scholarly journals Promoted dispersion and uniformity of active species on Fe–Ce–Al catalysts for efficient NO abatement

RSC Advances ◽  
2019 ◽  
Vol 9 (61) ◽  
pp. 35751-35759 ◽  
Author(s):  
Xiaobo Wang ◽  
Caojian Jiang ◽  
Jia Wang ◽  
Keting Gui ◽  
Hywel R. Thomas
Keyword(s):  
Active Species ◽  
Precipitation Method ◽  
Impregnation Method ◽  
Effective Removal ◽  
Mixing Method ◽  
No Abatement ◽  
Co Precipitation

Fe–Ce–Al catalysts were synthesized by the co-precipitation method (labeled as Fe–Ce–Al–P), co-impregnation method (Fe–Ce–Al–I), and direct mixing method (Fe–Ce–Al–M), respectively, and used for effective removal of NO.

Pd-Only Catalyst Modified by BaO with Co- Precipitation and Impregnation Methods towards the Methanol Fuel Emission Control

2012 ◽  
Vol 581-582 ◽  
pp. 313-316
Author(s):  
Xue Qiao Zhang ◽  
Zhi Xiang Ye ◽  
Cheng Hua Xu ◽  
Ming Zhao ◽  
Yao Qiang Chen
Keyword(s):  
Co Oxidation ◽  
Photoelectron Spectroscopy ◽  
Palladium Catalysts ◽  
Active Species ◽  
Precipitation Method ◽  
Impregnation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Programmed ◽  
Co Precipitation

Barium oxide was introduced to modify Palladium catalysts supported on CeO2–ZrO2-La2O3-Al2O3 (CZLA) by impregnation and co-precipitation. methods. Various techniques, including X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS), were employed to characterize the physicochemical properties of BaO-modified Pd-only catalyst. Catalytic activity for methanol, CO, C3H8 and NO conversions showed that BaO-modified catalyst prepared by impregnation method exhibited the best performance for methanol, C3H8 and NO removals, while the catalyst prepared by co-precipitation method was in favor of CO oxidation. Combined with the results of XRD, H2-TPR and XPS, it is concluded that the co-existence of PdO and Pd-O-Ce active species by impregnation played an important role in the methanol, C3H8 and NO removals, while the higher dispersion of palladium and improved reducibility were mostly favorable to the CO oxidation. The conversion of NO was co-effected by tow active species and the formation of Ba2AlLaO5 mixed oxide.

Ordered mesoporous silica/polyvinylidene fluoride composite membranes for effective removal of water contaminants

2016 ◽  
Vol 4 (10) ◽  
pp. 3850-3857 ◽  
Author(s):  
Jianwei Fan ◽  
Dandan Li ◽  
Wei Teng ◽  
Jianping Yang ◽  
Yong Liu ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Polyvinylidene Fluoride ◽  
Composite Membranes ◽  
Precipitation Method ◽  
Ordered Mesoporous Silica ◽  
Water Contaminants ◽  
Effective Removal ◽  
Ordered Mesoporous ◽  
One Step ◽  
Co Precipitation

Ordered mesoporous silica/polyvinylidene fluoride membranes were fabricated via a versatile and industrially compatible one-step immersion co-precipitation method. They exhibit effective decontamination performance for water containing methylene blue and Cu(ii) ions, respectively.

scholarly journals Study on quenching effect of nitrite ions on zinc oxide modified by polyvinylpyrrolidone

2015 ◽  
Vol 11 (3) ◽  
Author(s):  
Ing Hua Tang ◽  
Siti Zarina Mohd So’ad ◽  
Hendrik O. Lintang ◽  
Leny Yuliati
Keyword(s):  
Zinc Oxide ◽  
Chemical Properties ◽  
Precipitation Method ◽  
Broad Absorption Band ◽  
Quenching Effect ◽  
Physical Mixing ◽  
Mixing Method ◽  
Volmer Plot ◽  
Co Precipitation ◽  
Physical And Chemical

