Catalytic reduction of nitrates in water on Pt promoted Cu hydrotalcite-derived catalysts: Effect of the Pt–Cu alloy formation

2011 ◽  
Vol 110 ◽  
pp. 58-70 ◽  
Author(s):  
A. Aristizábal ◽  
S. Contreras ◽  
N. Barrabés ◽  
J. Llorca ◽  
D. Tichit ◽  
...  
Keyword(s):  
Catalytic Reduction ◽  
Alloy Formation ◽  
Cu Alloy

scholarly journals Al-Cu alloy formation by aluminium underpotential deposition from AlCl3+NaCl melts on copper substrate

2021 ◽  
Vol 48 (03) ◽  
pp. 159-171
Author(s):  
B. S. RADOVIĆ ◽  
V. S. CVETKOVIĆ ◽  
R. A. EDWARDS ◽  
J. N. JOVIĆEVIĆ
Keyword(s):  
Copper Substrate ◽  
Underpotential Deposition ◽  
Alloy Formation ◽  
Cu Alloy

Au-Cu Alloy Formation on Cubic Cu2O Nanocrystals at Ambient Temperature and Their Catalytic Performance

ChemNanoMat ◽  
2016 ◽  
Vol 2 (9) ◽  
pp. 861-865 ◽  
Author(s):  
Zhenhua Zhang ◽  
Tian Cao ◽  
Liangfeng Luo ◽  
Rui Song ◽  
Huijuan Wang ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Catalytic Performance ◽  
Alloy Formation ◽  
Cu Alloy

scholarly journals Highly N2-Selective Activated Carbon-Supported Pt-In Catalysts for the Reduction of Nitrites in Water

2021 ◽  
Vol 9 ◽  
Author(s):  
Olívia Salomé G. P. Soares ◽  
Erika O. Jardim ◽  
Enrique V. Ramos-Fernandez ◽  
Juan J. Villora-Picó ◽  
M. Mercedes Pastor-Blas ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Catalyst Surface ◽  
Catalytic Reduction ◽  
Batch Reactor ◽  
Indium Content ◽  
Nitrite Reduction ◽  
Alloy Formation ◽  
Pt Catalysts

The catalytic reduction of nitrites over Pt-In catalysts supported on activated carbon has been studied in a semi-batch reactor, at room temperature and atmospheric pressure, and using hydrogen as the reducing agent. The influence of the indium content on the activity and selectivity was evaluated. Monometallic Pt catalysts are very active for nitrite reduction, but the addition of up to 1 wt% of indium significantly increases the nitrogen selectivity from 0 to 96%. The decrease in the accessible noble metal surface area reduces the amount of hydrogen available at the catalyst surface, this favoring the combination of nitrogen-containing intermediate molecules to promote the formation of N2 instead of being deeply hydrogenated into NH4+. Several activated carbon-supported Pt-In catalysts, activated under different calcination and reduction temperatures, have been also evaluated in nitrite reduction. The catalyst calcined and reduced at 400°C showed the best performance considering both the activity and the selectivity to nitrogen. This enhanced selectivity is ascribed to the formation of Pt-In alloy. The electronic properties of Pt change upon alloy formation, as it is demonstrated by XPS.

Catalytic performance of Pd-promoted Cu hydrotalcite-derived catalysts in partial hydrogenation of acetylene: effect of Pd–Cu alloy formation

2016 ◽  
Vol 6 (9) ◽  
pp. 3027-3037 ◽  
Author(s):  
Yanan Liu ◽  
Yufei He ◽  
Daran Zhou ◽  
Junting Feng ◽  
Dianqing Li
Keyword(s):  
Catalytic Performance ◽  
Partial Hydrogenation ◽  
Alloy Formation ◽  
Cu Alloy ◽  
Highly Dispersed ◽  
Effect Of Pd

A highly dispersed PdCu nanoalloy catalyst derived from a CuMgAl-hydrotalcite precursor exhibited superior catalytic performance in partial hydrogenation of acetylene.

Properties of PdAu and PtCu alloy surfaces for the adsorption and catalytic reduction of O2 and NO by H2

1993 ◽  
Vol 80 (2-3) ◽  
pp. 121-126 ◽  
Author(s):  
Akira Obuchi ◽  
Atsushi Ogata ◽  
Koichi Mizuno ◽  
Akihiko Ohi ◽  
Hideo Ohuchi
Keyword(s):  
Catalytic Reduction ◽  
Cu Alloy

