scholarly journals Influence of hydrothermal time on the formation of SAPO-56 structure and its catalytic activity of removal NOx by NH3-SCR with Cu/SAPO-56

2021 ◽  
Vol 11 (1) ◽  
pp. xx-xx
Author(s):  
Anh Dang Thi Thu ◽  
Dat Nguyen Tien ◽  
Tuan Doan Anh ◽  
Huyen Vuong Thanh ◽  
Huyen Pham Thanh
Keyword(s):  
Catalytic Activity ◽  
Diffuse Reflectance Spectroscopy ◽  
Catalytic Reduction ◽  
Diffraction Field ◽  
Hydrothermal Conditions ◽  
Structure Directing Agent ◽  
Exchange Method ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Electron Microscopes

The SAPO-56 molecular sieve material was prepared under hydrothermal conditions at 200 °C with different hydrothermal times using precursors including Al(OH)3, LUDOX AS-30, H3PO4, and TMHD (N,N,N′,N′-tetramethyl-hexane-1,6-diamine) as an organic structure-directing agent. The samples were characterized by X-ray diffraction, field emission scanning electron microscopes, Energy-dispersive X-ray spectroscopy, NH3 temperature - programmed desorption, N2 adsorption-desorption, and UV-Vis Diffuse Reflectance Spectroscopy methods. Electron paramagnetic resonance technique was applied to determine isolated Cu2+ ions in the framework. Although materials shared the same AFX framework structure, they owned different physicochemical properties, especially in terms of crystal size, surface area, and acidity. Next, the catalytic activity of removal NOx of Cu/SAPO-56 and Cu/ZSM-5 using commercial ZSM-5 as support with the loading of 3 wt%Cu synthesized by aqueous ion-exchange method was assessed in the selective catalytic reduction with NH3.

Selective catalytic reduction of NO by Co-Mn based nanocatalysts

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.

scholarly journals Preparation and Characterization of Defective TiO2. The Effect of the Reaction Environment on Titanium Vacancies Formation

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2763
Author(s):  
Zuzanna Bielan ◽  
Szymon Dudziak ◽  
Agnieszka Sulowska ◽  
Daniel Pelczarski ◽  
Jacek Ryl ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Diffuse Reflectance Spectroscopy ◽  
Hydrothermal Reaction ◽  
High Photocatalytic Activity ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Light Activity ◽  
Cheap Alternative

Among various methods of improving visible light activity of titanium(IV) oxide, the formation of defects and vacancies (both oxygen and titanium) in the crystal structure of TiO2 is an easy and relatively cheap alternative to improve the photocatalytic activity. In the presented work, visible light active defective TiO2 was obtained by the hydrothermal reaction in the presence of three different oxidizing agents: HIO3, H2O2, and HNO3. Further study on the effect of used oxidant and calcination temperature on the physicochemical and photocatalytic properties of defective TiO2 was performed. Obtained nanostructures were characterized by X-ray diffractometry (XRD), specific surface area (BET) measurements, UV-Vis diffuse reflectance spectroscopy (DR-UV/Vis), photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) spectroscopy. Degradation of phenol as a model pollutant was measured in the range of UV-Vis and Vis irradiation, demonstrating a significant increase of photocatalytic activity of defective TiO2 samples above 420 nm, comparing to non-defected TiO2. Correlation of EPR, UV-Vis, PL, and photodegradation results revealed that the optimum concentration of HIO3 to achieve high photocatalytic activity was in the range of 20–50 mol%. Above that dosage, titanium vacancies amount is too high, and the obtained materials’ photoactivity was significantly decreased. Studies on the photocatalytic mechanism using defective TiO2 have also shown that •O2− radical is mainly responsible for pollutant degradation.