Zinc oxide (ZnO) is appeared to be an attractive material for application for multidisciplinary fields, owing to its unique physical and chemical properties. In this study, ZnO was synthesized using the co-precipitation method, where the zinc acetate was used as the precursor. The ZnO was further modified by adding different amounts of polyvinylpyrrolidone (PVP) via simple physical mixing method to obtain PVP/ZnO composites. The ZnO and the PVP/ZnO composites were characterized using Fourier transform infrared (FTIR), diffuse reflectance ultraviolet-visible (DR UV-Vis), and fluorescence spectroscopy. The FTIR spectra detected the presence of ZnO group and the functional groups from the PVP. The PVP peaks become more apparent with the increase of the PVP amount. From the DR UV-Vis spectra, no significant change was observed after modification with the PVP, and all composites showed similar broad absorption band to that of the ZnO. The fluorescence spectra showed that the addition of PVP decreased the emission intensity and red shifted the peak wavelength, indicating certain interactions between the ZnO and the added PVP. Quenching study was investigated in the presence of nitrite ions (NO2-) with various concentrations (2-10 mM). A linear Stern-Volmer plot was observed and the highest quenching constant rate (KSV) was obtained on the PVP/ZnO sample with PVP content of 0.1 wt%. This study demonstrated that the addition of the PVP on the ZnO improved the interaction between the ZnO and the NO2-, which will be one of the important factors for sensing and catalytic applications for detection and conversion of NO2-.

Study on Cu-Based Catalysts for Synthesis of Indole

2011 ◽  
Vol 295-297 ◽  
pp. 668-671 ◽  
Author(s):  
Jun De Xing ◽  
Xiao Fei Jia
Keyword(s):  
Grain Size ◽  
Ethylene Glycol ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Precipitation Method ◽  
Impregnation Method ◽  
Co Precipitation

A series of Cu-based catalysts for the synthesis of indole by the reaction of aniline and ethylene glycol were prepared and characterized by ICP-AES and XRD. The results indicated that the activity and stability of Cu/SiO2 catalyst was increased after adding Zn, Mn, Cr and Fe promoters. Mn promoter was favorable for the dispersion of Cu, Zn, Cr, Fe and enlarged the specific surface area of catalysts. It could be seen that the catalysts prepared by impregnation method had better stability and higher activity than the catalysts prepared by co-precipitation method. The catalysts with small grain size of Cu had higher activity than those with big grain size. Some catalysts showed excellent performances in this reaction.

The Effects of SiO2 and CeO2 Addition on the Performances of MnOx/TiO2 Catalysts

2016 ◽  
Vol 69 (10) ◽  
pp. 1180
Author(s):  
Juhua Luo ◽  
Hongkai Mao ◽  
Xu Wang ◽  
Wei Yao
Keyword(s):  
Low Temperature ◽  
Pore Diameter ◽  
Catalytic Reduction ◽  
Pure Tio2 ◽  
Precipitation Method ◽  
Impregnation Method ◽  
Average Pore ◽  
Reduction Of No ◽  
No Conversion ◽  
Co Precipitation

A TiO2-SiO2 mixed oxide was obtained by a co-precipitation method. MnOx-CeO2/TiO2-SiO2 were prepared by an impregnation method and their activity towards the selective catalytic reduction of NO with NH3 at low temperature were evaluated. Compared with pure TiO2, TiO2-SiO2 exhibited an evidently larger surface area and pore volume, and a smaller average pore diameter with narrow distribution. The NO conversion of the MnOx/TiO2-SiO2 catalyst could be improved by the addition of an appropriate amount of CeO2 in the temperature range of 100–180°C. MnOx-CeO2/TiO2-SiO2 with 10 wt-% CeO2 showed the highest activity with 96 % NO conversion at 180°C.