Plastic deformation of θ ' in Al-4%Cu alloy

1978 ◽  
Vol 36 (1) ◽  
pp. 576-577
Author(s):  
Shrikant P. Bhat
Keyword(s):  
Deformation Behavior ◽  
Room Temperature ◽  
Electron Microscopic Observation ◽  
Bulk Alloy ◽  
Electron Microscopic ◽  
Cu Alloy ◽  
Cu Alloys ◽  
Orowan Mechanism ◽  
The Subject ◽  
Cyclic Straining

deformation behavior of Al-Cu alloys aged to contain θ ' has been the subject of many investigations (e.g., Ref. 1-5). Since θ ' is strong and hard, dislocations bypass θ ' plates (Orowan mechanism) at low strains. However, at high strains the partially coherent θ ' plates are probably sheared, although the mechanism is complex, depending on the form of deformation. Particularly, the cyclic straining of the bulk alloy is known to produce gross bends and twists of θ '. However, no detailed investigation of the deformation of θ ' has yet been reported; moreover, Calabrese and Laird interpreted the deformation of θ ' as largely being elastic.During an investigation of high temperature cyclic deformation, the detailed electron-microscopic observation revealed that, under reversed straining conditions, θ ' particles are severely distorted--bent and twisted depending on the local matrix constraint. A typical electronmicrograph, showing the twist is shown in Fig. 1. In order to establish whether the deformation is elastic or plastic, a sample from a specimen cycled at room temperature was heated inside the microscope and the results are presented in a series of micrographs (Fig. 2a-e).

Deviations from Ideal Decagonal Symmetry in Electron Diffraction Patterns of the “Decagonal” Phase in the Al-Co-Cu Alloy System

1991 ◽  
Vol 49 ◽  
pp. 914-915
Author(s):  
Atul S. Ramani ◽  
Earle R. Ryba ◽  
Paul R. Howell
Keyword(s):  
Electron Microscope ◽  
Alloy System ◽  
Nominal Composition ◽  
Dimensional Lattice ◽  
3 Dimensional ◽  
Decagonal Phase ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Lattice Periodicity ◽  
Diffraction Patterns

The “decagonal” phase in the Al-Co-Cu system of nominal composition Al65CO15Cu20 first discovered by He et al. is especially suitable as a topic of investigation since it has been claimed that it is thermodynamically stable and is reported to be periodic in the dimension perpendicular to the plane of quasiperiodic 10-fold symmetry. It can thus be expected that it is an important link between fully periodic and fully quasiperiodic phases. In the present paper, we report important findings of our transmission electron microscope (TEM) study that concern deviations from ideal decagonal symmetry of selected area diffraction patterns (SADPs) obtained from several “decagonal” phase crystals and also observation of a lattice of main reflections on the 10-fold and 2-fold SADPs that implies complete 3-dimensional lattice periodicity and the fundamentally incommensurate nature of the “decagonal” phase. We also present diffraction evidence for a new transition phase that can be classified as being one-dimensionally quasiperiodic if the lattice of main reflections is ignored.

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.

Structure and composition of metal particles in Pt-Sn/Al2O3 bimetallic catalysts

1990 ◽  
Vol 48 (4) ◽  
pp. 278-279
Author(s):  
A. Sachdev ◽  
J. Schwank
Keyword(s):  
Bimetallic Catalysts ◽  
Bimetallic Catalyst ◽  
Size Structure ◽  
High Surface ◽  
High Surface Area ◽  
Metal Particles ◽  
Alloy Formation ◽  
Particle Size Range ◽  
Oxide Supports ◽  
Petroleum Fractions

Platinum - tin bimetallic catalysts have been primarily utilized in the chemical industry in the catalytic reforming of petroleum fractions. In this process the naphtha feedstock is converted to hydrocarbons with higher octane numbers and high anti-knock qualities. Most of these catalysts contain small metal particles or crystallites supported on high surface area insulating oxide supports. The determination of the structure and composition of these particles is crucial to the understanding of the catalytic behavior. In a bimetallic catalyst it is important to know how the two metals are distributed within the particle size range and in what way the addition of a second metal affects the size, structure and composition of the metal particles. An added complication in the Pt-Sn system is the possibility of alloy formation between the two elements for all atomic ratios.

Influence of ion-milling on the T2 phase in Al-2.5%Li-2.5%Cu alloy

1989 ◽  
Vol 47 ◽  
pp. 288-289
Author(s):  
J. R. Reed ◽  
D. J. Michel ◽  
P. R. Howell
Keyword(s):  
Thin Foil ◽  
Icosahedral Symmetry ◽  
Ion Milling ◽  
Cu Alloy ◽  
Thin Foils ◽  
Heat Treated ◽  
Aluminum Solid Solution ◽  
In Situ Heating ◽  
The Stability

The Al6Li3Cu (T2) phase, which exhibits five-fold or icosahedral symmetry, forms through solid state precipitation in dilute Al-Li-Cu alloys. Recent studies have reported that the T2 phase transforms either during TEM examination of thin foils or following ion-milling of thin foil specimens. Related studies have shown that T2 phase transforms to a microcrystalline array of the TB phase and a dilute aluminum solid solution during in-situ heating in the TEM. The purpose of this paper is to report results from an investigation of the influence of ion-milling on the stability of the T2 phase in dilute Al-Li-Cu alloy.The 3-mm diameter TEM disc specimens were prepared from a specially melted Al-2.5%Li-2.5%Cu alloy produced by conventional procedures. The TEM specimens were solution heat treated 1 h at 550°C and aged 1000 h at 190°C in air to develop the microstructure. The disc specimens were electropolished to achieve electron transparency using a 20:80 (vol. percent) nitric acid: methanol solution at -60°C.

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