scholarly journals Effect of Reaction Medium on V-Ti Oxide Catalyst Composition in 2-Methyl-5-Ethylpyridine Ammoxidation

2017 ◽  
Vol 4 (3) ◽  
pp. 183
Author(s):  
V.M. Pochtennaya ◽  
D.Kh. Sembaev
Keyword(s):  
Solid Solution ◽  
Chemical Composition ◽  
Concentration Gradient ◽  
Oxide Catalyst ◽  
Reaction Medium ◽  
Medium Composition ◽  
Oxidative Reaction ◽  
Catalyst Composition ◽  
Integral Reactor ◽  
Destructive Oxidation

<p>A chemical composition of V-Ti oxide catalyst changes in accordance with the reaction medium composition in a process of 2-methyl-5-ethylpyrydine ammoxidation into nicotinonitrile in an integral reactor. The presence of alkylpyridine concentration gradient along the catalyst bed leads to the appearance of V<sub>2</sub>O<sub>5</sub> content gradient in the catalyst. V<sub>2</sub>O<sub>5</sub> concentration increases in the conditions of alkylpyridine completed conversion in consequence of oxidative decomposition of VO<sub>2</sub>-TiO<sub>2</sub> solid solution under the influence of N2O nitrogen oxide, which is formed upon the NH<sub>3</sub> oxidation. An increase of V<sub>2</sub>O<sub>5</sub> contents over 5 wt% causes rising of the share of the 2-methyl-5-ethylpyridine and nicotinonitrile destructive oxidation. An introduction of small amounts of alkylpyridine directly into the catalyst bed permits to create the definite alkylpyridine concentration gradient, which the optimal content of V<sub>2</sub>O<sub>5</sub> is corresponding to, for any given conditions of oxidative reaction. The catalysts containing 1-5 wt% of V<sub>2</sub>O<sub>5</sub> and solid solution of VO<sub>2</sub>-TiO<sub>2</sub> possess of the highest selectivity to nicotinonitrile.</p>

Selectivity regulation of perovskite-based iron-manganese catalysts for the synthesis of light olefins from CO, CO2 and H2

2020 ◽  
pp. 8-23
Author(s):  
Anastasiya Kovaleva
Keyword(s):  
Carbon Dioxide ◽  
Reaction Medium ◽  
Hydrogenation Reaction ◽  
Medium Composition ◽  
Light Olefins ◽  
Catalytic Systems ◽  
Catalyst Composition ◽  
Manganese Catalysts ◽  
Global Problems ◽  
Iron Manganese

There is a solution to prevent global problems caused due to carbon dioxide increase in planet atmosphere – reuse of CO2 in hydrogenation reaction. Literature analysis provides information about catalytic conversion of synthesis gas and carbon dioxide to carbohydrates in modern catalytic systems. Actual investigation of catalytic properties in GdFeO3 and GdMnO3 systems with perovskite structure has been carried out in the joint hydrogenation of carbon mono- and dioxide. Scientific novelty of research is to determine influence of the catalyst composition and reaction medium composition on the selectivity of target products.

scholarly journals Synthesis and Characterization of Cu2FeSnS4–Cu2MnSnS4 Solid Solution Microspheres

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4440
Author(s):  
Edyta Waluś ◽  
Maciej Manecki ◽  
Grzegorz Cios
Keyword(s):  
Solid Solution ◽  
Chemical Composition ◽  
Reaction Medium ◽  
Synthesis And Characterization ◽  
Continuous Series ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Ligand ◽  
Scanning Electron

In this study, we used a hydrothermal method to synthesize microspheres of Cu2(Mn1−xFex)SnS4 solid solution (X = 1, 0.8, 0.6, 0.4, 0.2, 0). The process was optimized to improve the crystallinity, morphology, and purity of the obtained materials. All samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. The following conditions were optimized: A mixture of water and ethylene glycol at the ratio of 1:7 as the reaction medium, polyvinylpyrrolidone (PVP) as the surface ligand, and reaction temperature of 195 °C for 7 days. The product of synthesis precipitated in the form of aggregates of nanocrystals, which form homogeneous, often concentric microspheres with a diameter of 1–1.5 μm. The chemical composition of the product can be well controlled by the chemical composition of the reactants. The compound Cu2(Mn1−xFex)SnS4 forms a continuous series of solid solutions.

