- Structural characterization and catalytic activity of the rhodium-carbene complex Rh(PPh3)2(IMes)Cl (IMes = bis(1,3-(2,4,6-trimethylphenyl)imidazol-2-ylidene)
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The rhodium-carbene complex Rh(PPh3)2(IMes)Cl (2) is an active catalyst for the hydroboration of simple olefins at room temperature. The reactivity of 2 was also tested in the methylenation of aldehydes. The crystal structure of 2 is
- Grasa, Gabriela A.,Moore, Zakhia,Martin, Kenneth L.,Stevens, Edwin D.,Nolan, Steven P.,Paquet, Valérie,Lebel, Hélène
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- Subtle factors are important: Radical formation and transmetallation in reactions of butyl cuprates with cyclohexyl iodide
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The reactions of Bu2CuLi·LiI and Bu2CuLi LiCN with cyclohexyl iodide are critically dependent upon subtle factors such as the surface properties of the reaction vessel, nature of the solvent still and lot of 'ultrapure' copper salt i
- Bertz, Steven H.,Human, Jason,Ogle, Craig A.,Seagle, Paul
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- Effect of hydrohalogenation of metal/zeolite catalysts for cyclohexene hydroconversion -Part 3- Pd/H-ZSM-5 catalysts
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Cyclohexene (CHE) hydroconversion was performed in a flow reactor at atmospheric pressure and temperatures of 50-400 °C using: Pd/H-ZSM-5, Pd/H-ZSM-5(HCl), and Pd/H-ZSM-5(HF) catalysts. These catalysts were characterized for acid site strength distribution via NH3 TPD, Pd dispersion via H2 chemisorption, TPR via reduction of the metal oxide in the catalysts and XRD for tracing crystallinity. The hydroconversion steps proceeded as follows: CHE → Cyclohexane (CHA); CHE → Methylcyclopentenes (MCPEs) → Methylcyclopentane (MCPA); CHE → Cyclohexadienes (CHDEs) → Benzene → Alkylbenzenes; CHE and others → Hydrocracked products. The overall hydroconversion of CHE was achieved in the catalyst order: Pd/H-ZSM-5 > Pd/H-ZSM-5(HF) > Pd/H-ZSM-5(HCl). CHE hydrogenation step was the major reaction at low temperatures which significantly inhibited via HCl treatment, but slightly enhanced via HF treatment. At medium temperatures, on all catalysts, isomerisation to MCPEs and MCPA increase to a maximum then a decline with a further increase of temperature. The overall isomerisation of CHE was highest on the untreated catalyst. During the higher temperature range, dehydrogenation, alkylation and hydrocracking were increased with temperature. Dehydrogenation of CHE always yielded larger amounts of 1,3-CHDE than 1,4-CHDE. These cyclohexadienes were produced in the catalyst order: Pd/H-ZSM-5(HF) > Pd/H-ZSM-5(HCl) > Pd/H-ZSM-5. In general, benzene alkylation to toluene exceeded that of xylenes, indicating that the second methylation is more difficult than the first. However, the catalytic activities for benzene and toluene production were in the order: Pd/H-ZSM-5 ? Pd/H-ZSM-5(HCl) > Pd/H-ZSM-5(HF), whereas for xylenes production, Pd/H-ZSM-5 ? Pd/H-ZSM-5(HF) > Pd/H-ZSM-5(HCl). Intrapore diffusion plays an important role during the dehydrogenation reactions as well as during the interconversion of individual aromatic hydrocarbons.
- Aboul-Gheit, Noha A. K.
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- Doping effects of B in ZrO2 on structural and catalytic properties of Ru/B-ZrO2 catalysts for benzene partial hydrogenation
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The B-doped ZrO2 (B-ZrO2) samples with different B/Zr ratios were synthesized using zirconium oxychloride and boric acid as the precursors. Their crystallographic phase retained as tetragonal ZrO2 after the doping of B; however, the amount of the Lewis acid sites increased from 46.1 μmolNH3 g-1 on ZrO2 to 100.6 μmolNH3 g-1 on B-ZrO2(1/10) with the nominal B/Zr molar ratio of 1/10. The Ru/B-ZrO2 catalysts were then prepared by chemical reduction, and their electronic and structural properties were systematically characterized by spectroscopic techniques. It is identified that the Ru nanoparticles (NPs) supported on these B-ZrO2 samples exhibited similar size, chemical state, and microstructure. In the partial hydrogenation of benzene, the turnover frequency of benzene was linearly proportional to the amount of the acid sites on the supports, whereas the selectivity toward cyclohexene displayed a volcanic evolution passing through a maximum of 88% on the Ru/B-ZrO2(1/15) catalyst. Kinetic analysis indicated that the acid sites improved the rate constants of the benzene to cyclohexene step (k1) and the cyclohexene to cyclohexane step (k 2) to different degrees. The resulting k1/k2 ratio increased from 3.7 × 10-2 l mol-1 (Ru/ZrO 2) to 4.8 × 10-2 l mol-1 (Ru/B-ZrO 2(1/15)), and then declined to 4.1 × 10-2 l mol -1 (Ru/B-ZrO2(1/10)), which explained the volcanic evolution of the selectivity toward cyclohexene with respect to the acid amount.
