- Carrier-Induced Modification of Palladium Nanoparticles on Porous Boron Nitride for Alkyne Semi-Hydrogenation
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Chemical modifiers enhance the efficiency of metal catalysts in numerous applications, but their introduction often involves toxic or expensive precursors and complicates the synthesis. Here, we show that a porous boron nitride carrier can directly modify supported palladium nanoparticles, originating unparalleled performance in the continuous semi-hydrogenation of alkynes. Analysis of the impact of various structural parameters reveals that using a defective high surface area boron nitride and ensuring a palladium particle size of 4–5 nm is critical for maximizing the specific rate. The combined experimental and theoretical analyses point towards boron incorporation from defects in the support to the palladium subsurface, creating the desired isolated ensembles determining the selectivity. This practical approach highlights the unexplored potential of using tailored carriers for catalyst design.
- Büchele, Simon,Chen, Zupeng,Fako, Edvin,Hauert, Roland,Krumeich, Frank,López, Núria,Mitchell, Sharon,Pérez-Ramírez, Javier,Safonova, Olga V.
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- Regio- and Chemoselective Hydrogenation of Dienes to Monoenes Governed by a Well-Structured Bimetallic Surface
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Unprecedented surface chemistry, governed by specific atomic arrangements and the steric effect of ordered alloys, is reported. Rh-based ordered alloys supported on SiO2 (RhxMy/SiO2, M = Bi, Cu, Fe, Ga, In, Pb, Sn, and Zn) were prepared and tested as catalysts for selective hydrogenation of trans-1,4-hexadiene to trans-2-hexene. RhBi/SiO2 exhibited excellent regioselectivity for the terminal C=C bond and chemoselective hydrogenation to the monoene, not to the overhydrogenated alkane, resulting in a high trans-2-hexene yield. Various asymmetric dienes, including terpenoids, were converted into the corresponding inner monoenes in high yields. This is the first example of a regio- and chemoselective hydrogenation of dienes using heterogeneous catalysts. Kinetic studies and density functional theory calculations revealed the origin of the high selectivity: (1) one-dimensionally aligned Rh arrays geometrically limit hydrogen diffusion and attack to alkenyl carbons from one direction and (2) adsorption of the inner C=C moiety to Rh is inhibited by steric repulsion from the large Bi atoms. The combination of these effects preferentially hydrogenates the terminal C=C bond and prevents overhydrogenation to the alkane.
- Miyazaki, Masayoshi,Furukawa, Shinya,Komatsu, Takayuki
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- Competitive reactions and mechanisms in the simultaneous HDO of phenol and methyl heptanoate over sulphided NiMo/γ-Al2O3
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Hydrodeoxygenation (HDO) of phenol and methyl heptanoate separately and as mixtures was carried out over a sulphided NiMo catalyst to compare the HDO of aromatic and aliphatic reactants. Some experiments were also carried out in the presence of a sulphur additive. The conversion of phenol was suppressed in the presence of methyl heptanoate, whereas the conversion of methyl heptanoate was practically unaffected by phenol. In addition, distributions of the hydrocarbon products were different for reactants in the mixture and the reactants tested separately. Sulphur additive changed the product distribution of the separate components more than that of the mixture. The findings indicate that reduction (including hydrogenation) reactions occur on coordinatively unsaturated sites (CUS) independently of the aromatic or aliphatic character of the component. Sulphur, too, adsorbs on CUS and competes with other reactants that have an affinity to CUS. Decarbonylation and acid-catalysed reactions are, instead, proposed to occur on sulphur-saturated sites.
- Ryymin, Eeva-Maija,Honkela, Maija L.,Viljava, Tuula-Riitta,Krause, A.Outi I.
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- Direct Reduction of 1-Bromo-6-chlorohexane and 1-Chloro-6-iodohexane at Silver Cathodes in Dimethylformamide
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Cyclic voltammetry and controlled-potential (bulk) electrolyses have been employed to probe the electrochemical reductions of 1-bromo-6-chlorohexane and 1‐chloro-6-iodohexane at silver cathodes in dimethylformamide (DMF) containing 0.050?M tetra-n-butylammonium tetrafluoroborate (TBABF4). A cyclic voltammogram for reduction of 1-bromo-6-chlorohexane shows a single major irreversible cathodic peak, whereas reduction of 1-chloro-6-iodohexane gives rise to a pair of irreversible cathodic peaks. Controlled-potential (bulk) electrolyses of 1-bromo-6-chlorohexane at a silver gauze cathode reveal that the process involves a two-electron cleavage of the carbon–bromine bond to afford 1-chlorohexane as the major product, along with 6-chloro-1-hexene, n‐hexane, 1‐hexene, and 1,5-hexadiene as minor species. In contrast, bulk electrolyses of 1-chloro-6-iodohexane indicate that the first voltammetric peak corresponds to a one-electron process, leading to production of a dimer (1,12-dichlorododecane) together with 1-chlorohexane and 6-chloro-1-hexene as well as 1‐hexene and 1,5-hexadiene in trace amounts. At potentials corresponding to the second cathodic peak, reduction of 1-chloro-6-iodohexane is a mixture of one- and two-electron steps that yields the same set of products, but in different proportions. Mechanistic schemes are proposed to explain the electrochemical behavior of both 1‐bromo-6-chlorohexane and 1-chloro-6-iodohexane.
- Rose, John A.,McGuire, Caitlyn M.,Hansen, Angela M.,Karty, Jonathan A.,Mubarak, Mohammad S.,Peters, Dennis G.
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- Calcium Hydride Cation [CaH]+ Stabilized by an NNNN-type Macrocyclic Ligand: A Selective Catalyst for Olefin Hydrogenation
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Reaction of dibenzyl calcium complex [Ca(Me4TACD)(CH2Ph)2], containing the neutral NNNN-type macrocyclic ligand Me4TACD (Me4TACD=1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane), with triphenylsilane gave the cationic dinuclear calcium hydride [Ca2H2(Me4TACD)2](PhCHSiPh3)2 which was characterized by NMR spectroscopy and single-crystal X-ray diffraction. The cation can be regarded as the ligand-stabilized dimeric form of hypothetical [CaH]+. Hydrogenolysis of benzyl calcium cation [Ca(Me4TACD)(CH2Ph)(thf)]+ gave dicationic calcium hydrides [Ca2H2(Me4TACD)2][BAr4]2 (Ar=C6H4-4-tBu; C6H3-3,5-Me2) containing weakly coordinating anions. In THF, they catalyzed the isotope exchange of H2 and D2 to give HD and the hydrogenation of unactivated 1-alkenes.
- Schuhknecht, Danny,Lhotzky, Carolin,Spaniol, Thomas P.,Maron, Laurent,Okuda, Jun
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- Intrinsic role of pH in altering catalyst properties of NiMoP over alumino-silicate for the vapour phase hydrodeoxygenation of methyl heptanoate
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Monometallic and bimetallic Ni2P, MoP, and NiMoP active species were successfully impregnated on thermally stable, high surface area mesoporous alumino-silicate with an Si/Al ratio of 10 at room temperature via a facile wet impregnation method under both acidic and basic conditions using HCl and NH4OH as pH regulators, respectively. Furthermore, the intrinsic role of pH in altering the physicochemical properties of the catalysts was comprehensively evaluated. The catalysts were tested in a high-pressure stainless steel fixed bed reactor at different temperatures ranging from 275-350 °C, under 10-40 bar hydrogen pressure for the hydrodeoxygenation (HDO) of methyl heptanoate. The reaction pathway and product distribution of methyl heptanoate were manifested at different temperatures and pressures. The HDO activity and synergistic factor were found to be remarkably higher for the NiMoP/MAS (10)-A catalyst than the NiMoP/MAS (10)-B catalyst and its monometallic counterparts. This investigation proves that the NiMoP/MAS (10)-A catalyst is a promising catalyst for green fuel production from non-edible oils through hydrodeoxygenation. It was also unequivocally confirmed that the catalytic process does not suffer from any mass transfer resistance; thus, making the scaling up of the reaction more feasible.
- Ramesh, Arumugam,Tamizhdurai, Perumal,Suthagar, Krishnan,Sureshkumar, Kandhasamy,Theres, Gubert Sonia,Shanthi, Kannan
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- Biphasic hydroformylation of 1-hexene with carbon dioxide catalyzed by ruthenium complex in ionic liquids
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Hydroformylation of 1-hexene using carbon dioxide as carbonyl carbon source attained high yield and good chemoselectivity in heptanols when a ruthenium complex was used in biphasic ionic liquid-toluene system.
- Tominaga, Ken-Ichi,Sasaki, Yoshiyuki
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- Studies on organolanthanide complexes. XVIII. The reduction and isomerization of olefins with tricyclopentadienyllanthanides/sodium hydride
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Reduction of 1-hexene with Cp3Ln/NaH (Cp=cyclopentadienyl, Ln=rare earth metals) in THF at 45 deg C, after hydrolysis, gives hexane.The reducing activity of Cp3Ln depends strongly upon the ionic radius of the trivalent rare earth ion.The activity and selectivity of early rare earths for 1-hexene reduction are higher than those of heavy rare earths.The Cp3Ln/NaH systems can be used to regioselectively reduce dienes which contain a terminal carbon-carbon double bond as well as an internal one with high yield.Selectivity is 100percent.Moreover, the Cp3Ln/NaH systems are able to catalyze the hydrogenation of olefins.When Cp3Ln/NaH is used as catalyst, 1-hexene was isomerized at 45 deg C to cis-2-hexene and to trans-2-hexene in excellent yields.In contrast to reducing activity, the catalytic activity of heavy rare earths in the isomerization reaction is higher than that of the early earths.Hence, Cp3Sm/NaN and Cp3Y/NaH are new reducing agents and catalysts for 1-hexene reduction and isomerization, respectively.
- Qian, Changtao,Ge, Yuanwen,Deng, Daoli,Gu, Yongjie,Zhang, Caihua
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- Cationic pyridyl(benzoazole) ruthenium(II) complexes: Efficient and recyclable catalysts in biphasic hydrogenation of alkenes and alkynes
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The synthesis, structural characterization of cationic 2-(2-pyridyl)benzoazole)ruthenium(II) complexes and their applications in biphasic hydrogenations of alkenes is reported. Reactions of 2-(2-pyridyl)benzoimidazole (L1), 2-(2-pyridyl)benzothiazole (L2) and 2-(2-pyridyl)benzoxazole (L3) with [η6-(2-phenoxyethanol)RuCl2]2produced the corresponding cationic complexes [η6-(2-phenoxyethanol)RuCl(L1)]Cl (1), [η6-(2-phenoxyethanol)RuCl(L2)]Cl (2) and [η6-(2-phenoxyethanol)RuCl(L3)]Cl (3) in good yields. Solid state structures of 1-3 confirmed the bidentate coordination modes of L1-L3 and formation of cationic species through displacement of one chloride ligand from Ru(II) coordination sphere. Complexes 1-3 produced active catalysts for high pressure hydrogenation of alkenes both in methanol and biphasic conditions. Relatively lower activities were observed in the hydrogenation of terminal alkynes giving a mixture of alkane and alkene products. Complexes 1-3 were recyclable under biphasic conditions and retained significant catalytic activities in six cycles. Reaction parameters such as substrate/catalyst ratio, temperature, and aqueous/organic ratio affected the catalytic trends.
- Ogweno, Aloice O.,Ojwach, Stephen O.,Akerman, Matthew P.
