Preparation of MnOx/CNTs Catalyst by in-Situ Precipitation Method For Low-Temperature NO Reduction with NH3

Background: V2O5–WO3(MoO3)/TiO2 catalyst, as the core of selective catalytic reduction of NO with NH3 (SCR) has some drawbacks, such as high working temperature window (300-400oC), the toxicity of V-based catalyst and so on. Therefore, development of the catalyst with better low temperature denitration catalyst and weaker toxicity is necessary. Objective: Highly dispersed MnOx/CNTs catalysts with excellent denitration activity at 80-180oC, and weaker toxicity of MnOx. It is worth noting that an in-situ precipitation method based on the reaction of manganese acetate and sodium carbonate, which is advantageous to the in-situ deposition of active component, and the catalytic activity. Methods: MnOx/CNTs catalysts with different Mn/C molar ratio were fabricated by in-situ precipitation method due to the reaction of manganese acetate and sodium carbonate. And the microstructure, crystalline property, the content of surface element, valence state, redox property, and catalytic activity was confirmed by FESEM, TEM, XRD, XPS, TPD, and fixedbed reactor. Results: The as-prepared MnOx/CNTs catalysts exhibit outstanding low temperature SCR activity. And the NO conversion of the optimum 1.2% MnOx/CNTs catalyst reached 57.4-89.2% at 80-180oC, which resulted from the amorphous MnOx catalysts, higher ratio of Mn4+/Mn3+ and OS/(OS+OL). Conclusion: MnOx/CNTs catalysts have been prepared by the in-situ precipitation method based on the reaction of manganese acetate and sodium carbonate. And the resultant MnOx/CNTs catalysts presented excellent low temperature denitration activity between 80oC and 180oC. Among them, the 1.2% MnOx/CNTs catalyst exhibited the first rate low temperature denitration activity, and the denitration activity attained 57.4-89.2%, which may be owing to the presence of the weakly crystalline or amorphous MnOx, higher ratio of Mn4+/Mn3+ and OS/(OS+OL).

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Improving the Performance of Gd Addition on Catalytic Activity and SO2 Resistance over MnOx/ZSM-5 Catalysts for Low-Temperature NH3-SCR

Catalysts ◽

10.3390/catal11030324 ◽

2021 ◽

Vol 11 (3) ◽

pp. 324

Author(s):

Jinkun Guan ◽

Lusha Zhou ◽

Weiquan Li ◽

Die Hu ◽

Jie Wen ◽

...

Keyword(s):

Catalytic Activity ◽

Low Temperature ◽

Photoelectron Spectroscopy ◽

Active Sites ◽

Molar Ratio ◽

Manganese Sulfate ◽

Nh3 Scr ◽

So2 Resistance ◽

Temperature Programmed

SO2 poisoning is a great challenge for the practical application of Mn-based catalysts in low-temperature selective catalytic reduction (SCR) reactions of NOx with NH3. A series of Gadolinium (Gd)-modified MnOx/ZSM-5 catalysts were synthesized via a citric acid–ethanol dispersion method and evaluated by low-temperature NH3-SCR. Among them, the GdMn/Z-0.3 catalyst with the molar ratio of Gd/Mn of 0.3 presented the highest catalytic activity, in which a 100% NO conversion could be obtained in the temperature range of 120–240 °C. Furthermore, GdMn/Z-0.3 exhibited good SO2 resistance compared with Mn/Z in the presence of 100 ppm SO2. The results of Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction of H2 (H2-TPR) and temperature-programmed desorption of NH3 (NH3-TPD) illustrated that such catalytic performance was mainly caused by large surface area, abundant Mn4+ and surface chemisorbed oxygen species, strong reducibility and the suitable acidity of the catalyst. The in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) results revealed that the addition of Gd greatly inhibited the reaction between the SO2 and MnOx active sites to form bulk manganese sulfate, thus contributing to high SO2 resistance. Moreover, in situ DRIFTS experiments also shed light on the mechanism of low-temperature SCR reactions over Mn/Z and GdMn/Z-0.3, which both followed the Langmuir–Hinshelwood (L–H) and Eley–Rideal (E–R) mechanism.

