Comprehensive Comparison between Nanocatalysts of Mn-Co/TiO2 and Mn-Fe/TiO2 for NO Catalytic Conversion: An Insight from Nanostructure, Performance, Kinetics, and Thermodynamics

被引：33

作者：

Gao, Yan ^{[1
,2
]}

Luan, Tao ^{[3
]}

Zhang, Shitao ^{[2
]}

Jiang, Wenchao ^{[2
]}

Feng, Wenchen ^{[3
]}

Jiang, Haolin ^{[3
]}

机构：

[1] Shandong Jianzhu Univ, Key Lab Renewable Energy Bldg Applicat Technol Sh, Jinan 250101, Shandong, Peoples R China

[2] Shandong Jianzhu Univ, Dept Thermal Engn, Jinan 250101, Shandong, Peoples R China

[3] Shandong Univ, Engn Lab Power Plant Thermal Syst Energy Saving S, Jinan 250061, Shandong, Peoples R China

来源：

CATALYSTS | 2019年 / 9卷 / 02期

关键词：

NH3-SCR; nanostructure; kinetics; thermodynamics; manganese oxides; MIXED-OXIDE CATALYST; LOW-TEMPERATURE SCR; MN/TIO2; CATALYST; TRANSITION-METALS; REDUCTION; NH3; MECHANISM; NH3-SCR; MNOX/TIO2; OXIDATION;

D O I：

10.3390/catal9020175

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The nanocatalysts of Mn-Co/TiO2 and Mn-Fe/TiO2 were synthesized by hydrothermal method and comprehensively compared from nanostructures, catalytic performance, kinetics, and thermodynamics. The physicochemical properties of the nanocatalysts were analyzed by N-2 adsorption, transmission electron microscope (TEM), X-ray diffraction (XRD), H-2-temperature-programmed reduction (TPR), NH3-temperature-programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS). Based on the multiple characterizations performed on Mn-Co/TiO2 and Mn-Fe/TiO2 nanocatalysts, it can be confirmed that the catalytic properties were decidedly dependent on the phase compositions of the nanocatalysts. The Mn-Co/TiO2 sample presented superior structure characteristics than Mn-Fe/TiO2, with the increased surface area, the promoted active components distribution, the diminished crystallinity, and the reduced nanoparticle size. Meanwhile, the Mn4+/Mnn+ ratios in the Mn-Co/TiO2 nanocatalyst were higher than Mn-Fe/TiO2, which further confirmed the better oxidation ability and the larger amount of Lewis acid sites and Bronsted acid sites on the sample surface. Compared to Mn-Fe/TiO2 nanocatalyst, Mn-Co/TiO2 nanocatalyst displayed the preferable catalytic property with higher catalytic activity and stronger selectivity in the temperature range of 75-250 degrees C. The results of mechanism and kinetic study showed that both Eley-Rideal mechanism and Langmuir-Hinshelwood mechanism reactions contributed to selective catalytic reduction of NO with NH3 (NH3-SCR) over Mn-Fe/TiO2 and Mn-Co/TiO2 nanocatalysts. In this test condition, the NO conversion rate of Mn-Co/TiO2 nanocatalyst was always higher than that of Mn-Fe/TiO2. Furthermore, comparing the reaction between doping transition metal oxides and NH3, the order of temperature-Gibbs free energy under the same reaction temperature is as follows: Co3O4 < CoO < Fe2O3 < Fe3O4, which was exactly consistent with nanostructure characterization and NH3-SCR performance. Meanwhile, the activity difference of MnOx exhibited in reducibility properties and Ellingham Diagrams manifested the promotion effects of cobalt and iron dopings. Generally, it might offer a theoretical method to select superior doping metal oxides for NO conversion by comprehensive comparing the catalytic performance with the insight from nanostructure, catalytic performance, reaction kinetics, and thermodynamics.

引用

页数：21

共 55 条

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