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- Enhancing catalytic performance of activated carbon supported Rh catalyst on heterogeneous hydroformylation of 1-hexene via introducing surface oxygen-containing groups
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Activated carbon supported rhodium (Rh/AC) catalysts with different amounts of oxygen-containing functional groups were prepared by nitric acid (HNO3) treatment at varied temperatures. Thermal analyses of Rh/AC catalysts with or without this acidic treatment were characterized by thermogravimetric analysis (TGA) and temperature programmed desorption (TPD). The change of surface oxygen-containing functional groups was characterized by Fourier transform infrared spectrometry (FTIR) and X-ray photoelectron spectroscopy (XPS). These characterization results indicated that the amount of oxygen-containing functional groups increased with the treatment temperature. The influence of these oxygen-containing functional groups on the products selectivities in heterogeneous hydroformylation reaction was investigated in detail. These abundant functional groups were benefited to improve the selectivity of n-heptanal, resulting in higher n/i (normal to iso) ratio of heptanal. The Rh/AC catalyst being treated at 80?°C had the highest n/i ratio of 2.3, due to the maximum amount of oxygen-containing functional groups, which was almost double to that of raw Rh/AC catalyst. Moreover, abundant functional groups on catalyst suppressed hydrogenation of hexene, decreasing the selectivity of hexane from 4.9% of raw Rh/AC to 0.2%. These findings disclosed that these oxygen-containing functional groups on catalysts played an extremely important role in improving the catalytic performance of heterogeneous hydroformylation reaction, providing a new viewpoint for the studies on heterogeneous hydroformylation.
- Tan, Minghui,Wang, Ding,Ai, Peipei,Liu, Guoguo,Wu, Mingbo,Zheng, Jingtang,Yang, Guohui,Yoneyama, Yoshiharu,Tsubaki, Noritatsu
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- Catalytic conversion of cellulose into hydrocarbon fuel components
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The results of catalytic processing of cellulose to hydrocarbon fuel component are presented. Nanoscale Mo,Fe(III) catalytic systems have been formed from organic solutions of mono and bimetallic complex compounds on the surface of the substrate. Tetralin, an analogue of naphthenoaromatic compounds of crude oil and its refining products, has been used as a hydrogen donor. The effect of the precursor nature and catalyst activation method on the parameter of the process has been investigated. It has been shown that the cellulose conversion reaches 97-98% under optimal conditions, yielding up to 90% of liquid hydrocar- bons with the exhaustive deoxygenation. It has been found that the most efficient method of preliminary activation of both active components and cellulose is ultrasonic treatment leading to an increase of the rate of cellulose conversion into hydrocarbons. Pleiades Publishing, Ltd., 2013.
- Tsodikov,Chudakova,Chistyakov,Maksimov
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- Pd Nanocubes@ZIF-8: Integration of Plasmon-Driven Photothermal Conversion with a Metal-Organic Framework for Efficient and Selective Catalysis
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Composite nanomaterials usually possess synergetic properties resulting from the respective components and can be used for a wide range of applications. In this work, a Pd nanocubes@ZIF-8 composite material has been rationally fabricated by encapsulation of the Pd nanocubes in ZIF-8, a common metal-organic framework (MOF). This composite was used for the efficient and selective catalytic hydrogenation of olefins at room temperature under 1 atm H2 and light irradiation, and benefits from plasmonic photothermal effects of the Pd nanocube cores while the ZIF-8 shell plays multiple roles; it accelerates the reaction by H2 enrichment, acts as a "molecular sieve" for olefins with specific sizes, and stabilizes the Pd cores. Remarkably, the catalytic efficiency of a reaction under 60 mW cm-2 full-spectrum or 100 mW cm-2 visible-light irradiation at room temperature turned out to be comparable to that of a process driven by heating at 50 °C. Furthermore, the catalyst remained stable and could be easily recycled. To the best of our knowledge, this work represents the first combination of the photothermal effects of metal nanocrystals with the favorable properties of MOFs for efficient and selective catalysis.
- Yang, Qihao,Xu, Qiang,Yu, Shu-Hong,Jiang, Hai-Long
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- Microencapsulated ruthenium catalyst for the hydroformylation of 1-hexene
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A ruthenium complex [Ru(CO)3Cl2]2 microencapsulated into poly(4-vinylpyridine) (P4VP) cross-linked with 25% divinylbenzene (DVB) was developed as a new catalyst for the hydroformylation of 1-hexene. The highest catalytic activity with the 93% total conversion, and with yields of 44% aldehydes and 26% alcohols was achieved at 423 K. Typically, the polymer capsules are used at temperatures below 373 K. The DVB cross-linked P4VP capsules were, however, thermally stable at 423 K and could be recycled at least four times with moderate loss of catalytic activity. The catalysts were characterized by SEM, ICP-MS, and FT-IR.
- Kontkanen, Maija-Liisa,Haukka, Matti
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- Effect of Lead Acetate in the Preparation of the Lindlar Catalyst
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The effect of the Lindlar treatment in the preparation of Pd catalyst for the cis-selective hydrogenation of alkynes is investigated with hydrogenation studies on 2-hexyne.The study emphasizes the effect of lead on the hydrogenation selectivity of Pd catalyst.The role of the additives in the catalysts is examined by transmission electron microscopy.The effect of lead deposition on the catalytic activity and selectivity of Pd surfaces is studied with lead-coated Pd foils.No selectivity enhancing effects of the deposition of lead on the Pd particles could be identified
- Ulan, Judith G.,Kuo, Emilio,Maier, Wilhelm F.,Rai, Raghaw S.,Thomas, Gareth
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- Further studies of the PtII/SnCl2 catalyzed hydroformylation
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A convenient synthesis of the complexes trans- and trans- is described, and their NMR spectra in the presence of SnCl2 are discussed.These complexes have been examined as catalysts in 1-hexene hydroformylation in the presence of an excess of SnCl2.Their catalytic behaviour is compared with that of the systems based on complexes trans-, trans-, trans-, and cis-.
- Scrivanti, A.,Paganelli, S.,Matteoli, U.,Botteghi, C.
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- Structural and Catalytic Properties of Novel Au/Pd Bimetallic Colloid Particles: EXAFS, XRD, and Acetylene Coupling
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The structure, stability, and catalytic properties of an unusual bimetallic colloid having a well-defined Au core/Pd shell structure are reported.This material is an efficient catalyst for coupling and cyclization of acetylene, even at room temperature.XRD data and in situ EXAFS data combined with reaction studies reveal how large changes in activity and selectivity correlate with controlled variations in the degree of thermally induced Au/Pd intermixing.Increasing the Au content of the surface results in a large increase in overall activity and a pronounced increase in the selectivity for benzene formation relative to n-hexane.These findings may be rationalized very satisfactorily in the light of single-crystal data which provide information about the bonding and reactiivty of acetylene and benzene on Pd and Au-modified Pd and about the elementary steps involved in the conversion of reactants to products.
- Lee, Adam F.,Baddeley, Christopher J.,Hardacre, Christopher,Mark Ormerod, R.,Lambert, Richard M.,et al
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- Heterolytic H2 activation on a carbene-ligated rhodathiaborane promoted by isonido-nido cage opening
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A new mechanism of H2 activation is reported to occur on a carbene-ligated rhodathiaborane that features metal-thiaborane bifunctional synergistic effects. The key is the creation of vacant coordination sites by an isonido-nido structural transformation leading to the heterolytic H-H bond splitting.
- Calvo, Beatriz,Macias, Ramon,Polo, Victor,Artigas, Maria Jose,Lahoz, Fernando J.,Oro, Luis A.
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- Pd catalysed hexyne hydrogenation modified by Bi and by Pb
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Two Pd/Al2O3 catalysts of different loadings and dispersions were modified by the addition of various amounts of Bi and studied in the hydrogenation of 1-hexyne and 2-hexyne and in the consecutive reactions of the products formed. Ca
- Anderson, James A.,Mellor, Jane,Wells, Richard P.K.
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- Development of silica-supported frustrated Lewis pairs: Highly active transition metal-free catalysts for the Z-selective reduction of alkynes
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Supported Lewis acid/base systems based on a triphenyl phosphine fragment and Piers' reagent (HB(C6F5)2) or BArF have been prepared and characterized. Both materials show unprecedented catalytic activity in the Z-selective hydrogenation of 3-hexyne to Z-3-hexene with a selectivity up to 87%. Other alkynes can also be hydrogenated Z-selectively, albeit with moderate yields. The activity of the supported phosphine/HB(C6F5)2 adduct is similar to the only homogeneous example reported thus far based on bridged B/N frustrated Lewis pairs under high hydrogen pressure. Importantly, this transition metal-free supported catalyst was recycled five times in the challenging selective hydrogenation of a non-polar unactivated alkyne.
- Szeto, Kai C.,Sahyoun, Wissam,Merle, Nicolas,Castelbou, Jessica Llop,Popoff, Nicolas,Lefebvre, Frédéric,Raynaud, Jean,Godard, Cyril,Claver, Carmen,Delevoye, Laurent,Gauvin, Régis M.,Taoufik, Mostafa
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- Synthesis, characterization, and biphasic ionic liquid media 1-hexene hydrogenation reaction of RuCl2(DMSO)2(NC 5H4CO2Na-3)2
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RuCl2(DMSO)2(NC5H4CO 2Na-3)2 is very soluble in the ionic liquid (IL) 1-n-butyl-3-methylimidazolium tetrafluoroborate, [(BMIM)BF4]. The complex was prepared by reacting RuCl2(DMSO)4 with NC 5H4CO2Na-3, sodium nicotinate, in toluene, and was characterized by spectroscopic methods. The complex catalyzes the hydrogenation of 1-hexene (600 psi H2, 100 °C) in a two-phase system consisting of cyclohexane/[(BMIM)BF4] with 75% conversion in 24 h and modest substrate isomerization. The complex shows good stability and can be reused several times with little loss in activity.
- Suarez, Trino,Fontal, Bernardo,Vielma, Joel E.,Reyes, Marisela,Bellandi, Fernando,Cancines, Pedro,Diaz, Juan C.,Fonseca, Yuraima
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- Investigation of a system of protecting layer for the process of hydrorefining oily distillates of Uzbekistan's petroleum
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Complex investigation is conducted, directed to development of contacting materials (forcontacts) and catalysts for the protecting layer in the process of hydrorefining petroleum distillates taking into account their specificity and extensively attracting local raw materials. Forcontact FZS-7 is developed which, besides the function of uniform distribution of crude material over the reactor section, diminishes tarring and performs, owing to low nickel content, mild hydrogenation of unsaturated compounds. The proposed kaolin-bset catalyst of the protecting layer with low content of molybdenum oxide works reliably with the residual crude material with high content of iron and displays high enough demetallization activity.
- Yunusov,Molodozhenyuk,Ergashev,Dzhalalova,Gashenko,Saidulaev
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- Rational Design of a Heterogeneous Pd Catalyst for the Selective Hydrogenation of Alkynes
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Epitaxial palladium on tungsten film, which has a preferred (100) orientation, represents a rationally designed catalyst with a surface tailored to achieve high cis-semihydrogenation selectivity.Comparison with the Lindlar catalyst reveals improved cis selectivity and a much higher semihydrogenation selectivity.TEM studies provide evidence for bulk morphological changes of Pd foil that affect the selectivity of the hydrogenation reaction.Reactions on (111) and (110) Pd single crystals reveal a strong dependence of cis-selective semihydrogenation on the orientation of the metal, indicating surface structure sensitivity.Cyclic voltammetry is used to measure Pd foil surface areas and Pd foil was electrochemically roughened to alter its catalytic selectivity
- Ulan, Judith G.,Maier, Wilhelm F.,Smith, David A.
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- Electrochemical Reduction of 1,6-Dihalohexanes at Carbon Cathodes in Dimethylformamide
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Cyclic voltammograms for the reduction of 1,6-dibromo-, 1,6-diiodo-, 1-bromo-6-chloro-, and 1-chloro-6-iodohexane at glassy carbon electrodes in dimethylformamide containing tetramethylammonium perchlorate exhibit single irreversible waves that correspond to the reductive cleavage of carbon-bromine or carbon-iodine bonds.When large-scale controlled-potential electrolyses of either 1,6-dibromo- or 1,6-diiodohexane are performed at reticulated vitreous carbon, the principal products are n-hexane (30-45percent), 1-hexene (28-34percent), 1,5-hexadiene (6-16percent), and cyclohexane (7percent), with n-dodecane being another significant species obtained from 1,6-diiodohexane.Because a carbon-chlorine bond is not directly reducible, 1-bromo-6-chloro- and 1-chloro-5-iodohexane give rise mainly to 1-chlorohexane (47-64percent), 6-chloro-1-hexene (20-33percent), and 1,12-dichlorododecane (2-25percent).From these product distributions, and with the aid of experiments done in the presence of deuterium-labeled reagents, we conclude that the electrolytic reduction of 1,6-diiodo- and 1-chloro-6-iodohexane involves both radical and carbanion intermediates, whereas only carbanionic pathways are important for electrolyses of 1,6-dibromo- and 1-bromo-6-chlorohexane.
