scholarly journals Fabrication of Surfactant-Enhanced Metal Oxides Catalyst for Catalytic Ozonation Ammonia in Water

2018 ◽  
Vol 15 (8) ◽  
pp. 1654 ◽  
Author(s):  
Yunnen Chen ◽  
Lin Guo ◽  
Chang Li
Keyword(s):  
Catalytic Activity ◽  
Metal Oxides ◽  
Metal Salt ◽  
Removal Rate ◽  
Catalytic Ozonation ◽  
Molar Ratio ◽  
High Catalytic Activity ◽  
Gaseous Nitrogen ◽  
Solid State Method ◽  
X Ray

The new surfactant-enhanced metal oxides composite catalysts have been prepared using solid state method and characterized by the N2-adsorption-desorption, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), and X-ray diffraction (XRD) techniques. Catalytic activity of the synthesized powders has been investigated in the liquid-phase catalytic ozonation ammonia nitrogen (NH4+) (50 mg/L). Especially, the effect of parameters such as optimum molar ratio for metal salt, NaOH and surfactants, temperature, and time of calcinations was also considered. Leveraging both high catalytic activity in NH4+degradation and more harmless selectivity for gaseous nitrogen, the CTAB/NiO catalyst is the best among 24 tested catalysts, which was generated by calcining NiCl2·6H2O, NaOH, and CTAB under the molar ratio 1:2.1:0.155 at 300 °C for 2 h. With CTAB/NiO, NH4+ removal rate was 95.93% and gaseous nitrogen selectivity was 80.98%, under the conditions of a pH of 9, ozone flow of 12 mg/min, dosage of catalyst 1.0 g/L, reaction time 120 min, and magnetic stirring speed 600 r/min in room temperature.

Nanosized Pt-Co Catalysts for the Preferential CO Oxidation

2006 ◽  
Vol 6 (11) ◽  
pp. 3567-3571 ◽  
Author(s):  
Eun-Yong Ko ◽  
Eun Duck Park ◽  
Kyung Won Seo ◽  
Hyun Chul Lee ◽  
Doohwan Lee ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Peak Shift ◽  
Molar Ratio ◽  
High Catalytic Activity ◽  
Preferential Co Oxidation ◽  
X Ray ◽  
Co Catalysts ◽  
Transmission Electron ◽  
Temperature Programmed

The preferential CO oxidation in the presence of excess hydrogen was studied over Pt-Co/γ-Al2O3. CO chemisorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectrometer (EDX) and temperature programmed reduction (TPR) were conducted to characterize active catalysts. The catalytic activity for CO oxidation and methanation at low temperatures increased with the amounts of cobalt in Pt-Co/γ-Al2O3. This accompanied the TPR peak shift to lower temperatures. The optimum molar ratio between Co and Pt was determined to be 10. The co-impregnated Pt-Co/γ-Al2O3 appeared to be superior to Pt/Co/γ-Al2O3 and Co/Pt/γ-Al2O3. The reductive pretreatment at high temperature such as 773 K increased the CO2 selectivity over a wide reaction temperature. The bimetallic phase of Pt-Co seems to give rise to high catalytic activity in selective oxidation of CO in H2-rich stream.

scholarly journals Study of the Catalytic Activity of the Compounds Hydrotalcite Type Treated by Microwave in the Self-Condensation of Acetone

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Jamal Houssaini ◽  
Mohammed Naciri Bennani ◽  
Hamid Ziyat ◽  
Said Arhzaf ◽  
O. Qabaqous ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Condensation Reaction ◽  
Catalyst Activity ◽  
The Self ◽  
Conventional Heating ◽  
Molar Ratio ◽  
High Catalytic Activity ◽  
Adsorption Method ◽  
X Ray ◽  
Diacetone Alcohol

The self-condensation reaction of acetone, producing diacetone alcohol (DAA), is of great industrial importance. It was used to study the catalytic activity of Mg-Al catalysts synthesized by the coprecipitation method. For this purpose, we synthesized Mg-Al based hydrotalcite with a molar ratio of 3, obtained either after conventional heating or after microwave irradiation with of 100 W for three minutes. Structural and chemical properties of the obtained catalysts were characterized, using different techniques: X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), scanning electron microscope (SEM), equipped with energy dispersive X-ray (EDX), and specific surface area of the catalysts were determined by the methylene blue (MB) adsorption method. Also, these catalysts were tested in the self-condensation reaction of acetone at 273 K in the liquid phase without solvent, a reaction which requires very high catalytic activity. The microwave treatment improves the catalyst activity, and the conversion of acetone to diacetone alcohol increases from 13.2 to 18.3% after 8 h of reaction. Moreover, the microwave-treated hydrotalcite catalyst, calcined at 723 K and rehydrated under a flow of N2, is the most active and gives conversion of acetone of 52% under the same reaction conditions.