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Effect of Cerium on Manganese Base Catalysts by Co-Precipitation for Low-Temperature SCR of NO with NH3

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.633.121 ◽

2014 ◽

Vol 633 ◽

pp. 121-124 ◽

Cited By ~ 3

Author(s):

Liang Jing Zhang ◽

Su Ping Cui ◽

Hong Xia Guo ◽

Xiao Yu Ma ◽

Xiao Gen Luo

Keyword(s):

Catalytic Activity ◽

Low Temperature ◽

Selective Catalytic Reduction ◽

Catalytic Reduction ◽

Precipitation Method ◽

Base Catalysts ◽

Nox Conversion ◽

Scr Of No ◽

Co Precipitation ◽

Low Temperature Scr

Catalysts of Mn/TiO2 and Mn-Ce /TiO2 prepared by co-precipitation method for low temperature selective catalytic reduction (SCR) of NO with NH3 were investigated in this study. The experimental results showed that co-precipitation method after improvement, the NO conversion of Mn-Ce/TiO2 catalyst increased sharply. Meanwhile, the addition of cerium has significant effects on the catalytic activity. Characterizations of catalysts were carried out by XRD, BET and H2-TPR. The characterized results indicated that co-precipitation method after improvement, in temperature windows 150 to 300 °C, showed higher NOx conversion.

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Promoting Effect of Mn on In Situ Synthesized Cu-SSZ-13 for NH3-SCR

Catalysts ◽

10.3390/catal10121375 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1375

Author(s):

Jinpeng Du ◽

Jingyi Wang ◽

Xiaoyan Shi ◽

Yulong Shan ◽

Yan Zhang ◽

...

Keyword(s):

Low Temperature ◽

Active Sites ◽

Catalytic Reduction ◽

Acid Sites ◽

Promoting Effect ◽

Nh3 Scr ◽

Temperature Programmed ◽

Diffuse Reflectance Infrared ◽

Redox Ability

The effect of Mn impregnation on the NH3-SCR (selective catalytic reduction of NOx by NH3) activity of in situ synthesized Cu-SSZ-13 was investigated in this work. It was found that Mn addition could efficiently improve the low-temperature activity of Cu-SSZ-13. The optimal amount of Mn was 5 wt.%, and NOx conversion was improved by more than 20% over a temperature range of 120 °C to 150 °C. SEM (scanning electron microscopy), XRD (X-ray diffraction), N2 adsorption-desorption, H2-TPR (temperature programmed reduction of H2), NH3-TPD (temperature programmed desorption of NH3) and in situ DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) experiments were conducted to investigate the changes in the zeolite structure, active sites, acid sites and reaction mechanism. The impregnated MnOx species caused a decline in the crystallinity of Cu-SSZ-13 but markedly improved the redox ability. Nitrate and nitrite species were observed in the Mn-modified Cu-SSZ-13, and the formation of these species was thought to cause the observed increase in low-temperature NH3-SCR activity. The results show that the addition of Mn is a promising method for promoting the low-temperature catalytic activity of Cu-SSZ-13.

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Fabrication of γ-MnO2-Ce Pillared Montmorillonite for Low Temperature NH3-SCR

Zeitschrift für Physikalische Chemie ◽

10.1515/zpch-2017-1064 ◽

2018 ◽

Vol 232 (12) ◽

pp. 1755-1769 ◽

Cited By ~ 4

Author(s):

Xiaoyan Huang ◽

Aijuan Xie ◽

Xingmeng Zhou ◽

Jianwen Xia ◽

Shiping Luo ◽

...

