**Author details**

IR and XRD measurements may offer as an effective tool to identify nickel species and their interaction with support in differently supported and modified nickel-based catalyst precursors. From the results obtained by both IR and XRD instrumental techniques, it could be concluded that during the deposition reaction under alkaline conditions, the silica as the constitutive component of all studied supports reacts with the basic nickel carbonate precipitate

The TPR results demonstrate rather well the differences between Ni compounds formed on the surface of supports. The weak metal-support interaction in the Ni-Mg/PF system is probably responsible for the hydrosilicate formation at a low level, which could decrease the difficulty in the system reduction. The Ni-Mg/D and Ni/SiG systems are difficult to reduce and are comparable in reduction characteristics to nickel hydrosilicates. The addition of silver to the Ni-Mg/D system significantly affected reducibility of nickel-based catalysts. Larger nickel crystallites in silver modified nickel catalysts displayed easier nickel reduction than smaller ones in the Ni-Mg/D catalyst. The hydrogen chemisorption study showed that the size of nickel nanoparticles obtained in the studied catalyst precursor systems depended on the nature of precursor nickel salt from which they are formed, the kind and loading of metal modifier and the type of support used. The XPS study of Ni/SiG, Ni-Mg/D and Ni-Mg-Ag/D precursor samples confirm the formation surface species with different strength of interaction and different dispersion of the sup-

The silver modifier inhibits hydrogenation activity, this effect being more obvious as the Ag loading is higher. Modification by silver allowed us to promote the selectivity toward the *cis* isomers, but the catalyst is less active than the non-modified catalyst in the partial hydrogena-

Among the catalyst samples studied, the highest activity in the sunflower oil hydrogenation was observed over the Ni-Mg/PF-1 catalyst suggesting that the Ni-Mg/PF-1 catalyst is a promising catalyst for SFO hydrogenation. Although Ni/SiG catalysts show a lower overall activity, this system also could be considered as good, since they produced less amount of stearic acid

The kinetic models include the saturation of double bonds along the fatty acids chains and *cis*/*trans* isomerization. Under studied operating conditions models proved to adequately fit the experimental data for the evolution of product distribution with reaction time. It was shown that the catalysts of different activities had different reaction pathways. The more active catalysts, the reaction pathways multiply and require more complex reaction scheme

The authors are grateful to the Ministry of Education, Science and Technological Development of the Republic of Serbia (Project No. III 45001) for providing funding support. The support by Serbian Academy of Sciences and Arts and by Bulgarian Academy of Sciences (Joint Research Project: New nanosized hydrogenation catalysts based on metals of VIII group) is also appreciated.

and generates the new supported nickel hydrosilicate phase.

170 New Advances in Hydrogenation Processes - Fundamentals and Applications

ported nickel species.

tion of soybean oil.

compared to the Ni-Mg/PF system.

to describe the results of the catalytic tests.

**Acknowledgments**

Miroslav Stanković<sup>1</sup> \*, Jugoslav Krstić<sup>1</sup> , Margarita Gabrovska2 , Vojkan Radonjić<sup>1</sup> , Dimitrinka Nikolova2 , Davor Lončarević<sup>1</sup> and Dušan Jovanović<sup>1</sup>

