TY  - JOUR
AU  - Gabrovska, Margarita
AU  - Krstić, Jugoslav
AU  - Tzvetkov, P.
AU  - Tenchev, K.
AU  - Shopska, M.
AU  - Vukelić, Nikola
AU  - Jovanović, Dušan M.
PY  - 2011
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/829
AB  - Ni/SiO(2) materials with identical composition (SiO(2)/Ni = 1.0) have been synthesized by precipitation of Ni(NO(3))(2) center dot 6H(2)O solution with Na(2)CO(3) solution on the silica gel, obtained at three different pH values. The present investigation was undertaken in an endeavor to study the effects of the silica gel support type and the reduction temperature on the formation and dispersion of the metallic nickel phase in the reduced Ni/SiO(2) precursors of the vegetable oil hydrogenation catalyst. The physicochemical characterization of the unreduced and reduced precursors has been accomplished appropriately by powder X-ray diffraction, infrared spectroscopy, temperature programmed reduction and H(2)-chemisorption techniques. It can be stated that the texture peculiarities of the silica gels used as supports influence on the crystalline state and distribution of the deposited Ni-containing phases during the preparation of the precursors, on the reduction temperature of the investigated solids as well as on the bulk size and surface dispersion of the arising metallic nickel particles. It was shown that two types of Ni(2+)-species are formed during the synthesis procedure, namely basic nickel carbonate-like and Ni-phyllosilicate with different extent of presence, location and strength of interaction. The different location of these species is supposed to result in various strength of Ni-O and Ni-O-Si interaction, thus determining the overall reducibility of the precursors. It was specified that the Ni(2+)-species are strongly bonded to the surface of the silica gel obtained at neutral pH value and weakly bonded to the surface of those prepared in acidic and alkaline conditions. It was established that the precursor, derivates from the silica gel obtained at alkaline conditions, demonstrates both significant reduction of the Ni2+ ions at 430A degrees C and finely dispersed metallic nickel particles on its surface. High dispersion of the metallic nickel might be the crucial reason for achieving of high activity in the vegetable oil hydrogenation.
PB  - Maik Nauka/Interperiodica/Springer, New York
T2  - Russian Journal of Physical Chemistry A
T1  - Effect of the support and the reduction temperature on the formation of metallic nickel phase in Ni/silica gel precursors of vegetable oil hydrogenation catalysts
VL  - 85
IS  - 13
SP  - 2392
EP  - 2398
DO  - 10.1134/S0036024411130073
ER  - 

@article{
author = "Gabrovska, Margarita and Krstić, Jugoslav and Tzvetkov, P. and Tenchev, K. and Shopska, M. and Vukelić, Nikola and Jovanović, Dušan M.",
year = "2011",
abstract = "Ni/SiO(2) materials with identical composition (SiO(2)/Ni = 1.0) have been synthesized by precipitation of Ni(NO(3))(2) center dot 6H(2)O solution with Na(2)CO(3) solution on the silica gel, obtained at three different pH values. The present investigation was undertaken in an endeavor to study the effects of the silica gel support type and the reduction temperature on the formation and dispersion of the metallic nickel phase in the reduced Ni/SiO(2) precursors of the vegetable oil hydrogenation catalyst. The physicochemical characterization of the unreduced and reduced precursors has been accomplished appropriately by powder X-ray diffraction, infrared spectroscopy, temperature programmed reduction and H(2)-chemisorption techniques. It can be stated that the texture peculiarities of the silica gels used as supports influence on the crystalline state and distribution of the deposited Ni-containing phases during the preparation of the precursors, on the reduction temperature of the investigated solids as well as on the bulk size and surface dispersion of the arising metallic nickel particles. It was shown that two types of Ni(2+)-species are formed during the synthesis procedure, namely basic nickel carbonate-like and Ni-phyllosilicate with different extent of presence, location and strength of interaction. The different location of these species is supposed to result in various strength of Ni-O and Ni-O-Si interaction, thus determining the overall reducibility of the precursors. It was specified that the Ni(2+)-species are strongly bonded to the surface of the silica gel obtained at neutral pH value and weakly bonded to the surface of those prepared in acidic and alkaline conditions. It was established that the precursor, derivates from the silica gel obtained at alkaline conditions, demonstrates both significant reduction of the Ni2+ ions at 430A degrees C and finely dispersed metallic nickel particles on its surface. High dispersion of the metallic nickel might be the crucial reason for achieving of high activity in the vegetable oil hydrogenation.",
publisher = "Maik Nauka/Interperiodica/Springer, New York",
journal = "Russian Journal of Physical Chemistry A",
title = "Effect of the support and the reduction temperature on the formation of metallic nickel phase in Ni/silica gel precursors of vegetable oil hydrogenation catalysts",
volume = "85",
number = "13",
pages = "2392-2398",
doi = "10.1134/S0036024411130073"
}