- Zhou, Gongbing,Pei, Yan,Jiang, Zheng,Fan, Kangnian,Qiao, Minghua,Sun, Bin,Zong, Baoning
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- Surface engineering on a nanocatalyst: basic zinc salt nanoclusters improve catalytic performances of Ru nanoparticles
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Herein, we report novel surface-modified Ru-based catalysts by the chemisorption of basic zinc sulfate salts (3Zn(OH)2·ZnSO4·xH2O, BZSSs) and demonstrate their enhanced selectivity toward cyclohexene (CHE) in benzene-selective hydrogenation. BZSS nanoclusters are confirmed to regulate the surface and electronic properties of Ru nanoparticles. The surface active sites on Ru nanoparticles are reconstructed because the strong active sites are selectively occupied and blocked by BZSS nanoclusters. Lewis acid active sites, which are introduced by the BZSS and modified by the interaction between Ru(0) and the BZSS, can retain the activity of the Ru catalyst and greatly improve the selectivity toward CHE. Benefiting from the BZSS nanoclusters located on the Ru nanoparticles, the surface-modified catalysts present excellent selectivity with high activity for the hydrogenation reaction. This is particularly clear in that the catalyst operated stably for more than 600 h on an industrial production line; the benzene conversion was maintained at 40%, and the selectivity toward CHE was maintained over 80%.
- Peng, Zhikun,Liu, Xu,Lin, Huinan,Wang, Zhuo,Li, Zhongjun,Li, Baojun,Liu, Zhongyi,Liu, Shouchang
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- Effect of the thermal treatment temperature of RuNi bimetallic nanocatalysts on their catalytic performance for benzene hydrogenation
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The thermal treatment temperature of bimetallic nanocatalysts plays an important role in determining their catalytic performance. In this study, the synthesis of RuNi bimetallic nanoparticles (BNPs) supported on carbon black catalysts (denoted as RuNi BNS
- Zhu, Lihua,Zheng, Jinbao,Yu, Changlin,Zhang, Nuowei,Shu, Qing,Zhou, Hua,Li, Yunhua,Chen, Bing H.
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- Disproportionation of cyclohexadienes and cyclohexene under the action of catalysts based on supported tetranuclear potassium carbonylruthenate K2[Ru4(CO)13]
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The deposition of tetranuclear potassium carbonylruthenate K2[Ru4(CO)13] onto carbon Sibunit, SiO2, γ-Al2O3, and MgO followed by the thermal decomposition of the supported anionic cluster at 300°C in an H2 or Ar flow leads to systems capable of catalyzing the disproportionation of cyclohexa-1,3-diene and cyclohexa-1,4-diene. The reactions proceed at room temperature to form mixtures of benzene and cyclohexene, benzene, cyclohexene, and cyclohexane, or benzene and cyclohexane. The catalytic systems developed are also active in cyclohexene disproportionation to benzene and cyclohexane at 100-130 °C.
- Yunusov,Rummel,Kalyuzhnaya,Shur
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- Bimolecular Hydrogen Transfer over Zeolites and SAPOs having the Faujasite Structure
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Silica-rich Y zeolites prepared by primary or secondary synthesis and samples of SAPO-37 have been synthesized and characterized.These materials are then evaluated as catalysts for the transformation of cyclohexene.From product distribution at low conversion the relative rates of isomerization and bimolecular hydrogen tranfer are measured and discussed in terms of active site density.
- Dwyer, John,Karim, Khalid,Ojo, Adeola F.
