scholarly journals Effect of Transition Metal Additives on the Catalytic Performance of Cu–Mn/SAPO-34 for Selective Catalytic Reduction of NO with NH3 at Low Temperature

Catalysts ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 685
Author(s):  
Guofu Liu ◽  
Wenjie Zhang ◽  
Pengfei He ◽  
Dekui Shen ◽  
Chunfei Wu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transition Metal Oxides ◽  
Active Sites ◽  
Catalytic Reduction ◽  
Catalytic Performance ◽  
Decomposition Temperature ◽  
Impregnation Method ◽  
X Ray Diffraction ◽  
Before And After ◽  
So2 Resistance

The adsorption of NO, NH3, H2O, and SO2 gaseous molecules on different transition metal oxides was studied based on density function theory (DFT), and three better-performing transition metal elements (Fe, Co, and Ce) were selected. Cu–Mn/SAPO-34 catalysts were prepared by impregnation method and then modified by the selected transition metals (Fe, Co, and Ce); the SO2 resistance experiments and characterizations including Brunner−Emmet−Teller (BET), X-ray Diffraction (XRD), Scanning Electronic Microscopy (SEM), and thermal gravity analysis (TG)-differential thermal gravity (DTG) before and after SO2 poisoning were conducted. The results showed that the deactivation of the Cu–Mn/SAPO-34 catalyst is ascribed to the deposition of lots of ammonium sulfates on the surface, depositing on the active sites and inhibiting the adsorption of NH3. After the modification of Fe, Co, and Ce oxides, the SO2 resistance of the modified Cu–Mn/SAPO-34 catalyst was significantly enhanced due to the less formation of ammonium sulfates. Among all these modified Cu–Mn/SAPO-34 catalysts, the Cu–Mn–Ce/SAPO-34 exhibited the highest SO2 resistance owing to the decreased decomposition temperature and the trapper of ceria for capturing SO2 to form Ce(SO4)2, further inhibiting the deposition of ammonium sulfates.

scholarly journals Applicability of V2O5-WO3/TiO2 Catalysts for the SCR Denitrification of Alumina Calcining Flue Gas

Catalysts ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 220 ◽  
Author(s):  
Ruliang Ning ◽  
Li Chen ◽  
Erwei Li ◽  
Xiaolong Liu ◽  
Tingyu Zhu
Keyword(s):  
Flue Gas ◽  
Photoelectron Spectroscopy ◽  
Catalytic Performance ◽  
Inhibitory Effect ◽  
Impregnation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
So2 Resistance ◽  
Temperature Programmed ◽  
Diffuse Reflectance Infrared

V2O5-WO3/TiO2 catalysts with different V2O5 and WO3 loadings were prepared by the impregnation method. H2O and SO2 resistance of the catalysts under high H2O concentration (30 vol.%) was studied. Influence of various basic metal oxides, such as Al2O3, CaO, Na2O, and K2O on the catalytic performance was studied and compared. It is revealed that the inhibitory effect is in the sequence of K > Na > Ca > Al, which is consistent with their alkalinity. X-ray diffraction (XRD), N2 physisorption (BET), temperature-programmed desorption of NH3 (NH3-TPD), H2-temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were carried out, and the results were well-correlated with the catalytic studies.

scholarly journals Effects of V2O5 and WO3 loadings on the catalytic performance of V2O5-WO3/TiO2 catalyst for SCR of NO with NH3

2017 ◽  
Vol 19 (1) ◽  
pp. 160-166 ◽  
Keyword(s):  
Active Sites ◽  
Catalytic Reduction ◽  
Catalytic Performance ◽  
Impregnation Method ◽  
Spectra Analysis ◽  
Xps Spectra ◽  
Scr Of No ◽  
Morphology And Structure ◽  
Method Effects ◽  
Xrd Patterns