VISIBLE LIGHT ACTIVE Cu2+/TiO2 NANOCATALYST FOR DEGRADATION OF DICHLORVOS

2012 ◽  
Vol 11 (05) ◽  
pp. 1250030 ◽  
Author(s):  
TESHOME ABDO SEGNE ◽  
SIVA RAO TIRUKKOVALLURI ◽  
SUBRAHMANYAM CHALLAPALLI
Keyword(s):  
Catalytic Activity ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Diffuse Reflectance Spectroscopy ◽  
Sol Gel ◽  
Light Illumination ◽  
X Ray ◽  
Photo Catalytic Activity ◽  
Visible Light Active ◽  
Adsorption Desorption

The advantage of doping of TiO2 with copper has been utilized for enhanced degradation of pesticide under visible light irradiation. The sol–gel method has been undertaken for the synthesis of copper-doped TiO2 by varying the dopant loadings from 0.25 wt.% to 1.0 wt.% of Cu2+ . The doped samples were characterized by UV-Visible Diffuse Reflectance Spectroscopy (DRS), N2 adsorption–desorption (BET), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectrometry (EDS). The photocatalytic activity of the catalyst was tested by degradation of dichlorvos under visible light illumination. The results found that 0.75 wt.% of Cu2+ doped nanocatalysts have better photo catalytic activity than the rest of percentages doped, undoped TiO2 and Degussa P25. The reduction of band gap was estimated and the influence of the process parameters on photo catalytic activity of the catalyst has been explained.

scholarly journals Catalytic reduction of sulfuric acid to sulfur dioxide

2012 ◽  
Vol 10 (6) ◽  
pp. 1817-1823 ◽  
Author(s):  
Ancuţa Balla ◽  
Cristina Marcu ◽  
Damian Axente ◽  
Gheorghe Borodi ◽  
Diana Lazăr
Keyword(s):  
Catalytic Activity ◽  
Sulfuric Acid ◽  
Sulfur Dioxide ◽  
Atmospheric Pressure ◽  
Catalytic Reduction ◽  
X Ray Diffraction ◽  
Good Efficiency ◽  
X Ray ◽  
Bet Method ◽  
Spent Catalysts

AbstractThe reduction of H2SO4 to SO2 occurs with a relatively good efficiency only at high temperatures, in the presence of catalysts. Some experimental results, regarding conversion of sulfuric acid (96 wt.%) to sulfur dioxide and oxygen, are reported. The reduction has been performed at 800 – 900°C and atmospheric pressure, in a tubular quartz reactor. The following commercial catalysts were tested: Pd/Al2O3 (5 wt.% and 0.5 wt.% Pd), Pt/Al2O3 (0.1 wt.% Pt) and α-Fe2O3. The fresh and spent catalysts were characterized by X-Ray diffraction and BET method. The highest catalytic activity was determined for 5 wt.% Pd/Al2O3, a conversion of 80% being obtained for 5 hours time on stream, at 9 mL h−1 flow rate of 96 wt.% H2SO4. A conversion of 64% was determined for 0.5 wt.% Pd/Al2O3 and 0.1 wt.% Pt/Al2O3. For α-Fe2O3, a less expensive catalyst, a conversion of 61% for about 60 hours was obtained.

scholarly journals Synergistically homogeneous-heterogeneous Fenton catalysis of trace copper ion and g-C3N4 for degradation of organic pollutants

2021 ◽  
Author(s):  
Z. Y. Yao ◽  
G. X. Zhu ◽  
T. L. Lu ◽  
Y. Z. Zhan
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
Metal Ions ◽  
Photoelectron Spectroscopy ◽  
Organic Pollutant ◽  
Copper Ion ◽  
Heterogeneous Fenton ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Synergistic Catalysis