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- HYDROGENATION OF CYCLOHEXENE ON DIFFERENT TYPES OF CATALYSTS
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Hydrogenation of cyclohexene has been studied under pressure in a flow reactor on the following catalysts: Na- and H-forms of Y-type zeolites, erionite, magnesium and lanthanum oxides, palladium on silica and aluminum oxide.This reaction is accompanied by skeletal isomerization to give methylcyclopentane and methylcyclopentenes.The differences in activation energies for isomerization and hydrogenation reactions were estimated as 83-96 kJ/mole for NaY and Na,K-erionite, 33-50 kJ/mole for the H-forms of the zeolites, 33-37 kJ/mole on the Pd catalysts, and 25-33 kJ/mole on magnesium and lanthanum oxides.It is suggested that the cyclohexyl complex, formed as an intermediate during hydrogenation of cyclohexene on Na-forms of the zeolites, is neither a carbocation nor a radical. Keywords: cyclohexene, zeolites, hydrogenation.
- Kharlamov, V. V.,Garanin, V. I.,Karakhotin, S. N.,Minachev, Kh. M.
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- Production of Jet Fuel-Range Hydrocarbons from Hydrodeoxygenation of Lignin over Super Lewis Acid Combined with Metal Catalysts
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Super Lewis acids containing the triflate anion [e.g., Hf(OTf)4, Ln(OTf)3, In(OTf)3, Al(OTf)3] and noble metal catalysts (e.g., Ru/C, Ru/Al2O3) formed efficient catalytic systems to generate saturated hydrocarbons from lignin in high yields. In such catalytic systems, the metal triflates mediated rapid ether bond cleavage through selective bonding to etheric oxygens while the noble metal catalyzed subsequent hydrodeoxygenation (HDO) reactions. Near theoretical yields of hydrocarbons were produced from lignin model compounds by the combined catalysis of Hf(OTf)4 and ruthenium-based catalysts. When a technical lignin derived from a pilot-scale biorefinery was used, more than 30 wt % of the hydrocarbons produced with this catalytic system were cyclohexane and alkylcyclohexanes in the jet fuel range. Super Lewis acids are postulated to strongly interact with lignin substrates by protonating hydroxyl groups and ether linkages, forming intermediate species that enhance hydrogenation catalysis by supported noble metal catalysts. Meanwhile, the hydrogenation of aromatic rings by the noble metal catalysts can promote deoxygenation reactions catalyzed by super Lewis acids.
- Wang, Hongliang,Wang, Huamin,Kuhn, Eric,Tucker, Melvin P.,Yang, Bin
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- Hydrodesulfurization of dibenzothiophene over siliceous MCM-41-supported catalysts: I. Sulfided Co-Mo catalysts
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The HDS of dibenzothiophene (DBT) over Co-Mo catalysts supported over siliceous MCM-41 was studied. A radioisotope tracer method was used to trace the behavior of sulfur during HDS to elucidate the mechanism of HDS reaction. The extremely high surface are
- Wang, Anjie,Wang, Yao,Kabe, Toshiaki,Chen, Yongying,Ishihara, Atsushi,Qian, Weihua
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- Ru–Zn/ZrO2 Nanocomposite Catalysts Fabricated by Galvanic Replacement for Benzene Partial Hydrogenation
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A strategy based on galvanic replacement between metallic Zn and Ru salt followed by acid treatment was developed to fabricate supported Ru–Zn/ZrO2 nanocomposite catalysts with controlled contents of Zn for the benzene partial hydrogenation to cyclohexene. The catalysts were systematically characterized by techniques such as extended X-ray absorption fine structure, X-ray photoelectron spectroscopy, and transmission electron microscopy. In benzene partial hydrogenation, with the decrease in the content of Zn, the turnover frequency (TOF) of benzene increased monotonically, whereas the selectivity to cyclohexene evolved in a volcanic trend, passing through a maximum of 72 %. Kinetic analysis indicated that with the depletion of Zn, the rate constant for benzene hydrogenation to cyclohexene and that for cyclohexene hydrogenation to cyclohexane increased simultaneously, but the extents of the increments were at variance. It was identified that the ratios of the rate constants were in parallel with the change in the selectivity to cyclohexene, which is attributed to the electronic effect of metallic Zn that modifies the interactions of Ru with benzene and cyclohexene.
- Zhou, Gongbing,Wang, Hao,Tian, Jing,Pei, Yan,Fan, Kangnian,Qiao, Minghua,Sun, Bin,Zong, Baoning
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- Chemisorption of Cyclohexene on Nickel. A Volumetric and Neutron Inelastic Spectroscopy Study
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Absorption of cyclohexene on Raney nickel was studied at different surface coverages by using neutron inelastic spectroscopy and volumetric methods.At high coverage, hydrogen, benzene, and cyclohexane are detected on the surface.At low coverage, only hydrogen and benzene are present on the nickel.