Gabrovska, M., Krstić, J., Tzvetkov, P., Tenchev, K., Shopska, M., Vukelić, N.,& Jovanović, D. M.. (2011). Effect of the support and the reduction temperature on the formation of metallic nickel phase in Ni/silica gel precursors of vegetable oil hydrogenation catalysts. in Russian Journal of Physical Chemistry A
Maik Nauka/Interperiodica/Springer, New York., 85(13), 2392-2398.
https://doi.org/10.1134/S0036024411130073

Gabrovska M, Krstić J, Tzvetkov P, Tenchev K, Shopska M, Vukelić N, Jovanović DM. Effect of the support and the reduction temperature on the formation of metallic nickel phase in Ni/silica gel precursors of vegetable oil hydrogenation catalysts. in Russian Journal of Physical Chemistry A. 2011;85(13):2392-2398.
doi:10.1134/S0036024411130073 .

Gabrovska, Margarita, Krstić, Jugoslav, Tzvetkov, P., Tenchev, K., Shopska, M., Vukelić, Nikola, Jovanović, Dušan M., "Effect of the support and the reduction temperature on the formation of metallic nickel phase in Ni/silica gel precursors of vegetable oil hydrogenation catalysts" in Russian Journal of Physical Chemistry A, 85, no. 13 (2011):2392-2398,
https://doi.org/10.1134/S0036024411130073 . .

TY  - JOUR
AU  - Stanković, Miroslav
AU  - Gabrovska, Margarita
AU  - Krstić, Jugoslav
AU  - Tzvetkov, P.
AU  - Shopska, M.
AU  - Tsacheva, T.
AU  - Banković, Predrag
AU  - Edreva-Kardjieva, R.
AU  - Jovanović, D.
PY  - 2009
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/593
AB  - Silver modified Mg-Ni/diatomite materials with ratios of SiO2/Ni = 1.07 and Mg/Ni = 0.1, differing in Ag content (Ag/Ni = 0.025 and 0.1) were prepared by the precipitation-deposition method. The effects of silver presence and content on the structure, morphology, texture and H2-adsorption capacity of the obtained precursors were studied by X-ray diffraction, scanning electron microscopy, Hg-porosimetry and H2-chemisorption techniques. The catalytic performance of the corresponding catalysts in the soybean oil hydrogenation was investigated. The increase of the silver loading resulted in the development of macroporosity and increase in the total sample porosity. The decrease of both H2-adsorption capacity and hydrogenation activity are related to the metallic silver covering and blocking effects on the Ni2+ species, thus hampering the access of hydrogen. The decrease of hydrogenation activity and favorable limiting of cis-trans isomerization on the silver modified catalyst are explained by Horiuti-Polanyi mechanism based on the assumption that hydrogenation and isomerization proceed at the same active metallic nickel sites via half-hydrogenated intermediates. It was shown that the adjustment of the catalyst composition by changing the content of silver modifier offers the possibility to control the total amount of solid fat content, stearic acid and detrimental trans fatty acids in the hydrogenated derivatives. The catalyst with higher silver content is proposed as a promising candidate for selective edible oil hydrogenation catalyst.
PB  - Elsevier
T2  - Journal of Molecular Catalysis A: Chemical
T1  - Effect of silver modification on structure and catalytic performance of Ni-Mg/diatomite catalysts for edible oil hydrogenation
VL  - 297
IS  - 1-2
SP  - 54
EP  - 62
DO  - 10.1016/j.molcata.2008.09.004
ER  - 

