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U okviru ove doktorske disertacije ispitivana je mogućnost sinteze aktivnog niklenog katalizatora modifikovanog magnezijumom u reakciji hidrogenizacije suncokretovog ulja, upotrebom perlita kao nosača katalizatora. Da bi se ispitala moguća aktivacija odabranog perlitnog nosača (PF-295), on je tretiran u destilovanoj vodi na 90 °C, u 10 % rastvoru Na2CO3 na 90 °C i u 9 mol/dm3 HCl-u uz refluks na 100 °C. Karakterizacijom nosača nisu uočene značajne razlike u morfologiji, teksturi i strukturi dobijenih materijala. Za sintezu prekursora na različito tretiranim nosačima korišćen je precipitacionodepozicioni postupak, upotrebom čvrstog Na2CO3 kao taložnog agensa nikl (nNi:nSiO2 = 1) i magnezijum (nMg:nNi = 0,1) vrsta. Rezultati karakterizacija prekursora su pokazali da među njima ne postoje značajne razlike, osim u vrednostima disperznosti (određene hemisorpcijom H2). Takođe su uočene manje razlike u aktivnosti sintetisanih katalizatora u katalitičkim testovima hidrogenizacije suncokretovog ulja. Upotrebom različitih molskih odnosa (nNi:nSiO2 i nMg:nNi) dobijene su dve serije prekursora koje su okarakterisane morfološki, teksturalno i strukturno. Prekursori serije sa različitim sadržajem Ni pokazali su razlike u rezultatima svih karakterizacionih tehnika, a ove razlike su bile još izraženije kod serije sa različitim sadržajem Mg, naročito vrednosti disperznosti Ni0 . Primenom različitih temperatura redukcije (270 °C, 300 °C, 330 °C, 360 °C i 460 °C) i određivanjem vrednosti disperzije Ni0 redukovanih prekursora, utvrđen je optimalni molski odnos nNi:nSiO2 . Optimalna temperatura redukcije ovog prekursora (nNi:nSiO2 = 0,25) određena je na osnovu rezultata katalitičkih testova parcijalne hidrogenizacije suncokretovog ulja. Na ovoj temperaturi (345 °C) su redukovani svi prekursori i ispitani su u katalitičkim testovima, nakon čega je određivan sadržaj masnih kiselina parcijalno hidrogenizovanog suncokretovog ulja gasno-hromatografskom analizom. Utvrđeno je da najveću aktivnost pokazuje katalizator sa molskim odnosom nNi:nSiO2 = 0,25 i nMg:nNi = 0,1. Ovim je pokazano da je moguće sintetisati aktivni nikleni katalizator za hidrogenizaciju suncokretovog ulja upotrebom perlita kao nosača i magnezijuma kao promotora. Within the scope of this doctoral dissertation, the synthesis of a nickel catalyst modified with magnesium on perlite as support for the process of hydrogenation of sunflower oil was investigated. To examine the possible activation of the selected perlite support (PF-295), it was treated in distilled water at 90 °C, in 10% solution of Na2CO3 at 90 °C and in 9 mol/dm3 HCl with reflux at 100 °C. No significant differences in the morphology, texture or structure of the obtained materials were observed. For precursor synthesis, precipitation-deposition method was used with solid Na2CO3 as a precipitating agent of nickel (nNi:nSiO2 = 1) and magnesium (nMg:nNi = 0.1) species. Synthesis of Ni2+ precursors on various supports, using Mg as a modifier, no significant differences in the synthesized precursors were also shown, exept the differences observed in the dispersion values (measured by chemisorption of H2). Minor differences in the activity of afterwards synthesized catalysts were observed in catalytic tests of the hydrogenation of sunflower oil. Variation of the values of two synthesis parameters (nNi:nSiO2 and nMg:nNi) yielded a series of precursors, later characterized by morphological, textural and structural techniques. For different Ni contents, precursors showed an obvious difference in their characterization, while differences in characterization, especially in Ni0 dispersion, were were more obvious for different Mg contents in precursors. Measuring the dispersion of Ni0 at different temperatures (270 °C, 300 °C, 330 °C, 360 °C and 460 °C), the optimal molar ratio of nNi:nSiO2 was obtained. Optimal reduction temperature of this precursor (nNi:nSiO2 = 0.25) was established by their catalytic activity in partial hydrogenation of sunflower oil. At this temperature (345 °C), all precursors were reduced and tested in catalytic hydrogenation of sunflower oil, after which fatty acid composition was determined by gas chromatography. The catalyst with the molar ratio nNi:nSiO2 = 0.25 and nMg:nNi = 0.1 showed the highest activity. With this it was shown that it is possible to synthesize an active nickel catalyst for the hydrogenation of sunflower oil using perlite as support and magnesium as promotor.

