Oxidative coupling of methane over LaAlO3 perovskite catalysts prepared by a co-precipitation method: Effect of co-precipitation pH value

2019 ◽  
Vol 35 ◽  
pp. 1-8 ◽  
Author(s):  
Yujin Sim ◽  
Jihoon Yoo ◽  
Jeong-Myeong Ha ◽  
Ji Chul Jung
Keyword(s):  
Oxidative Coupling ◽  
Ph Value ◽  
Oxidative Coupling Of Methane ◽  
Precipitation Method ◽  
Method Effect ◽  
Precipitation Ph ◽  
Perovskite Catalysts ◽  
Co Precipitation

Catalytic Hydrolysis of Hydrogen Cyanide on Cu-Al Catalyst

2015 ◽  
Vol 1094 ◽  
pp. 15-19
Author(s):  
Lin Xia Yan ◽  
Sen Lin Tian ◽  
Qiu Lin Zhang
Keyword(s):  
Calcination Temperature ◽  
Hydrogen Cyanide ◽  
Influence Factor ◽  
Ph Value ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Cu Content ◽  
Co Precipitation ◽  
The Impact ◽  
Hydrolysis Of

Cu-Al catalysts were synthesized by the co-precipitation method to study hydrolysis of hydrogen cyanide. During the synthesis, the impact of Cu/Al molar ratio, pH value and calcination temperature was investigated and the best synthesis condition was found. The results indicate that the remove of hydrogen cyanide first increases and then decreases with increasing Cu/Al molar ratio, pH value and calcination temperature, which reaches the maxima and remains above 95% at 360 min when Cu/Al molar ratio is 2:1, pH value is approximately 8.0 and calcination temperature is 400°C around. The analysis of X-ray diffraction (XRD) shows that Cu content is the main influence factor at Cu/Al molar ratio below 2:1 whereas crystallinity of catalysts is the key factor at Cu/Al molar ratio above 2:1.

Sonochemical Synthesis of Silica Coated Super Paramagnetic Iron Oxide Nanoparticles

2013 ◽  
Vol 756 ◽  
pp. 74-79 ◽  
Author(s):  
Bashiru Kayode Sodipo ◽  
Azlan Abdul Aziz
Keyword(s):  
Iron Oxide ◽  
Silica Nanoparticles ◽  
Iron Oxide Nanoparticles ◽  
Ph Value ◽  
Superparamagnetic Iron Oxide ◽  
Silica Nanoparticle ◽  
Precipitation Method ◽  
Oxide Nanoparticles ◽  
Sonochemical Method ◽  
Co Precipitation

Superparamagnetic iron oxide nanoparticles (SPION) of sizes 5 to10 nm were synthesized by the co-precipitation method. They are coated with silica nanoparticles using sonication method. The SPION was produced under the optimum pH of 10, peptized in acidic medium and redispersed in water. The silica nanoparticles were produced through the Stöbermethod. Sonochemical coating of silica nanoparticle on the SPION was successfulat a pH value lower than 5. Otherwise, at higher pH value (but lower than point zero charge (PZC)), the SPION were found to be unstable. Fast hydrolysis of triethoxyvinylsilane(TEVS) shows that silica forms its own particles without coating onto the surfaces of the SPION. Under optimized experimental condition, sonochemical method of coating silica nanoparticles onto the SPION can be considered as an alternative for effective and prompt method that rely mainly on pH of the suspension.

Synthesis Conditions of Nano-Hydroxyapatite Using Chondroitin Sulfate by Co-Precipitation Method

2011 ◽  
Vol 236-238 ◽  
pp. 2076-2079
Author(s):  
Yan Rong Sun ◽  
Tao Fan ◽  
Yong Huang ◽  
Li Guo Ma ◽  
Feng Liu
Keyword(s):  
Chondroitin Sulfate ◽  
Ph Value ◽  
Orthogonal Design ◽  
Precipitation Method ◽  
Synthesis Process ◽  
X Ray Diffraction ◽  
Powder Morphology ◽  
Synthesis Conditions ◽  
Transmission Electron ◽  
Co Precipitation

The introduction of biomineralization was coupled with the co-precipitation synthesis process of nano-hydroxyapatite with the addition of chondroitin sulfate as a template agent. The effect of a variety of processing conditions on the properties of final hydroxyapatite (HA) product was investigated by orthogonal design. The ratio of calcium to phosphorus was detected by chemical analysis, the phase composition was evaluated by X-ray diffraction (XRD), and the powder morphology was characterized by transmission electron microscope (TEM). The process scheme, moreover, was optimized by the analysis of four aspects which may have different extent of influence on product properties. It can be concluded from the results that product properties can be affected remarkably by the content of chondroitin sulfate and the pH value of reactant, less remarkably by the reaction temperature and slightly by the reaction time.