- Mubarak, Mohammad S.,Peters, Dennis G.
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- Synthesis of highly dispersed cobalt catalyst for hydroformylation of 1-hexene
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Highly dispersed Co/SiO2 catalysts were prepared using an ethylene glycol (EG) modified silica support. The modified SiO2 support significantly promoted the dispersion of supported cobalt and adding a small amount of Ru increased the reducibility of the highly dispersed cobalt oxide. The Co-Ru/SiO2 (EG) catalyst exhibited 3 times higher 1-hexene conversion and 18 times higher heptanal yield than the conventional Co/SiO2 catalyst. This journal is
- Wang, Bin,Chen, Jian-Feng,Zhang, Yi
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- Decarboxylation and further transformation of oleic acid over bifunctional, Pt/SAPO-11 catalyst and Pt/chloride Al2O3 catalysts
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Catalytic decarboxylation and further conversion of oleic acid to branched and aromatic hydrocarbons in a single process step, over Pt-SAPO-11 and Pt/chloride Al2O3 is presented. An increase of both reaction time and temperature increase the selectivity to heptadecane. Higher selectivity to heptadecane was observed in the presence of hydrogen. Decarboxylation of oleic acid was as high as ～98 wt% (selectivity for heptadecane >30%) at 325 C in the presence of hydrogen. Branched isomers, alkyl aromatics, like dodecyl benzene and cracked (17) paraffins were the other products.
- Ahmadi, Masoudeh,Macias, Eugenia E.,Jasinski, Jacek B.,Ratnasamy, Paul,Carreon, Moises A.
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- Efficient Hydroformylation Rhodium Catalysts using Water as Solvent and Hydrogen Source
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The fast and selective conversion of alkenes into aldehydes can be achieved under mild conditions by using the CO/H2O couple in the presence of the water-soluble complexes Rh2(μ-SBut)2(CO)2(Ls)2, Rh(cod)(Ls)2+ (cod = cyclo-octa-1,5-diene), and RhH(CO)(Ls)3, where Ls is the trisulphonated phosphine, P(m-C6H4SO3Na).
- Escaffre, Pascale,Thorez, Alain,Kalck, Philippe
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- Effects of Catalyst Site Accessibility on Catalysis by Rhodium(I) Complexes of Amphiphilic Ligands (1+) (n = 2,3,6,or 10) tethered to a Cation-exchange Resin
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The effects of catalyst site accessibility on the activities of supported olefin hydrogenation catalysts have been assessed utilizing the complexes 3 4-norbornadiene; L = Ph2P(CH2)nPMe3(1+); n = 2, 3, 6 or 10> tethered to a cation-exchange resin via the tetraalkylphosphonium moieties of the co-ordinated ligands; the most active catalysts are those containing the longer-chain ligands, where the catalyst sites are farthest removed from steric hindrance by the resin surface.
- Renaud, Eric,Baird, Michael C.
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- Deoxygenation of methylesters over CsNaX
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The deoxygenation of methyl octanoate over a CsNaX zeolite catalyst has been investigated as a model reaction for the production of de-oxygenated liquid hydrocarbons from biodiesel. Several operating parameters were investigated, such as the type of basic catalyst used, the co-reactant incorporated in the reactor as a solvent of the liquid feed, and the reaction temperature. The CsNaX zeolite used in the study was prepared by ion exchange of NaX with CsNO3/CsOH solution. A significant role of the solvent (co-reactant) was found on the activity, selectivity, and stability of the catalyst. That is, when methanol was co-fed enhanced stability and decarbonylation activity were observed. By contrast, when nonane was used, the catalyst deactivated rapidly and the selectivity to coupling products was enhanced. Temperature programmed desorption (TPD) of methyl octanoate and methanol, as well as flow catalytic studies suggest that methyl octanoate first decomposes to an octanoate-like species. The decomposition of such species leads to the formation of heptenes and hexenes as major products. Octenes and other hydrogenated products are formed in lower amounts via hydrogenation by hydrogen produced on the surface by methanol decomposition, but not from gas phase H2, followed by dehydration. When the polarizable Cs cation is not present in the catalyst, reduced activity and formation of undesired products, such as aromatics and pentadecanone, occur. Similarly, non-zeolitic basic catalysts, such as MgO, exhibit low activity and low selectivity to de-oxygenated liquid hydrocarbons.
- Sooknoi, Tawan,Danuthai, Tanate,Lobban, Lance L.,Mallinson, Richard G.,Resasco, Daniel E.
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- Cryosynthesis of catalysts for propylene oligomerization based on titanium tetrachloride and magnesium
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A highly dispersed catalyst for oligo- and polymerization of propylene was synthesized by the interaction of TiCl4 with magnesium in the cocondensates of their vapor with benzene and pentane. The catalyst contains MgCl2 and organotitanium and organomagnesium cluster derivatives. The transformations of propylene and hex-1-ene over the catalysts were studied. The direction of catalytic reactions and activity of the catalyst depend on the TiCl4 : Mg molar ratio and the hydrocarbon used. Systems with an equimolar ratio of the reactants obtained in a benzene matrix exhibit the highest activity. Propylene oligomers containing a considerable fraction of unsaturated bonds are formed in the presence of the catalysts at room temperature and a pressure of 300 Torr.
- Tarkhanova,Smirnov,Tsvetkova,Tjurina
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- Steric control of a ruthenium-catalysed alkyne hydrogenation reaction
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The cations + and + have been used in a study of the effect of variation of group 15 donor ligands (L", L') on the hydrogenation reaction of alkynes. + was found to catalyse hydrogenation of both alkynes and alkenes, the course of the reaction being dependent on the size of the ligand L'.The rate of hydrogenation of alkynes catalysed by + was found to increase with the cone angle, Θ, until ca 120 deg C and then decrease as Θ is raised still further.When the cone angle of L' + was found to increase the selectivity of the alkyne hydrogenation reaction with concomitant decrease in the hydrogenation rate.Addition of a range of other ligands L' (2 - 3 equiv.) to solutions of + (L" = PMe3, PMe2Ph) also resulted in a decrease in the rate of the alkyne hydrogenation, but the decrease was dependent on the size of L'.The + complexes were found to catalytically hydrogenate alkynes exclusively when the sum of the cone angles for the L' and L" ligands was 5Θ = 610 +/- 20 deg C.No correlation between electronic parameters and the reaction rate and product selectivity is apparent from our results.Mechanistic features of the catalysed hydrogenation of alkenes and alkynes in the presence of these ruthenium complexes are discussed.
- Nkosi, Bongani S.,Coville, Neil J.,Albers, Michel O.,Gordon, Craig,Viney, Marjorie,Singleton, Eric
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- Artificial metalloenzymes via encapsulation of hydrophobic transition-metal catalysts in surface-crosslinked micelles (SCMs)
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Encapsulation of a hydrophobic rhodium catalyst in crosslinked micelles allowed nonpolar substrates to react in water with unusual selectivity. This journal is The Royal Society of Chemistry 2012.
- Zhang, Shiyong,Zhao, Yan
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- SYNTHESIS AND SPECTROSCOPIC AND CATALYTIC PROPERTIES OF A COMPLEX OF PALLADIUM(II) WITH ALIZARIN COMPLEXONE
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A 1:1 complex of Pd(II) with alizarin complexone was synthesized and characterized.This complex displays high catalytic activity in the hydrogenation of nitrobenzene and 1-hexene.
- Bulatov, A. V.,Ragkhavan, P. K. N.
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- Hydrogenation of unsaturated hydrocarbons catalyzed by homogeneous and supported Rh, Rh-Co, and Pd, Pd-Ni complexes with oligomeric allene ligands
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Mono-and bimetallic Rh and Rh-Co complexes containing oligoallene ligands were synthesized. Their catalytic activity was examined in the hydrogenation of unsaturated compounds, such as isoprene, hexene-1, and toluene. The catalytic activity of Rh(DMA)ol and Rh-Co(DMA)ol was shown to be 16 800 and 23000 mol/(mol h) in the hydrogenation of hexene-1 and 72 and 90 mol/(mol h) in the hydrogenation of toluene, respectively. Isoprene is hydrogenated completely: the rate curves exhibit two portions corresponding to hydrogenation of both double bonds. The catalytic activity of palladium oligodimethylallene complexes deposited on an inorganic support (γ-Al 2O3) in isoprene hydrogenation depends on the support preparation procedure, the particle size, and the metal loading on the surface. Heterogenization of the homogeneous mono-and bimetallic Rh and Pd complexes somewhat enhances the catalytic activity in hydrogenation of the given substrates. Pleiades Publishing, Ltd., 2010.
- Khar'kova,Rozantseva,Frolov
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- COLLOIDAL NOBLE METAL CATALYSTS SUPPORTED ON INORGANIC CARRIERS
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Hydrosols of rhodium, palladium, and platinum were prepared by the NaBH4-reduction of the corresponding metal salts in aqueous solution without using protective agents.Colloidal metals in the hydrosols were effectively adsorbed on inorganic carriers such
- Nakao, Yukimichi,Kaeriyama, Kyoji
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- Ruthenium carbonyl carboxylates with nitrogen containing ligands: IV. Catalytic activity in the hydroformylation of olefins in homogeneous phase 1
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Ruthenium carbonyl acetato complexes containing bipyridines or phenantrolines ligands are tested as catalysts in the hydroformylation of hex-1-ene in homogeneous phase. These catalysts are active also in solutions containing water and the selectivity to aldehyde is high. Only a moderate hydrogenation of the alkene occurs. The regioselectivity to the linear aldehyde reaches 85.7% when using the mononuclear complex containing 4,7-dmphen as ligand. In the course of the reaction the starting olefm is largely isomerized.
- Frediani, Piero,Bianchi, Mario,Salvini, Antonella,Carluccio, Luciano C.,Rosi, Luca
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- Ensemble Design in Nickel Phosphide Catalysts for Alkyne Semi-Hydrogenation
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Modification of transition metals with p-block elements is known to be effective to tune the ensemble characteristics of catalysts for the semi-hydrogenation of alkynes. To further explore this approach, here we prepare two nickel phosphides, namely Ni2P and Ni5P4. Assessment in the semi-hydrogenation of 1-hexyne and 2-methyl-3-butyn-2-ol shows that the phosphides present higher rate and selectivity than unmodified nickel catalysts. While no activity and selectivity differences are displayed in the semi-hydrogenation of 1-hexyne over Ni2P and Ni5P4, in the case of 2-methyl-3-butyn-2-ol a higher rate and lower selectivity to 2-methyl-3-buten-2-ol are observed over Ni2P. Density functional theory reveals that the hydroxyl group facilitates the reaction, but also increases the barrier for product desorption. Detailed analyses of the ensemble show the potential of phosphorus to create spatially-isolated nickel trimers that surpass the performance of unmodified nickel, but also its limited ability to modulate the electronic properties and related binding energies of organic intermediates, which is key to preventing undesired side reactions.
- Albani, Davide,Karajovic, Konstantin,Tata, Bharath,Li, Qiang,Mitchell, Sharon,López, Núria,Pérez-Ramírez, Javier
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- The catalytic activity of alkali metal alkoxides and titanium alkoxides in the hydrosilylation of unfunctionalized olefins
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The catalytic activities of titanium alkoxides and alkali metal alkoxides for hydrosilylation of unfunctionalized olefins have been studied. Titanium(IV) alkoxides showed excellent catalytic activity, while alkali metal alkoxides have low catalytic activity for the hydrosilylation of olefins. However, by using titanocene dichloride as an additive, alkali metal alkoxides showed also excellent catalytic property for hydrosilylation. In comparison with titanium alkoxides, no α-adduct was obtained by using alkali metal alkoxides/Cp2TiCl2 as catalysts.
- Yang, Xiaoling,Bai, Ying,Li, Jiayun,Liu, Yu,Peng, Jiajian,Li, Tianbo,Lang, Rui,Qiao, Botao
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- Synthesis of the Solid Superacid of SO42-/SnO2 with Acid Strength of Ho
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A solid superacid catalyst with an acid strength of Ho -1 H2SO4 followed by calcination in air at 823 K; the catalyst was active for the skeletal isomerization of butane to isobutane at room temperature.
