Long Ding, Hexi Zhao, Lei Ni, Zhongbin Wang, Lixin Qian, Hongming Long
{"title":"Inhibition Mechanism of H2O on CO Oxidation Over CeMnOx Catalyst in Iron Ore Sintering Flue Gas","authors":"Long Ding, Hexi Zhao, Lei Ni, Zhongbin Wang, Lixin Qian, Hongming Long","doi":"10.1007/s10562-024-04733-8","DOIUrl":null,"url":null,"abstract":"<div><p>The emission of CO in sintering flue gas contributes to environmental pollution and energy wastage. Achieving full oxidation of CO presents a viable strategy for elevating the sintering flue gas temperature by over 50°C, thereby significantly reducing energy consumption during the heating of flue gas in NH<sub>3</sub>-SCR denitrification systems. In this work, MnCeOx catalysts were synthesized under various conditions, including different calcination temperatures, durations, and molar ratios. Their catalytic activity and resistance to H<sub>2</sub>O were evaluated under simulated sintering flue gas conditions at different temperatures. Our findings indicated that the M<sub>8</sub>C<sub>1</sub> catalyst exhibited exceptional activity, achieving CO conversion rates exceeding 95% within 125–250°C. However, the catalytic activity experienced a notable decline during the H<sub>2</sub>O resistance test at 150°C, while remaining unaffected at 250°C. Investigating the inhibition mechanism of H<sub>2</sub>O on CO oxidation at varying temperatures through H<sub>2</sub>-TPR, O<sub>2</sub>-TPD, and in situ DRIFTS. At lower temperatures (150°C), CO and O<sub>2</sub> adsorption on the catalyst surface led to the formation of CO<sub>2</sub>, with O<sub>2</sub> adsorption exerting a more significant influence on activity, consistent with the Langmuir–Hinshelwood mechanism. Introduction of H<sub>2</sub>O into the flue gas resulted in the formation of OH<sup>−</sup>, which competed with CO and O<sub>2</sub> for adsorption on the catalyst surface, thereby diminishing catalyst oxidation activity due to competitive adsorption hindering CO and O<sub>2</sub> adsorption. Conversely, at higher temperatures (250°C), the reaction process between CO and lattice oxygen to produce CO<sub>2</sub> followed the Mars-van Krevelen mechanism. Notably, at these temperatures, no adsorbed OH<sup>−</sup> were detected on the catalyst surface, leaving the activity unaffected. Based on our research, employing the MnCeOx catalyst during the high-temperature stage in conjunction with the NH<sub>3</sub>-SCR catalyst is recommended for enhanced CO oxidation efficiency in sintering flue gas treatment processes.</p><h3>Graphical Abstract</h3>\n<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":508,"journal":{"name":"Catalysis Letters","volume":null,"pages":null},"PeriodicalIF":2.3000,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Catalysis Letters","FirstCategoryId":"92","ListUrlMain":"https://link.springer.com/article/10.1007/s10562-024-04733-8","RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
The emission of CO in sintering flue gas contributes to environmental pollution and energy wastage. Achieving full oxidation of CO presents a viable strategy for elevating the sintering flue gas temperature by over 50°C, thereby significantly reducing energy consumption during the heating of flue gas in NH3-SCR denitrification systems. In this work, MnCeOx catalysts were synthesized under various conditions, including different calcination temperatures, durations, and molar ratios. Their catalytic activity and resistance to H2O were evaluated under simulated sintering flue gas conditions at different temperatures. Our findings indicated that the M8C1 catalyst exhibited exceptional activity, achieving CO conversion rates exceeding 95% within 125–250°C. However, the catalytic activity experienced a notable decline during the H2O resistance test at 150°C, while remaining unaffected at 250°C. Investigating the inhibition mechanism of H2O on CO oxidation at varying temperatures through H2-TPR, O2-TPD, and in situ DRIFTS. At lower temperatures (150°C), CO and O2 adsorption on the catalyst surface led to the formation of CO2, with O2 adsorption exerting a more significant influence on activity, consistent with the Langmuir–Hinshelwood mechanism. Introduction of H2O into the flue gas resulted in the formation of OH−, which competed with CO and O2 for adsorption on the catalyst surface, thereby diminishing catalyst oxidation activity due to competitive adsorption hindering CO and O2 adsorption. Conversely, at higher temperatures (250°C), the reaction process between CO and lattice oxygen to produce CO2 followed the Mars-van Krevelen mechanism. Notably, at these temperatures, no adsorbed OH− were detected on the catalyst surface, leaving the activity unaffected. Based on our research, employing the MnCeOx catalyst during the high-temperature stage in conjunction with the NH3-SCR catalyst is recommended for enhanced CO oxidation efficiency in sintering flue gas treatment processes.
期刊介绍:
Catalysis Letters aim is the rapid publication of outstanding and high-impact original research articles in catalysis. The scope of the journal covers a broad range of topics in all fields of both applied and theoretical catalysis, including heterogeneous, homogeneous and biocatalysis.
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