- Candy, J. P.,Jobic, H.,Renouprez, A. J.
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- Catalytic ring expansion, contraction, and metathesis-polymerization of cycloalkanes
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Tandem dehydrogenation-olefin-metathesis catalyst systems, comprising a pincer-ligated iridium-based alkane dehydrogenation catalyst and a molybdenum-based olefin-metathesis catalyst, are reported to effect the metathesis-cyclooligomerization of cyclooctane and cyclodecane to give cycloalkanes with various carbon numbers, predominantly multiples of the substrate carbon number, and polymers. The Royal Society of Chemistry.
- Ahuja, Ritu,Kundu, Sabuj,Goldman, Alan S.,Brookhart, Maurice,Vicente, Brian C.,Scott, Susannah L.
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- Reactions of free radicals with η3-allylpalladium(II) complexes: Cyclohexyl radicals
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Allyl palladium complexes of the types [(η3-allyl)PdCl] 2, (η3-allyl)PdCl(PPh3) and [(η3-allyl)Pd(PPh3)2]Cl (allyl=C3H5, 1-MeC3H4, 2-MeC3H4, 1-PhC3H4, 2-PhC3H4) react with cyclohexyl radicals derived from the visible light photolysis of (c-hex)Co(DMG)2(py). The reactions proceed via initial attack of the free radical at the metal center, followed by β-hydrogen elimination and subsequent reductive elimination of propene, 1-butene, isobutene, 3-phenylpropene and 2-phenylpropene, respectively. The 3-phenylpropene can be catalytically isomerized to the thermodynamically more stable 1-phenylpropene by either palladium metal or palladium(0) products, but the formation of 1-butene and 3-phenylpropene as primary products is unusual. A mechanism, differing in many ways from that proposed previously for analogous reactions of phenyl and trityl radicals, is proposed for the overall reaction and supported by use of the labeled cobaloxime, (2,2,6,6-D4-c-hex)Co(DMG)2(py).
- Reid, Simon J.,Baird, Michael C.
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- Electrochemical Reduction of Benzene by Solvated Electrons in HMPA-Alcohol Solutions
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Reduction of benzene to cyclohexadiene, cyclohexene, and cyclohexane is studied in ethanol-HMPA and 2-propanol-HMPA solutions.The effect of hydrogen bonding of the alcohol-HMPA on the repression of hydrogen production via alcohol is reported.In addition, the degree and nature of the reduction process are investigated as a function of the nature and concentration of the alcohol, the hydrogen overvoltage of the electrode, and the current applied to the cell.Under suitable conditions, over 60percent of the benzene is reduced at a current of 240 mA with an overall current efficiency greater than 86percent.
- Pasquariello, D.,Foise, J.,Kershaw, R.,Zoski, G.,Dwight, K.,Wold, A.
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- Benzene Hydrogenation: An Isotopic Transient Study
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This paper reflects how the kinetic method of isotopic transients widely used in CO hydrogenation up to now can be extended to the case of benzene hydrogenation.The stationary amounts of reactive adspecies are thus determined during reaction on nickel cat
- Mirodatos, C.
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- NOVEL APPLICATIONS OF ZIEGLER-TYPE CATALYSTS, AROMATIZATION OF TETRALIN AND DISPROPORTIONATION OF CYCLIC OLEFINS
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Ziegler catalysts based on Co and Ni efficiently promote the aromatization of tetralin as well as the disproportionation of cyclohexadiene and cyclohexene into benzene and cyclohexane.
- Costa, J. L.,Noels, A. F.,Hubert, A. J.,Teyssie, Ph.
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- Influence of Support on the Availability of Nickel in Supported Catalysts for Hydrogen Chemisorption and Hydrogenation of Benzene
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Oxides such as SiO2, γ-Al2O3, TiO2 (anatase and rutile), ZrO2 and MgO with different properties have been used as supports for loading nickel by the pore volume impregnation method.Catalysts were calcined in air at 723 K for 6 h before reduction at the sa
- Narayanan, Sankarasubbier,Sreekanth, Gutala
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- Colloid and Nanosized Catalysts in Organic Synthesis: XIX.1 Influence of the Support Nature on Hydrogenation Catalysis of Cyclic Olefins by Nickel Nanoparticles
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Gas-phase hydrogenation of cycloalkenes in the presence of nickel nanoparticles supported on Ceokar-2, BAU-A activated carbon, alumina, and NaX zeolite proceeds at 140–240°C and atmospheric pressure of hydrogen. The conversion and selectivity depend on the type of support and on the hydrogen excess.
