scholarly journals Preparation of Quasi-MIL-101(Cr) Loaded Ceria Catalysts for the Selective Catalytic Reduction of NOx at Low Temperature

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 140 ◽  
Author(s):  
Min Lu ◽  
Haili Hou ◽  
Chuanying Wei ◽  
Xiaohui Guan ◽  
Wei Wei ◽  
...  
Keyword(s):  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
Great Influence ◽  
X Ray ◽  
Nh3 Scr ◽  
Transmission Electron ◽  
Ir Transmission ◽  
Ceria Catalysts

At present, the development of novel catalysts with high activity Selective Catalytic Reduction (SCR) reaction at the low temperature is still a challenge. In this work, the authors prepare CeO2/quasi-MIL-101 catalysts with various amounts of deposited ceria by a double-solvent method, which are characterized by X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and so on. The results show that the increase of Ce content has a great influence on the catalytic property of the catalyst. The introduction of Ce can promote the conversion between Cr3+ and Cr5+ and increase the proportion of lattice oxygen, which improves the activity of the catalyst. However, the catalyst will be peroxidized when the content of Ce is too high, resulting in the decline of the catalytic activity. This experiment indicates that CeO2/quasi-MIL-101 plays a significant role in the NH3-SCR process at the low temperature when the loading of Ce is 0.5%. This work has proved the potential of this kind of material in NH3-SCR process at the low temperature, providing help for subsequent studies.

scholarly journals Nanosized V-Ce Oxides Supported on TiO2 as a Superior Catalyst for the Selective Catalytic Reduction of NO

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 202
Author(s):  
Long Lu ◽  
Xueman Wang ◽  
Chunhua Hu ◽  
Ying Liu ◽  
Xiongbo Chen ◽  
...  
Keyword(s):  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Redox Capacity ◽  
Scr Of No ◽  
Temperature Programmed

Nanosized V-Ce oxides supported on TiO2 (VCT) were prepared and utilized in the low-temperature selective catalytic reduction (SCR) of NO with NH3. Compared with the other V-Ce oxides-based catalysts supported on Al2O3, ZrO2, and ZSM-5, VCT showed the best SCR activity in a low-temperature range. The NOx conversion of 90% could be achieved at 220 °C. Characterizations including X-ray diffraction (XRD), scanning election micrograph (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption with NH3 (NH3-TPD), and temperature-programmed reduction with H2 (H2-TPR) showed that V1.05Ce1/TiO2 exhibited a good dispersion of V2O5, enrichment of surface Ce3+ and chemical-absorbed oxygen, and excellent redox capacity and acidity, which resulted in the best SCR performance at low temperature.

scholarly journals Precursor Effect on Mn-Fe-Ce/TiO2 Catalysts for Selective Catalytic Reduction of NO with NH3 at Low Temperatures

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 259
Author(s):  
Siva Sankar Reddy Putluru ◽  
Leonhard Schill ◽  
Anker Degn Jensen ◽  
Bernard Siret ◽  
Frank Tabaries ◽  
...  
Keyword(s):  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
Reduction Of No ◽  
X Ray ◽  
Nh3 Scr ◽  
Fast Scr ◽  
Oxide Phases ◽  
Temperature Programmed

Preparation of Mn/TiO2, Mn-Fe/TiO2, and Mn-Fe-Ce/TiO2 by the deposition-precipitation (DP) method can afford very active catalysts for low-temperature NH3-SCR (selective catalytic reduction of NO with NH3). The effect of precursor choice (nitrate vs. acetate) of Mn, Fe, and Ce on the physiochemical properties including thermal stability and the resulting SCR activity were investigated. The resulting materials were characterized by N2-Physisorption, XRD (Powder X-ray diffraction), XPS (X-ray photoelectron spectroscopy), H2-TPR (temperature-programmed reduction with hydrogen), and the oxidation of NO to NO2 measured at 300 °C. Among all the prepared catalysts 5MnAce/Ti, 25Mn0.75AceFe0.25Nit/Ti, and 25Mn0.75AceFe0.20NitCe0.05Ace/Ti showed superior SCR activity at low temperature. The superior activity of the latter two materials is likely attributable to the presence of amorphous active metal oxide phases (manganese-, iron- and cerium-oxide) and the ease of the reduction of metal oxides on TiO2. Enhanced ability to convert NO to NO2, which can promote fast-SCR like pathways, could be another reason. Cerium was found to stabilize amorphous manganese oxide phases when exposed to high temperatures.

