Укріплення системи матеріально-технічного забезпечення аграрного сектора

Запропоновано методику розрахунку мінімально необхідного ефективного комплекту сільськогосподарської техніки в ході формування і укріплення системи матеріально-технічного забезпечення аграрного сектора. Метою статті є висвітлення процедури формування системи забезпечення аграрного сектора сільськогосподарською технікою на основі її зв’язку з підвищенням ефективності діяльності аграрних підприємств. Ключові слова: аграрний сектор, система матеріально-технічного забезпечення, мінімально-необхідний комплект техніки, ефективність господарської діяльності.Предложена методика расчета минимально необходимого эффективного комплекта сельскохозяйственной техники в ходе формирования и укрепления системы материально-технического обеспечения аграрного сектора. Целью данной статьи является освещение процедуры формирования системы обеспечения аграрного сектора сельскохозяйственной техникой на основе ее связи с повышением эффективности деятельности аграрных предприятий. Ключевые слова: аграрный сектор, система материально-технического обеспечения, минимально необходимый комплект техники, эффективность хозяйственной деятельности.The method of calculation minimum of necessary effective complete set of agricultural technique is offered during forming and strengthening of the system of logistical support of agrarian sector. The purpose of this article is illumination of procedure of forming of the system of providing of agrarian sector an agricultural technique on the basis of its connection with the increase of efficiency of activity of agrarian enterprises. Key words: agrarian sector, system of logistical support, minimally necessary complete set of technique, efficiency of economic activity

Generating parahydrogen-induced polarization using immobilized iridium complexes in the gas-phase hydrogenation of carbon-carbon double and triple bonds

Immobilized iridium complexes synthesized using [Ir(COD)Cl]2 by anchoring on hydrous and anhydrous silica gels were studied in terms of generating parahydrogen-induced polarization (PHIP) in the gas-phase hydrogenation of propylene and propyne. Distinguishing differences in the hydrogenations of carbon– carbon double and triple bonds were found. It has been shown that in the double bond hydrogenation both catalysts are very active even at 25 C. The reaction yield in continuous flow experiments is more than 70 %, whereas the obtained PHIP degrees are very low. In the case of the triple bond hydrogenation, a more or less active hydrogenation reaction was observed at relatively high temperatures (&70–80 C) for the catalyst immobilized on anhydrous silica, while the catalyst immobilized on hydrous silica was inactive at these temperatures. Contrary to the double bond hydrogenation, the triple bond hydrogenation provided significant signal enhancements observed in 1H nuclear magnetic resonance spectra for the signals corresponding to protons of vinyl fragments of product propylene in both PASADENA and ALTADENA experiments. The catalyst, however, is not stable under the triple bond hydrogenation reaction conditions, and deactivates within several minutes. It was also found that at higher temperatures (100–120 C), this catalyst demonstrates a reactivation most likely associated with the reduction of Ir(I) that results in the formation of Ir(0) surface metal nanoparticles

Generating parahydrogen-induced polarization using immobilized iridium complexes in the gas-phase hydrogenation of carbon-carbon double and triple bonds

Immobilized iridium complexes synthesized using [Ir(COD)Cl]2 by anchoring on hydrous and anhydrous silica gels were studied in terms of generating parahydrogen-induced polarization (PHIP) in the gas-phase hydrogenation of propylene and propyne. Distinguishing differences in the hydrogenations of carbon– carbon double and triple bonds were found. It has been shown that in the double bond hydrogenation both catalysts are very active even at 25 C. The reaction yield in continuous flow experiments is more than 70 %, whereas the obtained PHIP degrees are very low. In the case of the triple bond hydrogenation, a more or less active hydrogenation reaction was observed at relatively high temperatures (&70–80 C) for the catalyst immobilized on anhydrous silica, while the catalyst immobilized on hydrous silica was inactive at these temperatures. Contrary to the double bond hydrogenation, the triple bond hydrogenation provided significant signal enhancements observed in 1H nuclear magnetic resonance spectra for the signals corresponding to protons of vinyl fragments of product propylene in both PASADENA and ALTADENA experiments. The catalyst, however, is not stable under the triple bond hydrogenation reaction conditions, and deactivates within several minutes. It was also found that at higher temperatures (100–120 C), this catalyst demonstrates a reactivation most likely associated with the reduction of Ir(I) that results in the formation of Ir(0) surface metal nanoparticles