- Matsuhashi, Hiromi,Hino, Makoto,Arata, Kazushi
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- Catalytic Activity of Supported f-Element Organometallic Complexes
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When supported on alumina, the organoactinoids M(η-Me5C5)2Me2 (M = U or Th) exhibit very high catalytic activity for the hydrogenation of propene and the polymerization of ethene.
- Bowman, Robert G.,Nakamura, Ryuichi,Fagan, Paul J.,Burwell, Robert L.,Marks, Tobin J.
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- Fabricating nickel phyllosilicate-like nanosheets to prepare a defect-rich catalyst for the one-pot conversion of lignin into hydrocarbons under mild conditions
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The one-pot conversion of lignin biomass into high-grade hydrocarbon biofuels via catalytic hydrodeoxygenation (HDO) holds significant promise for renewable energy. A great challenge for this route involves developing efficient non-noble metal catalysts to obtain a high yield of hydrocarbons under relatively mild conditions. Herein, a high-performance catalyst has been prepared via the in situ reduction of Ni phyllosilicate-like nanosheets (Ni-PS) synthesized by a reduction-oxidation strategy at room temperature. The Ni-PS precursors are partly converted into Ni0 nanoparticles by in situ reduction and the rest remain as supports. The Si-containing supports are found to have strong interactions with the nickel species, hindering the aggregation of Ni0 particles and minimizing the Ni0 particle size. The catalyst contains abundant surface defects, weak Lewis acid sites and highly dispersed Ni0 particles. The catalyst exhibits excellent catalytic activity towards the depolymerization and HDO of the lignin model compound, 2-phenylethyl phenyl ether (PPE), and the enzymatic hydrolysis of lignin under mild conditions, with 98.3% cycloalkane yield for the HDO of PPE under 3 MPa H2 pressure at 160 °C and 40.4% hydrocarbon yield for that of lignin under 3 MPa H2 pressure at 240 °C, and its catalytic activity can compete with reported noble metal catalysts.
- Cao, Meifang,Chen, Bo,He, Chengzhi,Ouyang, Xinping,Qian, Yong,Qiu, Xueqing
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supporting information
p. 846 - 857
(2022/02/09)
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- COMPOUNDS, INFRARED ABSORBERS, INFRARED ABSORBING/BLOCKING FILMS, PHOTOELECTRIC DEVICES, SENSORS, AND ELECTRONIC DEVICES
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A compound is represented by Chemical Formula 1. In Chemical Formula 1, R1 to R4, R11a to R14c, and n are the same as defined in the detailed description.
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- Conversion of Phenol and Lignin as Components of Renewable Raw Materials on Pt and Ru-Supported Catalysts
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Hydrogenation of phenol in aqueous solutions on Pt-Ni/SiO2, Pt-Ni-Cr/Al2 O3, Pt/C, and Ru/C catalysts was studied at temperatures of 150–250? C and pressures of 40–80 bar. The possibility of hydrogenation of hydrolysis lignin in an aqueous medium in the presence of a Ru/C catalyst is shown. The conversion of hydrolysis lignin and water-soluble sodium lignosulfonate occurs with the formation of a complex mixture of monomeric products: a number of phenols, products of their catalytic hydrogenation (cyclohexanol and cyclohexanone), and hydrogenolysis products (cyclic and aliphatic C2 –C7 hydrocarbons).
- Bobrova, Nataliia A.,Bogdan, Tatiana V.,Bogdan, Viktor I.,Koklin, Aleksey E.,Mishanin, Igor I.
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- Metallic Barium: A Versatile and Efficient Hydrogenation Catalyst
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Ba metal was activated by evaporation and cocondensation with heptane. This black powder is a highly active hydrogenation catalyst for the reduction of a variety of unactivated (non-conjugated) mono-, di- and tri-substituted alkenes, tetraphenylethylene, benzene, a number of polycyclic aromatic hydrocarbons, aldimines, ketimines and various pyridines. The performance of metallic Ba in hydrogenation catalysis tops that of the hitherto most active molecular group 2 metal catalysts. Depending on the substrate, two different catalytic cycles are proposed. A: a classical metal hydride cycle and B: the Ba metal cycle. The latter is proposed for substrates that are easily reduced by Ba0, that is, conjugated alkenes, alkynes, annulated rings, imines and pyridines. In addition, a mechanism in which Ba0 and BaH2 are both essential is discussed. DFT calculations on benzene hydrogenation with a simple model system (Ba/BaH2) confirm that the presence of metallic Ba has an accelerating effect.
- Stegner, Philipp,F?rber, Christian,Zenneck, Ulrich,Knüpfer, Christian,Eyselein, Jonathan,Wiesinger, Michael,Harder, Sjoerd
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supporting information
p. 4252 - 4258
(2020/12/22)
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- Room temperature iron catalyzed transfer hydrogenation usingn-butanol and poly(methylhydrosiloxane)
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Reduction of carbon-carbon double bonds is reported using a three-coordinate iron(ii) β-diketiminate pre-catalyst. The reaction is believed to proceedviaa formal transfer hydrogenation using poly(methylhydrosiloxane), PMHS, as the hydride donor and a bio-alcohol as the proton source. The reaction proceeds well usingn-butanol and ethanol, withn-butanol being used for substrate scoping studies. Allyl arene substrates, styrenes and aliphatic substrates all undergo reduction at room temperature. Unfortunately, clean transfer of a deuterium atom usingd-alcohol does not take place, indicating a complex catalytic mechanism. However, changing the deuterium source tod-aniline gives close to complete regioselectivity for mono-deuteration of the terminal position of the double bond. Finally, we demonstrate that efficient dehydrocoupling of alcohol and PMHS can be undertaken using the same pre-catalyst, giving high yields of H2within 30 minutes at room temperature.
- Coles, Nathan T.,Linford-Wood, Thomas G.,Webster, Ruth L.
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supporting information
p. 2703 - 2709
(2021/04/21)
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- Ambient Hydrogenation and Deuteration of Alkenes Using a Nanostructured Ni-Core–Shell Catalyst
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A general protocol for the selective hydrogenation and deuteration of a variety of alkenes is presented. Key to success for these reactions is the use of a specific nickel-graphitic shell-based core–shell-structured catalyst, which is conveniently prepared by impregnation and subsequent calcination of nickel nitrate on carbon at 450 °C under argon. Applying this nanostructured catalyst, both terminal and internal alkenes, which are of industrial and commercial importance, were selectively hydrogenated and deuterated at ambient conditions (room temperature, using 1 bar hydrogen or 1 bar deuterium), giving access to the corresponding alkanes and deuterium-labeled alkanes in good to excellent yields. The synthetic utility and practicability of this Ni-based hydrogenation protocol is demonstrated by gram-scale reactions as well as efficient catalyst recycling experiments.
- Beller, Matthias,Feng, Lu,Gao, Jie,Jackstell, Ralf,Jagadeesh, Rajenahally V.,Liu, Yuefeng,Ma, Rui
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supporting information
p. 18591 - 18598
(2021/06/28)
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- Heterometallic Mg?Ba Hydride Clusters in Hydrogenation Catalysis
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Reaction of a MgN“2/BaN”2 mixture (N“=N(SiMe3)2) with PhSiH3 gave three unique heterometallic Mg/Ba hydride clusters: Mg5Ba4H11N”7 ? (benzene)2 (1), Mg4Ba7H13N“9 ? (toluene)2 (2) and Mg7Ba12H26N”12 (3). Product formation is controlled by the Mg/Ba ratio and temperature. Crystal structures are described. While 3 is fully insoluble, clusters 1 and 2 retain their structures in aromatic solvents. DFT calculations and AIM analyses indicate highly ionic bonding with Mg?H and Ba?H bond paths. Also unusual H????H? bond paths are observed. Catalytic hydrogenation with MgN“2, BaN”2 and the mixture MgN“2/BaN”2 has been studied. Whereas MgN“2 is only active in imine hydrogenation, alkene and alkyne hydrogenation needs the presence of Ba. The catalytic activity of the MgN”2/BaN“2 mixture lies in general between that of its individual components and strong cooperative effects are not evident.
- Wiesinger, Michael,Knüpfer, Christian,Elsen, Holger,Mai, Jonathan,Langer, Jens,Harder, Sjoerd
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p. 4567 - 4577
(2021/09/09)
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- Photo-Initiated Cobalt-Catalyzed Radical Olefin Hydrogenation
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Outer-sphere radical hydrogenation of olefins proceeds via stepwise hydrogen atom transfer (HAT) from transition metal hydride species to the substrate. Typical catalysts exhibit M?H bonds that are either too weak to efficiently activate H2 or too strong to reduce unactivated olefins. This contribution evaluates an alternative approach, that starts from a square-planar cobalt(II) hydride complex. Photoactivation results in Co?H bond homolysis. The three-coordinate cobalt(I) photoproduct binds H2 to give a dihydrogen complex, which is a strong hydrogen atom donor, enabling the stepwise hydrogenation of both styrenes and unactivated aliphatic olefins with H2 via HAT.
- Sang, Sier,Unruh, Tobias,Demeshko, Serhiy,Domenianni, Luis I.,van Leest, Nicolaas P.,Marquetand, Philipp,Schneck, Felix,Würtele, Christian,de Zwart, Felix J.,de Bruin, Bas,González, Leticia,V?hringer, Peter,Schneider, Sven
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p. 16978 - 16989
(2021/08/09)
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- Oxidative Addition of Aryl and Alkyl Halides to a Reduced Iron Pincer Complex
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The two-electron oxidative addition of aryl and alkyl halides to a reduced iron dinitrogen complex with a strong-field tridentate pincer ligand has been demonstrated. Addition of iodobenzene or bromobenzene to (3,5-Me2MesCNC)Fe(N2)2 (3,5-Me2MesCNC = 2,6-(2,4,6-Me-C6H2-imidazol-2-ylidene)2-3,5-Me2-pyridine) resulted in rapid oxidative addition and formation of the diamagnetic, octahedral Fe(II) products (3,5-Me2MesCNC)Fe(Ph)(N2)(X), where X = I or Br. Competition experiments established the relative rate of oxidative addition of aryl halides as I > Br > Cl. A linear free energy of relative reaction rates of electronically differentiated aryl bromides (ρ = 1.5) was consistent with a concerted-type pathway. The oxidative addition of alkyl halides such as methyl-, isobutyl-, or neopentyl halides was also rapid at room temperature, but substrates with more accessible β-hydrogen positions (e.g., 1-bromobutane) underwent subsequent β-hydride elimination. Cyclization of an alkyl halide containing a radical clock and epimerization of neohexyl iodide-d2 upon oxidative addition to (3,5-Me2MesCNC)Fe(N2)2 are consistent with radical intermediates during C(sp3)-X bond cleavage. Importantly, while C(sp2)-X and C(sp3)-X oxidative addition produces net two-electron chemistry, the preferred pathway for obtaining the products is concerted and stepwise, respectively.
- Rummelt, Stephan M.,Peterson, Paul O.,Zhong, Hongyu,Chirik, Paul J.
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p. 5928 - 5936
(2021/05/06)
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- Carbon-Halogen Bond Activation with Powerful Heavy Alkaline Earth Metal Hydrides
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Reaction of [(DIPePBDI)SrH]2 with C6H5X (X=Cl, Br, I) led to hydride-halogenide exchange (DIPePBDI=HC[(Me)CN-2,6-(3-pentyl)phenyl]2). Conversion rates increase with increasing halogen size (FDIPePBDI)SrH]2 with C6H5F was slow and ill-defined but addition of C6H4F2 gave smooth hydride-fluoride exchange. After addition of THF the full range of Sr halogenides was structurally characterized: [(DIPePBDI)SrX ? THF]2 (X=F, Cl, Br, I). Mixtures of AeN“2 and PhSiH3 in situ formed less defined but more robust Ae metal hydride clusters (AexN”yHz, Ae=Ca, Sr, Ba and N“=N(SiMe3)2) which are able to hydrodefluorinate C6H5F. Conversion rates increase with increasing metal size (Ca2/PhSiH3 mixtures also converted SF6 at room temperature to give undefined decomposition products. Addition of Me6Tren to a SrN“2/PhSiH3 led to crystallization of [Sr6N”2H9 ? (Me6Tren)3+][SrN“3?]; Me6Tren=tris[2-(dimethylamino)ethyl]amine). After hydrodefluorination, Sr6N”4F8 ? (Me6Tren)2 was formed and structurally characterized. Dissolution in THF led to cluster growth and the larger cluster Sr16N“8F24 ? (THF)12 is structurally characterized. DFT calculations support that hydrodehalogenation of halobenzenes follows a concerted nucleophilic aromatic substitution mechanism (cSNAr).