<p>V<sub>2</sub>O<sub>5</sub>-WO<sub>3</sub>/TiO<sub>2 </sub>catalysts were fabricated by a simple impregnation method. Effects of V<sub>2</sub>O<sub>5</sub> and WO<sub>3</sub> loadings on the catalytic performance of V<sub>2</sub>O<sub>5</sub>-WO<sub>3</sub>/TiO<sub>2</sub> catalyst for selective catalytic reduction (SCR) of NO with NH<sub>3</sub> were investigated. Morphology and structure of the V<sub>2</sub>O<sub>5</sub>-WO<sub>3</sub>/TiO<sub>2 </sub>catalysts were characterised by XRD, SEM, XPS, and N<sub>2</sub> adsorption techniques. The XRD patterns of the V<sub>2</sub>O<sub>5</sub>-WO<sub>3</sub>/TiO<sub>2 </sub>catalyst are indexed to anatase-TiO<sub>2</sub>. XPS spectra analysis confirms that V, Ti, W and O species exist on the surface of V<sub>2</sub>O<sub>5</sub>-WO<sub>3</sub>/TiO<sub>2 </sub>catalyst. V<sub>2</sub>O<sub>5</sub> species are the main active sites in the process of SCR reaction. Increasing V<sub>2</sub>O<sub>5</sub> loading in the V<sub>2</sub>O<sub>5</sub>-WO<sub>3</sub>/TiO<sub>2 </sub>catalysts can improve their catalytic performance. Exceeding 2 wt%, the catalytic performance of V<sub>2</sub>O<sub>5</sub>-WO<sub>3</sub>/TiO<sub>2 </sub>catalyst begins to decline because high V<sub>2</sub>O<sub>5</sub> loading on TiO<sub>2</sub> speeds up the growth of anatase grains, which leads to the loss of catalytic activity. Appropriate WO<sub>3</sub> species can significantly improve the catalytic performance of V<sub>2</sub>O<sub>5</sub>-WO<sub>3</sub>/TiO<sub>2 </sub>catalysts. However, as the WO<sub>3 </sub>loadings reaches 6 wt%, NO conversion decreases instead.</p>

scholarly journals A Review of Low Temperature NH3-SCR for Removal of NOx

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 349 ◽  
Author(s):  
Devaiah Damma ◽  
Padmanabha Ettireddy ◽  
Benjaram Reddy ◽  
Panagiotis Smirniotis
Keyword(s):  
Low Temperature ◽  
Transition Metal ◽  
Transition Metal Oxides ◽  
Active Sites ◽  
Catalytic Reduction ◽  
Operating Conditions ◽  
Advanced Materials ◽  
Research Progress ◽  
Nh3 Scr ◽  
Mixed Transition

The importance of the low-temperature selective catalytic reduction (LT-SCR) of NOx by NH3 is increasing due to the recent severe pollution regulations being imposed around the world. Supported and mixed transition metal oxides have been widely investigated for LT-SCR technology. However, these catalytic materials have some drawbacks, especially in terms of catalyst poisoning by H2O or/and SO2. Hence, the development of catalysts for the LT-SCR process is still under active investigation throughout seeking better performance. Extensive research efforts have been made to develop new advanced materials for this technology. This article critically reviews the recent research progress on supported transition and mixed transition metal oxide catalysts for the LT-SCR reaction. The review covered the description of the influence of operating conditions and promoters on the LT-SCR performance. The reaction mechanism, reaction intermediates, and active sites are also discussed in detail using isotopic labelling and in situ FT-IR studies.