Abstract Using the bulk g-C3N4 as a precursor, four g-C3N4 nanosheets were further prepared by ultrasonic, thermal, acid, and alkali exfoliation. The structures of these materials were characterized by various techniques such as X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-Ray spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The synergistical Fenton catalysis of these materials with Cu2+ was evaluated by using rhodamine B as a simulated organic pollutant. The results showed that there existed a significant synergistical Fenton catalysis between Cu2+ and g-C3N4. This synergistic effect can be observed even when the concentration of Cu2+ was as low as 0.064 mg L−1. The properties of g-C3N4 strongly influenced the catalytic activity of the Cu2+/g-C3N4 system. The coexistent of Cu2+ and the alkali exfoliated g-C3N4 showed the most excellent catalytic activity. Hydroxyl radicals as oxidizing species were confirmed in the Cu2+/g-C3N4 system by electron paramagnetic resonance spectrum. The synergistic catalysis may be attributed to the easier reduction of Cu2+ adsorbed on the g-C3N4. This study provided an excellent Fenton catalytic system, and partly solved the rapid deactivation of heterogeneous Fenton catalysts caused by the leaching of metal ions. HIGHTLIGHTS There exists a significant synergistical Fenton catalysis between trace Cu2+ and g-C3N4. The Cu2+ concentration is lower than the maximum acceptable limit in drinking water. This study partly solved the rapid deactivation caused by the leaching of metal ions. This study reminds researchers to pay attention to the possible synergistic catalysis between leached ions and supports.

scholarly journals Synthesis of porous LaFeO3 prepared by nanocasting method for photo-Fenton degradation of oily-containing wastewater

2021 ◽  
Vol 11 (1) ◽  
pp. xx-xx
Author(s):  
Nga Phan To ◽  
Lien Nguyen Hong ◽  
Tuyen Le Van ◽  
Nhan Phan Chi ◽  
Huyen Phan Thanh
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
Visible Light ◽  
Diffuse Reflectance Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalytic Activities ◽  
Transmission Electron ◽  
Visible Light Driven ◽  
Adsorption Desorption

Porous LaFeO3 were synthesised by nanocasting method using mesoporous silica (SBA-15) as a hard template and used as a visible-light-driven photocatalyst. The as-synthesised LaFeO3 photocatalyst were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray Diffraction (XRD), N2 adsorption-desorption, and Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV-vis DRS). The photo-Fenton catalytic activities of porous LaFeO3 were investigated for the degradation of oily-containing wastewater. The results showed that porous LaFeO3 had better photo-Fenton catalytic activity under visilbe light irradiation than pure LaFeO3. The remarkable improvement photo-Fenton catalytic activity of porous LaFeO3 material could be attributed to the synergistic effect of adsorption and visible light photo-Fenton processes thanks to its porous structure.

scholarly journals Visible Light-Driven Mn-MoS2/rGO Composite Photocatalysts for the Photocatalytic Degradation of Rhodamine B

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Thi Thuy Trang Phan ◽  
Thanh Tam Truong ◽  
Ha Tran Huu ◽  
Le Tuan Nguyen ◽  
Van Thang Nguyen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Visible Light ◽  
Rhodamine B ◽  
Photoelectron Spectroscopy ◽  
Diffuse Reflectance Spectroscopy ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Composite Photocatalysts

The n%Mn-MoS2/rGO (labeled as n%MMS/rGO, where n% = Mn/(Mn + Mo) in mol) composites were successfully prepared by a facile hydrothermal method from the Mn-MoS2 (MMS) and rGO precursors, in which the MMS was obtained by a facile one-step calcination of (NH4)6Mo7O24·4H2O, (NH2)2CS, and Mn(CH3COO)2·4H2O as precursors in N2 gas at 650°C. The samples were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron paramagnetic resonance spectroscopy (EPR), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), and X-ray photoelectron spectroscopy (XPS), which indicates the composites containing nanosheets of Mn-MoS2 and rGO components. The photocatalytic activities of the n%MMS/rGO composite photocatalysts were evaluated through the photodegradation of rhodamine B (RhB) under the visible light irradiation. The enhancement in the photocatalytic performance of the achieved composites was attributed to the synergic effect of Mn doping and rGO matrix. The investigation of photocatalytic mechanism was also conducted.

