Low-Temperature Selective Catalytic Reduction of NO with NH3 over Natural Iron Ore Catalyst

The selective catalytic reduction of NO with NH3 at low temperatures has been investigated with natural iron ore catalysts. Four iron ore raw materials from different locations were taken and processed to be used as catalysts. The methods of X-ray diffraction (XRD), X-ray fluorescence (XRF), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), ammonia temperature-programmed desorption (NH3-TPD), scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) were used to characterize the materials. The results showed that the sample A (comprised mainly of α-Fe2O3 and γ-Fe2O3), calcined at 250 °C, achieved excellent selective catalytic reduction (SCR) activity (above 80% at 170–350 °C) and N2 selectivity (above 90% up to 250 °C) at low temperatures. Suitable calcination temperature, large surface area, high concentration of surface-adsorbed oxygen, good reducibility, lots of acid sites and adsorption of the reactants were responsible for the excellent SCR performance of the iron ore. However, the addition of H2O and SO2 in the feed gas showed some adverse effects on the SCR activity. The FT-IR analysis indicated the formation of sulfate salts on the surface of the catalyst during the SCR reaction in the presence of SO2, which could cause pore plugging and result in the suppression of the catalytic activity.

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

Catalysts ◽

10.3390/catal11020259 ◽

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.

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

Catalysts ◽

10.3390/catal10020202 ◽

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.

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Promotional Effect of Cerium and/or Zirconium Doping on Cu/ZSM-5 Catalysts for Selective Catalytic Reduction of NO by NH3

Catalysts ◽

10.3390/catal8080306 ◽

2018 ◽

Vol 8 (8) ◽

pp. 306 ◽

Cited By ~ 5

Author(s):

Ye Liu ◽

Chonglin Song ◽

Gang Lv ◽

Chenyang Fan ◽

Xiaodong Li

Keyword(s):

Selective Catalytic Reduction ◽

Photoelectron Spectroscopy ◽

Catalytic Reduction ◽

Copper Ions ◽

N2o Formation ◽

Copper Species ◽

X Ray ◽

Promotional Effect ◽

Zirconium Doping ◽

Temperature Programmed

The cerium and/or zirconium-doped Cu/ZSM-5 catalysts (CuCexZr1−xOy/ZSM-5) were prepared by ion exchange and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction by hydrogen (H2-TPR). Activities of the catalysts obtained on the selective catalytic reduction (SCR) of nitric oxide (NO) by ammonia were measured using temperature programmed reactions. Among all the catalysts tested, the CuCe0.75Zr0.25Oy/ZSM-5 catalyst presented the highest catalytic activity for the removal of NO, corresponding to the broadest active window of 175–468 °C. The cerium and zirconium addition enhanced the activity of catalysts, and the cerium-rich catalysts exhibited more excellent SCR activities as compared to the zirconium-rich catalysts. XRD and TEM results indicated that zirconium additions improved the copper dispersion and prevented copper crystallization. According to XPS and H2-TPR analysis, copper species were enriched on the ZSM-5 grain surfaces, and part of the copper ions were incorporated into the zirconium and/or cerium lattice. The strong interaction between copper species and cerium/zirconium improved the redox abilities of catalysts. Furthermore, the introduction of zirconium abates N2O formation in the tested temperature range.

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Effect of the Addition of In to Co/HMCM-49 Catalyst for the Selective Catalytic Reduction of NO Under Lean-burn Conditions

Zeitschrift für Physikalische Chemie ◽

10.1524/zpch.2010.5534 ◽

2010 ◽

Vol 224 (06) ◽

pp. 907-920 ◽

Cited By ~ 1

Author(s):

Fei Li ◽

Dehai Xiao ◽

Jing Li ◽

Xiangguang Yang

Keyword(s):

Selective Catalytic Reduction ◽

Wide Temperature Range ◽

Catalytic Reduction ◽

Temperature Programmed Desorption ◽

X Ray Diffraction ◽

Lean Burn ◽

Reduction Of No ◽

X Ray ◽

Scr Of No ◽

Temperature Programmed

AbstractSelective catalytic reduction (SCR) of NO with propane using bimetals (3Co2Ce, 3Co2Sr, 3Co2Sn and 3Co2In) loaded on HMCM-49 zeolite was studied under lean-burn condition. Only 3Co2In/HMCM-49 exhibited higher deNOx activity in a wide temperature range. The catalysts were characterized by N2-adsoption, X-ray diffraction (XRD), temperature-programmed surface reactions (TPSR) and temperature-programmed desorption (TPD) of NO. TPSR and TPD results exhibited that the addition of In inhibited the oxidation ability of Co on 3Co2In/HMCM-49 catalyst, but enhanced NOx adsorption.