- Harder, Sjoerd,Knüpfer, Christian,Langer, Jens,Mai, Jonathan,R?sch, Bastian,Wiesinger, Michael
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p. 3731 - 3741
(2021/08/23)
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- Facile gas-phase hydrodeoxygenation of 2,5-dimethylfuran over bifunctional metal-acid catalyst Pt-Cs2.5H0.5PW12O40
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2,5-Dimethylfuran is deoxygenated to n-hexane with 100% yield on a bifunctional Pt/C-Cs2.5H0.5PW12O40 catalyst under very mild conditions (90 °C, 1 bar H2) in a one-step gas-phase process. A proposed mechanism includes a sequence of hydrogenolysis, hydrogenation and dehydration steps occurring on Pt and proton sites of the bifunctional catalyst.
- Althikrallah, Hanan,Kozhevnikova, Elena F.,Kozhevnikov, Ivan V.
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supporting information
p. 227 - 230
(2021/01/14)
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- Acidic metal-organic framework empowered precise hydrodeoxygenation of bio-based furan compounds and cyclic ethers for sustainable fuels
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Target synthesis of hydrocarbons from abundant biomass is highly desired for sustainable aviation fuels (SAFs) to meet the need for both net zero carbon emission and air pollution control. However, precise hydrodeoxygenation (PHDO) of bio-based furan compounds and cyclic ethers to isomerically pure alkanes remains a challenge in heterogenous catalysis, which usually requires delicate control of the distribution of acid and metal catalytic sites in nanoconfined space. Here we show that a nanoporous acidic metal-organic framework (MOF), namely MIL-101-SO3H, enables one-pot PHDO reactions from furan-derivative oxygenates to solely single-component alkanes by just mechanical mixing with commercial Pd/C towards highly efficient and highly selective hydrocarbon production. The superior performance of such tandem catalysts can be attributed to the preferential adsorption of oxygenate precursors and expulsion of deoxygenated intermediates benefiting from Lewis acid sites embedded in the MOF. The strong Br?nsted acidity of MIL-101-SO3H is contributed by both the -SO3H groups and the adsorbed H2O, which makes it a water-tolerant solid acid for durable PHDO processes. The simplicity of mechanical mixing of different heterogenous catalysts allows the modulation of the tandem catalysis system for optimization of the ultimate catalytic performance. This journal is
- Gao, Xiang-Yu,He, Hai-Long,Li, Zhi,Liu, Dong-Huang,Wang, Jun-Jie,Xiao, Yao,Yi, Xianfeng,Zeng, Tengwu,Zhang, Yue-Biao,Zheng, Anmin,Zhou, Si-Yu
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supporting information
p. 9974 - 9981
(2021/12/27)
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- Hydrodeoxygenation of 2,5-dimethyltetrahydrofuran over bifunctional metal-acid catalyst Pt–Cs2.5H0.5PW12O40 in the gas phase: Kinetics and mechanism
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Hydrodeoxygenation (HDO) of 2,5-dimethyltetrahydrofuran (DMTHF) was studied at a gas-solid interface in a fixed-bed microreactor in the presence of bifunctional metal-acid catalysts comprising Pt/C and acidic heteropoly salt Cs2.5H0.5PW12O40 (CsPW). The Pt–CsPW catalyst deoxygenated DMTHF to n-hexane with >99% selectivity under mild conditions (90–100 °C, ambient pressure) and was much more efficient than monofunctional Pt/C. On the basis of kinetic studies, a mechanism for the HDO of DMTHF over Pt–CsPW was proposed, which includes a sequence of hydrogenolysis, dehydration and hydrogenation steps catalysed by Pt and proton sites of the bifunctional catalyst. The turnover rate of HDO increased with increasing Pt particle size suggesting that the hydrogenolysis of C–O bond in furanic compounds on Pt is a structure-sensitive reaction.
- Althikrallah, Hanan,Kozhevnikov, Ivan V.,Kozhevnikova, Elena F.
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- A Heterogeneous Pt-ReOx/C Catalyst for Making Renewable Adipates in One Step from Sugar Acids
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Renewable adipic acid is a value-added chemical for the production of bioderived nylon. Here, the one-step conversion of mucic acid to adipates was achieved in high yield through deoxydehydration (DODH) and catalytic transfer hydrogenation (CTH) by a bifunctional Pt-ReOx/C heterogeneous catalyst with isopropanol as solvent and reductant. The Pt-ReOx/C catalyst is reusable and was regenerated at least five times. The catalyst exhibits a broad substrate scope of various diols. Spectroscopic studies of Pt-ReOx/C revealed ReVII and Pt0 as the relevant species for DODH and CTH, respectively. Isotope labeling experiments support a monohydride mechanism for CTH over Pt. This work demonstrates a reusable bifunctional catalyst for a one-step valorization of sugar acids to a practical monomer, which opens the door to multifunctional catalysis streamlining valorization of biomass-derived molecules.
- Jang, Jun Hee,Ro, Insoo,Christopher, Phillip,Abu-Omar, Mahdi M.
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- A chemiresistive methane sensor
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A chemiresistive sensor is described for the detection of methane (CH4), a potent greenhouse gas that also poses an explosion hazard in air. The chemiresistor allows for the low-power, low-cost, and distributed sensing of CH4 at room temperature in air with environmental implications for gas leak detection in homes, production facilities, and pipelines. Specifically, the chemiresistors are based on single-walled carbon nanotubes (SWCNTs) noncovalently functionalized with poly(4-vinylpyridine) (P4VP) that enables the incorporation of a platinum-polyoxometalate (Pt-POM) CH4 oxidation precatalyst into the sensor by P4VP coordination. The resulting SWCNT-P4VP-Pt-POM composite showed ppm-level sensitivity to CH4 and good stability to air as well as time, wherein the generation of a high-valent platinum intermediate during CH4 oxidation is proposed as the origin of the observed chemiresistive response. The chemiresistor was found to exhibit selectivity for CH4 over heavier hydrocarbons such as n-hexane, benzene, toluene, and o-xylene, as well as gases, including carbon dioxide and hydrogen. The utility of the sensor in detecting CH4 using a simple handheld multimeter was also demonstrated.
- Bezdek, Máté J.,Luo, Shao-Xiong Lennon,Ku, Kang Hee,Swager, Timothy M.
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- Direct Visualization of Substitutional Li Doping in Supported Pt Nanoparticles and Their Ultra-selective Catalytic Hydrogenation Performance
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It has only recently been established that doping light elements (lithium, boron, and carbon) into supported transition metals can fill interstitial sites, which can be observed by the expanded unit cell. As an example, interstitial lithium (intLi) can block H filling octahedral interstices of palladium metal lattice, which improves partial hydrogenation of alkynes to alkenes under hydrogen. In contrast, herein, we report intLi is not found in the case of Pt/C. Instead, we observe for the first time a direct ‘substitution’ of Pt with substitutional lithium (subLi) in alternating atomic columns using scanning transmission electron microscopy-annular dark field (STEM-ADF). This ordered substitutional doping results in a contraction of the unit cell as shown by high-quality synchrotron X-ray diffraction (SXRD). The electron donation of d-band of Pt without higher orbital hybridizations by subLi offers an alternative way for ultra-selectivity in catalytic hydrogenation of carbonyl compounds by suppressing the facile CO bond breakage that would form alcohols.
- Chen, Tianyi,Foo, Christopher,Zheng, Jianwei J. W.,Fang, Huihuang,Nellist, Peter,Tsang, Shik Chi Edman
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supporting information
p. 12041 - 12046
(2021/07/14)
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- Linear Hydrocarbon Chain Growth from a Molecular Diruthenium Carbide Platform
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The formation of linear hydrocarbon chains by sequential coupling of C1units on the metal surface is the central part of the Fischer-Tropsch (F-T) synthesis. Organometallic complexes have provided numerous models of relevant individual C-C coupling events but have failed to reproduce the complete chain lengthening sequence that transforms a linear Cnhydrocarbon chain into its Cn+1homologue in an iterative fashion. In this work, we demonstrate stepwise growth of linear Cnhydrocarbon chains and their conversion to their Cn+1homologues via consecutive addition of CH2units on a molecular diruthenium carbide platform. The chain growth sequence is initiated by the formation of a μ-η1:η1-C═CH2ligand from a C + CH2coupling between the μ-carbido complex [(Cp*Ru)2(η-NPh)(μ-C)] (1; Cp* = η5-C5Me5) and Ph2SCH2. Then, the chain propagates via a general C═CHR + CH2coupling and subsequent hydrogen-assisted isomerization of the resulting allene ligand μ-η1:η3-H2C═C═CHR to a higher vinylidene homologue μ-η1:η1-C═CH(CH2)R. By repeating this reaction sequence, up to C6chains have been synthesized in a stepwise fashion. The key step of this chain homologation sequence is the selective hydrogenation of the μ-η1:η3-allene unit to the corresponding μ-alkylidene ligand. Isotope labeling and computational studies indicate that this transformation proceeds via the hydrogenation of the allene ligand to a terminal alkene form and its isomerization to the μ-alkylidene ligand facilitated by the coordinatively unsaturated diruthenium platform.
- Fujita, Hiroaki,Matsuzaka, Hiroyuki,Ohata, Jun,Takemoto, Shin,Teramoto, Akira
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p. 16105 - 16112
(2021/10/01)
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- Hydrodeoxygenation of Diphenyl Ether over an In Situ NiMoS Catalyst
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Abstract: The study investigates the activity of an in situ nanosized NiMoS catalyst in the hydrodeoxygenation of diphenyl ether. The hydrodeoxygenation product was found to primarily contain benzene, cyclohexane, and n-hexane. The study identified the effects of reaction temperature and reaction mixture composition on the conversion rate and on the quantitative composition of the product. The conversion rate reached 100% at a substrate : Mo molar ratio of 10.5 : 1. The catalysts isolated after the reaction were analyzed by transmission electron microscopy and X-ray photoelectron spectroscopy. The catalyst dispersion was 1.1. [Figure not available: see fulltext.].
- Kuchinskaya,Mamian,Kniazeva
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p. 1124 - 1130
(2021/11/17)
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- Highly Active Superbulky Alkaline Earth Metal Amide Catalysts for Hydrogenation of Challenging Alkenes and Aromatic Rings
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Two series of bulky alkaline earth (Ae) metal amide complexes have been prepared: Ae[N(TRIP)2]2 (1-Ae) and Ae[N(TRIP)(DIPP)]2 (2-Ae) (Ae=Mg, Ca, Sr, Ba; TRIP=SiiPr3, DIPP=2,6-diisopropylphenyl). While monomeric 1-Ca was already known, the new complexes have been structurally characterized. Monomers 1-Ae are highly linear while the monomers 2-Ae are slightly bent. The bulkier amide complexes 1-Ae are by far the most active catalysts in alkene hydrogenation with activities increasing from Mg to Ba. Catalyst 1-Ba can reduce internal alkenes like cyclohexene or 3-hexene and highly challenging substrates like 1-Me-cyclohexene or tetraphenylethylene. It is also active in arene hydrogenation reducing anthracene and naphthalene (even when substituted with an alkyl) as well as biphenyl. Benzene could be reduced to cyclohexane but full conversion was not reached. The first step in catalytic hydrogenation is formation of an (amide)AeH species, which can form larger aggregates. Increasing the bulk of the amide ligand decreases aggregate size but it is unclear what the true catalyst(s) is (are). DFT calculations suggest that amide bulk also has a noticeable influence on the thermodynamics for formation of the (amide)AeH species. Complex 1-Ba is currently the most powerful Ae metal hydrogenation catalyst. Due to tremendously increased activities in comparison to those of previously reported catalysts, the substrate scope in hydrogenation catalysis could be extended to challenging multi-substituted unactivated alkenes and even to arenes among which benzene.