A One-step Process for the Modification of Wool Fibers with Titanate Tetrabutyl by Low Temperature Hydrothermal Method

2014 ◽  
Vol 18 (2) ◽  
pp. 23-31 ◽  
Author(s):  
Hui Zhang ◽  
Zhenwei Yang ◽  
Xingtao Zhang
Keyword(s):  
Electron Microscopy ◽  
Low Temperature ◽  
Diffuse Reflectance Spectroscopy ◽  
Degradation Process ◽  
Volume Density ◽  
Blue Dye ◽  
Gravimetric Analysis ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Wool Fibers

In this paper, wool fibers are modified with titanate tetrabutyl by coating and grafting titanium dioxide (TiO2) nanoparticles under low temperature hydrothermal conditions. Field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis and diffuse reflectance spectroscopy are used as the characterization techniques. It is found that anatase TiO2 nanocrystals with crystal sizes smaller than 10 nm can be synthesized and simultaneously grafted onto fiber surfaces. In comparison with pristine wool fibers, the thermal stability for the TiO2-coated wool fibers is slightly changed. The ability to block ultraviolet radiation is improved. The volume density is slightly increased. The tensile properties are enhanced, while the crimp properties worsened. A photocatalytic degradation process of methylene blue dye and a decoloration rocess of chlorophyll are developed.

scholarly journals Modification Effects of B2O3 on The Structure and Catalytic Activity of WO3-UiO-66 Catalyst

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 781
Author(s):  
Xinli Yang ◽  
Nan Wu ◽  
Yongxia Miao ◽  
Haobo Li
Keyword(s):  
Electron Microscopy ◽  
Fourier Transform ◽  
Catalytic Activity ◽  
Diffuse Reflectance Spectroscopy ◽  
Synergistic Effects ◽  
Co Adsorption ◽  
Fourier Transform Infrared ◽  
Catalytic Performance ◽  
High Dispersion ◽  
X Ray

Tungsten oxide (WO3) and boron oxide (B2O3) were irreversibly encapsulated into the nanocages of the Zr-based metal organic framework UiO-66, affording a hybrid material B2O3-WO3/UiO-66 by a simple microwave-assisted deposition method. The novel B2O3-WO3/UiO-66 material was systematically characterized by X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption, ultraviolet–visible diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray phosphorescence, and Fourier transform infrared (FTIR)-CO adsorption methods. It was found that WO3 and B2O3 were highly dispersed in the nanocages of UiO-66, and the morphology and crystal structure of UiO-66 were well preserved. The B2O3 species are wrapped by WO3 species, thus increasing the polymeric degree of the WO3 species, which are mainly located in low-condensed oligomeric environments. Moreover, when compared with WO3/UiO-66, the B2O3-WO3/UiO-66 material has a little weaker acidity, which decreased by 10% upon the B2O3 introduction. The as-obtained novel material exhibits higher catalytic performance in the cyclopentene selective oxidation to glutaraldehyde than WO3/UiO-66. The high catalytic performance was attributed to a proper amount of B2O3 and WO3 with an appropriate acidity, their high dispersion, and the synergistic effects between them. In addition, these oxide species hardly leached in the reaction solution, endowing the catalyst with a good stability. The catalyst could be used for six reaction cycles without an obvious loss of catalytic activity.

The Synthesis and Photocatalytic Performance of Samarium Doped Mesoporous Titania

2018 ◽  
Vol 876 ◽  
pp. 15-19
Author(s):  
Jian Wen Shi ◽  
Dan Dan Ma ◽  
Ya Jun Zou
Keyword(s):  
Diffuse Reflectance ◽  
Photocatalytic Performance ◽  
Diffuse Reflectance Spectroscopy ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Reflectance Spectroscopy ◽  
Mesoporous Titania ◽  
X Ray Diffraction ◽  
Structure Directing Agent ◽  
X Ray

The meso-porous TiO2 and Sm-doped meso-porous TiO2 were synthesized by a sol-gel method. Polyethylene glycol, with different added content, was added as a structure-directing agent. The prepared meso-porous TiO2 was characterized by nitrogen adsorption, X-ray diffraction and ultraviolet-visible diffuse reflectance spectroscopy, and the photocatalytic performance was evaluated by the decomposition of methyl orange. The results revealed that PEG plays a key role in creating porous structure during the heat-treatment. The photocatalytic performance of TiO2 is improved by adding proper content PEG, and Sm-doping can further promote the photocatalytic performance.

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