scholarly journals Potential of Carica papaya peels as effective biocatalyst in the optimized parametric transesterification of used vegetable oil

2020 ◽  
Vol 26 (4) ◽  
pp. 200299-0
Author(s):  
A.O. Etim ◽  
Andrew C. Eloka-Eboka ◽  
P. Musonge
Keyword(s):  
Catalytic Activity ◽  
Reaction Time ◽  
Vegetable Oil ◽  
Carica Papaya ◽  
Molar Ratio ◽  
Catalyst Loading ◽  
Biodiesel Fuel ◽  
High Catalytic Activity ◽  
X Ray ◽  
Used Vegetable Oil

This study investigates the effectiveness of a base heterogenous catalyst derived from waste Carica papaya peels in the transesterification of used vegetable oil (UVO). The calcined Carica papaya peels (CCPP) were characterised using scanning electron microscope-energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The EDX result indicated that the ash contains various minerals with potassium (K) as the main active element in remove for the charge of the high catalytic activity. Response surface methodology (RSM) based on the Box Behnken design (BBD) was used to optimise and investigate the effect of the critical process parameters which include: the reaction time (50 – 70 min), catalyst loading (2.5 – 4.5 wt%) and methanol-to-oil molar ratio (9:1 – 15:1). The optimal reaction condition for the transesterification process was found to be catalyst loading of 3.5 wt%, methanol/oil molar ratio of 12:1, process reaction time of 60 min at constant reaction temperature of 65 <sup>o</sup>C which resulted in the maximum biodiesel yield of 97.5 wt%. The quality of the produced biodiesel was in agreement with ASTM standards. The catalyst was reused up to three times with minimal decrease in the catalytic activity in the biodiesel conversion. The study demonstrates the potential of waste biomass feedstocks in the production of sustainable biodiesel fuel.

The Influence of Fe/Al Molar Ratio on Microreactor-Based Catalyst Preparation and Carbon Nanotube Preparation

2021 ◽  
Vol 1036 ◽  
pp. 130-136
Author(s):  
Ting Qun Tan ◽  
Lei Geng ◽  
Yan Lin ◽  
Yan He
Keyword(s):  
Carbon Nanotubes ◽  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Small Diameter ◽  
High Specific Surface Area ◽  
Detection Methods ◽  
Molar Ratio ◽  
High Catalytic Activity

In order to prepare carbon nanotubes with high specific surface area, small diameter, low resistivity, high purity and high catalytic activity, the Fe-Mo/Al2O3 catalyst was prepared based on the microreactor. The influence of different Fe/Al molar ratios on the catalyst and the carbon nanotubes prepared was studied through BET, SEM, TEM and other detection methods. Studies have shown that the pore structure of the catalyst is dominated by slit pores at a lower Fe/Al molar ratio. The catalytic activity is the highest when the Fe/Al molar ratio is 1:1, reaching 74.1%. When the Fe/Al molar ratio is 1:2, the catalyst has a higher specific surface area, the maximum pore size is 8.63 nm, and the four-probe resistivity and ash content of the corresponding carbon nanotubes are the lowest. The higher the proportion of aluminum, the higher the specific surface area of the catalyst and the carbon nanotubes, and the finer the diameter of the carbon nanotubes, which gradually tends to relax. The results show that when the Fe/Al molar ratio is 1:2, although the catalytic activity of the catalyst is not the highest, the carbon nanotubes prepared have the best performance.

Hollow structured CoSn(OH)6-supported Pt for effective room-temperature oxidation of gaseous formaldehyde

2016 ◽  
Vol 09 (06) ◽  
pp. 1642009 ◽  
Author(s):  
Jing Zhou ◽  
Yong Zhao ◽  
Lifan Qin ◽  
Chen Zeng ◽  
Wei Xiao
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
Room Temperature ◽  
Synergetic Effect ◽  
Hollow Structure ◽  
Pt Nanoparticles ◽  
Hydroxyl Groups ◽  
High Catalytic Activity ◽  
Temperature Oxidation ◽  
X Ray