Keyword(s):

Low Temperature ◽

Selective Catalytic Reduction ◽

Catalytic Reduction ◽

Precipitation Method ◽

X Ray Diffraction ◽

Layer Spacing ◽

Surface Areas ◽

Nh3 Scr ◽

Homogeneous Precipitation Method ◽

Scr Of No

Abstract A series of γ-MnO2-Ce/MMT catalyst materials synthesized by homogeneous precipitation method was investigated for the selective catalytic reduction (SCR) of NOx with NH3. X-ray diffraction and specific surface areas were utilized for micro structure and layer spacing investigation. And NH3-TPD, Pyridoxine IR, H2-TPR and XPS were used to investigate Brønsted acid and Lewis acid, redox properties, atomic concentrations and element chemical state for as-prepared catalysts. The results showed that the γ-MnO2-Ce/MMT had superior NOx conversion compared to the bulk particles, among which 6 wt.% γ-MnO2-Ce/MMT displayed the best deNOx of 95.3% for the low temperature selective catalytic reduction of NOx with NH3 (NH3-SCR) under the GHSV of 25,000 h−1, therefore it is a promising catalyst for low temperature NH3-SCR.

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Insight into the Promoting Role of Er Modification on SO2 Resistance for NH3-SCR at Low Temperature over FeMn/TiO2 Catalysts

Catalysts ◽

10.3390/catal11050618 ◽

2021 ◽

Vol 11 (5) ◽

pp. 618

Author(s):

Huan Du ◽

Zhitao Han ◽

Xitian Wu ◽

Chenglong Li ◽

Yu Gao ◽

...

Keyword(s):

Low Temperature ◽

Catalyst Surface ◽

Impregnation Method ◽

In Situ Drifts ◽

Tio2 Catalyst ◽

Nh3 Scr ◽

Nh3 Adsorption ◽

So2 Resistance ◽

Fast Scr

Er-modified FeMn/TiO2 catalysts were prepared through the wet impregnation method, and their NH3-SCR activities were tested. The results showed that Er modification could obviously promote SO2 resistance of FeMn/TiO2 catalysts at a low temperature. The promoting effect and mechanism were explored in detail using various techniques, such as BET, XRD, H2-TPR, XPS, TG, and in-situ DRIFTS. The characterization results indicated that Er modification on FeMn/TiO2 catalysts could increase the Mn4+ concentration and surface chemisorbed labile oxygen ratio, which was favorable for NO oxidation to NO2, further accelerating low-temperature SCR activity through the “fast SCR” reaction. As fast SCR reaction could accelerate the consumption of adsorbed NH3 species, it would benefit to restrain the competitive adsorption of SO2 and limit the reaction between adsorbed SO2 and NH3 species. XPS results indicated that ammonium sulfates and Mn sulfates formed were found on Er-modified FeMn/TiO2 catalyst surface seemed much less than those on FeMn/TiO2 catalyst surface, suggested that Er modification was helpful for reducing the generation or deposition of sulfate salts on the catalyst surface. According to in-situ DRIFTS the results of, the presence of SO2 in feeding gas imposed a stronger impact on the NO adsorption than NH3 adsorption on Lewis acid sites of Er-modified FeMn/TiO2 catalysts, gradually making NH3-SCR reaction to proceed in E–R mechanism rather than L–H mechanism. DRIFTS.

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Positive effects of a halloysite-supported Cu/Co catalyst fabricated by a urea-driven deposition precipitation method on the CO-SCR reaction and SO2 poisoning

Catalysis Science & Technology ◽

10.1039/d0cy02261f ◽

2021 ◽

Author(s):

Wei-Jing Li ◽

Shu Tsai ◽

Ming-Yen Wey

Keyword(s):

Co Oxidation ◽

Catalytic Reduction ◽

Precipitation Method ◽

Molar Ratio ◽

Halloysite Nanotube ◽

Co Catalyst ◽

Reduction Of No ◽

Co Catalysts ◽

Positive Effects ◽

So2 Poisoning

Cu/Co catalysts were prepared on halloysite nanotube supports by a urea-driven deposition-precipitation method for CO oxidation and the selective catalytic reduction of NO (CO-SCR). First, the Cu/NH3 molar ratio was...

