Issue 39, 2018, Issue in Progress

Environment-friendly magnetic Fe–Ce–W catalyst for the selective catalytic reduction of NOx with NH3: influence of citric acid content on its activity-structure relationship

Abstract

The influence of the citric acid content on the structural and redox properties of a magnetic iron–cerium–tungsten mixed oxide catalyst prepared through a microwave-assisted citric acid sol–gel method is investigated via TG–DTG–DSC, XRD, N2 adsorption–desorption, XPS, H2-TPR and NH3-TPD. Additionally, the NH3-SCR activity of the magnetic FeCeW-m (m = 0.25, 0.5 and 1.0) catalysts are also studied. The results indicate that an increase in citric acid content strengthens the sol–gel reaction between citric acid and metal ions and promotes the formation of the γ-Fe2O3 crystallite not α-Fe2O3. Meanwhile, it decreases the BET surface area and pore volume of the catalyst. Furthermore, the surface concentration of iron species on the catalyst is enhanced when the molar ratio of citric acid/(Fe + Ce + W) increases from 0.25 to 1.0, but its surface absorbed oxygen and total oxygen concentration decrease. The magnetic FeCeW-0.5 catalyst shows the best reducibility at temperatures below 790 °C. The increase in the citric acid content inhibits the formation of acid sites in the catalyst, thus the magnetic FeCeW-0.25 catalyst possesses the most Lewis acid sites and Brønsted acid sites among the catalysts. The enhancement in citric acid content is beneficial to improve the SCR reaction rates normalized by the surface area of the catalyst. This catalyst exhibits high anti-SO2 and H2O poisoning, and the molar ratio of citric acid/(Fe + Ce + W) affects the adsorption of NOx species on its surface.

Graphical abstract: Environment-friendly magnetic Fe–Ce–W catalyst for the selective catalytic reduction of NOx with NH3: influence of citric acid content on its activity-structure relationship

Supplementary files

Article information

Article type
Paper
Submitted
12 Apr 2018
Accepted
31 May 2018
First published
14 Jun 2018
This article is Open Access
Creative Commons BY license

RSC Adv., 2018,8, 21915-21925

Environment-friendly magnetic Fe–Ce–W catalyst for the selective catalytic reduction of NOx with NH3: influence of citric acid content on its activity-structure relationship

Z. Xiong, X. Ning, F. Zhou, B. Yang, Y. Tu, J. Jin, W. Lu and Z. Liu, RSC Adv., 2018, 8, 21915 DOI: 10.1039/C8RA03131B

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