scholarly journals Synthesis, characterization and catalytic activity estimation of WO3/MeO2 (Me: Zr, Ti, Si) oxides for fructose conversion reaction into 5-hydroxymethylfurfural

2021 ◽  
Vol 10 (3) ◽  
pp. xx-xx
Author(s):  
Ho Pham Thi ◽  
Ngan Pham Thi Thanh ◽  
Binh Nguyen Thanh
Keyword(s):  
Catalytic Activity ◽  
Crystalline Structure ◽  
Phase Structure ◽  
Monoclinic Phase ◽  
Mixed Oxides ◽  
Experimental Conditions ◽  
Good Catalytic Activity ◽  
Xrd Patterns ◽  
Nano Cluster ◽  
Activity Estimation

Series of WO3/MeO2(Me: Zr, Ti, Si) oxides were synthesized by impregnationmethod with 1:9 atomic ration of W:Me.The oxides were characterized by various techniques such as XRD, IR. The XRD patterns showed the crystalline structure of ZrO2, TiO2,WO3 and amorphous of SiO2. They were formed in tetragonal, anatase, monoclinic phase structure. All oxide and mixed oxides were estimated its catalytic activity through fructose conversion into 5-hydroxymethylfurfural in DMSO solvent. The results indicated that all mixed oxides owned good catalytic activity for the reaction in comparison with case of only presence DMSO solvent. Especially, The oxide WO3/ZrO2 showed the best HMF yield, 81,6%, at experimental conditions. This property could be due to the well dispersionand acidity of nano cluster WO3 on the surface s of oxides MeO2.

scholarly journals Investigation of Thermal Behavior of Layered Double Hydroxides Intercalated with Carboxymethylcellulose Aiming Bio-Carbon Based Nanocomposites

2019 ◽  
Vol 3 (2) ◽  
pp. 55
Author(s):  
Vagner R. Magri ◽  
Alfredo Duarte ◽  
Gustavo F. Perotti ◽  
Vera R.L. Constantino
Keyword(s):  
Layered Double Hydroxides ◽  
Mixed Oxides ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
X Ray ◽  
Vibrational Spectroscopies ◽  
Xrd Patterns ◽  
Double Hydroxides ◽  
The Degree Of Crystallinity

Carboxymethylcellulose (CMC), a polymer derived from biomass, was intercalated into layered double hydroxides (LDH) composed by M2+/Al3+ (M2Al-CMC, M = Mg or Zn) and evaluated as precursors for the preparation of biocarbon-based nanocomposites by pyrolysis. M2Al-CMC hybrids were obtained by coprecipitation and characterized by X ray diffraction (XRD), vibrational spectroscopies, chemical analysis, and thermal analysis coupled to mass spectrometry. Following, pyrolyzed materials obtained between 500–1000 °C were characterized by XRD, Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Above 600 °C, Raman spectra of all samples showed the presence of graphitic carbon, which plays a role in the degree of crystallinity of produced inorganic phases (for comparison purposes, M2Al-CO3 materials were investigated after calcination in the same experimental conditions). XRD patterns of Mg2Al-CMC pyrolyzed between 600–1000 °C showed poorly crystallized MgO and absence of spinel reflections, whereas for Zn2Al-CMC, it was observed well crystallized nanometric ZnO at 800 °C, and ZnAl2O4 and γ-Al2O3 phases at 1000 °C. Above 800 °C, the carbothermic reaction was noticed, transforming ZnO to zinc vapour. This study opens perspectives for nanocomposites preparation based on carbon and inorganic (mixed) oxides through precursors having organic-inorganic interactions at the nanoscale domain.

scholarly journals The Determing Activation Energy of Total Oxidation Reaction of m-xylene over La0,7Sr0,3BO3 (B = Mn, Fe, Ni) Perovskite Catalysts

2017 ◽  
Vol 33 (4) ◽  
Author(s):  
Tran Thi Thu Huyen ◽  
Tran Thi Luyen ◽  
Nguyen Thi Tuyet Mai
Keyword(s):  
Activation Energy ◽  
Catalytic Activity ◽  
Oxidation Reaction ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Rare Earth Ions ◽  
Exhaust Emission ◽  
Total Oxidation ◽  
Low Reaction Temperature ◽  
Good Catalytic Activity

