Characterization of silica supported Ni and Mg basic carbonate catalyst precursors

Babu, G.P.; Ghuge, K. D.; Rammohan, S. V.; Krishnan, V.; Bhat, Adarsh

doi:10.1007/bf00770902

Cited by 4 publications

(6 citation statements)

References 6 publications

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“…Therefore the presence of Mg 2+ minimizes the reducibility difference between the two Ni species, resulting in a symmetric TPR peak. 31 In the metalcatalyzed CVD process, the morphologies of the as-synthesized nanostructures are normally closely related to the shape and size of the metal clusters. The shape and size distribution of the metal clusters are determined by the reaction conditions, which are chosen primarily based on the reduction stability of the metal catalysts.…”

Section: Characterization Of Metal Incorporated Mcm-41mentioning

confidence: 99%

Templated one-step catalytic fabrication of uniform diameter MgxBy nanostructures

et al. 2013

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Direct fabrication of Mg x B y nanostructures is achieved by employing Ni-Mg incorporated MCM-41 in the Hybrid Physical-Chemical Vapor Deposition (HPCVD) reaction. Different reaction conditions are tested to optimize the fabrication process. TEM analysis shows the fabrication of Mg x B y nanostructures starting at a reaction temperature of 600 C, and the yield of the nanostructures increases with the reaction temperature. The as-synthesized Mg x B y nanostructures have the diameters in the range of 3-5 nm, which do not increase with the reaction temperature. EELS analysis of the template removed nanostructures confirms the existence of B and Mg with minimal contamination of Si and O. NEXAFS and Raman spectroscopy analyses suggested a concentric layered structure for our as-synthesized Mg x B y nanotube/nanowire, which is in good agreement with the theoretical calculations. Ni K-edge XAS indicates that the formation of MgNi alloy particles is important for the Vapor-Liquid-Solid (VLS) growth of Mg x B y nanostructures with fine diameters, and the presence of Mg vapor not just Mg in the catalyst is crucial for the formation of Ni-Mg clusters. Physical templating by MCM-41 might also help to confine the diameter of the nanostructures. DC magnetization measurements indicate possible superconductive behaviors in the as-synthesized sample.

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Section: Characterization Of Metal Incorporated Mcm-41mentioning

confidence: 99%

Templated one-step catalytic fabrication of uniform diameter MgxBy nanostructures

et al. 2013

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“…In general, such nanoparticles of metals such as nickel, palladium, ruthenium, or platinum are used for hydrogenation, since the dissociatively adsorbed hydrogen is easily accessible on these group VIII metals. Supported metal catalysts containing both a group VIII and a group II metal [32,35,36], or a case where the catalysts containing both a group VIII and a group IB metal [22,29,[37][38][39][40] although insufficiently studied, can be found in the literature. In these catalysts, the metal of group II or group IB is added as the modifier with the purpose of promoting the cis-isomer selectivity.…”

Section: Introductionmentioning

confidence: 99%

“…In the partial hydrogenation process of edible oils, a catalyst with the high activity and selectivity is required [50][51][52]. To meet these requirements, the catalyst support should provide sufficient surface area for the metal to disperse and there must be adequate metalsupport interaction [35,43,46,48,49,[53][54][55][56][57]. The nickel phase on different support surfaces exhibits different extents of metal-support effects.…”

Section: Introductionmentioning

confidence: 99%

Supported Nickel-Based Catalysts for Partial Hydrogenation of Edible Oils

Stanković¹,

Krstić²,

Gabrovska³

et al. 2017

New Advances in Hydrogenation Processes - Fundamentals and Applications

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Nickel-based catalysts, supported on diatomite, silica gel and perlite, with high nickel loadings, have been prepared by precipitation-deposition method. Various nickel precursor salts were used for the preparation of catalyst precursors. In the precursor state, the catalysts were characterized using nitrogen physisorption, mercury porosimetry, infrared, and X-ray diffraction spectroscopy. The reducibility of catalyst precursors was evaluated using hydrogen temperature programmed reduction. Hydrogen chemisorption and X-ray photoelectron spectroscopy measurements were performed with the aim of characterizing the chemical state of the catalyst precursors. This research was focused on the study of some major factors on the state, dispersion and reducibility of a deposited Ni 2+ phase by the combined use of mentioned experimental techniques. We have examined the influence of the nature of support and the use of modifiers on activity of nickel-based catalysts in the partial hydrogenation of sunflower and soybean oils. Nitrogen physisorption and mercury porosimetry data showed that synthesis operating conditions and pore structure of supports have a profound effect on the textural properties of catalyst precursors. The analysis of infrared and X-ray diffraction spectra showed the existence of chemical species and phases which indicate the different extent of interaction between the support and the active metal. Temperature programmed reduction study revealed that the reduction features depend on the identity of the nickel precursor salt and its interaction with the support. A stronger interaction of the supported Ni 2+ phase with support hinders the reduction of catalyst precursors. Hydrogen chemisorption results showed the presence of nickel crystallites varying from 5 to 47 nm in size. The X-ray photoelectron spectroscopy data confirmed the formation surface species with different strength of interaction and different nickel crystallite sizes. The hydrogenation results showed significant differences, depending on the support and the modifier, as well as structural characteristics of reduced catalyst precursors. The results show the importance of modifiers in the control of the activity and selectivity of the partial hydrogenation

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“…21,22 To investigate the correlation between o-Ps lifetimes and pore size/pore size distribution, a series of compounds having a varying SiO 2 /Ni ratio and doped with Mg and Li separately were synthesized in a controlled manner with different pore sizes. 20 An attempt has been made to correlate the results of PAL investigations with BET data.…”

Section: Introductionmentioning

confidence: 99%

“…They are reduced at (400−450 °C) to convert them into supported nickel catalysts used in the hydrogenation of oils. In these amorphous systems, reduced nickel crystallite is attached/bonded to the porous network structure of Si−O−Ni linkages. , Evidence of such bonding comes from higher reduction temperature (400−500 °C) for nickel in these compounds compared to unsupported systems (300−320 °C) as well as incomplete reduction of nickel in supported systems even at 450 °C. , To investigate the correlation between o-Ps lifetimes and pore size/pore size distribution, a series of compounds having a varying SiO 2 /Ni ratio and doped with Mg and Li separately were synthesized in a controlled manner with different pore sizes . An attempt has been made to correlate the results of PAL investigations with BET data.…”

Section: Introductionmentioning

confidence: 99%

Positron Annihilation Studies in Silica Supported Nickel Carbonate Systems

and¹,

Manohar²,

Sudarshan³

et al. 2002

J. Phys. Chem. B

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A number of silica supported nickel carbonate systems were studied by positron annihilation lifetime spectroscopy (PAS) and nitrogen gas adsorption method (BET) to evaluate the pore size distribution in the samples. Results show that the long-lived o-Ps component gives a pore size much smaller than the average pore radius obtained from BET analysis. This indicates that o-Ps represents the pores of smaller size in a sample with wide pore size distribution.

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Characterization of silica supported Ni and Mg basic carbonate catalyst precursors

Cited by 4 publications

References 6 publications

Templated one-step catalytic fabrication of uniform diameter MgxBy nanostructures

Templated one-step catalytic fabrication of uniform diameter MgxBy nanostructures

Supported Nickel-Based Catalysts for Partial Hydrogenation of Edible Oils

Positron Annihilation Studies in Silica Supported Nickel Carbonate Systems

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