Research of Catalytic Performance over Transition Metal Modified MnOx-CeOx/ACF Catalysts

2011 ◽  
Vol 383-390 ◽  
pp. 1945-1950 ◽  
Author(s):  
Bo Xiong Shen ◽  
Ting Liu ◽  
Ning Zhao ◽  
Juan Ma ◽  
Xiao Cui Hao
Keyword(s):  
Catalytic Activity ◽  
Thermal Treatment ◽  
Transition Metal ◽  
Catalytic Reduction ◽  
Surface Acidity ◽  
Catalytic Performance ◽  
Impregnation Method ◽  
Active Components ◽  
Scr Of No ◽  
Negative Effect

The catalyst of MnOx-CeOx/ACF prepared by impregnation method was used for low-temperature selective catalytic reduction (SCR) of NO with NH3, and more than 90% NO conversion was obtained at 230°C. Fe、Cu or V was used respectively to prepare transition metal modified MnOx-CeOx/ ACF catalysts which had lower catalytic activity than that over MnOx-CeOx/ACF. SEM, N2 adsorption and NH3-TPD were used to analyze the catalysts. The results showed that transition metal modified catalysts had a reduced surface area, pore volume and surface acidity. SO2 had a negative effect on SCR performance of the catalysts. Fe modified catalyst exhibited SO2 tolerance in the first 6h in the presence of 100ppm SO2. Thermal treatment in N2 at 350°C was used to regenerate the deactivated catalysts by SO2. The decomposition of ammonium salts recovered the catalytic activity to some extent. The sulfated active components in deactivated catalysts after the thermal treatment enhanced the surface acidity of the catalysts.

Structural/Texture Evolution During Facile Substitution of Ni into ZSM-5 Nanostructure vs. its Impregnation Dispersion Used in Selective Transformation of Methanol to Ethylene and Propylene

2020 ◽  
Vol 23 ◽  
Author(s):  
Parisa Sadeghpour ◽  
Mohammad Haghighi ◽  
Mehrdad Esmaeili
Keyword(s):  
High Temperature ◽  
Physicochemical Properties ◽  
Active Sites ◽  
Catalytic Performance ◽  
Fixed Bed Reactor ◽  
Light Olefins ◽  
Isomorphous Substitution ◽  
Impregnation Method ◽  
Hydrothermal Temperature ◽  
X Ray

Aim and Objective: Effect of two different modification methods for introducing Ni into ZSM-5 framework was investigated under high temperature synthesis conditions. The nickel successfully introduced into the MFI structures at different crystallization conditions to enhance the physicochemical properties and catalytic performance. Materials and Methods: A series of impregnated Ni/ZSM-5 and isomorphous substituted NiZSM-5 nanostructure catalysts were prepared hydrothermally at different high temperatures and within short times. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray (EDX), Brunner, Emmett and Teller-Barrett, Joyner and Halenda (BET-BJH), Fourier transform infrared (FTIR) and Temperature-programmed desorption of ammonia (TPDNH3) were applied to investigate the physicochemical properties. Results: Although all the catalysts showed pure silica MFI–type nanosheets and coffin-like morphology, using the isomorphous substitution for Ni incorporation into the ZSM-5 framework led to the formation of materials with lower crystallinity, higher pore volume and stronger acidity compared to using impregnation method. Moreover, it was found that raising the hydrothermal temperature increased the crystallinity and enhanced more uniform incorporation of Ni atoms in the crystalline structure of catalysts. TPD-NH3 analysis demonstrated that high crystallization temperature and short crystallization time of NiZSM-5(350-0.5) resulted in fewer weak acid sites and medium acid strength. The MTO catalytic performance was tested in a fixed bed reactor at 460ºC and GHSV=10500 cm3 /gcat.h. A slightly different reaction pathway was proposed for the production of light olefins over impregnated Ni/ZSM-5 catalysts based on the role of NiO species. The enhanced methanol conversion for isomorphous substituted NiZSM-5 catalysts could be related to the most accessible active sites located inside the pores. Conclusion: The impregnated Ni/ZSM-5 catalyst prepared at low hydrothermal temperature showed the best catalytic performance, while the isomorphous substituted NiZSM-5 prepared at high temperature was found to be the active molecular sieve regarding the stability performance.