scholarly journals Facile synthesis of a high purity α-MnO2 nanorod for rapid degradation of Rhodamine B

2021 ◽  
Author(s):  
shumin wang ◽  
Ao Guan ◽  
Jiahan Wang ◽  
Xiaofang Fu ◽  
Xiang Guo ◽  
...  
Keyword(s):  
Rhodamine B ◽  
High Efficiency ◽  
Catalytic Mechanism ◽  
Ph Value ◽  
Removal Rate ◽  
Precipitation Method ◽  
Characteristic Peak ◽  
Catalytic Stability ◽  
Rapid Removal ◽  
Co Precipitation

Abstract Manganese dioxide (α-MnO2) nanorods with diameters of about 5-15 nm and lengths of 100-150 nm were synthesized by a simple co-precipitation method. XRD, TEM, HRTEM, SAED and XPS were used to analyze the crystallographic information, microstructure and chemical bonding of the as-prepared sample. The α-MnO2 nanorod exhibited a high efficiency and rapid removal rate of rhodamine B (RhB), which reached about 97.5% within 10 min when pH=4 (and pH=6.6) and 97.7% within 50 min when pH = 9 in the presence of H2O2. The results also indicated that a lower pH value is conducive to the movement of the characteristic peak and the attenuation of the intensity of the characteristic peak of RhB dye. Then a possible catalytic mechanism was revealed. Moreover, the α-MnO2 nanorod exhibits an excellent recyclability and catalytic stability. This research indicates that α-MnO2 nanorods have a potential application in practical dye pollutant treatment.

scholarly journals Gd/Sm-Pr Co-Doped Ceria: A First Report of the Precipitation Method Effect on Flash Sintering

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1218 ◽  
Author(s):  
Luca Spiridigliozzi ◽  
Lorenzo Pinter ◽  
Mattia Biesuz ◽  
Gianfranco Dell’Agli ◽  
Grazia Accardo ◽  
...  
Keyword(s):  
Ammonia Solution ◽  
Current Control ◽  
Precipitation Method ◽  
Precipitation Process ◽  
Sintering Behavior ◽  
Method Effect ◽  
Flash Sintering ◽  
Co Precipitation ◽  
First Time ◽  
Flash Event

In this work, ceria-based ceramics with the composition Gd0.14Pr0.06Ce0.8O2-δ and Sm0.14Pr0.06Ce0.8O2-δ, were synthesized by a simple co-precipitation process using either ammonium carbonate or ammonia solution as a precipitating agent. After the calcination, all of the produced samples were constituted by fluorite-structured ceria only, thus showing that both dopant and co-dopant cations were dissolved in the fluorite lattice. The ceria-based nanopowders were uniaxially compacted and consequently flash-sintered using different electrical cycles (including current-ramps). Different results were obtained as a function of both the adopted precipitating agent and the applied electrical cycle. In particular, highly densified products were obtained using current-ramps instead of “traditional” flash treatments (with the power source switching from voltage to current control at the flash event). Moreover, the powders that were synthesized using ammonia solution exhibited a low tendency to hotspot formation, whereas the materials obtained using carbonates as the precipitating agent were highly inhomogeneous. This points out for the first time the unexpected relevance of the precipitating agent (and of the powder shape/degree of agglomeration) for the flash sintering behavior.

The Thermodynamic Analysis of Ni1/2Mn1/2(OH)2 Prepared by Hydroxide Co-Precipitation Method

2013 ◽  
Vol 643 ◽  
pp. 104-107
Author(s):  
Yi Jie Gu ◽  
Qing Gang Zhang ◽  
Yun Bo Chen ◽  
Hong Quan Liu ◽  
Yan Min Wang ◽  
...  
Keyword(s):  
Thermodynamic Analysis ◽  
Ph Value ◽  
Chelating Agent ◽  
Ammonia Concentration ◽  
Precipitation Method ◽  
Mixed Solution ◽  
Sem Images ◽  
Precipitation System ◽  
Co Precipitation

The thermodynamic analysis of Ni2+-Mn2+-NH3-OH--H2O in co-precipitation system was carried out, and the precursor Ni1/2Mn1/2(OH)2 was prepared by hydroxide co-precipitation method. The analysis showed that the best pH value of mixed solution is 11 and the ammonia concentration is 0.4 mol/L, when NaOH is precipitating agent and ammonia is chelating agent. When the pH value is 11, the SEM images confirm that the morphology of Ni1/2Mn1/2(OH)2 is the best.