The Effect of B2O3–Li2CO3 Addition on Sintering Behavior and Dielectric Properties of Ba 0.6Sr0.4TiO3 Ceramics

2011 ◽  
Vol 197-198 ◽  
pp. 333-338 ◽  
Author(s):  
Ming Li Li ◽  
Qiong Yu ◽  
Kun Ming Qian ◽  
Song Ji ◽  
Pi Yi Du
Keyword(s):  
Dielectric Properties ◽  
Precipitation Method ◽  
Sintering Behavior ◽  
X Ray Diffraction ◽  
Dense Microstructure ◽  
Barium Strontium ◽  
Mixing Method ◽  
Powder Properties ◽  
Dilatometric Studies ◽  
Co Precipitation

Barium strontium titanate (Ba0.6Sr0.4TiO3: BST) powders were prepared by the oxalate co-precipitation method. The ceramics from thus obtained BST powders with B2O3-Li2CO3 addition were prepared by conventional oxide mixing method. The powders and the ceramics were observed and analyzed by SEM and X-ray diffraction. The effects of B2O3-Li2CO3 addition and powder properties on the sintering behavior and the dielectric properties of BST-based ceramics were investigated. SEM results revealed that the BST powders are micron-sized with cauliflower-shaped rough surface leading the specific surface area reaches 18.52m2/g. In dilatometric studies, the ceramics without B2O3-Li2CO3 addition didn’t produce the desired shrinkage and dense microstructure at relative low temperatures (<1000°C). However, the sintering temperature is decreased to 850°C by addition of small amount (≤3wt %) of B2O3 and Li2CO3. This was also verified in sintered microstructures. The XRD results showed that the main phase of the ceramics was BST without any other crystalline phases of remarkable extent. With increasing of B2O3-Li2CO3 content, the permittivity and the tunability of the ceramics were decreased.

scholarly journals Selective Hydrogenation of Benzene to Cyclohexene over Ru-Zn Catalysts: Investigations on the Effect of Zn Content and ZrO2 as the Support and Dispersant

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 513 ◽  
Author(s):  
Haijie Sun ◽  
Zhihao Chen ◽  
Lingxia Chen ◽  
Huiji Li ◽  
Zhikun Peng ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Selective Hydrogenation ◽  
Photoelectron Spectroscopy ◽  
Supported Catalyst ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Impregnation Method ◽  
X Ray ◽  
Zn Content ◽  
Co Precipitation

m-ZrO2 (monoclinic phase) supported Ru-Zn catalysts and unsupported Ru-Zn catalysts were synthesized via the impregnation method and co-precipitation method, respectively. The catalytic activity and selectivity were evaluated for selective hydrogenation of benzene towards cyclohexene formation. Catalyst samples before and after catalytic experiments were thoroughly characterized via X-ray diffraction (XRD), X-ray Fluorescence (XRF), transmission electron microscopy (TEM), N2-sorption, X-ray photoelectron spectroscopy (XPS), H2-temperature programmed reduction (H2-TPR), and a contact angle meter. It was found that Zn mainly existed as ZnO, and its content was increased in Ru-Zn/m-ZrO2 by enhancing the Zn content during the preparation procedure. This results in the amount of formed (Zn(OH)2)3(ZnSO4)(H2O)3 increasing and the catalyst becoming more hydrophilic. Therefore, Ru-Zn/m-ZrO2 with adsorbed benzene would easily move from the oil phase into the aqueous phase, in which the synthesis of cyclohexene took place. The generated cyclohexene then went back into the oil phase, and the further hydrogenation of cyclohexene would be retarded because of the high hydrophilicity of Ru-Zn/m-ZrO2. Hence, the selectivity towards cyclohexene formation over Ru-Zn/m-ZrO2 improved by increasing the Zn content. When the theoretical molar ratio of Zn to Ru was 0.60, the highest cyclohexene yield of 60.9% was obtained over Ru-Zn (0.60)/m-ZrO2. On the other hand, when m-ZrO2 was utilized as the dispersant (i.e., employed as an additive during the reaction), the catalytic activity and selectivity towards cyclohexene synthesis over the unsupported Ru-Zn catalyst was lower than that achieved over the Ru-Zn catalyst with m-ZrO2 as the support. This is mainly because the supported catalyst sample demonstrated superior dispersion of Ru, higher content of (Zn(OH)2)3(ZnSO4)(H2O)3, and a stronger electronic effect between Ru and ZrO2. The Ru-Zn(0.60)/m-ZrO2 was reused 17 times without any regeneration, and no loss of catalytic activity and selectivity towards cyclohexene formation was observed.

