64 research outputs found

    Разработка основного массообменного оборудования установки получения азота

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    В данной дипломной работе разработана ректификационная колонна установки получения жидкого азота на производстве АО "СДС Азот". Представлено описание технологической схемы производства. Был проведен технологический, тепловой и механический расчеты, разработан раздел финансового менеджмента, ресурсоэффективности и ресурсосбережения, разработан раздел социальной безопасности. Сделаны выводы по проделанной работе.The diploma work is dedicated to the main-exchange equipment of the nitrogen production at OA "СДС Азот". The graduate work includes technological, thermal and mechanical calculations of the distillation column. The section "Social management" and the section "Financial management, resource efficiency and resource saving" are given. Conclusions are drawn on the work

    Upgrading castor oil: From heptanal to non-isocyanate poly(amide-hydroxyurethane)s

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    Intensive research has recently been carried out to synthesize non-isocyanate polyurethanes (NIPUs) from five-membered cyclic carbonates and amines as a sustainable route to industrial relevant polyurethanes. Herein, an activated disubstituted cyclic carbonate and methyl ester containing monomer CE was prepared using castor oil based heptanal and CO2. Good results for the catalytic cycloaddition have been obtained using renewable sugar cane bagasse in combination with TBAB, and this system has been shown to be recyclable. A novel poly(amide-hydroxyurethane) (PAHU) was obtained by bulk ringopening and amidation polymerization of high reactive CE with 1,6-diaminohexane at low temperature and in absence of catalyst. PAHU contains aliphatic pendant moieties allowing its self-assembling into nanoparticles in aqueous solution, showing potential application in catalysis or drug delivery among other applications

    Heterogeneous dehalogenation of arylhalides in the presence of ionic liquids

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    Dehydrohalogenation of haloaromatics in ionic liquids derived from ethylmethylimidazolium or similar salts has been performed using Pd-C, Pd(OAc)2 and other catalysts using formate salts as a hydrogen source. In the ionic liquid [emim][BF4], chlorobenzene was dehalogenated by up to 40%, bromobenzene up to 25% and iodobenzene up to 41% in 2 h. Reactions in the absence of the ionic liquid were also performed

    Compressed carbon dioxide as a medium in catalytic hydrogenations: Engineering and chemistry

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    International audienceIn the frame of designing eco-friendly chemical processes, solvents represent a crucial economic and environmental concern. Compressed carbon dioxide (CO2) is an alternative green solvent for many industrial applications. Herein, we present the most relevant aspects of using compressed CO2 in metal-catalyzed hydrogenation reactions. In the first part, we discuss engineering fundamentals for the description of processes in supercritical fluids, gas-expanded liquids, continuous-flow applications and process design, including safety aspects and examples of heterogeneous catalysis. In the second part, we focus on catalytic systems based on both metal complexes and nano-systems, emphasizing how the catalysts have been adapted to the specificity of CO2. For this purpose, significant aspects such as the catalyst design, the reaction conditions and the use of co-solvents are considered. The main goal of this review is to show the advantages of using this green solvent in catalytic hydrogenations, including a critical analysis concerning its limitations

    Hydroformylation of oct-1-ene catalyzed by dinuclear gem-dithiolato-bridged rhodium(I) complexes and phosphorus donor ligands

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    The dinuclear gem-dithiolato bridged compounds [Rh2(μ-S2Cptn)(cod)2] (1) (CptnS2 2- = 1,1-cyclopentanedithiolato), [Rh2(μ-S2Chxn)(cod)2] (2) (ChxnS2 2- = 1,1-cyclohexanedithiolato), [Rh2(μ-S2CBn2)(cod)2] (3) (Bn2CS2 2- = 1,3-diphenyl-2,2-dithiolatopropane) and [Rh2(μ-S2CiPr2)(cod)2] (4) (iPr2CS2 2- = 2,4-dimethyl-2,2-dithiolatopentane) dissolved in toluene in the presence of monodentate phosphine or phosphite P-donor ligands under carbon monoxide/hydrogen (1:1) atmosphere are efficient catalysts for the hydroformylation of oct-1-ene under mild conditions (6.8 atm of CO/H2 and 80 °C). The influence of the gem-dithiolato ligand, the P-donor co-catalyst and the P/Rh ratio on the catalytic activity and selectivity has been explored. Aldehyde selectivities higher than 95% and turnover frequencies up to 245 h-1 have been obtained using P(OMe)3 as modifying ligand. Similar activity figures have been obtained using P(OPh)3 although the selectivities are lower. Regioselectivities toward linear aldehyde are in the range 75-85%. The performance of the catalytic systems [Rh2(μ-S2CR2)(CO)2(PPh3)2]/PPh3 has been found to be comparable to the systems [Rh2(μ-S2CR2)(cod)2] at the same P/Rh ratio. The system [Rh2(μ-S2CBn2)(cod)2] (3)/P(OPh)3 has been tested in the hydroformylation-isomerization of trans-oct-2-ene. Under optimized conditions up to 54% nonanal was obtained. Spectroscopic studies under pressure (HPNMR and HPIR) evidenced the formation of hydrido mononuclear species under catalytic conditions that are most probably responsible for the observed catalytic activity.The financial support from Ministerio de Educación y Ciencia (MEC/FEDER) Project CTQ2006-03973/BQU is gratefully acknowledged. A.B.R. thanks the Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo (CYTED) for a fellowship. A.B.R. and A.J.P. thank to Fonacit-Venezuela (S1-2002000260) for financial support.Peer Reviewe

    Novel chromium (III) complexes with N4-donor ligands as catalysts for the coupling of CO2 and epoxides in supercritical CO2

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    10.1016/j.molcata.2013.10.021New neutral and cationic chromium(III) complexes with N4 Schiff base ligands have been prepared and characterized. These complexes are active catalysts for the cycloaddition of CO2 and styrene oxide in CH2Cl2 solutions, affording epoxide conversions in a 39¿92% range, with encouraging cyclic carbonate yields (up to 63%). It is to notice that the cationic species were significantly more active than their neutral analogs. Addition of tetrabutylammonium halides improved the selectivity toward styrene carbonate (87% yield). Dichloromethane could be avoided using solvent free or supercritical carbon dioxide as a solvent (scCO2) and, moreover, this improved the catalytic activity of the cationic complexes (TOF up to 652 h-1). Using scCO2, these chromium catalysts afforded the rapid and selective formation of cyclic carbonates from the coupling of CO2 to various linear terminal epoxides, such as epichlorydrin, propylene oxide and long chain terminal oxiranes. Coupling of cyclohexene oxide and carbon dioxide led to mixtures of poly(cyclohexene) carbonate and cyclic carbonate depending on the conditions (pressure and co-catalyst/catalyst ratio). Poly(cyclohexene) carbonate was isolated with a productivity 388 g/g Cr. Selective formation of the cyclic cyclohexene carbonate was obtained working under scCO2 conditions

    Hydrocarboxylation of Terminal Alkenes in Supercritical Carbon Dioxide

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    The catalytic hydrocarboxylation of linear alkenes to carboxylic acids using supercritical carbon dioxide as a solvent was studied. High selectivities in acids have been obtained. The best results were achieved when adding a perfluorinated surfactant to the reaction mixture (93% conversions and ca. 80% selectivity). Comparative multinuclear high-pressure NMR spectroscopic studies in [D8]THF and in supercritical CO2 show the formation of Pd0 species
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