Perovskite-type oxides containing rare earth ions and transition metals are of interest for catalytic oxidation and reduction reactions associated with automotive exhaust emission control. They are known to exhibit a good catalytic activity in the total oxidation reaction of carbon monoxide or hydrocarbon and removal of nitrogen oxides. By partially substitution of A and B ions of the perovskite with others, a wide variety of mixed oxides A1-xA’xB1-yB’yO3 can be obtained, allowing the systematic modification of the catalytic properties. We presented the preparation and the catalytic properties of and La0.7Sr0.3BO3 (B = Mn, Fe, Ni) perovskites in total oxidation of m-xylene in previous report. Obtained results showed that they exhibit a good catalytic activity in total oxidation of  m-xylene at relatively low reaction temperature. In present work, the activation energy of total oxidation reaction of m-xylene over these catalysts are determined. The results show that the activation energy of studied catalyst is ranging about from 11.5 to 13.4 kcal/mol. The replacement of Mn by Fe and Ni in La0.7Sr0.3MnO3  perovskite catalyst reduces the catalytic property of  La0.7Sr0.3MnO3 catalyst and increases the activation energy of the total oxidation reaction of m-xylene. 

High resolution electron microscopy of lanthanum phosphate crystals

1978 ◽  
Vol 36 (1) ◽  
pp. 274-275
Author(s):  
J. C. Wheatley ◽  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
High Resolution ◽  
Petroleum Industry ◽  
High Resolution Electron Microscopy ◽  
Lanthanum Phosphate ◽  
Good Catalyst ◽  
Resolution Electron ◽  
Good Catalytic Activity ◽  
Physical And Chemical

Rare-earth phosphates are of particular interest because of their catalytic properties associated with the hydrolysis of many aromatic chlorides in the petroleum industry. Lanthanum phosphates (LaPO4) which have been doped with small amounts of copper have shown increased catalytic activity (1). However the physical and chemical characteristics of the samples leading to good catalytic activity are not known.Many catalysts are amorphous and thus do not easily lend themselves to methods of investigation which would include electron microscopy. However, the LaPO4, crystals are quite suitable samples for high resolution techniques.The samples used were obtained from William L. Kehl of Gulf Research and Development Company. The electron microscopy was carried out on a JEOL JEM-100B which had been modified for high resolution microscopy (2). Standard high resolution techniques were employed. Three different sample types were observed: 669A-1-5-7 (poor catalyst), H-L-2 (good catalyst) and 27-011 (good catalyst).

Study of nickel-molybdenum catalysts for methanation of carbon monoxide

1980 ◽  
Vol 45 (3) ◽  
pp. 783-790 ◽  
Author(s):  
Petr Taras ◽  
Milan Pospíšil
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Mixed Oxides ◽  
Minor Component ◽  
Fast Neutrons ◽  
Scanning Calorimetry ◽  
Low Concentrations ◽  
Γ Rays ◽  
Molybdenum Catalysts ◽  
Kinetics Of

Catalytic activity of nickel-molybdenum catalysts for methanation of carbon monoxide and hydrogen was studied by means of differential scanning calorimetry. The activity of NiMoOx systems exceeds that of carrier-free nickel if x < 2, and is conditioned by the oxidation degree of molybdenum, changing in dependence on the composition in the region Mo-MoO2. The activity of the catalysts is adversely affected by irradiation by fast neutrons, dose 28.1 Gy, or by γ rays using doses in the region 0.8-52 kGy. The system is most susceptible to irradiation in the region of low concentrations of the minor component (about 1 mol.%). The dependence of changes in catalytic activity of γ-irradiated samples on the dose exhibits a maximum in the range of 2-5 kGy. The changes in catalytic activity are stimulated by the change of reactivity of the starting mixed oxides, leading to different kinetics of their reduction and modification of their adsorption properties. The irradiation of the catalysts results in lowered concentration of the active centres for the methanation reaction.

scholarly journals CO Oxidation Efficiency and Hysteresis Behavior over Mesoporous Pd/SiO2 Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 131 ◽  
Author(s):  
Rola Mohammad Al Soubaihi ◽  
Khaled Mohammad Saoud ◽  
Myo Tay Zar Myint ◽  
Mats A. Göthelid ◽  
Joydeep Dutta
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Active Sites ◽  
Bond Activation ◽  
Dissociative Adsorption ◽  
High Catalytic Activity ◽  
Good Catalytic Activity ◽  
Pretreatment Conditions ◽  
Oxidation Efficiency