Synthesis of Fe–Ni–Ce trimetallic catalyst nanoparticles via impregnation and co-precipitation and their application to dye degradation

2016 ◽  
Vol 70 (2) ◽  
Author(s):  
Ghazaleh Allaedini ◽  
Siti M. Tasirin ◽  
Payam Aminayi
Keyword(s):  
Fourier Transform ◽  
Dye Degradation ◽  
Nitrogen Adsorption ◽  
High Specific Surface Area ◽  
Precipitation Method ◽  
Impregnation Method ◽  
Catalyst Nanoparticles ◽  
Nitrogen Adsorption Isotherm ◽  
Trimetallic Catalyst ◽  
Co Precipitation

In this study, trimetallic catalysts were prepared via the co-precipitation and impregnation methods. In order to investigate the effect of impregnation on the catalytic activity and crystallite size, a trimetallic catalyst, Fe–Ni–Ce, was prepared through the co-precipitation method in one set of experiments, and cerium was impregnated with the Ni–Fe mixture in the final stage of the preparation in another set. Fourier transform infrared spectroscopy was employed to confirm the formation of trimetallic catalysts and the success of the impregnation method. The Brunauer–Emmett–Teller nitrogen adsorption isotherm exhibits a high specific surface area (approximately 39 m

scholarly journals Facile Co-precipitation Synthesis of Nanosized MnFe2O4 for Effective Removal of Zn(II) Ions From Aqueous Media

2021 ◽  
Author(s):  
Ahmed Alharbi ◽  
Ahmad A. Alluhaybi ◽  
Salwa AlReshaidan ◽  
Hany M. Youssef
Keyword(s):  
Aqueous Media ◽  
Precipitation Method ◽  
Maximum Adsorption Capacity ◽  
Sem Image ◽  
Effective Removal ◽  
Initial Ph ◽  
Pseudo Second Order ◽  
Ft Ir ◽  
Co Precipitation ◽  
Average Size

Abstract In this work, the spinel nanosized MnFe2O4 (18.14 nm) was facilely synthesized through the co-precipitation method to study the removal of Zn(II) ions from aqueous media. The fabricated MnFe2O4 sample was characterized using VSM, XRD, HR-TEM, EDS, FE-SEM, and FT-IR analyses. The principal XRD peaks, which are ascribed to (4 4 0), (3 3 3), (4 2 2), (4 0 0), (2 2 2), (3 1 1), (2 2 0), and (1 1 1) crystal planes, prove the cubic assembly of nanosized manganese ferrite as shown from JCPDS No. 74-2403. The EDS pattern confirmed that the % Wt of Mn, Fe, and O is 24.12, 48.04, and 28.15, respectively. The FE-SEM image confirmed the cubic nature of the surface of MnFe2O4 nanoparticles which have an average size of 110 nm. The saturation magnetization was 65 emu/g. The impacts of initial pH, concentration of Zn(II) ions, contact time, and temperature on the uptake of Zn(II) ions were accurately investigated. The removal of Zn(II) ions is spontaneous, exothermic, and followed the pseudo-second-order model and the Langmuir isotherm. The maximum adsorption capacity equals 330.03 mg/g.

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