- Eyselein, Jonathan,F?rber, Christian,Grams, Samuel,Harder, Sjoerd,Knüpfer, Christian,Langer, Jens,Martin, Johannes,Thum, Katharina,Wiesinger, Michael
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supporting information
p. 9102 - 9112
(2020/03/30)
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- Transfer hydrogenation of alkynes into alkenes by ammonia borane over Pd-MOF catalysts
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Ammonia borane with both hydridic and protic hydrogens in its structure acted as an efficient transfer hydrogenation agent for selective transformation of alkynes into alkenes in non-protic solvents. Catalytic synergy between the μ3-OH groups of the UiO-66(Hf) MOF and Pd active sites in Pd/UiO-66(Hf) furnished an elusive >98% styrene selectivity and full phenylacetylene conversion at room temperature. Such performance is not achievable by a Pd + UiO-66(Hf) physical mixture or by a commercial Pd/C catalyst.
- Bakuru, Vasudeva Rao,Samanta, Debabrata,Maji, Tapas Kumar,Kalidindi, Suresh Babu
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supporting information
p. 5024 - 5028
(2020/05/08)
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- Transition metal complexes of a bis(carbene) ligand featuring 1,2,4-triazolin-5-ylidene donors: structural diversity and catalytic applications
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Dialkylation of the 1,3-bis(1,2,4-triazol-1-yl)benzene with ethyl bromide results in the formation of [L-H2]Br2which, upon salt metathesis with NH4PF6, readily yields the bis(triazolium) salt [L-H2](PF6)2with non-coordinating counterions. [L-H2](PF6)2and Ag2O react in a 1?:?1 ratio to yield a binuclear AgI-tetracarbene complex of the composition [(L)2Ag2](PF6)2which undergoes a facile transmetalation reaction with [Cu(SMe2)Br] to deliver the corresponding CuI-NHC complex [(L)2Cu2](PF6)2. In contrast, the [L-H2]Br2reacts with [Ir(Cp*)Cl2]2to generate a doubly C-H activated IrIII-NHC complex5. Similarly, the triazolinylidene donor supported diorthometalated RuII-complex6is also obtained. Complexes5and6represent the first examples of a stable diorthometalated binuclear IrIII/RuII-complex supported by 1,2,4-triazolin-5-ylidene donors. The synthesized IrIII-NHC complex5is found to be more effective than its RuII-analogue (6) for the reduction of a range of alkenes/alkynesviathe transfer hydrogenation strategy. Conversely, RuII-complex6is identified as an efficient catalyst (0.01 mol% loading) for the β-alkylation of a wide range of secondary alcohols using primary alcohols as alkylating partnersviaa borrowing hydrogen strategy.
- Donthireddy, S. N. R.,Illam, Praseetha Mathoor,Rit, Arnab,Singh, Vivek Kumar
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p. 11958 - 11970
(2020/09/21)
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- Comparative Study of Homogeneous and Silica Immobilized N^N and N^O Palladium(II) Complexes as Catalysts for Hydrogenation of Alkenes, Alkynes and Functionalized Benzenes
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Abstract: This work reports the use of homogeneous and silica immobilized palladium(II) complexes of ligands (2-phenyl-2-((3(triethoxysilyl)propyl)imino)ethanol) (L1), (4-methyl-2-((3(triethoxysilyl)propyl)imino)methyl)phenol) (L2), [L1-MCM-41] (L1im), and [L2-MCM-41] (L2im) as catalysts in molecular hydrogenation of alkenes, alkynes and functionalized benzenes. The homogeneous complexes [Pd(L1)2] (Pd1), [Pd(L2)2] (Pd2), [Pd(L1)(Cl2)] (Pd3),?and [Pd(L2)(Cl2)] (Pd4), and their respective silica immobilized?complexes [Pd(L1)2]-MCM-41] (Pd1im), [Pd(L2)2)-MCM-4] (Pd2im), [Pd (L1)(Cl2)-MCM-41] (Pd3im) and [Pd(L2)(Cl2)]-MCM-41] (Pd4im) formed active catalysts in?the molecular hydrogenation of these substrates. The catalytic activities and product distribution in these reactions were largely dictated by the nature of the substrate. The kinetic studies revealed a pseudo-first order dependence on styrene substrate for both the homogeneous and immobilized catalysts. Significantly, the selectivity of both homogeneous and immobilized catalysts were comparable in the hydrogenation of both?alkynes and multi-functionalized benzenes. The supported catalysts could be recycled up to four times with minimum loss of catalytic activity and showed absence of any leaching from hot filtration experiments. Kinetics and poisoning studies established that complexes Pd1–Pd4 were largely homogeneous in nature, while the immobilized complexes Pd1im–Pd4im formed Pd(0) nanoparticles as the main active species. Graphic Abstract: [Figure not available: see fulltext.].
- Akiri, Saphan O.,Ngcobo, Nondumiso L.,Ojwach, Stephen O.
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p. 2850 - 2862
(2020/03/30)
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- Rh-catalyzed highly regioselective hydroformylation to linear aldehydes by employing porous organic polymer as a ligand
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In this work, we developed a new structural porous organic polymer containing biphosphoramidite unit, which can be used as a solid bidentate phosphorous ligand for rhodium-catalyzed solvent-free higher olefins hydroformylation. The resultant catalyst demonstrated unprecedently high regioselectivity to linear aldehydes and could be readily recovered for successive reuses with good stability in both catalytic activity and regioselectivity. This journal is
- Wang, Zhaozhan,Yang, Yong
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p. 29263 - 29267
(2020/10/06)
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- Flexible polyurethanes, renewable fuels, and flavorings from a microalgae oil waste stream
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Renewable polymers have become an important focus in next-generation materials, and algae biomass offers an environmentally low-impact feedstock that can serve multiple uses. This study aims to develop a scalable methodology for production of microalgae-based polyols for polyurethane synthesis from waste oils derived from algae biomass. Following separation of omega-3 fatty acids from algae oil, residual oils can offer valuable building blocks for petrochemical replacements. However, unlike vegetable oils, algae oils contain organic contaminants, including photosynthetic pigments and hydrophobic cofactors that can complicate preparative methodologies. Here we convert and purify waste streams from omega-3 depleted Nannochloropsis salina algae oil, with major components consisting of palmitic and palmitoleic acid, into azelaic acid (AA) as a building block for flexible polyurethanes, with a simultaneous production of heptanoic acid (HA) as a flavor and fragrance precursor. Conversion of free fatty acid mixtures into a soft soap allows extraction of organic contaminants, and urea complexation provides isolated palmitoleic acid, which is subsequently ozonolyzed to produce AA and HA. Bio-based polyester diols are prepared from AA via esterification to provide a polyol monomer for flexible polyurethane foam preparation. The HA co-product is modified to produce the flavoring agent methyl heptanoate and also decarboxylated to produce hexane as a renewable solvent. This scalable process can be performed on oils from multiple algal species, offering valuable monomers from a highly sustainable source.
- Burkart, Michael D.,Griffin, Graham,Mayfield, Stephen P.,Neelakantan, Nitin,Phung Hai, Thien An,Pomeroy, Robert,Sherman, Suryendra D.,Tessman, Marissa
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supporting information
p. 3088 - 3094
(2020/06/17)
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- Novel nickel nanoparticles stabilized by imidazolium-amidinate ligands for selective hydrogenation of alkynes
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The main challenge in the hydrogenation of alkynes into (E)- or (Z)-alkenes is to control the selective formation of the alkene, avoiding the over-reduction to the corresponding alkane. In addition, the preparation of recoverable and reusable catalysts is of high interest. In this work, we report novel nickel nanoparticles (Ni NPs) stabilized by three different imidazolium-amidinate ligands (ICy·(Ar)NCN; L1: Ar = p-tol, L2: Ar = p-anisyl and L3: Ar = p-ClC6H4). The as-prepared Ni NPs were fully characterized by (HR)-TEM, XRD, WASX, XPS and VSM. The nanocatalysts are active in the hydrogenation of various substrates. They present a remarkable selectivity in the hydrogenation of alkynes towards (Z)-alkenes, particularly in the hydrogenation of 3-hexyne into (Z)-3-hexene under mild reaction conditions (room temperature, 3% mol Ni and 1 bar H2). The catalytic behaviour of Ni NPs was influenced by the electron donor/acceptor groups (-Me, -OMe, -Cl) in the N-aryl substituents of the amidinate moiety of the ligands. Due to the magnetic character of the Ni NPs, recycling experiments were successfully performed after decantation in the presence of an external magnet, which allowed us to recover and reuse these catalysts at least 3 times preserving both activity and chemoselectivity.
- López-Vinasco, Angela M.,Martínez-Prieto, Luis M.,Asensio, Juan M.,Lecante, Pierre,Chaudret, Bruno,Cámpora, Juan,Van Leeuwen, Piet W. N. M.
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p. 342 - 350
(2020/02/04)
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- One-pot reductive amination of carboxylic acids: a sustainable method for primary amine synthesis
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The reductive amination of carboxylic acids is a very green, efficient and sustainable method for the production of (bio-based) amines. However, with current technology, this reaction requires two to three reaction steps. Here, we report the first (heterogeneous) catalytic system for the one-pot reductive amination of carboxylic acids to amines, with solely H2 and NH3 as the reactants. This reaction can be performed with relatively cheap ruthenium-tungsten bimetallic catalysts in the green and benign solvent cyclopentyl methyl ether (CPME). Selectivities of up to 99% for the primary amine could be achieved at high conversions. Additionally, the catalyst is recyclable and tolerant for common impurities such as water and cations (e.g. sodium carboxylate).
- Coeck, Robin,De Vos, Dirk E.
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supporting information
p. 5105 - 5114
(2020/08/25)
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- Multistep Engineering of Synergistic Catalysts in a Metal-Organic Framework for Tandem C-O Bond Cleavage
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Cleavage of strong C-O bonds without breaking C-C/C-H bonds is a key step for catalytic conversion of renewable biomass to hydrocarbon feedstocks. Herein we report multistep sequential engineering of orthogonal Lewis acid and palladium nanoparticle (NP) catalysts in a metal-organic framework (MOF) built from (Al-OH)n secondary building units and a mixture of 2,2′-bipyridine-5,5′-dicarboxylate (dcbpy) and 1,4-benzenediacrylate (pdac) ligands (1) for tandem C-O bond cleavage. Ozonolysis of 1 selectively removed pdac ligands to generate Al2(OH)(OH2) sites, which were subsequently triflated with trimethylsilyl triflate to afford strongly Lewis acidic sites for dehydroalkoxylation. Coordination of Pd(MeCN)2Cl2 to dcbpy ligands followed by in situ reduction produced orthogonal Pd NP sites in 1-OTf-PdNP as the hydrogenation catalyst. The selective and precise transformation of 1 into 1-OTf-PdNP was characterized step by step using powder X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, inductively coupled plasma mass spectrometry, infrared spectroscopy, and X-ray absorption spectroscopy. The hierarchical incorporation of orthogonal Lewis acid and Pd NP active sites endowed 1-OTf-PdNP with outstanding catalytic performance in apparent hydrogenolysis of etheric, alcoholic, and esteric C-O bonds to generate saturated alkanes via a tandem dehydroalkoxylation-hydrogenation process under relatively mild conditions. The reactivity of C-O bonds followed the trend of tertiary carbon > secondary carbon > primary carbon. Control experiments demonstrated the heterogeneous nature and recyclability of 1-OTf-PdNP and its superior catalytic activity over the homogeneous counterparts. Sequential engineering of multiple catalytic sites in MOFs thus presents a unique opportunity to address outstanding challenges in sustainable catalysis.