Role of the Structure and Electronic Properties of Fe2O3-MoO3 Catalyst on the Dehydration of Isopropyl Alcohol

1993 ◽  
Vol 58 (7) ◽  
pp. 1591-1599 ◽  
Author(s):  
Abd El-Aziz A. Said
Keyword(s):  
Active Sites ◽  
Isopropyl Alcohol ◽  
Oxide Catalyst ◽  
Flow System ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalyst Composition ◽  
Surface Active

Molybdenum oxide catalyst doped or mixed with (1 - 50) mole % Fe3+ ions were prepared. The structure of the original samples and the samples calcined at 400 °C were characterized using DTA, X-ray diffraction and IR spectra. Measurements of the electrical conductivity of calcined samples with and without isopropyl alcohol revealed that the conductance increases on increasing the content of Fe3+ ions up to 50 mole %. The activation energies of charge carriers were determined in presence and absence of the alcohol. The catalytic dehydration of isopropyl alcohol was carried out at 250 °C using a flow system. The results obtained showed that the doped or mixed catalysts are active and selective towards propene formation. However, the catalyst containing 40 mole % Fe3+ ions exhibited the highest activity and selectivity. Correlations were attempted to the catalyst composition with their electronic and catalytic properties. Probable mechanism for the dehydration process is proposed in terms of surface active sites.

scholarly journals Preparation of Li3PS4–Li3PO4 Solid Electrolytes by Liquid-Phase Shaking for All-Solid-State Batteries

2021 ◽  
Vol 2 (1) ◽  
pp. 39-48
Author(s):  
Nguyen H. H. Phuc ◽  
Takaki Maeda ◽  
Tokoharu Yamamoto ◽  
Hiroyuki Muto ◽  
Atsunori Matsuda
Keyword(s):  
Solid Solution ◽  
Solid State ◽  
Liquid Phase ◽  
Room Temperature ◽  
Reaction Medium ◽  
Magic Angle Spinning ◽  
Resonance Spectroscopy ◽  
Synthesis Methods ◽  
Magic Angle ◽  
Angle Spinning

A solid solution of a 100Li3PS4·xLi3PO4 solid electrolyte was easily prepared by liquid-phase synthesis. Instead of the conventional solid-state synthesis methods, ethyl propionate was used as the reaction medium. The initial stage of the reaction among Li2S, P2S5 and Li3PO4 was proved by ultraviolet-visible spectroscopy. The powder X-ray diffraction (XRD) results showed that the solid solution was formed up to x = 6. At x = 20, XRD peaks of Li3PO4 were detected in the prepared sample after heat treatment at 170 °C. However, the samples obtained at room temperature showed no evidence of Li3PO4 remaining for x = 20. Solid phosphorus-31 magic angle spinning nuclear magnetic resonance spectroscopy results proved the formation of a POS33− unit in the sample with x = 6. Improvements of ionic conductivity at room temperature and activation energy were obtained with the formation of the solid solution. The sample with x = 6 exhibited a better stability against Li metal than that with x = 0. The all-solid-state half-cell employing the sample with x = 6 at the positive electrode exhibited a better charge–discharge capacity than that employing the sample with x = 0.

scholarly journals On the Reaction Pathways and Growth Mechanisms of LiNbO3 Nanocrystals from the Non-Aqueous Solvothermal Alkoxide Route

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 154
Author(s):  
Mathias Urbain ◽  
Florian Riporto ◽  
Sandrine Beauquis ◽  
Virginie Monnier ◽  
Jean-Christophe Marty ◽  
...  
Keyword(s):  
Colloidal Stability ◽  
Formation Rate ◽  
Reaction Medium ◽  
Precursor Solution ◽  
Medium Composition ◽  
Shape Anisotropy ◽  
Reaction Pathways ◽  
Growth Mechanisms ◽  
Shape Distribution ◽  
Size And Shape

