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Pd/Fiber glass and Pd/5% γ-Al2O3/Fiber glass catalysts by surface self-propagating thermal synthesis
O. O. Mironenko N. B. Shitova Y. S. Kotolevich M. R. Sharafutdinov N. O. Struikhina N. S. Smirnova D. I. Kochubey O. V. Protasova M. V. Trenikhin O. A. Stonkus V. I. Zaikovskii V. B. Goncharov P. G. Tsyrul’nikov 《International Journal of Self-Propagating High-Temperature Synthesis》2012,21(2):139-145
The technique of Surface Self-propagating Thermal Synthesis (SSTS) was used to prepare Pd/??-Al2O3/fiber glass (FG) catalysts for selective liquid-phase hydrogenation of acetylene in the presence of CO. The results of XRD SR analysis (in synchrotron radiation) in combination with the technique of arrested combustion shed new light on the dynamic of phase transformations in the systems under study and variation in the size of diffraction-active crystallites. The catalytic performance of synthesized catalysts was found to be close to that of similar conventionally prepared catalysts. The EXAFS and TEM data afforded to estimate the variation in relative amounts of Pd0 and PdO in synthesized catalysts. In the course of selective hydrogenation, PdO rapidly (<15 min) reduced to Pd0. 相似文献
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O. O. Mironenko G. A. Sosnin P. M. Eletskii Yu. K. Gulyaeva O. A. Bulavchenko O. A. Stonkus V. O. Rodina V. A. Yakovlev 《Petroleum Chemistry》2017,57(7):618-629
The features of the steam cracking of heavy crude oil in the presence of a dispersed molybdenumcontaining catalyst are studied. The effect of water, the catalyst, and process conditions on the composition and properties of the products of the thermal conversion of heavy crude oil is determined in experiments on thermal cracking, steam cracking, catalytic cracking in the absence of water, and hydrocracking. A complex analysis of the resulting products is conducted; the catalyst-containing solid residue (coke) has been studied by XRD and HRTEM. The effect of the process temperature (425 and 450°C) and time on the yields and properties of the resulting products is studied. The efficiencies of hydrocracking and steam cracking for the production of upgraded low-viscosity semisynthetic oil are compared; the fundamental changes that occur in the catalyst during the studied processes are discussed. Some assumptions about the principle of the catalytic action of the molybdenum-containing catalyst in the steam cracking process are made. 相似文献
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Assessing the degradation of electrical cable insulation is an important feature in extending plant life. The older generating stations are extensively wired with PVC insulated cables, and procedures have been developed to assess degradation using micro specimens in a manner that does not destroy the function of the cable. Material degradation of accelerated aged specimens was systematically monitored by measuring melting or glass transition temperatures ( Tg ), gel content, infrared peroxide absorbance, relative hardness, and plasticizer loss. The shift in the Tg or the characteristic melting peak predicted the maximum exposure temperature of the PVC. The peroxide absorbance and gel content measurements were sensitive indicators of degradation. The relative hardness as measured by thermo-mechanical analyzer (TMA) penetration distance and plasticizer content decreased as the material aged. The results obtained on micro specimens were related to the ultimate elongation values, which have been the traditional measure of degradation. 相似文献
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This paper presents procedures to monitor oxidation degradation of two commonly used cable insulations, crosslinked polyethylene (XLPE) and ethylene propylene rubber (EPR). Since the techniques described require only micro specimens, deterioration of cable insulation can be monitored without destroying the function of the cable. The techniques described are melting point, crystallinity, infrared carbonyl absorbance, gel content, relative hardness, and differential scanning calorimetry (DSC) oxidation induction time. The techniques were applied following accelerated aging over a period in excess of two years. The results from the micro specimens were directly related to embrittlement and the decrease in ultimate elongation. The previous thermal history of XLPE was determined using DSC melting peak analysis. 相似文献
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Arina N. Suboch Svetlana V. Cherepanova Lidiya S. Kibis Dmitry A. Svintsitskiy Olga A. Stonkus Andrei I. Boronin 《Fullerenes, Nanotubes and Carbon Nanostructures》2016,24(8):520-530
A superstructural peak at ~12° in X-ray diffraction patterns of nitrogen-doped carbon nanotubes compared to the undoped carbon nanotubes was observed and assigned to the formation of spatially ordered defects. The simulation of the N-CNT structure using the graphitic g-C3N4 phase and turbostratic ordering made it possible to propose a new model of the spatially ordered defects in the N-CNT layer, which consist of clusters of carbon vacancies and pyridine-like nitrogen. A correlation between this type of defects and electrical conductivity of the N-CNTs is defined. 相似文献