Uniform CoSn(OH)6 hollow nanoboxes and the derivative with Pt loading (Pt/CoSn(OH)6) were herein synthesized and characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). SEM and TEM analyses showed that CoSn(OH)6 possessed mesoporous hollow structure and Pt nanoparticles with size of 2–8[Formula: see text]nm were uniformly dispersed on the surface of CoSn(OH)6 nanoboxes. The performances of the catalysts for the formaldehyde (HCHO) removal at room temperature were evaluated. These Pt/CoSn(OH)6 catalysts exhibited a remarkable catalytic activity as well as stability for room-temperature oxidative decomposition of gaseous HCHO, while the corresponding CoSn(OH)6 only showed adsorption. The synergetic effect between the highly dispersed Pt nanoparticles and the CoSn(OH)6 nanoboxes with mesoporous hollow structure, a large surface area and abundant surface hydroxyl groups is considered to be the main reason for the observed high catalytic activity of Pt/CoSn(OH)6.

scholarly journals CO Oxidation over Metal Oxide (La2O3, Fe2O3, PrO2, Sm2O3, and MnO2) Doped CuO-Based Catalysts Supported on Mesoporous Ce0.8Zr0.2O2 with Intensified Low-Temperature Activity

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 724 ◽  
Author(s):  
Yan Cui ◽  
Leilei Xu ◽  
Mindong Chen ◽  
Chufei Lv ◽  
Xinbo Lian ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Metal Oxide ◽  
Metal Oxides ◽  
Co Oxidation ◽  
Active Sites ◽  
Earth Metal ◽  
High Dispersion ◽  
Impregnation Method ◽  
X Ray

CuO-based catalysts are usually used for CO oxidation owing to their low cost and excellent catalytic activities. In this study, a series of metal oxide (La2O3, Fe2O3, PrO2, Sm2O3, and MnO2)-doped CuO-based catalysts with mesoporous Ce0.8Zr0.2O2 support were simply prepared by the incipient impregnation method and used directly as catalysts for CO catalytic oxidation. These mesoporous catalysts were systematically characterized by X-ray powder diffraction (XRD), N2 physisorption, transmission electron microscopy (TEM), energy-dispersed spectroscopy (EDS) mapping, X-ray photoelectron spectroscopy (XPS), and H2 temperature programmed reduction (H2-TPR). It was found that the CuO and the dopants were highly dispersed among the mesoporous framework via the incipient impregnation method, and the strong metal framework interaction had been formed. The effects of the types of the dopants and the loading amounts of the dopants on the low-temperature catalytic performances were carefully studied. It was concluded that doped transition metal oxides could regulate the oxygen mobility and reduction ability of catalysts, further improving the catalytic activity. It was also found that the high dispersion of rare earth metal oxides (PrO2, Sm2O3) was able to prevent the thermal sintering and aggregation of CuO-based catalysts during the process of calcination. In addition, their presence also evidently improved the reducibility and significantly reduced the particle size of the CuO active sites for CO oxidation. The results demonstrated that the 15CuO-3Fe2O3/M-Ce80Zr20 catalyst with 3 wt. % of Fe2O3 showed the best low-temperature catalytic activity toward CO oxidation. Overall, the present Fe2O3-doped CuO-based catalysts with mesoporous nanocrystalline Ce0.8Zr0.2O2 solid solution as support were considered a promising series of catalysts for low-temperature CO oxidation.

scholarly journals Copper-Containing Mixed Metal Oxides (Al, Fe, Mn) for Application in Three-Way Catalysis

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1344
Author(s):  
Tim Van Everbroeck ◽  
Radu-George Ciocarlan ◽  
Wouter Van Hoey ◽  
Myrjam Mertens ◽  
Pegie Cool
Keyword(s):  
Catalytic Activity ◽  
Spinel Structure ◽  
Mixed Oxides ◽  
High Catalytic Activity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalytic Application ◽  
Mixed Spinel ◽  
Co Precipitation ◽  
Three Way Catalysis

Mixed oxides were synthesized by co-precipitation of a Cu source in combination with Al, Fe or Mn corresponding salts as precursors. The materials were calcined at 600 and 1000 °C in order to crystallize the phases and to mimic the reaction conditions of the catalytic application. At 600 °C a mixed spinel structure was only formed for the combination of Cu and Mn, while at 1000 °C all the materials showed mixed spinel formation. The catalysts were applied in three-way catalysis using a reactor with a gas mixture containing CO, NO and O2. All the materials calcined at 600 °C displayed the remarkable ability to oxidize CO with O2 but also to reduce NO with CO, while the pure oxides such as CuO and MnO2 were not able to. The high catalytic activity at 600 °C was attributed to small supported CuO particles present and imperfections in the spinel structure. Calcination at 1000 °C crystallized the structure further which led to a dramatic loss in catalytic activity, although CuAl2O4 and CuFe2O4 still converted some NO. The materials were characterized by X-ray diffraction (XRD), Raman spectroscopy, H2-Temperatrue Programmed Reduction (H2-TPR), N2-sorption and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX).

