The roles of Co-precipitation pH, phase-purity and alloy formation for the ammonia decomposition activity of Ga-promoted Fe/MgO catalysts

2017 ◽  
Vol 548 ◽  
pp. 52-61 ◽  
Author(s):  
Denise Rein ◽  
Klaus Friedel Ortega ◽  
Claudia Weidenthaler ◽  
Eckhard Bill ◽  
Malte Behrens
Keyword(s):  
Ammonia Decomposition ◽  
Alloy Formation ◽  
Phase Purity ◽  
Precipitation Ph ◽  
Co Precipitation

Influence of the co-precipitation pH on the physico-chemical and catalytic properties of vanadium aluminum oxide catalyst

2004 ◽  
Vol 263 (2) ◽  
pp. 163-170 ◽  
Author(s):  
Nathalie Blangenois ◽  
Mihaela Florea ◽  
Paul Grange ◽  
Ricardo Prada Silvy ◽  
Sergey P Chenakin ◽  
...  
Keyword(s):  
Aluminum Oxide ◽  
Oxide Catalyst ◽  
Catalytic Properties ◽  
Aluminum Oxide Catalyst ◽  
Physico Chemical ◽  
Precipitation Ph ◽  
Co Precipitation

scholarly journals Exploiting the Synergetic Behavior of PtPd Bimetallic Catalysts in the Selective Hydrogenation of Glucose and Furfural

Catalysts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 132
Author(s):  
Priscilla de Souza ◽  
Lishil Silvester ◽  
Anderson da Silva ◽  
Cibele Fernandes ◽  
Thenner Rodrigues ◽  
...  
Keyword(s):  
Bimetallic Catalysts ◽  
Furfuryl Alcohol ◽  
Surface Composition ◽  
Major Product ◽  
Precipitation Method ◽  
Alloy Formation ◽  
Tio2 Nanowires ◽  
Liquid Phase Hydrogenation ◽  
Hydrogenation Reactions ◽  
Co Precipitation

Mono and bimetallic catalysts based on Pt and Pd were prepared by a co-precipitation method. They were tested in liquid phase hydrogenation reactions of glucose and furfural at low temperature and pressure. The bimetallic PtPd/TiO2 catalyst proved to be an efficient material in selectively hydrogenating glucose to sorbitol. Moreover, high furfural conversion was attained under relatively soft conditions, and the furfuryl alcohol selectivity was strongly affected by the chemical composition of the catalysts. Furfuryl alcohol (FA) was the major product in most cases, along with side products such as methylfuran (MF), furan, and traces of tetrahydrofuran (THF). These results showed that the PtPd bimetallic sample was more active relative to the monometallic counterparts. A correlation between the catalytic results and the physicochemical properties of the supported nanoparticles identified key factors responsible for the synergetic behavior of the PtPd system. The high activity and selectivity were due to the formation of ultra-small particles, alloy formation, and the Pt-rich surface composition of the bimetallic particles supported on the TiO2 nanowires.

Effect of Synthesis methods on the Properties of Magnetic Material

2015 ◽  
Vol 10 (1) ◽  
pp. 2566-2582
Author(s):  
Anwar Ul Haq ◽  
Farwa Mushtaq ◽  
M. Anis-ur-Rehman
Keyword(s):  
Sol Gel ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Basic Material ◽  
Synthesis Methods ◽  
Hydraulic Pressure ◽  
Phase Purity ◽  
Gel Method ◽  
Sol Gel Method ◽  
Co Precipitation

Ba1-xPbxFe12O19 composition (x=0.0 to 1.0) synthesized by Co-precipitation and Sol-Gel  methods. In Co-precipitation method BaCO3, PbO and Fe (NO3)3 .9H2O were used as basic ingredients. Acids and Di-H2O  were used as solvents. Molar ratio of cations was 12.   pH of solution kept constant at 13.  All samples sintered at 965±5oC for three hours.  Lead own properties, synthesis at room temperature and substitution in R-block of structure were the reasons for decrease of phase purity from “x” =0.0 to 70% for “x”=1.0. Decrease in phase purity   and heterogeneity of material caused the properties to decrease. In Sol gel method, Nitrates (salts) and Ethylene glycol (liquid) were the basic material used. The mixed solutions dried out on a hot plate whose temperature was maintained constant at 200±2oC. Pellets formed by applying suitable hydraulic pressure and then sintered at same temperature written above i.e. 965±5oC for three hours. 100% phase purity achieved. All properties modified. Temperature and frequency dependent electrical properties investigated and reported here. DC and AC obtained properties were useful for different electronics and computer devices like capacitors, smart storage devices and multilayer chip inductors. Overall, both these properties improved through sol-gel method as compared to co-precipitation method. It was because of improvement in phase purity and change in morphology of synthesized material. 

Synthesis, Characterization and Optical Properties of CdxZn1-xS Nanocrystals

2015 ◽  
Vol 832 ◽  
pp. 158-167 ◽  
Author(s):  
J. Theerthagiri ◽  
R.A. Senthil ◽  
J. Madhavan
Keyword(s):  
Optical Properties ◽  
Chemical Method ◽  
Synthetic Approach ◽  
X Ray Diffraction ◽  
Wet Chemical Method ◽  
Phase Purity ◽  
X Ray ◽  
Wet Chemical ◽  
Co Precipitation ◽  
Formation Phase

Nanocrystalline Cd1-XZnXS (X=0.0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1.0) were synthesized by simple wet chemical method via co-precipitation. The formation, phase purity and crystalline size were ascertained by X-ray diffraction (XRD). The shape and surface morphology of the synthesized samples were characterized by scanning electron microscopy (SEM). The optical properties of the Cd1-XZnXS samples were investigated using UV-vis absorption spectroscopy and photoluminescence spectroscopy (PL) studies. The optical properties of the sample was dramatically changed by varying the composition of Cd1-XZnXS system, which may be due to the synergic effect originated by combining CdS and ZnS. The obtained optical behaviors suggest that the material can be suitable for the photocatalytic degradation of organic pollutants. The prsent investigation demontrated that the synthetic approach developed in this is highly reproducible and can be readily scaled up for potential industrial production.

HREM observations of internetallic alloy formation in Pt-Sn thin films

1992 ◽  
Vol 50 (1) ◽  
pp. 52-53
Author(s):  
D.C. Dufner
Keyword(s):  
Thin Films ◽  
Cross Sections ◽  
Carbon Films ◽  
Solid State Reactions ◽  
Alloy Formation ◽  
Reaction Behavior ◽  
Interdiffusion Process ◽  
Compositional Changes ◽  
General Goal ◽  
Film Method

The general goal of this research is to clarify mechanisms of solid state reactions at the atomic level as a step in the rationalization of macroscopic reaction behavior in solids. A study of intermetallic alloy formation resulting from interdiffusion of metals in thin films can be made by HREM. In this work, reactions between Pt and Sn in thin films are studied to elucidate mechanisms for structural and compositional changes during the interdiffusion process.Thin films of Pt and Sn used in this study were prepared by the two-film method introduced by Shiojiri. Few hundred angstroms of Pt were vacuum-deposited onto holey carbon films mounted on TEM grids. Sn films with an average thickness of 200Å were created by evaporation at rates of 15-30 Å/sec onto air-cleaved KBr substrates. The Sn films were wet-stripped and collected on the holey Pt grids. Figure 1 shows a cross-section schematic of a Pt-Sn couple. While this two-film arrangement did not allow observations of the actual reaction interface, microtomy was used to produce cross-sections.

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