592-13-2Relevant academic research and scientific papers
Design of dendrimer-based nanostructured catalyst systems and their catalytic activity in hydrogenation: Synthesis of ruthenium nanoparticles immobilized in dendrimer networks
Karakhanov,Maksimov,Zolotukhina,Kardashev
, p. 290 - 297 (2010)
A new method has been proposed for immobilization of 3-nm ruthenium nanoparticles on special supports synthesized for this purpose, polymer networks based on poly(propylene imine) dendrimers. It has been shown that the structure of the support has a substantial effect on the size of particles and their catalytic activity in the hydrogenation reactions of unsaturated and aromatic compounds. The catalysts can be reused without loss of activity.
Selective hydrogenation of terminal alkynes over palladium nanoparticles within the pores of amino-modified porous aromatic frameworks
Karakhanov, Edward,Maximov, Anton,Terenina, Maria,Vinokurov, Vladimir,Kulikov, Leonid,Makeeva, Daria,Glotov, Aleksandr
, p. 176 - 184 (2019/05/24)
Palladium catalysts, based on porous aromatic frameworks, synthesized via Suzuki cross-coupling reaction and further modified with amino groups, were prepared and tested in hydrogenation of several unsaturated compounds. Catalysts obtained were characterized by several techniques including IR spectroscopy, solid-state NMR spectroscopy, low-temperature nitrogen adsorption, transmission electron microscopy, atomic emission spectroscopy and X-ray photoelectron spectroscopy. It was shown that the amino-groups within the structure of aromatic frameworks interact with palladium nanoparticles and enhance their selectivity towards hydrogenation of terminal alkynes.
Potassium Yttrium Ate Complexes: Synergistic Effect Enabled Reversible H2 Activation and Catalytic Hydrogenation
Zhai, Dan-Dan,Du, Hui-Zhen,Zhang, Xiang-Yu,Liu, Yu-Feng,Guan, Bing-Tao
, p. 8766 - 8771 (2019/09/30)
A potassium yttrium benzyl ate complex was generated simply by mixing an yttrium amide and potassium benzyl. The benzyl ate complex could undergo peripheral deprotonation to produce a cyclometalated complex or hydrogenation to give a hydride ate complex. The latter hydride ate complex features a (KH)2 structure protected by two yttrium amide complexes. The synergistic effect between potassium hydride and the amide ligand enables the complex to deprotonate a methyl C-H bond. The combination of intramolecular deprotonation of the hydride ate complex and hydrogenation of the cyclometalated complex constitutes a reversible H2 activation process. Using this process involving formal addition and elimination of H2, we accomplished the catalytic hydrogenation of alkenes, alkynes, and imines.
Electrochemical cross-coupling of biogenic di-acids for sustainable fuel production
Holzh?user, F. Joschka,Creusen, Guido,Moos, Gilles,Dahmen, Manuel,K?nig, Andrea,Artz, Jens,Palkovits, Stefan,Palkovits, Regina
, p. 2334 - 2344 (2019/05/21)
Direct electrocatalytic conversion of bio-derivable acids represents a promising technique for the production of value-added chemicals and tailor-made fuels from lignocellulosic biomass. In the present contribution, we report the electrochemical decarboxylation and cross-coupling of ethyl hydrogen succinate, methyl hydrogen methylsuccinate and methylhexanoic acid with isovaleric acid. The reactions were performed in aqueous solutions or methanol at ambient temperatures, following the principles of green chemistry. High conversions of the starting materials have been obtained with maximum yields between 42 and 61% towards the desired branched alkane products. Besides costly Pt electrodes also (RuxTi1-x)O2 on Ti electrodes exhibited a notable activity for cross-Kolbe electrolysis. As some of the products are insoluble in water, easy product isolation and reuse of the reaction solvent is enabled via phase separation. Several side products have been identified to evaluate the efficiency of the reaction and to elucidate the factors influencing the product selectivity. The yielded alkanes and esters were assessed with regard to their potential as fuels for internal combustion engines. While the longer alkanes constitute promising candidates for the compression-ignition engine, the smaller ester represents an interesting option for the spark-ignition engine.
Dendrimer-Encapsulated Pd Nanoparticles, Immobilized in Silica Pores, as Catalysts for Selective Hydrogenation of Unsaturated Compounds
Karakanov, Edward A.,Zolotukhina, Anna V.,Ivanov, Andrey O.,Maximov, Anton L.