- Popov, Yu. V.,Mokhov,Nebykov,Shcherbakova,Dontsova
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- Supported organoactinide complexes as heterogeneous catalysts. A kinetic and mechanistic study of facile arene hydrogenation
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This contribution reports a kinetic and mechanistic study of arene hydrogenation by the supported organoactinide complexes Cp′Th(benzyl)3/DA (1/DA), Th(1,3,5-CH2C6H3Me2)4/DA (2/DA), and Th(
- Eisen, Moris S.,Marks, Tobin J.
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- Modification of Metal Complex on the Hydrogenation of Chlorobenzene over Polymer-Stabilized Platinum Colloidal Nanocatalyst
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The metal complex effect on the hydrogenation of chlorobenzene over a poly(N-vinyl-2-pyrrolidone)-stabilized platinum colloidal nanocatalyst (PVP-Pt) has been studied under 298 K and atmospheric pressure. The introduction of metal complexes and ligands exhibited great effect on the activity and the selectivity of the nanocatalyst. It is evidently manifested that the modification of metal complexes is not the simple sum of those of the metal central ions and the corresponding ligands.
- Li, Dan,Bai, Qiang,Sui, Ning,Xiao, Hailian,Wan, Jun,Liu, Shaojie,Liu, Manhong
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- Natural zeolite supported Ni catalysts for hydrodeoxygenation of anisole
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Natural and synthetic (BEA, MOR) zeolite-supported nickel (～5 wt%) catalysts were prepared and employed for the hydrogenation of toluene and hydrodeoxygenation of anisole in a continuous-flow reactor. Ni/BEA and Ni/MOR display a higher level of metal dispersion and stronger metal-support interaction compared to the Ni/NZ and Ni/Escott catalysts, resulting in a higher concentration of charge-compensating Ni species and a larger high-temperature reduction peak. The Ni/BEA and Ni/MOR also present a significant mass of low-temperature desorbed H2(centred at 150 °C) based on H2-TPD, suggesting the H species are weakly adsorbed on small Ni clusters. In contrast, the H species were strongly adsorbed by the bulk Ni crystal over Ni/Escott and Ni/NZ, which were desorbed at maxima between 211 and 222 °C. We propose that the strongly adsorbed H species play a crucial role in the hydrogenation of toluene, leading to a significantly higher yield of methylcyclohexane over Ni/Escott and Ni/NZ compared to Ni/BEA and Ni/MOR. Both metal and acid sites are required in the hydrodeoxygenation of anisole. The strong Br?nsted acid sites and numerous smaller Ni species over Ni/BEA facilitated the transalkylation of anisole to phenol and methylanisole and subsequently hydrogenolysis of phenol to benzene, followed by the hydrogenation of benzene to cyclohexane.
- Kennedy, Eric,Stockenhuber, Michael,Yan, Penghui
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- Isothermal Titration of Supported Platinum; Part 2.-Alkene Titration using Cyclohexene
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Isothermal alkene titrations (AT) of Pt/SiO2 have been studied on a continuous basis with simultaneous measurement of hydrogen, cyclohexene, cyclohexane and benzene concentrations.Cyclohexene either donates H atoms to the catalyst at 423 K or extracts them from the catalyst at 293-353 K, the temperature being determined by the kinetics and thermodynamics of the titration.Agter optimisation of titration parameters, standard temperatures for the dehydrogenation and hydrogenation steps in the titration were chosen to be 423 K and 310 K.At these temperatures rates of donation of H atoms (dehydrogenation) increased with increasing cyclohexene partial pressure, but subsequent rates of extraction of H atoms passed through a maximum at 500-630 Pa; the optimum partial pressure of cyclohexene selected for standard titrations was, therefore, ca. 460 Pa.Titration mechanisms are considered in detail and suggest that Pt surfaces areas can be estimated from the first phase of H-atom donation by cyclohexene; indeed these (51.8 m2 per g Pt).However, alkene adsorption can affect results from numerous repeated titrations.The alkene titrations when operated in a dehydrogenation mode (ATO) with hydrogen donation to an oxygen-covered catalyst appeared far more satisfactory than previously used titrations involving alkene hydrogenation (ATh) by preabsorbed hydrogen.Since a complete differentiation of Pt-held from support-held hydrogen could not be achieved under isothermal conditions a temperature-programmed titration is proposed.