Novel Homogeneous and Mesoporous MnOx-Doped Ceria Nanosheets as Catalysts for Low-Temperature Selective Catalytic Reduction

2019 ◽  
Vol 72 (9) ◽  
pp. 657
Author(s):  
Yan Yue ◽  
Yanhua Wang ◽  
Jun Ling ◽  
Weilin Sun ◽  
Zhiquan Shen
Keyword(s):  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
Bet Surface Area ◽  
Homogeneous Distribution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Precipitation ◽  
Scr Of Nox

The development of a catalyst for the selective catalytic reduction (SCR) of NOx is essential for purifying air and the denitration of coal-burning exhaust. Herein, we prepare novel MnOx-CeO2 nanosheets with porous structures by a homogeneous coordination precipitation (HCP) method which exhibit a high NO removal efficiency above 90% in the SCR reaction at low temperature (150–240°C). The MnOx-CeO2(HCP) catalysts have a higher Brunauer–Emmett–Teller (BET) surface area and more homogeneous distribution of Mnx+ in the CeO2 lattice than those prepared by co-precipitation and precursor mixture combustion methods according to BET, X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy characterizations. Together with a higher ratio of Mn4+, Ce3+, and Oα, the above properties are responsible for the high catalytic performances of MnOx-CeO2(HCP) in the SCR of NOx.

scholarly journals Selective Catalytic Reduction of NOx with NH3 over Mn2O3 supported with different morphology of CeO2 Catalysts

2021 ◽  
Author(s):  
Shyam Rao ◽  
VIVEK PATEL ◽  
Sweta Sharma
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
Catalytic Performance ◽  
X Ray Diffraction ◽  
Wet Impregnation ◽  
X Ray ◽  
Nh3 Scr ◽  
Transmission Electron ◽  
Reduction Of Nox

Three different morphologies of CeO2 supports (NP, NC, and NR) were prepared by hydrothermal method and further Mn2O3 is impregnated on CeO2 supports using wet-impregnation methods, and their activity for NO reduction using NH3-SCR technique is analysed. The prepared catalysts and supports are further characterized through scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET). The catalytic performance of Mn2O3/CeO2-NP has shown the highest conversion (76.06 %) compared to the other two catalysts in the temperature range of 50 - 450°C.

scholarly journals Comparision on the Low-Temperature NH3-SCR Performance of γ-Fe2O3 Catalysts Prepared by Two Different Methods

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1018
Author(s):  
Naveed Husnain ◽  
Enlu Wang ◽  
Shagufta Fareed ◽  
Muhammad Tuoqeer Anwar
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
Acid Sites ◽  
High Concentration ◽  
X Ray ◽  
Nh3 Scr ◽  
Transmission Electron ◽  
Temperature Programmed ◽  
Diffuse Reflectance Infrared

Maghemite (γ-Fe2O3) catalysts were prepared by two different methods, and their activities and selectivities for selective catalytic reduction of NO with NH3 were investigated. The methods of X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), ammonia temperature-programmed desorption (NH3-TPD), transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) were used to characterize the catalysts. The resulted demonstrated that the γ-Fe2O3 nanoparticles prepared by the facile method (γ-Fe2O3–FM) not only exhibited better NH3-SCR activity and selectivity than the catalyst prepared by the coprecipitation method but also showed improved SO2 tolerance. This superior NH3-SCR performance was credited to the existence of the larger surface area, better pore structure, a high concentration of lattice oxygen and surface-adsorbed oxygen, good reducibility, a lot of acid sites, lower activation energy, adsorption of the reactants, and the existence of unstable nitrates on the surface of the γ-Fe2O3–FM.

scholarly journals Ce regulated surface properties of Mn/SAPO-34 for improved NH3-SCR at low temperature

RSC Advances ◽  
2020 ◽  
Vol 10 (66) ◽  
pp. 40047-40054
Author(s):  
Qizhi Chen ◽  
Yong Yang ◽  
Hang Luo ◽  
Zuohua Liu ◽  
Zhangfa Tong ◽  
...  
Keyword(s):  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Surface Properties ◽  
Catalytic Reduction ◽  
Reduction Of No ◽  
Nh3 Scr

Ce modified MnOx/SAPO-34 was prepared and investigated for low-temperature selective catalytic reduction of NOx with ammonia (NH3-SCR).

scholarly journals Effect of Organic Assistant on the Performance of Ceria-Based Catalysts for the Selective Catalytic Reduction of NO with Ammonia

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 357 ◽  
Author(s):  
Huang ◽  
Li ◽  
Qiu ◽  
Chen ◽  
Cheng ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Ball Milling ◽  
Catalytic Reduction ◽  
Temperature Programmed Desorption ◽  
Milling Process ◽  
X Ray ◽  
Ball Milling Process ◽  
Nh3 Scr ◽  
Temperature Programmed ◽  
Catalytic Performances