- Brzezinski, Carter,Chen, Justin S.,Feng, Xuanyu,Lin, Wenbin,Song, Yang,Xu, Ziwan
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supporting information
p. 4872 - 4882
(2020/04/01)
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- Deoxygenation of heptanoic acid to hexene over cobalt-based catalysts: A model study for α-olefin production from renewable fatty acid
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Deoxygenation of heptanoic acid, a model compound, over bimetallic cobalt (Co-Pt, Co-Au, Co-Pd, Co-Ru) supported silica catalysts, was examined for α-olefin production. The catalysts were prepared by conventional impregnation of the metal precursors on silica and characterized by XRF, TEM, H2-TPR, acetic acid-TPD, and XANES. Catalytic testing was performed in a fixed-bed flow reactor under atmospheric H2 pressure. Monometallic cobalt catalysts yielded mainly 1-hexene, but rapid deactivation was observed. Incorporation of 0.5percentwt secondary metal, particularly Pt, increases activity and stability under H2. A relatively higher olefin/paraffin ratio can be obtained from the reaction over 5percentCo+0.5percentPt/SiO2 when compared to that with higher Pt loading. The co-impregnation method offers Co-Pt catalysts with stability higher than that prepared by the sequential impregnation method. Over cobalt-based catalysts, the deoxygenation is proposed to proceed via reduction of heptanoic acid to heptanal that is an intermediate for decarbonylation to hexene; while other side reactions are suppressed.
- Choojun, Kittisak,Phichitsurathaworn, Ploynisa,Poo-arporn, Yingyot,Sooknoi, Tawan
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- Ruthenium-catalyzed selective hydroboronolysis of ethers
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A ruthenium-catalyzed reaction of HBpin with substituted organic ethers leads to the activation of C?O bonds, resulting in the formation of alkanes and boronate esters via hydroboronolysis. A ruthenium precatalyst, [Ru (p-cymene)Cl]2Cl2 (1), is employed, and the reactions proceed under neat conditions at 135 °C and atmospheric pressure (ca. 1.5 bar at 135 °C). Unsymmetrical dibenzyl ethers undergo selective hydroboronolysis on relatively electron-poor C?O bonds. In arylbenzyl or alkylbenzyl ethers, C?O bond cleavage occurs selectively on CBn?OR bonds (Bn = benzyl); in alkylmethyl ethers, selective deconstruction of CMe?OR bonds leads to the formation of alkylboronate esters and methane. Cyclic ethers are also amenable to catalytic hydroboronolysis. Mechanistic studies indicated the immediate in situ formation of a mono-hydridobridged dinuclear ruthenium complex [{(η6-p-cymene)RuCl}2(μ?H?μ?Cl)] (2), which is highly active for hydroboronolysis of ethers. Over time, the dinuclear species decompose to produce ruthenium nanoparticles that are also active for this transformation. Using this catalytic system, hydroboronolysis could be applied effectively to a very large scope of ethers, demonstrating its great potential to cleave C?O bonds in ethers as an alternative to traditional hydrogenolysis.
- Kaithal, Akash,Kalsi, Deepti,Krishnakumar, Varadhan,Pattanaik, Sandip,Bordet, Alexis,Leitner, Walter,Gunanathan, Chidambaram
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p. 14390 - 14397
(2020/12/21)
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- Molybdenum Oxide-Modified Iridium Catalysts for Selective Production of Renewable Oils for Jet and Diesel Fuels and Lubricants
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Supported inverse metal-metal oxide catalysts have received significant research interest owing to their effective hydrodeoxygenation (HDO) activity toward biomass substrates, but the high cost of the reported catalysts poses a challenge for commercialization. We present the synthesis of a series of metal-metal oxide catalysts, Ir-MOx/SiO2 (M = Re, Mo, W, V, or Nb) and M′-MoOx/SiO2 (M = Rh, Ru, Pt, or Pd) and their HDO performance on multifuran (high carbon) substrates to produce renewable jet and diesel fuels and lubricant base oils. A MoOx-modified Ir/SiO2 catalyst with a Mo/Ir ratio of 0.13 (Ir-MoOx/SiO2) exhibits the highest product yield (78-96%) under mild reaction conditions. Controlled experiments using probe substrates reveal that furan ring hydrogenation and C-O hydrogenolysis of saturated and unsaturated furan rings occur in a sequential manner. The carbon atom adjacent to the furan or saturated furan ring of substrates or intermediate compounds undergoes slow C-C bond scission, resulting in a small fraction of lighter alkanes. Catalyst characterization suggests that Ir is reduced to a fully metallic state to dissociate hydrogen for hydrogenation. Intact MoOx, partly covering the Ir metal surface, promotes ring opening, hydrogenolysis of etheric and alcoholic C-O bonds, and hydrogenation of Ca? O bonds. This study highlights the potential of low-cost metal-metal oxide catalysts with low loading of oxophilic metals to enable cost-competitive production of bioproducts and demonstrates applicability of these catalysts on other substrates, including fatty acids, fatty esters, and lipids.
- Liu, Sibao,Zheng, Weiqing,Fu, Jiayi,Alexopoulos, Konstantinos,Saha, Basudeb,Vlachos, Dionisios G.
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p. 7679 - 7689
(2019/08/20)
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- Mechanochemistry-assisted encapsulation of metal nanoparticles in MOF matrices: Via a sacrificial strategy
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Metal-organic framework (MOF)-supported metal nanoparticle (MNP) composites, especially those with encapsulation structures (MNPs@MOF), hold significant promise for versatile applications. Massive efforts have been devoted towards the preparation of these composites; however, the poor stability of MOFs and their homogeneous growth in solution make these synthetic strategies complex and tedious; this greatly hampers their practical application. Herein, a general mechanochemistry-assisted encapsulation approach was developed to entrap MNPs in MOF matrices. In this approach, metal precursor-supported MNP hybrids were in situ sacrificed to form MNPs@MOF composites via simple ball milling, and the MNPs were encapsulated in the MOF matrices in the solid state during the sacrificial process. This method completely avoids the homogeneous growth of MOFs; furthermore, this approach proceeds with trace amounts of solvents and does not require stabilizing agents; this enables a clean and sustainable synthesis. By this facile approach, many interesting MNPs@MOF composites were prepared. All the composites showed good crystalline structures, and no obvious damages to the MOF were observed. Moreover, in these structures, small MNPs were well encapsulated in the MOF matrices and mainly distributed near the surface of the MOFs, resulting in high catalytic activity and selectivity for the hydrogenation of olefins. Moreover, the MNPs@MOF composites can be easily synthesized on a gram-scale (8 g of Pd@ZIF-8); this achievement would advance their practical application.
- Li, Xiaochen,Zhang, Zhihua,Xiao, Weiming,Deng, Shengjun,Chen, Chao,Zhang, Ning
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supporting information
p. 14504 - 14509
(2019/06/24)
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- Room Temperature Iron-Catalyzed Transfer Hydrogenation and Regioselective Deuteration of Carbon-Carbon Double Bonds
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An iron catalyst has been developed for the transfer hydrogenation of carbon-carbon multiple bonds. Using a well-defined β-diketiminate iron(II) precatalyst, a sacrificial amine and a borane, even simple, unactivated alkenes such as 1-hexene undergo hydrogenation within 1 h at room temperature. Tuning the reagent stoichiometry allows for semi- and complete hydrogenation of terminal alkynes. It is also possible to hydrogenate aminoalkenes and aminoalkynes without poisoning the catalyst through competitive amine ligation. Furthermore, by exploiting the separate protic and hydridic nature of the reagents, it is possible to regioselectively prepare monoisotopically labeled products. DFT calculations define a mechanism for the transfer hydrogenation of propene with nBuNH2 and HBpin that involves the initial formation of an iron(II)-hydride active species, 1,2-insertion of propene, and rate-limiting protonolysis of the resultant alkyl by the amine N-H bond. This mechanism is fully consistent with the selective deuteration studies, although the calculations also highlight alkene hydroboration and amine-borane dehydrocoupling as competitive processes. This was resolved by reassessing the nature of the active transfer hydrogenation agent: experimentally, a gel is observed in catalysis, and calculations suggest this can be formulated as an oligomeric species comprising H-bonded amine-borane adducts. Gel formation serves to reduce the effective concentrations of free HBpin and nBuNH2 and so disfavors both hydroboration and dehydrocoupling while allowing alkene migratory insertion (and hence transfer hydrogenation) to dominate.
- Espinal-Viguri, Maialen,Neale, Samuel E.,Coles, Nathan T.,MacGregor, Stuart A.,Webster, Ruth L.
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supporting information
p. 572 - 582
(2019/01/08)
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- Ru subnanoparticles on N-doped carbon layer coated SBA-15 as efficient Catalysts for arene hydrogenation
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The N-doped carbon layer coated SBA-15 support has been accomplished via a pyrolysis process. The ultra-low loading Ru nanoparticles (ca. 0.1 wt.%) was incorporated into the support by impregnation and the sequential reduction. The images of HAADF-STEM revealed that the Ru particles with sub-1-nm size (0.2-0.7 nm) were uniformly dispersed on the support. The ultrafine Ru particles displayed the excellent activity for the hydrogenation of olefins, arenes, phenol derivatives and heteroarenes in aqueous phase. The aliphatic or alicyclic compounds were produced selectively without the hydrogenolysis of C–O and C–N bonds. The high turnover frequency (TOF) values can reach up to 10,000 h?1. Notably, the activity of these catalysts improved dramatically with decreasing the sizes of Ru particles. Meanwhile, the N-doped carbon layer coating endowed the high stability of the Ru catalysts and prevented the leaching of the Ru species owning to the strong interaction between doped-N atoms and the ultrafine Ru particles. Overall, this work provides a highly attractive strategy to construct the supported sub-1-nm Ru particles utilized for the aqueous hydrogenation.
- Qian, Wei,Lin, Lina,Qiao, Yunxiang,Zhao,Xu, Zichen,Gong, Honghui,Li,Chen,Huang, Rong,Hou, Zhenshan
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- Supported palladium membrane reactor architecture for electrocatalytic hydrogenation
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Electrolytic palladium membrane reactors offer a means to perform hydrogenation chemistry utilizing electrolytically produced hydrogen derived from water instead of hydrogen gas. While previous embodiments of these reactors employed thick (≥25 μm) palladium foil membranes, we report here that the amount of palladium can be reduced by depositing a thin (1-2 μm) layer of palladium onto a porous polytetrafluoroethylene (PTFE) support. The supported palladium membrane can be designed to ensure the fast diffusion of reagent and hydrogen to the palladium layer. The hydrogenation of 1-hexyne, for example, shows that the supported Pd/PTFE membrane can achieve reaction rates (e.g., 0.71 mmol h-1) which are comparable to 0.92 mmol h-1 measured for palladium membranes with a high-surface area palladium electrocatalyst layer. The root cause of these comparable rates is that the high porosity of PTFE enables a 12-fold increase in electrocatalytic surface area compared to planar palladium foil membranes. These results provide a pathway for designing a cost-effective and potentially scalable electrolytic palladium membrane reactor.
- Delima, Roxanna S.,Sherbo, Rebecca S.,Dvorak, David J.,Kurimoto, Aiko,Berlinguette, Curtis P.
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p. 26586 - 26595
(2019/12/04)
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- Study of the Structure of Cobalt-Containing Catalysts Synthesized under Subcritical Conditions
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Abstract: A physicochemical study of cobalt-containing (10 wt %) silica-supported Fischer–Tropsch catalysts was carried out. The catalysts were obtained under subcritical conditions (T = 200°C, P = 8 MPa) using water (Tc = 374.1°C, Pc = 22.1 MPa) and propanol-2 (Tc = 235.6°C, Pc = 5.8 MPa). The obtained samples were compared with a 10 wt % Co/SiO2 catalyst prepared by incipient-wetness impregnation. Comparison of the properties of catalysts in the liquid-phase Fischer–Tropsch synthesis showed that the sample prepared in subcritical water was the most active and selective to aliphatic C6–C7 hydrocarbons. This sample is characterized by a high surface area (131.7 m2/g), a uniform distribution of particles in the active phase with an average size of 5 nm and higher accessibility of cobalt species for reagents. According to XPS data, the composition of catalyst active phase is mainly represented by two compounds: Co(OH)2 and Co3O4.