Mg-doped co-precipitated Ni/SIG precursors were studied as edible sunflower oil hydrogenation catalysts applying two types of commercial silica gels (SIG) as supports of different texture characteristics: a microporous type (SIG-A) and a mesoporous type (SIG-C). It was found that texture parameters of both the silica gels and magnesium addition allow obtaining of catalysts of various hydrogenation activities and fatty acid composition of the products. The results reveal the highest hydrogenation activity of MgNi/SIG-C catalyst because of higher amount and accessibility of metal nickel particles on the catalyst surface generated through reduction procedure. A dominant activity of MgNi/SIG-C catalyst is ascribed to appropriate mesoporosity, which controls diffusion. It was established that Mg-doped Ni/SIG-C possessed a capacity for use as an efficient edible vegetable oil hydrogenation catalyst due to high hydrogenation activity, high saturation level of linoleic acid (C18:2cis), moderate amounts of C18:1trans fatty acids, and C18:0 stearin acid formation in the partially hydrogenated sunflower oil.

Diatomite supported Ni-Mg catalyst precursors (Ni-Mg/D) with a constant Ni/Mg ratio, prepared by the precipitation-deposition method using different nickel salts, sulfamate, nitrate, chloride, acetate or formate, were studied by hydrogen chemisorptions and temperature programmed reduction (H2- TPR).The results showed that the dispersion of nickel and the reducibility of the prepared catalyst precursors were different depending upon the counter ion of the nickel salt. Among the studied nickel salts, the best results for the dispersion of metallic Ni and reducibility of Ni-Mg/D catalyst precursors were achieved using nickel sulfamate salt.

U radu su sprovedena istraživanja načina poboljšanja tehnologije srednjeg nivoa održavanja radio-relejnih uređaja. Poboljšani model tehnologije održavanja biće primenjen u praksi tokom korektivnog održavanja radio-relejnih uređaja. Rezultati dobijeni tokom primene predloženog modela poslužiće za donošenje zaključaka o uspešnosti primene definisanog modela tehnologije održavanja., The work was conducted to investigate the manner of improving the technology of intermediate level maintenance of radio-relay devices. The Improved model of maintenance techniques will be applied in practice du ring corrective maintenance of radio-relay devices. The results obtained during the application of the proposed model will serve to draw conclusions about the effectiveness of the defined model of maintenance techno logy.

Diatomite supported nickel catalyst precursors (Ni/D) were prepared by the precipitation-deposition (PD) method using different nickel salts such as nitrate, chloride, acetate and formate. The effect of counter ions (NO3-, Cl-, CH3COO-, and HCOO-) on the texture of prepared samples was studied. For determination of the textural characteristics mercury intrusion porosimetry (MIP) and N2 physisorption techniques were used. MIP and physisorption data (pore volume, pore size distribution, porosity as well as N2 adsorptiondesorption isotherms and BET surface area) showed that counter ions were found to have a profound effect on the microstructure and porosity characteristics of Ni/D precursors. An order of the counter ions effect on the textural characteristics of prepared precursors was determined.