In the present study, a series of CeO2/TiO2 catalysts were fabricated by dry ball milling method in the absence and presence of organic assistants, and their catalytic performances for the selective catalytic reduction (SCR) of NO by NH3 were investigated. It was found that the addition of organic assistants in the ball milling process and the calcining ambience exerted a significant influence on the catalytic performances of CeO2/TiO2 catalysts. The nitrogen sorption isotherm measurement (BET), powder X-ray diffraction (XRD), Raman spectra, high-resolution transmission electron microscopy (HR-TEM), hydrogen temperature-programmed reduction (H2-TPR), ammonia temperature-programmed desorption (NH3-TPD), sulfur dioxide temperature-programmed desorption (SO2-TPD), thermogravimetric analysis (TG), Fourier transform infrared (FT-IR) and X-ray photoelectron spectra (XPS) characterizations showed that the introduction of citric acid in the ball milling process could significantly change the decomposition process of the precursor mixture, which can lead to improved dispersion and reducibility of cerium species, surface acidity as well as the surface microstructure, all which were responsible for the high low temperature activity of CeTi-C-N in an NH3-SCR reaction. In contrast, the addition of sucrose in the milling process showed an inhibitory effect on the catalytic performance of CeO2/TiO2 catalyst in an NH3-SCR reaction, possibly due to the decrease of the crystallinity of the TiO2 support and the carbon residue covering the active sites.

scholarly journals Optimization of sol-immobilized bimetallic Au–Pd/TiO 2 catalysts: reduction of 4-nitrophenol to 4-aminophenol for wastewater remediation

2020 ◽  
Vol 378 (2176) ◽  
pp. 20200057
Author(s):  
Khaled Alshammari ◽  
Yubiao Niu ◽  
Richard E. Palmer ◽  
Nikolaos Dimitratos
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
Catalytic Performance ◽  
Reducing Agent ◽  
Wastewater Remediation ◽  
X Ray ◽  
Molar Ratios ◽  
Highly Active ◽  
Transmission Electron ◽  
Complementary Techniques

A sol-immobilization method is used to synthesize a series of highly active and stable Au x Pd 1− x /TiO 2 catalysts (where x  = 0, 0.13, 0.25, 0.5, 0.75, 0.87 and 1) for wastewater remediation. The catalytic performance of the materials was evaluated for the catalytic reduction of 4-nitrophenol, a model wastewater contaminant, using NaBH 4 as the reducing agent under mild reaction conditions. Reaction parameters such as substrate/metal and substrate/reducing agent molar ratios, reaction temperature and stirring rate were investigated. Structure-activity correlations were studied using a number of complementary techniques including X-ray powder diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. The sol-immobilization route provides very small Au–Pd alloyed nanoparticles, with the highest catalytic performance shown by the Au 0.5 Pd 0.5 /TiO 2 catalyst. This article is part of a discussion meeting issue ‘Science to enable the circular economy’.

scholarly journals Selective Catalytic Reduction of NO with NH3 over Ce-W-Ti Oxide Catalysts Prepared by Solvent Combustion Method

2018 ◽  
Vol 8 (12) ◽  
pp. 2430 ◽  
Author(s):  
Xinbo Zhu ◽  
Yaolin Wang ◽  
Yu Huang ◽  
Yuxiang Cai
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Space Velocity ◽  
Combustion Method ◽  
Catalytic Performance ◽  
Solution Combustion ◽  
X Ray ◽  
Nh3 Scr ◽  
Scr Of No ◽  
Temperature Programmed

In this work, a series of Ce-W-Ti catalysts were synthesized using a solution combustion method for the selective catalytic reduction (SCR) of NO with NH3 at low temperatures. The reaction performance of NH3-SCR of NO was significantly improved over the Ce-W-Ti catalysts compared to Ce0.4Ti and W0.4Ti catalysts, while Ce0.2W0.2Ti showed the best activity among all the samples. The Ce0.2W0.2Ti catalyst exhibited over 90% removal of NO and 100% N2 selectivity in the temperature range of 250–400 °C at a gas hourly space velocity (GHSV) of 120,000 mL·g−1·h−1. The Ce-W-Ti catalysts were characterized using N2 adsorption-desorption, X-ray diffraction, X-ray photoelectron spectrometry and temperature programmed desorption of NH3 to establish the structure-activity relationships of the Ce-W-Ti catalysts. The excellent catalytic performance of the Ce0.2W0.2Ti catalyst could be associated with the larger specific surface area, highly dispersed Ce and W species, increased amount of surface adsorbed oxygen (Oads) and enhanced total acidity on the catalyst surfaces.

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