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Characteristics of Vanadium-Based Coal Gasification Slag and the NH3-Selective Catalytic Reduction of NO

Catalysts ◽

10.3390/catal8080327 ◽

2018 ◽

Vol 8 (8) ◽

pp. 327 ◽

Cited By ~ 2

Author(s):

Fang Han ◽

Yanchun Gao ◽

Qihuang Huo ◽

Lina Han ◽

Jiancheng Wang ◽

...

Keyword(s):

Selective Catalytic Reduction ◽

Active Component ◽

Coal Gasification ◽

Catalytic Reduction ◽

Acid Sites ◽

No Removal ◽

Reduction Of No ◽

X Ray ◽

Temperature Programmed ◽

Coal Gasification Slag

In order to realize the resource utilization of coal gasification slag (CGS) and to effectively control the emission of nitrogen oxides (NOx) in coke oven gas, the effect of the reaction conditions and vanadium loading over the CGS catalysts was carried out for the selective catalytic reduction (SCR) of NO by NH3. The various vanadium loaded CGS catalysts were prepared using impregnation methods. The addition of 1% vanadium to the CGS catalyst (V1/CGS) significantly enhanced the NO conversion at a wide temperature range of 180–290 °C. The catalysts were characterized by N2 adsorption/desorption, X-ray photoelectron spectroscopy, H2-temperature programmed reduction, NH3-temperature programmed desorption, Inductively coupled plasma optical emission spectrometer (ICP-OES), thermo gravimetric analyses (TGA), Fourier Transform infrared spectroscopy (FTIR), Scanning electron microscope-Energy dispersive spectrometer (SEM-EDS), and X-ray powder diffraction (XRD). The experimental results show the following: That (1) the NO removal efficiency of the sample CGS3 was the best, and it could be up to 100% under the experimental conditions; (2) The NO removal efficiency of the catalysts was higher in the atmosphere with SO2 than that without SO2; (3) The XRD results indicated the active component of vanadium was homogeneously dispersed over CGS and the active component of catalyst was V2O5 according to the XPS results. In particular, the NH3-TPD spectra of the vanadium loaded CGS catalyst showed that vanadium produced more acid sites, and the Lewis acid sites on the vanadium species were the active sites for the catalytic reduction of NO at 240–290 °C.

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

Catalysts ◽

10.3390/catal9121018 ◽

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.

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The synergistic effects between Ce and Cu in CuyCe1−yW5Ox catalysts for enhanced NH3-SCR of NOx and SO2 tolerance

Catalysis Science & Technology ◽

10.1039/c8cy01949e ◽

2019 ◽

Vol 9 (3) ◽

pp. 718-730 ◽

Cited By ~ 17

Author(s):

Jian-Wen Shi ◽

Yao Wang ◽

Ruibin Duan ◽

Chen Gao ◽

Baorui Wang ◽

...

Keyword(s):

Metal Oxides ◽

Selective Catalytic Reduction ◽

Low Temperatures ◽

Catalytic Reduction ◽

Synergistic Effects ◽

Reduction Of No ◽

Nh3 Scr ◽

So2 Tolerance ◽

Scr Of Nox

Non-manganese-based metal oxides are promising catalysts for the NH3-SCR (selective catalytic reduction) of NOx at low temperatures.

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Selective catalytic reduction of NO by Co-Mn based nanocatalysts

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2020-0240 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Vahid Zabihi ◽

Mohammad Hasan Eikani ◽

Mehdi Ardjmand ◽

Seyed Mahdi Latifi ◽

Alireza Salehirad

Keyword(s):

Selective Catalytic Reduction ◽

Catalytic Reduction ◽

Energy Dispersive ◽

Diffraction Field ◽

X Ray Diffraction ◽

X Ray ◽

Analysis Techniques ◽

Acidic Sites ◽

Temperature Window ◽

Temperature Programmed

Abstract One of the most significant aspects in selective catalytic reduction (SCR) of nitrogen oxides (NOx) is developing suitable catalysts by which the process occurs in a favorable way. At the present work SCR reaction by ammonia (NH3-SCR) was conducted using Co-Mn spinel and its composite with Fe-Mn spinel, as nanocatalysts. The nanocatalysts were fabricated through liquid routes and then their physicochemical properties such as phase composition, degree of agglomeration, particle size distribution, specific surface area and also surface acidic sites have been investigated by X-ray diffraction, Field Emission Scanning Electron Microscope, Energy-dispersive X-ray spectroscopy, energy dispersive spectroscopy mapping, Brunauer–Emmett–Teller, temperature-programmed reduction (H2-TPR) and temperature-programmed desorption of ammonia (NH3-TPD) analysis techniques. The catalytic activity tests in a temperature window of 150–400 °C and gas hourly space velocities of 10,000, 18,000 and 30,000 h−1 revealed that almost in all studied conditions, CoMn2O4/FeMn2O4 nanocomposite exhibited better performance in SCR reaction than CoMn2O4 spinel.

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