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Experimental Study on Preparation and Operating Conditions over a Promising Monolithic Catalysts for NOx Removal: MnOx/TiO2/Cordierite

Materials Science Forum ◽

10.4028/www.scientific.net/msf.898.1905 ◽

2017 ◽

Vol 898 ◽

pp. 1905-1915 ◽

Cited By ~ 6

Author(s):

Kai Qi ◽

Jun Lin Xie ◽

Feng Xiang Li ◽

Feng He

Keyword(s):

Low Temperature ◽

Catalytic Reduction ◽

Sol Gel ◽

Operating Conditions ◽

Molar Ratio ◽

Impregnation Method ◽

Scope Of Application ◽

Catalyst Dosage ◽

Cordierite Honeycomb ◽

Low Temperature Scr

The samples of MnOx/TiO2 catalysts supported on cordierite honeycomb ceramics were prepared by a sol-gel-impregnation method, and evaluated for low-temperature (353-473 K) selective catalytic reduction (SCR) of NOx with NH3. The influences of pretreatment on cordierite and catalyst dosage were investigated at first and optimized as follows: pickling for cordierite honeycomb ceramics with 1 mol/L HNO3 for 3 h prior to loading procedure as well as the catalyst dosage of 3-5 wt.%. The activity results indicated that there was an optimum working condition for MnOx/TiO2/cordierite catalysts: NH3/NO molar ratio=1.1, [O2]=3 vol.%, GHSV=5514 h-1, the highest activity of nearly 100% NO conversion could be obtained. As a comparison, the performances of commercialized vanadium-based honeycomb catalyst were also employed, which revealed the narrower scope of application of GHSV and the higher active temperature window. In conclusion, it turns out that the prepared MnOx/TiO2/cordierite catalysts are more applicable as a low-temperature SCR catalyst for NOx removal in a more complicated application environment.

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Microstructure of Porous V2O-CeO2-SiO2 Catalyst for SCR of NO with NH3 at Low Temperature

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.875-877.213 ◽

2014 ◽

Vol 875-877 ◽

pp. 213-217 ◽

Cited By ~ 1

Author(s):

Mohd Razali Sohot ◽

Umi Sarah Jais ◽

Muhd Rosli Sulaiman

Keyword(s):

Catalytic Activity ◽

Low Temperature ◽

Catalytic Reduction ◽

Sol Gel ◽

Reduction Process ◽

No Emission ◽

Scr Of No ◽

Before And After ◽

The Right ◽

Proven Method

Selective catalytic reduction (SCR) is a well-proven method to reduce NO emission. However, to choose the right catalyst that provides a surface for reaction between NO and ammonia at low temperatures is a challenging task for a catalysts developers. In an earlier study, we prepared V2O5-CeO2-SiO2 catalyst with increasing V2O5 content by sol-gel route and found that the catalytic activity improved with increasing the V2O5 loading up to 0.5%. The catalytic activity, however, dropped when V2O5 loading was about 1% and increased back when the loading of V2O5 was about 5%. In this study, we looked into the microstructural relationship to explain these findings. The microstructures of the catalysts before and after exposure to NO gas revealed that the catalysts with 0.2% and 0.5% V2O5 were more porous after the reduction process possibly due to improved breakdown of (NH4)HCO3 to NH3 by the possible interaction with the V2O5 and CeO2-containing catalysts which consequently resulted in a more efficient NO reduction to N2 and H2O at low temperature. The microstructure of the catalyst with 1% V2O5 content to 5%, improved back the efficiency although clogging by CeVO4 phase still possible due to its presence based on XRD. The well-ordered micropores before exposure to NO and the more efficient breakdown of (NH4)HCO3 could have contributed to increase back the catalytic activity at low temperature.

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Time-resolved in situ DRIFTS study on NH3–SCR of NO on CeO2/TiO2 catalyst

Catalysis Science & Technology ◽

10.1039/d1cy02089g ◽

2022 ◽

Author(s):

Jie Yang ◽

Shan Ren ◽

Mingming Wang ◽

Zhicaho Chen ◽

Lin Chen ◽

...

Keyword(s):

Nitrogen Oxides ◽

Selective Catalytic Reduction ◽

Catalytic Reduction ◽

Time Resolved ◽

In Situ Drifts ◽

Tio2 Catalyst ◽

Nh3 Scr ◽

Scr Of No

Ce–Ti catalysts were considered as promising replacement for V–Ti based catalysts for selective catalytic reduction (SCR) of nitrogen oxides (NO and NO2) with NH3. In this work, CeO2/TiO2 catalyst was...

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