Phase-pure, highly crystalline sub-50 nm LiNbO3 nanocrystals were prepared from a non-aqueous solvothermal process for 72 h at 230 °C and a commercial precursor solution of mixed lithium niobium ethoxide in its parent alcohol. A systematic variation of the reaction medium composition with the addition of different amounts of co-solvent including butanol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol resulted in the formation of nanocrystals of adjustable mean size and shape anisotropy, as demonstrated from XRD measurements and TEM imaging. Colloidal stability of ethanol- and water-based suspensions was evaluated from dynamic light scattering (DLS)/zeta potential studies and correlated with FTIR data. Thanks to the evolution in the nanocrystal size and shape distribution we observed, as well as to the available literature on the alkoxide chemistry, the reaction pathways and growth mechanisms were finally discussed with a special attention on the monomer formation rate, leading to the nucleation step. The polar, non-perovskite crystalline structure of LiNbO3 was also evidenced to play a major role in the nanocrystal shape anisotropy.

scholarly journals Formation of Intermediate Phases and Supersaturated Solid Solution in Al-Cu System during Diffusion

2018 ◽  
Vol 383 ◽  
pp. 31-35 ◽  
Author(s):  
Alexey Rodin ◽  
Nataliya Goreslavets
Keyword(s):  
Phase Diagram ◽  
Solid Solution ◽  
High Temperature ◽  
Chemical Composition ◽  
Low Temperature ◽  
Supersaturated Solid Solution ◽  
Diffusion Processes ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
Intermediate Phases

The study of diffusion processes in the aluminum - copper system was carried out at the temperature 350 and 520 °C. Special attention was paid on the chemical composition of the system near Al/Cu interface. It was determined that the intermediate phases in the system, corresponding to the equilibrium phase diagram, were not formed at low temperature. At high temperature the intermediate phases forms starting with Cu - rich phases. In both cases supersaturated solid solution of copper in aluminum could be observed near the interface.

scholarly journals On solid solution in minerals; II, The chemical composition of analcite

1912 ◽  
Vol s4-33 (197) ◽  
pp. 433-439
Author(s):  
H. W. Foote ◽  
W. M. Bradley
Keyword(s):  
Solid Solution ◽  
Chemical Composition

Kinetic Assessment of the Dry Reforming of Methane over a Solid Solution Ni–La Oxide Catalyst

2021 ◽  
Author(s):  
Victor Stivenson Sandoval-Bohorquez ◽  
Edgar M. Morales-Valencia ◽  
Carlos Omar Castillo-Araiza ◽  
Luz Marina Ballesteros Rueda ◽  
Víctor Gabriel Baldovino Medrano
Keyword(s):  
Solid Solution ◽  
Active Sites ◽  
Oxide Catalyst ◽  
Bond Cleavage ◽  
Scale Up ◽  
Active Surface ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Nickel Surface ◽  
Kinetics Of

The dry reforming of methane is a promising technology for the abatement of CH<sub>4</sub> and CO<sub>2</sub>. Solid solution Ni–La oxide catalysts are characterized by their long–term stability (100h) when tested at full conversion. The kinetics of dry reforming over this type of catalysts has been studied using both power law and Langmuir–Hinshelwood based approaches. However, these studies typically deal with fitting the net CH<sub>4</sub> rate hence disregarding competing and parallel surface processes and the different possible configurations of the active surface. In this work, we synthesized a solid solution Ni–La oxide catalyst and tested six Langmuir–Hinshelwood mechanisms considering both single and dual active sites for assessing the kinetics of dry reforming and the competing reverse water gas shift reaction and investigated the performance of the derived kinetic models. In doing this, it was found that: (1) all the net rates were better fitted by a single–site model that considered that the first C–H bond cleavage in methane occurred over a <a>metal−oxygen </a>pair site; (2) this model predicted the existence of a nearly saturated nickel surface with chemisorbed oxygen adatoms derived from the dissociation of CO<sub>2</sub>; (3) the dissociation of CO<sub>2</sub> can either be an inhibitory or an irrelevant step, and it can also modify the apparent activation energy for CH<sub>4</sub> activation. These findings contribute to a better understanding of the dry reforming reaction's kinetics and provide a robust kinetic model for the design and scale–up of the process.

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