Synthesis of Non-Toxic Fe2(WO4)3 Photocatalyst with Efficient Performance

2020 ◽  
Vol 16 ◽  
Author(s):  
Imran Aslam ◽  
M. Saqib ◽  
M. W. Iqbal ◽  
Rajender Boddula ◽  
Tariq Mahmood ◽  
...  
Keyword(s):  
Ph Value ◽  
Uv Light ◽  
Light Exposure ◽  
Precipitation Method ◽  
Adequate Model ◽  
Efficient Performance ◽  
Toxicological Studies ◽  
Co Precipitation ◽  
Compound Concentration ◽  
Catalyst Load

Background: Environmental pollution has become a worldwide problem. In this regard, decontamination of wastewater and removal of organic pollutants from environment by photocatalysis has emerged as one of the most promising techniques from last few decades. Objective : In order to degrade the harmful pollutants from wastewater, highly efficient non-toxic Fe2(WO4)3 photocatalyst will be synthesized via co precipitation method. The photocatalytic activity of the as-synthesized material will be examined by degrading methylene blue (MB) under various conditions. Methods: For this purpose, different experimental parameters such as catalyst load, model compound concentration, H2O2 percentage and pH value were adjusted for excellent degradation of MB, and response surface methodology (RSM) along with central composite design (CCD) as adequate model was employed for optimization process. Results: The experimental results revealed that 1.2 g/L of catalyst load, 10 g/L for dye concentration, 0.5 percentage of H2O2 and pH 7 are found to be the optimized values for the aforesaid parameters. The optimized values led to 93% degradation of MB under UV light exposure. In addition, toxicological studies have been analysed by using various bioassays for both untreated and treated samples and a conspicuous reduction (69.12%) in the toxicity level was observed. Conclusion: The study signifies that this method is useful for reclamation of water making it useful for industry and irrigation.

Study on Nanometer ATO Powder Prepared with Citric Acid as Dispersant and its Conductive Properties

2014 ◽  
Vol 599-601 ◽  
pp. 118-123
Author(s):  
Xie Bin Zhu ◽  
Jing Chen ◽  
Zhong Jia Huang
Keyword(s):  
Citric Acid ◽  
Ph Value ◽  
Ammonia Solution ◽  
Raw Material ◽  
Precipitation Method ◽  
Technological Condition ◽  
Nano Powder ◽  
Sb Doping ◽  
Co Precipitation ◽  
Conductive Properties

Antimony doped tin oxide (ATO) Nano powder was prepared by co-precipitation method, selecting SnCl4 • 5H2O and SbCl3 as the main raw material, citric acid as dispersant, ammonia solution (1:3) as precipitant, which was characterized, analyzed and tested by XRD, SEM, and digital conductivity meter. The optimum technological condition is that evenly-scattered powder whose crystalline structure is rutile, particle is sphere, size is about 10nm and conductivity is 1.32 ×102 µs/cm can be obtained when the reaction temperature is 60°C, Sb doping ratio is 10%, pH value is 2, calcinations temperature are 600°C and calcinations time are 2 hours.

scholarly journals Alkali-Added Catalysts Based on LaAlO3 Perovskite for the Oxidative Coupling of Methane

2021 ◽  
Vol 5 (1) ◽  
pp. 14
Author(s):  
Suna An ◽  
JeongHyun Cho ◽  
Dahye Kwon ◽  
Ji Chul Jung
Keyword(s):  
Catalytic Activity ◽  
Oxidative Coupling ◽  
Oxidative Coupling Of Methane ◽  
Lattice Oxygen ◽  
Oxygen Species ◽  
Methyl Radicals ◽  
Ethylene Selectivity ◽  
Perovskite Catalysts ◽  
C2 Hydrocarbons ◽  
Selective Formation

In this study, we aimed to enhance the catalytic activity of perovskite catalysts and elucidate their catalytic behavior in the oxidative coupling of methane (OCM), using alkali-added LaAlO3 perovskite catalysts. We prepared LaAlO3_XY (X = Li, Na, K, Y = mol %) catalysts and applied them to the OCM reaction. The results showed that the alkali-added catalysts’ activities were promoted compared to the LaAlO3 catalyst. In this reaction, ethane was first synthesized through the dimerization of methyl radicals, which were produced from the reaction of methane and oxygen vacancy in the perovskite catalysts. The high ethylene selectivity of the alkali-added catalysts originated from their abundance of electrophilic lattice oxygen species, facilitating the selective formation of C2 hydrocarbons from ethane. The high COx (carbon monoxide and carbon dioxide) selectivity of the LaAlO3 catalyst originated from its abundance of nucleophilic lattice oxygen species, favoring the selective production of COx from ethane. We concluded that electrophilic lattice oxygen species play a significant role in producing ethylene. We obtained that alkali-adding could be an effective method for improving the catalytic activity of perovskite catalysts in the OCM reaction.

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