In situ assembly of ultrafine Mn3O4 nanoparticles into MIL-101 for selective aerobic oxidation

2017 ◽  
Vol 7 (18) ◽  
pp. 4136-4144 ◽  
Author(s):  
Yu Fu ◽  
Yanglong Guo ◽  
Yun Guo ◽  
Yunsong Wang ◽  
Li Wang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Metal Oxides ◽  
Aerobic Oxidation ◽  
High Catalytic Activity ◽  
Selective Aerobic Oxidation ◽  
Mn3o4 Nanoparticles

Nanosize metal oxides generally possess high catalytic activity, but they tend to agglomerate into larger particles during a reaction.

scholarly journals Biodiesel Production over Niobium-Containing Catalysts: A Review

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5506
Author(s):  
Daniel Carreira Batalha ◽  
Márcio José da Silva
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Raw Materials ◽  
Catalytic Performance ◽  
High Specific Surface Area ◽  
Biodiesel Production ◽  
Molar Ratio ◽  
Main Reaction ◽  
High Catalytic Activity

Nowadays, the synthesis of biofuels from renewable raw materials is very popular. Among the various challenges involved in improving these processes, environmentally benign catalysts compatible with an inexpensive feedstock have become more important. Herein, we report the recent advances achieved in the development of Niobium-containing heterogeneous catalysts as well as their use in routes to produce biodiesel. The efficiency of different Niobium catalysts in esterification and transesterification reactions of lipids and oleaginous raw materials was evaluated, considering the effect of main reaction parameters such as temperature, time, catalyst load, and oil:alcohol molar ratio on the biodiesel yield. The catalytic performance of Niobium compounds was discussed considering the characterization data obtained by different techniques, including NH3-TPD, BET, and Pyr-FT-IR analysis. The high catalytic activity is attributed to its inherent properties, such as the active sites distribution over a high specific surface area, strength of acidity, nature, amount of acidic sites, and inherent mesoporosity. On top of this, recycling experiments have proven that most Niobium catalysts are stable and can be repeatedly used with consistent catalytic activity.

scholarly journals Yttrium and Lithium Keto-β-Diketiminate Complexes [{2,6-Me2C6H3N=C(Me)}2CС(tert-Bu)=O]2Y(μ2-Cl)2Li(THF)2 and {[{2,6-Me2C6H3N=C(Me)}2CС(tert-Bu)=O]Li(THF)}n. Synthesis, Molecular Structures, and Catalytic Activity in ε-Caprolactone Polymerization

2021 ◽  
Vol 47 (2) ◽  
pp. 144-154
Author(s):  
G. G. Skvortsov ◽  
A. V. Cherkasov ◽  
D. L. Vorozhtsov ◽  
E. S. Shchegravina ◽  
A. A. Trifonov
Keyword(s):  
Catalytic Activity ◽  
Diffraction Analysis ◽  
Exchange Reaction ◽  
Ring Opening ◽  
Crystalline State ◽  
Ring Opening Polymerization ◽  
Molecular Structures ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray

Abstract The reaction of lithium β-diketiminate [{2,6-Me2C6H3N=CMe}2CH]Li with benzophenone in toluene at 25°C affords the coordination complex [{2,6-Me2C6H3N=CMe}2CH]Li(Ph2C=O) (I). New keto-β-diketimine {2,6-Me2C6H3N=C(Me)}2CHC(tert-Bu)=O (II) is synthesized by the reaction of tert-Bu(C=O)Cl with [{2,6-Me2C6H3N=CMe}2CH]Li. The metallation of keto-β-diketimine II with n-butyllithium in THF at 0°C gives lithium keto-β-diketiminate {[{2,6-Me2C6H3N=C(Me)}2CС(tert-Bu)=O]Li(THF)}n (III). The exchange reaction of YCl3 with compound III (molar ratio 1 : 2, THF) affords the yttrium bis(keto-diketiminate) complex [{2,6-Me2C6H3N=C(Me)}2CС(tert-Bu)=O]2Y(μ2-Cl)2L-(THF)2 (IV). The molecular structures of complexes I, III, and IV are determined by X-ray diffraction analysis (CIF files CCDC nos. 2001131 (I), 2001132 (III), and 2001133 (IV)). Complex IV in the crystalline state exists as an ate complex with one LiCl molecule. Complexes I, III, and IV are catalysts of ring-opening polymerization of ε-caprolactone in toluene at 25°С.

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