作者单位:

1 National Engineering Laboratory for Coal-Burning Pollutants Emission Reduction, School of Energy and Power Engineering, Shandong University, Jinan 250061, China

2 Brook Byers Institute for Sustainable Systems and School of Civil and Environmental Engineering, Georgia Institute of Technology, 828 West Peachtree Street, Atlanta, GA 30332, USA

3 State Key Joint Laboratory of Environment Simulation and Pollution Control, National Engineering Laboratory for Multi Flue Gas Pollution Control Technology and Equipment, School of Environment, Tsinghua University, Beijing 100084, China

4 Energy Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250013, China

关键词:

NOx (氮氧化物); Selective catalytic reduction (选择性催化还原); Iron-basedcatalyst (铁基催化剂); Redmud (赤泥); Activated carbon (活性炭)

文章亮点

活性炭被认为是成型赤泥催化剂的有效促进剂。

催化剂表面酸度、还原性和孔隙结构得到了极大地改善。

催化剂性能改善归因于丰富的表面Fe(II)和吸附氧。

文章简介

化石燃料大量燃烧产生的氮氧化物(NOx)排放量逐渐增加,导致酸雨、温室效应、光化学烟雾等环境问题日益严重。氨法选择性催化还原(NH3-SCR)技术是目前最有前途的氮氧化物脱除技术之一,通常用于控制燃煤电厂、焚烧炉和机动车尾气等行业中的氮氧化物。作为该技术的核心,SCR催化剂的性能直接决定了整个SCR系统的安全性、经济性和高效性。迄今为止,商用V-W-Ti催化剂已经表现出成本高和钒生物毒性等缺点,限制了其进一步发展。为此,本文以粉末状赤泥催化剂和活性炭为原料,制备了整体式蜂窝状赤泥催化剂用于NOx选择性催化还原研究。

研究结果表明,活性炭(AC)作为促进剂可以有效地提高整体式蜂窝状赤泥催化剂(MHRM)在SCR反应中的活性。结合实验和表征分析,从离子层面分析了活性成分与促进剂之间的相互作用,并揭示了活性炭对整体式蜂窝状赤泥催化剂SCR性能的促进机制。活性炭含量为3 wt.%的整体式蜂窝状赤泥催化剂(MHRM-AC3)表现出最好的SCR性能,其在350°C时NOx转化率超过90%。与MHRM、MHRM-AC1和MHRM-AC5相比,MHRM-AC3具有更为丰富的Brønsted酸位点,对NH3表现出优异的吸附能力。活性炭的引入可以增加整体式蜂窝状赤泥催化剂的比表面积以及介孔和大孔含量,有利于反应分子的传质与扩散,并提高催化剂活性组分的分散度,使催化剂暴露更多的酸性位点和活性位点。同时活性炭可以促进Fe2O3的还原,Fe(II)浓度和表面吸附氧含量增加,促进NOx的还原。但活性炭添加量过量(即含量超过5 wt.%)会导致孔结构坍塌,从而覆盖表面活性位点,不利于SCR反应的进行。

图1 摘要图

摘要

Our previous study proved that the acid-pretreatment process could efficiently activate red mud (RM) for the selective catalytic reduction (SCR) of NOx. However, in terms of the molding process, which is the key step determining whether it can be applied in large-scale industrial, the surface acidity and reducibility of catalyst always decreased dramatically, and part of surface area and pore structure were lost. In this study, we prepared monolithic honeycomb red mud (MHRM) catalysts with activated carbon (AC) as an accelerant and investigated the effect of AC on the MHRM. The results showed that the MHRM with 3 wt.% of AC (MHRM-AC3) exhibited the best SCR performance, and kept more than 80% NOx conversion in the range of 325°C–400°C. Compared with the MHRM, MHRM-AC1, and HMRM-AC5, the MHRM-AC3 has more mesoporous and macroporous structures, which can provide more adsorption active sites. The AC significantly improved NH3 adsorption and surface reducibility, which was mainly due to the increase of the surface acid sites (especially the Brönsted acid sites), the concentration of Fe(II), and the surface adsorbed oxygen. The presence of more Fe(II) enriched the surface oxygen vacancies, as well as the surface adsorbed oxygen, due to the charge imbalance and unsaturated chemical bond. And surface adsorbed oxygen exhibited more active than lattice oxygen owing to its higher mobility, which was conducive to NOx reduction in the SCR reaction.

编者点评

赤泥催化剂是氮氧化物选择性催化还原反应中有效的催化剂之一。为了解决赤泥催化剂成型后表面酸度和还原性下降的问题,作者以活性炭为促进剂制备了整体式蜂窝状赤泥催化剂,并研究了催化剂表面物理化学特性,深入地探讨了热处理过程中催化剂中金属氧化物和活性炭之间的相互作用。引入的活性炭在热氧化过程中增加了催化剂表面酸位点、Fe(II)浓度和表面吸附氧含量,提升了催化剂对NOx的氧化还原活性。本研究为活性炭作为促进剂对整体式蜂窝状赤泥催化剂的改性研究提供了见解。

本期编辑

李志锋,男,25岁,北京化工大学化学工程学院2019级环境科学与工程专业硕士生,导师为张婷婷教授,研究方向为二维层状材料(g-C3N4,Ti3C2Tx)的改性研究及其对水中有机污染物的去除性能。

《前沿》系列英文学术期刊

由教育部主管、高等教育出版社主办的《前沿》(Frontiers)系列英文学术期刊,于2006年正式创刊,以网络版和印刷版向全球发行。系列期刊包括基础科学、生命科学、工程技术和人文社会科学四个主题,是我国覆盖学科最广泛的英文学术期刊群,其中13种被SCI收录,其他也被A&HCI、Ei、MEDLINE或相应学科国际权威检索系统收录,具有一定的国际学术影响力。系列期刊采用在线优先出版方式,保证文章以最快速度发表。

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