Monitoring transport phenomena of paramagnetic metal-ion complexes inside catalyst bodies with magnetic resonance imaging

An indirect magnetic resonance imaging (MRI) method has been developed to determine in a noninvasive manner the distribution of paramagnetic Co2+ complexes inside Co/Al2O3 catalyst extrudates after impregnation with Co2+/citrate solutions of different pH and citrate concentrations. UV/Vis/NIR microspectroscopic measurements were carried out simultaneously to obtain complementary information on the nature of the Co2+ complexes. In this way, it could be confirmed that the actual distribution of Co2+ inside the extrudates could be derived from the MRI images. By combining these space- and time-resolved techniques, information was obtained on both the strength and the mode of interaction between [Co(H2O)6]2+ and different Co2+ citrate complexes with the Al2O3 support. Complexation of Co2+ by citrate was found to lead to a stronger interaction of Co with the support surface and formation of an eggshell distribution of Co2+ complexes after impregnation. By addition of free citrate and by changing the pH of the impregnation solution, it was possible to obtain the rather uncommon egg-yolk and egg-white distributions of Co2+ inside the extrudates after impregnation. In other words, by carefully altering the chemical composition and pH of the impregnation solution, the macrodistribution of Co2+ complexes inside catalyst extrudates could be fine-tuned from eggshell over egg white and egg yolk to uniform

Solid-state 27 Al MRI and NMR thermometry for catalytic applications with conventional (liquids) MRI instrumentation and techniques

Multidimensional images of Al2O3 pellets, cordierite monolith, glass tube, polycrystalline V2O5 and other materials have been detected by 27Al, 51V, and 23Na NMR imaging using techniques and instrumentation conventionally employed for imaging of liquids. These results demonstrate that, contrary to the widely accepted opinion, imaging of ¿rigid¿ solids does not necessarily require utilization of solid state NMR imaging approaches, pulse sequences and hardware even for quadrupolar nuclei which exhibit line widths in excess of 100 kHz, such as 51V in polycrystalline V2O5. It is further demonstrated that both 27Al NMR signal intensity and spin-lattice relaxation time decrease with increasing temperature and thus can potentially serve as temperature sensitive parameters for spatially resolved NMR thermometry

Magnetic resonance imaging as an emerging tool for studying the preparation of supported catalysts

Several magnetic resonance imaging (MRI) approaches are presented that can be used to study transport processes when supported catalysts are prepared by impregnating mm-sized porous support bodies. Both diamagnetic and paramagnetic components of an impregnation solution such as the solvent, the metal-containing precursors of an active component, and various organic and inorganic additives can be visualized with MRI. Their spatial distributions within a catalyst support body and the evolution of these distributions in time can be characterized not only qualitatively but also quantitatively, if calibration procedures are used to convert the images into corresponding concentration profiles. In particular, the physicochemical interactions between γ-Al2O3 support bodies and the aqueous solutions containing Cu, Co, Mo, citrate and phosphate ions are investigated upon pore volume impregnation as a function of concentration and solution pH. Furthermore, it is shown that multinuclear and solid state MRI can be used to map the solid phase distribution of the active component precursors and additives within the impregnated support bodies after their drying. Based on the case studies discussed, it can be concluded that MRI is an emerging versatile tool for studying the transport processes in support bodies upon their impregnation and the distribution of the key components after drying of the impregnated bodies

Kinetic Study of Propylene Hydrogenation over Pt/Al2O3 by Parahydrogen-Induced Polarization

Parahydrogen-induced polarization has been successfully used for a kinetic study of propylene hydrogenation over a Pt/Al2O3 catalyst. It was shown that the reaction orders with respect to hydrogen are different for the pairwise and the non-pairwise hydrogen addition and are equal to 0.7 and 0.1, respectively. This observation of different reaction orders confirms the coexistence of different types of active sites which are responsible for the overall and the pairwise hydrogen addition to the propylene C=C double bond. Moreover, 0.7 reaction order with respect to H2 for pairwise hydrogen addition indicates that the contribution of pairwise addition depends on the concentration of molecular hydrogen. Therefore, this observation can be developed into a practical tool for producing fluids with highly polarized nuclear spins by changing the hydrogen concentration