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Vladislavs Stonkus Ludmila Leite Anton Lebedev Edmunds Lukevics Augusts Ruplis Jerzy Stoch Maciej Mikolajczyk 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2001,76(1):101-105
The cyclodehydration of 1,4‐butanediol over cobalt catalysts in the liquid phase is used for the production of 2,3‐dihydrofuran. The catalyst preparation parameters considered were the metal loading, precipitation pH and reduction temperature of cobalt salt. It was found that the use of Co(NO3)2 together with Na2CO3 in a 1:1 ratio yielded better catalysts. Under the conditions used in this study the optimum cobalt loading for the selective production of 2,3‐dihydrofuran is in the range 15–50 wt%. The optimum reduction temperature of Co/porcelain catalyst depends on cobalt loading. The optimum reduction temperatures for 15 and 50 wt% cobalt loading are 773 and 723 K (reduction time 20 min), respectively. © 2001 Society of Chemical Industry 相似文献
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O. O. Mironenko G. A. Sosnin P. M. Eletskii Yu. K. Gulyaeva O. A. Bulavchenko O. A. Stonkus V. O. Rodina V. A. Yakovlev 《Catalysis in Industry》2017,9(3):221-229
The catalytic steam cracking (CSC) of heavy crude oil with high amount of sulfur (4.3 wt %) and high-boiling fractions (>500°C) is studied using Mo and Ni nanodispersed catalysts under static conditions (in an autoclave) at 425°C. Experiments on thermal cracking, steam cracking, and catalytic cracking without water are performed to compare and identify the features of CSC. The relationship between the composition and properties of liquid and gaseous products and process conditions, the type of catalyst, and water is studied. Using Ni catalyst in CSC raises the H: C ratio (1.69) in liquid products, compared to other types of cracking, but also increases the yield of coke and gaseous products, so the yield of liquid products falls. When Mo catalyst is used in CSC, low-viscosity semi-synthetic oil with a higher H: C ratio (1.70) and the lowest amount of sulfur in liquid products (2.8 wt %) is produced. XRF and HRTEM studies of the catalyst-containing solid residue (coke) show that under CSC conditions, nickel is present in the form of well-crystallized nanoparticles of Ni9S8 15–40 nm in size, while molybdenum exists in two phases: MoO2 and MoS2, the ratio between which depends on the conditions of the transformation of heavy crude oil. The findings indicate that CSC is a promising process for improving heavy crude oil. 相似文献
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P. M. Eletskii O. O. Mironenko G. A. Sosnin O. A. Bulavchenko O. A. Stonkus V. A. Yakovlev 《Catalysis in Industry》2016,8(4):328-335
The process of heavy crude oil (HCO) steam cracking under a batch regime at 425°C in the presence of Ni-containing nanodispersed catalyst (0.3–2.0 wt % with respect to Ni) is investigated. It is established that using this catalyst facilitates the upgrading of semi-synthetic oil produced from HCO: the Н: С ratio rises (in comparison to steam cracking with no catalyst), and the sulfur content and viscosity are reduced. The Н: С ratio in the liquid products grows slightly along with the catalyst content, but the yield of liquid products falls from 81 to 76% during the process with a simultaneous increase in the yield of coke and gaseous products (from 8 to 13 and from 2 to 4 wt %, respectively). Catalyst with coke residue is investigated by means of XRD and TEM. It is shown that nanosized particles of the Ni9S8 phase with sizes of 15–40 nm form from the catalyst precursor (Ni(NO3)2 · 6H2O) under the process conditions. The selection and investigation of catalytic systems for heavy crude oil cracking in the presence of superheated steam, along with optimization of the process conditions, are required to further enhance the efficiency of the upgrading process. 相似文献
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Ilze Kumpina Vladislavs Baskevics Khoi D. Nguyen Dr. Martins Katkevics Prof. Eriks Rozners 《Chembiochem : a European journal of chemical biology》2023,24(15):e202300291
Triple-helical recognition of any sequence of double-stranded RNA requires high affinity Hoogsteen hydrogen binding to pyrimidine interruptions of polypurine tracts. Because pyrimidines have only one hydrogen bond donor/acceptor on Hoogsteen face, their triple-helical recognition is a formidable problem. The present study explored various five-membered heterocycles and linkers that connect nucleobases to backbone of peptide nucleic acid (PNA) to optimize formation of X•C-G and Y•U-A triplets. Molecular modeling and biophysical (UV melting and isothermal titration calorimetry) results revealed a complex interplay between the heterocyclic nucleobase and linker to PNA backbone. While the five-membered heterocycles did not improve pyrimidine recognition, increasing the linker length by four atoms provided promising gains in binding affinity and selectivity. The results suggest that further optimization of heterocyclic bases with extended linkers to PNA backbone may be a promising approach to triple-helical recognition of RNA. 相似文献
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