, p. 358 - 381 (2019/04/04)
Heterogeneous Pd-containing nanocatalysts, based on poly (propylene imine) dendrimers immobilized in silica pores and networks, obtained by co-hydrolysis in situ, have been synthesized and examined in the hydrogenation of various unsaturated compounds. The catalyst activity and selectivity were found to strongly depend on the carrier structure as well as on the substrate electron and geometric features. Thus, mesoporous catalyst, synthesized in presence of both polymeric template and tetraethoxysilane, revealed the maximum activity in the hydrogenation of various styrenes, including bulky and rigid stilbene and its isomers, reaching TOF values of about 230000 h?1. Other mesoporous catalyst, synthesized in the presence of polymeric template, but without addition of Si(OEt)4, provided the trans-cyclooctene formation with the selectivity of 90–95 %, appearing as similar to homogeneous dendrimer-based catalysts. Microporous catalyst, obtained only on the presence of Si(OEt)4, while dendrimer molecules acting as both anchored ligands and template, demonstrated the maximum activity in the hydrogenation of terminal linear alkynes and conjugated dienes, reaching TOF values up to 400000 h?1. Herein the total selectivity on alkene in the case of terminal alkynes and conjugated dienes reached 95–99 % even at hydrogen pressure of 30 atm. The catalysts synthesized can be easily isolated from reaction products and recycled without significant loss of activity.
Unsaturated-compound hydrogenation nanocatalysts based on palladium and platinum particles immobilized in pores of mesoporous aromatic frameworks
Kulikov,Terenina,Kryazheva, I. Yu.,Karakhanov
, p. 222 - 229 (2017/04/07)
Heterogeneous catalysts for the hydrogenation of unsaturated hydrocarbons have been synthesized on the basis of palladium and platinum nanoparticles immobilized in pores of mesoporous aromatic frameworks, which represent a new class of carbon supports with a diamond-like ordered structure. The resulting materials have been characterized by transmission electron microscopy, IR spectroscopy, and NMR spectroscopy. It has been shown that the catalyst activity in the hydrogenation reaction depends on the substrate molecule size and adsorbability on the surface of nanoparticles. Catalytic activity has been studied in the hydrogenation of a number of unsaturated compounds at temperatures of 60 and 80°C and pressures of 1.0 and 3.0 MPa.
IONIC LIQUID ALKYLATION OF 1-BUTENE TO PRODUCE 2,5-DIMETHYLHEXANE
-
Page/Page column 17, (2015/09/23)
A process for producing dimethylhexanes (DMH) is provided. The DMH can be used to produce p-xylene. The process involves the alkylation of isobutane and 1-butene using an ionic liquid to produce naphtha that is rich in DMH. The DMH is then converted in high selectivity to xylene, including p-xylene, by dehydrocyclization.
IONIC LIQUID ALKYLATION OF 1-BUTENE TO PRODUCE 2,5-DIMETHYLHEXANE
-
Paragraph 0072, (2015/08/04)
A process for producing dimethylhexanes (DMH) is provided. The DMH can be used to produce p-xylene. The process involves the alkylation of isobutane and 1-butene using an ionic liquid to produce naphtha that is rich in DMH. The DMH is then converted in high selectivity to xylene, including p-xylene, by dehydrocyclization.
Mesoporous organic Pd-containing catalysts for the selective hydrogenation of conjugated hydrocarbons
Karakhanov,Maksimov,Aksenov,Kuznetsov,Filippova,Kardashev,Volkov
, p. 1710 - 1716 (2015/05/20)
Palladium catalysts supported on ordered organic mesoporous polymers were synthesized. The catalysts are characterized by the narrow size distribution of palladium nanoparticles with an average particle size of 2.2-5.2 nm. They demonstrate high catalytic activity and selectivity in phenylacetylene hydrogenation (896-2590 min-1, selectivity 89-98%). High activity and selectivity for alkenes are observed in the hydrogenation of conjugated dienes (for isoprene, TOF = 1850-5000 min-1, selectivity 99%; for 2,5-dimethyl-2,4-hexadiene, TOF = = 1294-2400 min-1, selectivity 100%; for 1,4-diphenyl-1,3-butadiene, TOF = 14-22 min-1, selectivity 7-16%). A dependence of the selectivity on the nature of the support and substrate was found for the hydrogenation of 1,4-diphenyl-1,3-butadiene.
Enhancement of dehydrogenation and hydride transfer by La3+ cations in zeolites during acid catalyzed alkane reactions
Schuessler, Florian,Schallmoser, Stefan,Shi, Hui,Haller, Gary L.,Ember, Erika,Lercher, Johannes A.
, p. 1743 - 1752 (2014/06/24)
La3+ cations exchanged into ultrastable zeolite Y and zeolite X promote catalytic isomerization, cracking, and alkylation of alkanes. La 3+ cations stabilize the zeolite lattices and, more importantly, polarize alkane C-H bonds to enhance the rates of all three reactions. This unique activity leads to stable cracking and isomerization of reactive alkanes, with polarizable C-H bonds with adjacent tertiary or quaternary carbon atoms below 370 K. The presence of La3+ cations also enhances the zeolite catalyzed hydride transfer rate for isobutane alkylation with 2-butene leading to high catalyst stability. Solid state MAS NMR shows that the strongest positive effects are associated with nonhydroxylated La3+ cations accessible to the reacting molecules in supercages of the zeolite. The high activity is the result of a cooperative polarization of C-H bonds of alkanes by La3+ cations and the presence of stable and strong Bronsted acid sites.