- Vong, Mariana S. W.,Sermon, Paul A.
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- Estimation of Electron-Transfer Contributions in Reactions of Alkyl Bromides with (Trimethyltin)sodium
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Estimates of the minimum degrees of electron-transfer contributions to the mechanisms of reaction of primary, secondary, and tertiary bromides with (trimethyltin)sodium have been obtained by the use of dicyclohexylphosphine as a free-radical trap.
- Kuivila, Henry G.,Smith, Gary F.
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- ON THE MECHANISM OF THE Co2(CO)8 CATALYZED HYDROFORMYLATION OF OLEFINS IN HYDROCARBON SOLVENTS. A HIGH PRESSURE UV AND IR STUDY
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High pressure IR and UV spectroscopic experiments confirm the Heck and Breslow mechanism of the hydroformylation of 1-octene and cyclohexene with Co2(CO)8 as the starting catalyst.The major repeating unit is HCo(CO)4, which is formed via the reaction of acylcobalt tetracarbonyl with H2.The rates are 6.7 x 10-4 mol l-1 min-1 and 8.8 x 10-5 mol l-1 min-1 for 1-octene and cyclohexene, respectively at 80 deg C and 95 bar CO/H2 = 1 in methylcyclohexane.The alternative reaction of RCOCo(CO)4 with HCo(CO)4 is only a minor pathway, with rates of 1.8 x 10-5 mol l-1 min-1 and 1.1 x 10-5 mol l-1 min-1 for 1-octene and cyclohexene, respectively.It represents an exit from the catalytic cycle.The activation of the catalyst precursor Co2(CO)8 is the slowest step of the reaction.
- Mirbach, Marlis F.
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- (Me3Si)3SiSH: a new radical-based reducing agent
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Tris(trimethylsilyl)silanethiol is an effective and useful reducing agent for some organic substrates.The reduction involves free-radical chain reactions.
- Ballestri, M.,Chatgilialoglu, C.,Seconi, G.
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- Palladium(II) based imines; synthesis, characterization, X-Ray structural analysis; DFT and catalytic hydrogenation study
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Based on the bridge alkyl chain length between the two azomethine linkages of the bis ortho naphtholimine ligands, two synthetic techniques were used to prepare a novel series of palladium(II) complexes. The molecular formulae of the isolated metal chelat
- Ibrahim, Mohamed M.,Fathy, Ahmed M.,Al-Harbi, Sami A.,Sallam, Shehab A.,Al-Juaid, Saleh,Ramadan, Abd El-Motaleb M.
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- Ruthenium-catalyzed selective hydrogenation of benzene to cyclohexene in the presence of an ionic liquid
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Reducing circumstances: The hydrogenation of benzene in organic phase leads rapidly to cyclohexane. A very simple catalyst system comprising only supported ruthenium in water with the addition of the ionic liquid 1 (R=Me) in the ppm range catalyzes the extremely difficult selective hydrogenation of benzene to cyclohexene. It is not necessary to add large amounts of salt (ZnSO4) or other metals, which is otherwise done to control selectivity. Copyright
- Schwab, Frederick,Lucas, Martin,Claus, Peter
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- Pd/Al2O3 catalyst for selective hydrogenation of benzene in benzene-toluene mixture
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Pd/Al2O3 demonstrates (in comparison with Pt/Al2O3 and Ni/Al2O3) higher selectivity toward benzene hydrogenation in competitive hydrogenation of a benzene-toluene mixture, which can be enha
- Mashkovsky, Igor S.,Baeva, Galina N.,Stakheev, Aleksandr Yu.,Voskoboynikov, Timur V.,Barger, Paul T.
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- Mechanism of Tritium-Atom-Promoted Isotope Exchange in the Benzene Ring: Application to Tritium Labeling of Biologically Important Aryl Compounds
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Reaction of thermal tritium atoms, generated by microwave activation os T2 gas, with benzene and biphenyl was studies at ca.-50 and -196 deg C.The saturation reactions (i.e.,benzene->cyclohexane-t6)predominated over isotope exchange (i.e.,benzene->benzene-t( at -196 deg C.However, significant exchange labeling occurred at ca.-50 deg C, with a concomitant reduction in the yields of saturated products.This reversal in labeled product yields at the different temperatures is due, in part, to the faster rate of H expulsion from the intermediate cyclohexadienyl radical at -50 deg C and to the increased mobility of the warmer matrix that retards multiple T- reactions with the same aryl molecule by covering up singly tritiated intermediates.The less volatile aryl compound, biphenyl, was labeled in a diffusionally active matrix of either benezene or cyclohexane, whereas it could not be labeled otherwise.