Carbon monoxide (CO) oxidation is considered an important reaction in heterogeneous industrial catalysis and has been extensively studied. Pd supported on SiO2 aerogel catalysts exhibit good catalytic activity toward this reaction owing to their CO bond activation capability and thermal stability. Pd/SiO2 catalysts were investigated using carbon monoxide (CO) oxidation as a model reaction. The catalyst becomes active, and the conversion increases after the temperature reaches the ignition temperature (Tig). A normal hysteresis in carbon monoxide (CO) oxidation has been observed, where the catalysts continue to exhibit high catalytic activity (CO conversion remains at 100%) during the extinction even at temperatures lower than Tig. The catalyst was characterized using BET, TEM, XPS, TGA-DSC, and FTIR. In this work, the influence of pretreatment conditions and stability of the active sites on the catalytic activity and hysteresis is presented. The CO oxidation on the Pd/SiO2 catalyst has been attributed to the dissociative adsorption of molecular oxygen and the activation of the C-O bond, followed by diffusion of adsorbates at Tig to form CO2. Whereas, the hysteresis has been explained by the enhanced stability of the active site caused by thermal effects, pretreatment conditions, Pd-SiO2 support interaction, and PdO formation and decomposition.

Microstructure Characterization of Metal Mixed Oxides

MRS Advances ◽  
2017 ◽  
Vol 2 (64) ◽  
pp. 4025-4030 ◽  
Author(s):  
T. Kryshtab ◽  
H. A. Calderon ◽  
A. Kryvko
Keyword(s):  
Mixed Oxides ◽  
Profile Analysis ◽  
Atomic Resolution ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Reconstruction Procedure ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Co Precipitation

ABSTRACTThe microstructure of Ni-Mg-Al mixed oxides obtained by thermal decomposition of hydrotalcite-like compounds synthesized by a co-precipitation method has been studied by using X-ray diffraction (XRD) and atomic resolution transmission electron microscopy (TEM). XRD patterns revealed the formation of NixMg1-xO (x=0÷1), α-Al2O3 and traces of MgAl2O4 and NiAl2O4 phases. The peaks profile analysis indicated a small grain size, microdeformations and partial overlapping of peaks due to phases with different, but similar interplanar spacings. The microdeformations point out the presence of dislocations and the peaks shift associated with the presence of excess vacancies. The use of atomic resolution TEM made it possible to identify the phases, directly observe dislocations and demonstrate the vacancies excess. Atomic resolution TEM is achieved by applying an Exit Wave Reconstruction procedure with 40 low dose images taken at different defocus. The current results suggest that vacancies of metals are predominant in MgO (NiO) crystals and that vacancies of Oxygen are predominant in Al2O3 crystals.

scholarly journals Palladium-Supported Zirconia-Based Catalytic Degradation of Rhodamine-B Dye from Wastewater

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1522
Author(s):  
Salma Jabeen ◽  
Muhammad Sufaid Khan ◽  
Rozina Khattak ◽  
Ivar Zekker ◽  
Juris Burlakovs ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Rhodamine B ◽  
Dye Degradation ◽  
Freundlich Isotherm ◽  
Impregnation Method ◽  
K Value ◽  
First Order Kinetics ◽  
Good Catalytic Activity ◽  
Rhodamine B Dye ◽  
Best Fit

The catalytic activity of Pd/ZrO2 was studied in terms of the degradation of rhodamine-B dye in the presence of hydrogen peroxide. Pd/ZrO2 was prepared by impregnation method, calcined at 750 °C and characterized by XRD, SEM and EDX. The catalyst showed good catalytic activity for dye degradation at 333 K, using 0.05 g of the catalyst during 5 h. The reaction kinetics followed the pseudo-first order kinetics. The Freundlich, Langmuir and Temkin isotherms were applied to the data and the best fit was obtained with Freundlich isotherm. Thermodynamic parameters, like ΔH, ΔG and ΔS were also calculated. The negative values of ΔH (−291.406 KJ/mol) and Gibbs free energy (ΔG) showed the exothermic and spontaneous nature of the process. The positive ΔS (0.04832 KJ/mol K) value showed suitable affinity of catalyst for dye degradation. The catalyst was very stable, active and was easily separated from the reaction mixture by filtration. It can be concluded from the results that the prepared catalyst could be effectively used in dyes degradation/removal from water subjected to further validation and use for various dyes.

Synthesis by sol–gel process, characterization and catalytic activity of vanadia–silica mixed oxides

2005 ◽  
Vol 351 (46-48) ◽  
pp. 3624-3629 ◽  
Author(s):  
Mariza Alves Figueiredo ◽  
André Luiz de Faria ◽  
Marilda das Dores Assis ◽  
Herenilton Paulino Oliveira
Keyword(s):  
Catalytic Activity ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Process Characterization ◽  
Sol Gel Process
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