Analysis of doped rodlike surface fibers in Al–Al3Ni eutectic alloys

1995 ◽  
Vol 10 (5) ◽  
pp. 1154-1158 ◽  
Author(s):  
E. Rosell-Laclau ◽  
M. Durand-Charre ◽  
J-C. Joud
Keyword(s):  
High Resolution ◽  
Raney Nickel ◽  
Initial Phase ◽  
Nickel Catalysts ◽  
Auger Spectroscopy ◽  
Hydrogenation Reaction ◽  
Eutectic Alloys ◽  
Stem Analysis ◽  
Initial Alloy ◽  
Catalyst Life

Undoped and Cr doped rodlike Al-Al3Ni eutectics have been studied as initial alloys of Raney nickel catalysts. The aim was to localize the dopant at different stages of the catalyst life: in the initial alloy, after Al leaching out, and after hydrogenation reaction. We have followed this dopant by STEM analysis and high resolution Auger spectroscopy. The outcome is that during Al leaching out, the dopant is also extracted from its initial phase and then forms a deposit on the Ni crystallites of the catalyst. Moreover, during the hydrogenation, the quantity of Cr remains roughly constant.

scholarly journals IINVESTigation of the catalytic and isomerization activity of multi-component skeletal nickel catalysts in the hydrogenation of hexene-1

2021 ◽  
Vol 2 (446) ◽  
pp. 58-64
Author(s):  
Zh. K. Kairbekov ◽  
S. M. Suimbayeva ◽  
I. M. Jeldybayeva ◽  
E. T. Yermoldina
Keyword(s):  
Phase Composition ◽  
High Activity ◽  
Chromatographic Analysis ◽  
Reaction Medium ◽  
Nickel Catalysts ◽  
Hydrogenation Reaction ◽  
Skeletal Nickel ◽  
Modifying Additives ◽  
Initial Alloy ◽  
Initial Stage

In this work, the effect of the amount of catalyst, modifying additives, and the phase composition of the alloys on the catalytic and isomerizing activity of skeletal in the hydrogenation reaction of hexane-1 is investigated. It has been shown that for all studied catalysts, the yield of products in the processes of migration and isomerization depends very strongly on the weighed portion of the catalyst introduced into the reaction medium. So, for example, the yield of hexane-2 with an increase in the catalyst weight increases linearly to 0.5g of nickel, while at the initial stage of the reaction the yield of hexane-2 reaches 62%. With a further increase in the catalyst weight (up to 1 g of Ni), the yield of hexane-2 decreases. The results of chromatographic analysis indicate a high activity of modified skeletal nickel catalysts in the reaction of migration of -C = C- bonds during hydrogenation of hexene-1. Modification of Fe, Pd, Sn and Ag increases the migration coefficient (Kmigr) from 0.66 to 0.70-0.77, while additions of Ti, Mo, Ti-Mo and Zr practically do not change it. The activity of the catalyst increases with the introduction of the metals Cu, Zn, Pb, Ti-Mo, Mo, Bi, Ag, and Mo-Cu (W=120-290 cm3/min·g Ni) into the initial alloy, while the addition of Fe, Pd and Mn (W=56-80 cm3/min·g Ni), while the influence of the components Ti, Zr and Sn is insignificant (W=115-117 cm3/min·g Ni).

The Preparation and Aging of Raney Nickel Catalysts

1949 ◽  
Vol 71 (11) ◽  
pp. 3769-3771 ◽  
Author(s):  
Hilton A. Smith ◽  
William C. Bedoit ◽  
John F. Fuzek
Keyword(s):  
Raney Nickel ◽  
Nickel Catalysts

scholarly journals Swarm v2: highly-scalable and high-resolution amplicon clustering