- Powell, M. F.,Morimoto, H.,Erwin, W. R.,Gordon, B. E.,Lemmon, R. M.
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- Effect of H2S on Hydrogenation Activity of Sulfided Co/Mo/Al2O3
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Effect of gas-phase H2S on the reactions of aromatic hydrocarbons over sulfided Co/Mo/Al2O3 was studied at 400 deg C.The added H2S inhibited hydrogenation of benzene but accelerated hydrogenation of o-xylene.No effect was exerted upon hydrogenation of toluene.At all instances, the added H2S accelerated skeletal isomerization.
- Yamada, Muneyoshi,Saito, Atsushi,Wakatsuki, Toshitaka,Obara, Toshiyuki
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- Palladium hydrogenation catalyst based on a porous carbon material obtained upon the dehydrochlorination of a chloro polymer
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The applicability of a porous carbon material obtained as a result of the “chemical” dehydrochlorination of chlorinated polyvinyl chloride as a support for palladium hydrogenation catalysts was demonstrated. The efficiency of the catalyst was evaluated in the liquid-phase reactions of nitrobenzene hydrogenation and chlorobenzene hydrodechlorination. Although the specific activity of the catalyst was lower by a factor of 3–4 than that of the samples based on Sibunit and carbon nanotubes, the complete conversion of the initial compounds with the selective formation of end products under mild conditions was achieved at a relatively low palladium content (1.5%).
- Mironenko,Belskaya,Solodovnichenko,Gulyaeva,Kryazhev, Yu. G.,Likholobov
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- On the behaviour of Ru(I) and Ru(II) carbonyl acetates in the presence of H2 and/or acetic acid and their role in the catalytic hydrogenation of acetic acid
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The reactivity of phosphine substituted ruthenium carbonyl carboxylates Ru(CO)2(MeCOO)2(PBu3)2, Ru 2(CO)4(μ-MeCOO)2(PBu3) 2, Ru4(CO)8(μ-MeCOO)4(PBu 3)2 with H2 and/or acetic acid was investigated by IR and NMR spectroscopy to clarify their role in the catalytic hydrogenation of acetic acid. Evidences were collected to suggest hydride ruthenium complexes as the catalytically active species. Equilibria among ruthenium hydrides and carboxylato complexes take place in the presence of hydrogen and acetic acid, that is in the conditions of the catalytic reaction. Nevertheless the presence of acetic acid reduces the rate of the formation of hydrides. Working at a very high temperature (180°C) polynuclear phosphido hydrides such as [Ru 6(μ-H)6(CO)10(μ-PHBu)(μ-PBu 2)2(PBu3)2(μ6-P)] were formed. These phosphido clusters are suggested as the resting state of the catalytic system. Furthermore the bi- or tetranuclear Ru(I) carboxylato complexes react with acetic acid giving a mononuclear ruthenium complex Ru(CO)2(MeCOO)(μ-MeCOO)(PBu3), containing a monodentate and a chelato acetato ligands. This complex was spectroscopically characterised. Its identity and structure were confirmed by its reactivity with stoichiometric amount of PPh3 to give Ru(CO)2(MeCOO) 2(PBu3)(PPh3), a new mononuclear ruthenium carbonyl carboxylate containing two different phosphines, that was fully characterised.
- Salvini, Antonella,Frediani, Piero,Giannelli, Carlo,Rosi, Luca
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- Rational synthesis of palladium nanoparticles modified by phosphorous for the conversion of diphenyl ether to KA oil
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Conversion of lignin-derived molecules into value-added chemicals is critical for sustainable chemistry but still challenging. Herein, phosphorus-modified palladium catalyzed the degradation of lignin-derived 4-O-5 linkage to produce KA oil (cyclohexanone-cyclohexanol oil) was reported. The reaction proceeds via a restricted partial hydrogenation-hydrolysis pathway. Phosphorus-modified palladium catalyst suppressed the full hydrogenation of diary ether, which was the key point to produce KA oil selectively. Under the optimized conditions, the 4.5 nm Pd-P NPs could catalyze the conversion of 4-O-5 linkage into KA oil in 83% selectivity with a high production rate of 32.5 mmol·g?1Pd·min?1. This study represented an original method for KA oil production.