- Markova,Gavrilenko,Stepacheva,Molchanov,Matveeva,Sulman,Sulman
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p. 618 - 626
(2019/10/19)
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- Well-dispersed nickel nanoparticles on the external and internal surfaces of SBA-15 for hydrocracking of pyrolyzed α-cellulose
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Catalysts comprising nickel supported on SBA-15 were prepared by wet impregnation and co-impregnation methods. Wet impregnation was performed by directly dispersing an Ni(NO3)2·6H2O aqueous solution into SBA-15, whereas in co-impregnation, ethylene glycol (EG) was added to nickel nitrate aqueous solution prior to dispersion into SBA-15. After drying and calcination, NiO/SBA-15w and NiO/SBA-15c were produced. Later, after the reduction process, Ni/SBA-15w and Ni/SBA-15c were obtained. The prepared catalysts were evaluated for the hydrocracking of pyrolyzed α-cellulose. The TEM images revealed that the catalysts prepared by wet impregnation showed inhomogeneous distribution of nickel loading, whereas catalysts prepared by co-impregnation using EG exhibited homogeneous distribution and formed no nickel aggregates. During hydrocracking of pyrolyzed α-cellulose, Ni/SBA-15c with total acidity, nickel loading, particle size, and specific surface area of 7.27 m mol g?1, 5.20 wt%, 3.17 nm, and 310.0 m2 g?1, respectively, exhibited the best catalytic performance compared to other prepared catalysts with 67.35 wt% conversion of liquid product with maximum selectivity in producing 13.09 wt% of 3-methyl-pentane. Moreover, Ni/SBA-15w with total acidity, nickel loading, particle size, and specific surface area of 10.87 m mol g?1, 8.15 wt%, 7.01 nm, and 628.0 m2 g?1, respectively, produced 69.89 wt% liquid product without hydrocarbons. Study of selectivity towards the formation of liquid hydrocarbons was carried out via double step hydrocracking using Ni/SBA-15w, and 18.55 wt% of n-hexane was produced in the liquid product.
- Trisunaryanti, Wega,Suarsih, Endah,Triyono,Falah, Iip Izul
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p. 1230 - 1237
(2019/01/23)
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- Mechanistic Characterization of (Xantphos)Ni(I)-Mediated Alkyl Bromide Activation: Oxidative Addition, Electron Transfer, or Halogen-Atom Abstraction
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Ni(I)-mediated single-electron oxidative activation of alkyl halides has been extensively proposed as a key step in Ni-catalyzed cross-coupling reactions to generate radical intermediates. There are four mechanisms through which this step could take place: oxidative addition, outer-sphere electron transfer, inner-sphere electron transfer, and concerted halogen-atom abstraction. Despite considerable computational studies, there is no experimental study to evaluate all four pathways for Ni(I)-mediated alkyl radical formation. Herein, we report the isolation of a series of (Xantphos)Ni(I)-Ar complexes that selectively activate alkyl halides over aryl halides to eject radicals and form Ni(II) complexes. This observation allows the application of kinetic studies on the steric, electronic, and solvent effects, in combination with DFT calculations, to systematically assess the four possible pathways. Our data reveal that (Xantphos)Ni(I)-mediated alkyl halide activation proceeds via a concerted halogen-atom abstraction mechanism. This result corroborates previous DFT studies on (terpy)Ni(I)- and (py)Ni(I)-mediated alkyl radical formation, and contrasts with the outer-sphere electron transfer pathway observed for (PPh3)4Ni(0)-mediated aryl halide activation. This study of a model system provides insight into the overall mechanism of Ni-catalyzed cross-coupling reactions and offers a basis for differentiating electrophiles in cross-electrophile coupling reactions.
- Diccianni, Justin B.,Katigbak, Joseph,Hu, Chunhua,Diao, Tianning
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supporting information
p. 1788 - 1796
(2019/01/26)
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- Titanium-catalyzed hydrosilylation of olefins: A comparison study on Cp2TiCl2/Sm and Cp2TiCl2/LiAlH4 catalyst system
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Hydrosilylation of olefins catalyzed by Cp2TiCl2/Sm (Cp = cyclopentadienyl) under solvent free conditions have been investigated. By using Cp2TiCl2/Sm as catalyst system, β-adducts and hydrogenation products were detected. Hydrosilylation of olefins catalyzed by Cp2TiCl2/LiAlH4 under room temperature has also been studied. The influence of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) on Cp2TiCl2/Sm and Cp2TiCl2/LiAlH4, respectively, indicated that hydrosilylation of olefins catalyzed with Cp2TiCl2/Sm went through a free radical reaction pathway while a coordination mechanism was applied for Cp2TiCl2/LiAlH4 catalyst system.
- Yang, Xiaoling,Bai, Ying,Li, Jiayun,Liu, Yu,Peng, Jiajian,Li, Tianbo,Lang, Rui,Qiao, Botao
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- Phosphine-ligated Ir(III)-complex as a bi-functional catalyst for one-pot tandem hydroformylation-acetalization
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The complexation of IrCl3?3H2O with the electron-deficient phosphines (L1-L6) respectively afforded a bi-functional catalyst possessing the dual functions of transition metal complex (IrIII-P) and IrIII-Lewis acid for tandem hydroformylation-acetalization of olefins. The best result was obtained over L5-based IrCl3?3H2O catalytic system which corresponded to 97% conversion of 1-hexene along with 92% selectivity to the target acetals free of any additive. The crystal structure of the novel IrIII-complex of IrIII-L4 indicated that the electron-deficient nature of the involved phosphine warranted Ir-center in +3 valence state without reduction, which served as the Lewis acid catalyst for the subsequent acetalization of the aldehydes as well. Moreover, as an ionic phosphine, L6-based IrCl3?3H2O system immobilized in RTIL of [Bmim]PF6 could be recycled for 6 runs without the obvious activity loss or metal leaching.
- Liu, Huan,Liu, Lei,Guo, Wen-Di,Lu, Yong,Zhao, Xiao-Li,Liu, Ye
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p. 215 - 221
(2019/04/17)
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- Alkene Transfer Hydrogenation with Alkaline-Earth Metal Catalysts
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The alkene transfer hydrogenation (TH) of a variety of alkenes has been achieved with simple AeN′′2 catalysts [Ae=Ca, Sr, Ba; N′′=N(SiMe3)2] using 1,4-cyclohexadiene (1,4-CHD) as a H source. Reaction of 1,4-CHD with AeN′′2 gave benzene, N′′H, and the metal hydride species N′′AeH (or aggregates thereof), which is a catalyst for alkene hydrogenation. BaN′′2 is by far the most active catalyst. Hydrogenation of activated C=C bonds (e.g. styrene) proceeded at room temperature without polymer formation. Unactivated (isolated) C=C bonds (e.g. 1-hexene) needed a higher temperature (120 °C) but proceeded without double-bond isomerization. The ligands fully control the course of the catalytic reaction, which can be: 1) alkene TH, 2) 1,4-CHD dehydrogenation, or 3) alkene polymerization. DFT calculations support formation of a metal hydride species by deprotonation of 1,4-CHD followed by H transfer. Convenient access to larger quantities of BaN′′2, its high activity and selectivity, and the many advantages of TH make this a simple but attractive procedure for alkene hydrogenation.
- Bauer, Heiko,Thum, Katharina,Alonso, Mercedes,Fischer, Christian,Harder, Sjoerd
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supporting information
p. 4248 - 4253
(2019/03/07)
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- Porous organic polymer supported rhodium as a reusable heterogeneous catalyst for hydroformylation of olefins
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A new porous organic polymer has been prepared via copolymerization of divinyl-functionalized phosphoramidite ligand and tris(4-vinylphenyl)phosphine. The porous polymer was loaded with Rh(acac)CO2 to yield a supported Rh catalyst, which demonstrated good regioselectivity (l/b = 6.7-52.8) and high catalytic activity (TON up to 45.3 × 104) in hydroformylation of terminal and internal olefins. Remarkably, the heterogeneous catalyst can be reused at least 10 cycles without losing activity and selectivity in hydroformylation of 1-hexene.
- Jia, Xiaofei,Liang, Zuyu,Chen, Jianbin,Lv, Jinhe,Zhang, Kai,Gao, Mingjie,Zong, Lingbo,Xie, Congxia
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supporting information
p. 2147 - 2150
(2019/03/26)
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- High-Quality Gasoline Directly from Syngas by Dual Metal Oxide–Zeolite (OX-ZEO) Catalysis
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Despite significant efforts towards the direct conversion of syngas into liquid fuels, the selectivity remains a challenge, particularly with regard to high-quality gasoline with a high octane number and a low content of aromatic compounds. Herein, we show that zeolites with 1D ten-membered-ring (10-MR) channel structures such as SAPO-11 and ZSM-22 in combination with zinc- and manganese-based metal oxides (ZnaMnbOx) enable the selective synthesis of gasoline-range hydrocarbons C5–C11 directly from syngas. The gasoline selectivity reached 76.7 % among hydrocarbons, with only 2.3 % CH4 at 20.3 % CO conversion. The ratio of isoparaffins to n-paraffins was as high as 15, and the research octane number was estimated to be 92. Furthermore, the content of aromatic compounds in the gasoline was as low as 16 %. The composition and structure of ZnaMnbOx play an important role in determining the overall activity. This process constitutes a potential technology for the one-step synthesis of environmentally friendly gasoline with a high octane number from a variety of carbon resources via syngas.
- Li, Na,Jiao, Feng,Pan, Xiulian,Chen, Yuxiang,Feng, Jingyao,Li, Gen,Bao, Xinhe
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supporting information
p. 7400 - 7404
(2019/05/10)
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- Selective hydrothermal reductions using geomimicry
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Reduction of carbon-carbon π-bonds has been demonstrated using iron powder as the reductant and simple powdered nickel as the catalyst in water as the solvent at 250 °C and the saturated water vapor pressure, 40 bars. Stereochemical, kinetic and electronic probes of the mechanism suggest reaction via a conventional Horiuti-Polyani process for hydrogenation at the nickel metal surface. Selective reduction of carbon-carbon π-bonds is observed in the presence of other functional groups. The reactions use benign and Earth-abundant reagents that are at low depletion risk and take place in water as the only solvent under conditions that are characteristic of many geochemical processes.
- Bockisch, Christiana,Lorance, Edward D.,Shaver, Garrett,Williams, Lynda B.,Hartnett, Hilairy E.,Shock, Everett L.,Gould, Ian R.
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p. 4159 - 4168
(2019/08/07)
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- Potassium Yttrium Ate Complexes: Synergistic Effect Enabled Reversible H2 Activation and Catalytic Hydrogenation
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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.
- Zhai, Dan-Dan,Du, Hui-Zhen,Zhang, Xiang-Yu,Liu, Yu-Feng,Guan, Bing-Tao
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p. 8766 - 8771
(2019/09/30)
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- Reactions in the Photocatalytic Conversion of Tertiary Alcohols on Rutile TiO2(110)
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According to textbooks, tertiary alcohols are inert towards oxidation. The photocatalysis of tertiary alcohols under highly defined vacuum conditions on a titania single crystal reveals unexpected and new reactions, which can be described as disproportionation into an alkane and the respective ketone. In contrast to primary and secondary alcohols, in tertiary alcohols the absence of an α-H leads to a C?C-bond cleavage instead of the common abstraction of hydrogen. Surprisingly, bonds to methyl groups are not cleaved when the alcohol exhibits longer alkyl chains in the α-position to the hydroxyl group. The presence of platinum loadings not only increases the reaction rate but also opens up a new reaction channel: the formation of molecular hydrogen and a long-chain alkane resulting from recombination of two alkyl moieties. This work demonstrates that new synthetic routes may become possible by introducing photocatalytic reaction steps in which the co-catalysts may also play a decisive role.
- Courtois, Carla,Eder, Moritz,Schnabl, Kordula,Walenta, Constantin A.,Tschurl, Martin,Heiz, Ulrich
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supporting information
p. 14255 - 14259
(2019/09/06)
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- AUTOPHAGY ENHANCER AND USE THEREOF
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Provided are a compound of chemical formula 1 or 2 and a use thereof. The compound can be advantageously used in the prevention or treatment of metabolic diseases including type 2 diabetes, insulin resistance, or obesity, on the basis of a mechanism of autophagy activation through the promotion of lysosome production.
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