@article{
author = "Stanković, Miroslav and Gabrovska, Margarita and Krstić, Jugoslav and Tzvetkov, P. and Shopska, M. and Tsacheva, T. and Banković, Predrag and Edreva-Kardjieva, R. and Jovanović, D.",
year = "2009",
abstract = "Silver modified Mg-Ni/diatomite materials with ratios of SiO2/Ni = 1.07 and Mg/Ni = 0.1, differing in Ag content (Ag/Ni = 0.025 and 0.1) were prepared by the precipitation-deposition method. The effects of silver presence and content on the structure, morphology, texture and H2-adsorption capacity of the obtained precursors were studied by X-ray diffraction, scanning electron microscopy, Hg-porosimetry and H2-chemisorption techniques. The catalytic performance of the corresponding catalysts in the soybean oil hydrogenation was investigated. The increase of the silver loading resulted in the development of macroporosity and increase in the total sample porosity. The decrease of both H2-adsorption capacity and hydrogenation activity are related to the metallic silver covering and blocking effects on the Ni2+ species, thus hampering the access of hydrogen. The decrease of hydrogenation activity and favorable limiting of cis-trans isomerization on the silver modified catalyst are explained by Horiuti-Polanyi mechanism based on the assumption that hydrogenation and isomerization proceed at the same active metallic nickel sites via half-hydrogenated intermediates. It was shown that the adjustment of the catalyst composition by changing the content of silver modifier offers the possibility to control the total amount of solid fat content, stearic acid and detrimental trans fatty acids in the hydrogenated derivatives. The catalyst with higher silver content is proposed as a promising candidate for selective edible oil hydrogenation catalyst.",
publisher = "Elsevier",
journal = "Journal of Molecular Catalysis A: Chemical",
title = "Effect of silver modification on structure and catalytic performance of Ni-Mg/diatomite catalysts for edible oil hydrogenation",
volume = "297",
number = "1-2",
pages = "54-62",
doi = "10.1016/j.molcata.2008.09.004"
}

Stanković, M., Gabrovska, M., Krstić, J., Tzvetkov, P., Shopska, M., Tsacheva, T., Banković, P., Edreva-Kardjieva, R.,& Jovanović, D.. (2009). Effect of silver modification on structure and catalytic performance of Ni-Mg/diatomite catalysts for edible oil hydrogenation. in Journal of Molecular Catalysis A: Chemical
Elsevier., 297(1-2), 54-62.
https://doi.org/10.1016/j.molcata.2008.09.004

Stanković M, Gabrovska M, Krstić J, Tzvetkov P, Shopska M, Tsacheva T, Banković P, Edreva-Kardjieva R, Jovanović D. Effect of silver modification on structure and catalytic performance of Ni-Mg/diatomite catalysts for edible oil hydrogenation. in Journal of Molecular Catalysis A: Chemical. 2009;297(1-2):54-62.
doi:10.1016/j.molcata.2008.09.004 .

Stanković, Miroslav, Gabrovska, Margarita, Krstić, Jugoslav, Tzvetkov, P., Shopska, M., Tsacheva, T., Banković, Predrag, Edreva-Kardjieva, R., Jovanović, D., "Effect of silver modification on structure and catalytic performance of Ni-Mg/diatomite catalysts for edible oil hydrogenation" in Journal of Molecular Catalysis A: Chemical, 297, no. 1-2 (2009):54-62,
https://doi.org/10.1016/j.molcata.2008.09.004 . .