2015 ◽  
Author(s):  
Frédéric Mahé ◽  
Torbjørn Rognes ◽  
Christopher Quince ◽  
Colomban de Vargas ◽  
Micah S Dunthorn
Keyword(s):  
High Resolution ◽  
Initial Phase ◽  
Computation Time ◽  
Two Dimensional ◽  
Fine Scale ◽  
Single Linkage ◽  
Fasta Format ◽  
Operational Taxonomic Units ◽  
Abundant Otus ◽  
Local Clustering

Previously we presented Swarm v1, a novel and open source amplicon clustering program that produced fine-scale molecular operational taxonomic units (OTUs), free of arbitrary global clustering thresholds and input-order dependency. Swarm v1 worked with an initial phase that used iterative single-linkage with a local clustering threshold (d), followed by a phase that used the internal abundance structures of clusters to break chained OTUs. Here we present Swarm v2 that has two important novel features: 1) a new algorithm for d = 1 that allows the computation time of the program to scale linearly with increasing amounts of data; and 2) the new fastidious option that reduces under-grouping by grafting low abundant OTUs (e.g., singletons and doubletons) onto larger ones. Swarm v2 also directly integrates the clustering and breaking phases, dereplicates sequencing reads with d = 0, outputs OTU representatives in fasta format, and plots individual OTUs as two-dimensional networks.

ChemInform Abstract: The Quantitative Recycling of Raney—Nickel Catalysts on a Lab-Scale.

ChemInform ◽  
2008 ◽  
Vol 39 (11) ◽  
Author(s):  
Waldemar M. Czaplik ◽  
Joerg-M. Neudoerfl ◽  
Axel Jacobi von Wangelin
Keyword(s):  
Raney Nickel ◽  
Nickel Catalysts

Synthetical Applications of Activated Metal Catalysts. XVI. The Role of Hydrogen in the Formation of 2,2'-Bipyridyl from Pyridine under the Influence of Degassed Raney Nickel

1963 ◽  
Vol 16 (1) ◽  
pp. 14 ◽  
Author(s):  
WHF Sasse ◽  
CP Whittle
Keyword(s):  
Raney Nickel ◽  
Nickel Catalysts ◽  
Nickel Atom ◽  
Metal Catalysts ◽  
Published Data ◽  
Hydrogen Atoms ◽  
Adsorbed Pyridine

The efficiency of W7 Raney nickel catalysts degassed between 30 and 400�C in the preparation of 2,2'-bipyridyl has been examined. The highest activities are observed with catalysts which have been degassed at 200�C, and these catalysts arc up to 20% more efficient than catalysts previously used and degassed at 100�C. The results obtained are compared with published data concerning the hydrogen contents of degassed Raney nickel catalysts (Kokes and Emmett 1959, 1960). This shows that catalysts which are virtually free of hydrogen are only 25% less efficient than catalysts degassed at l00�C (containing 65 to 70% of their original hydrogen). Because of this finding a new mechanism is proposed in which the adsorbed pyridine is activated by the transfer of an electron from the catalyst. On stereochemical grounds it is proposed that meso-2,2'-dihydro-2,2'-bipyridyl with axially disposed hydrogen atoms at the 2,2'-positions and bonded via both nitrogen atoms to one nickel atom is the energetically most favoured intermediate.

Stereoselective reduction with raney nickel catalysts

1973 ◽  
Vol 14 (20) ◽  
pp. 1773-1775 ◽  
Author(s):  
J.H.P. Tyman ◽  
S.W. Wilkins
Keyword(s):  
Raney Nickel ◽  
Nickel Catalysts ◽  
Stereoselective Reduction

Nuclear Motion of Core ExcitedBF3Probed by High Resolution Resonant Auger Spectroscopy

1997 ◽  
Vol 79 (20) ◽  
pp. 3857-3860 ◽  
Author(s):  
M. Simon ◽  
C. Miron ◽  
N. Leclercq ◽  
P. Morin ◽  
K. Ueda ◽  
...  
Keyword(s):  
High Resolution ◽  
Auger Spectroscopy ◽  
Nuclear Motion
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