Vanadium-doped titania-pillared montmorillonite clay as a catalyst for selective catalytic reduction of NO by ammonia

Clay Minerals ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 665-672 ◽  
Author(s):  
K. Bahranowski ◽  
J. Janas ◽  
T. Machej ◽  
E. M. Serwicka ◽  
L. A. Vartikian
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Catalytic Performance ◽  
Pillared Clay ◽  
Area Measurement ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Reduction Of No ◽  
Pillared Montmorillonite ◽  
Doped Titania

AbstractA series of V-doped titania-pillared clay catalysts, characterized by ICP-AES chemical analysis, X-ray diffraction, BET surface area measurement, and ESR spectroscopy, have been tested in the selective catalytic reduction of NO by NH3. An ESR analysis shows that V dopant is anchored to the titania pillars. Vanadyl species with differing degrees of in-plane V-O π-covalent bonding are produced depending on the method of sample preparation. Polymeric V species appear as the V content is increased. Catalytic performance of these systems depends on the method of preparation and on the V content. The best catalyst, converting 90-100% NO in the temperature range 523-623 K, is obtained by exchange of pillared montmorillonite with vanadyl ions, at an extent of exchange below the level where significant amounts of polymeric V species appear. The co-pillared catalyst, containing vanadyl centres characterized by a higher degree of in-plane ncovalent bonding (according to ESR), is less selective than the exchanged samples.

Synthesis of Transition-Metal-Oxides Meso-Structured Thin Films

1998 ◽  
Vol 549 ◽  
Author(s):  
H.S. Zhou ◽  
I. Honma
Keyword(s):  
Thin Films ◽  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Self Assembly ◽  
Magnetic Interactions ◽  
X Ray Diffraction ◽  
Structured Materials ◽  
Coating Method ◽  
Diffraction Patterns

AbstractHighly ordered self-assembly organized silica meso-structured architectures have attracted increasing attention because these materials provide a rich source for scientific research and technological applications. This approach to meso-structured materials has been extended to non-silica oxides, especially transition-metal-oxides which might promise applications involving electron transfer or magnetic interactions. We report the syntheses of transition-metal-oxides meso-structured thin films (MSTF), such as TiO2, V2O5, Fe2O3 and Nb2O5, using a surfactant templating processing with spin coating method. X-ray diffraction patterns of the films showed that the films generally oriented in a lamellar structure. The phase transferring in V205 MSTF was also investigated.

Facile fabrication of hollow tubular mixed oxides for selective catalytic reduction of NOx at low temperature: a combined experimental and theoretical study

2017 ◽  
Vol 53 (5) ◽  
pp. 967-970 ◽  
Author(s):  
Xiuyun Wang ◽  
Zhixin Lan ◽  
Yi Liu ◽  
Yongjin Luo ◽  
Jianjun Chen ◽  
...  
Keyword(s):  
Low Temperature ◽  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Theoretical Study ◽  
Mixed Oxides ◽  
Catalytic Reduction ◽  
Heating Rates ◽  
Facile Fabrication ◽  
Reduction Of Nox

The 1D nanowire or hollow tubular structure of various transition metal oxides can be tuned by controlling heating rates.

Theoretical Design of Transition Metal-Doped TiO2 for the Selective Catalytic Reduction of NO with NH3 by DFT Calculations

2022 ◽  
Author(s):  
Huiling Zheng ◽  
Renjie Li ◽  
Chengming Zhong ◽  
Zhi Li ◽  
Yikun Kang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Transition Metal ◽  
Selective Catalytic Reduction ◽  
Transition Metal Oxides ◽  
Catalytic Reduction ◽  
Trade Off ◽  
Reduction Of No ◽  
Theoretical Design ◽  
Scr Of No ◽  
Metal Doped

Many transition metal oxides supported on TiO2 have been studied for selective catalytic reduction (SCR) of NO with NH3. However, the trade-off exists between the low-temperature activity and N2 selectivity....

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