- Bai, Hong-Cun,Cao, Jing-Pei,Jiang, Wei,Wei, Yu-Lei,Xie, Jin-Xuan,Zhang, Chuang,Zhao, Liang,Zhao, Ming,Zhao, Xiao-Yan
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- Synergies of surface-interface multiple active sites over Al-Zr oxide solid solution supported nickel catalysts for enhancing the hydrodeoxygenation of anisole
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Currently, the catalytic hydrodeoxygenation (HDO) of oxygen-containing compounds derived from biomass to highly valuable chemicals or hydrocarbon bio-fuels is attracting more and more attention. Concerning the design and synthesis of high-performance supported metal catalysts for HDO, the efficient deposition/immobilization of active metal species on supports, as well as the construction of the favorable properties of supports, is quite necessary. In this work, we fabricated series of aluminum-zirconium oxide solid solution supported Ni-based catalysts by a simple surfactant-assisted homogeneous coprecipitation and applied them in the HDO of anisole. Various structural characterizations showed that surface-interface properties of Ni-based catalysts (i.e., surface acidity, defective structures, and metal-support interactions) could be finely tuned by adjusting the amount of Al introduced into Al-Zr oxide solid solutions, thus profoundly governing their catalytic HDO activities. It was demonstrated that the introduction of an appropriate amount of Al could not only enhance surface acidity and promote the formation of defective Zr-Ov-Al structures (Ov: oxygen vacancy) but also facilitate the generation of interfacial Niδ+ species bound to the support. Over the Ni-based catalyst bearing an Al2O3:ZrO2 mass ratio of 5:2, a high cyclohexane yield of ～77.4% was attained at 230 °C and 1.0 MPa initial hydrogen pressure. The high catalytic HDO efficiency was revealed to be correlated with the catalytic synergy between Ni0 and adjacent interfacial Niδ+ species, together with the promotion of neighboring defective oxygen vacancies and acidic sites, which contributed to the enhanced activation of the methoxy group in anisole and reaction intermediate and thus greatly improved HDO activity. The present findings offer a new and promising guidance for constructing high-performance metal-based catalysts via a rational surface-interface engineering.
- Fan, Guoli,Li, Feng,Lin, Yanjun,Yang, Lan,Zhang, Yaowen
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- Hydrodeoxygenation of lignin and its model compounds to hydrocarbon fuels over a bifunctional Ga-doped HZSM-5 supported metal Ru catalyst
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Hydrodeoxygenation (HDO) of lignin to value-added biofuels and chemicals has a great significance for the advanced utilization of renewable lignocelluloses and the future biobased economy but is always a big challenge. Herein, a Ga-doped HZSM-5 supported metal Ru catalyst (bifunctional Ru/Ga-HZSM-5) exhibited the excellent HDO performance for converting diphenyl ether (DPE) to produce the only product, i.e., cyclohexane, under extremely mild conditions (180 °C, 1 MPa H2 and 2 h). The oxygen-containing group in DPE was mainly removed through the cleavage of the C-O ether bond, followed by metal- and acid-catalyzed comprehensive hydrogenation and deoxygenation. Further characterization results confirmed that the doping of Ga remarkably enhanced the interaction between the metal Ru and the support. For the depolymerization of real lignin, Ru/Ga-HZSM-5 could not only significantly improve the total liquid yield of lignin, but also convert the oxygen-containing species into the aliphatic hydrocarbons.
- Cao, Jing-Pei,Jiang, Wei,Xie, Jin-Xuan,Yang, Zhen,Zhang, Chuang,Zhang, Jian-Li,Zhao, Liang,Zhao, Xiao-Yan,Zhao, Yun-Peng,Zhu, Chen
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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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- Highly Selective Hydrodeoxygenation of Lignin to Naphthenes over Three-Dimensional Flower-like Ni2P Derived from Hydrotalcite
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A strategy for low-temperature synthesis of hydrotalcite-based nickel phosphide catalysts (Ni2P-Al2O3) with flower-like porous structures was proposed. The in situ reduction of red phosphorus at 500 °C enables Ni2P catalysts with small particle size and abundant active and acidic sites, which facilitate the activation of substrates and H2. In the hydrodeoxygenation of guaiacol, a 100% conversion and 94.5% yield of cyclohexane were obtained over the Ni2P-Al2O3 catalyst under 5 MPa H2 at 250 °C for 3 h. Other lignin-derived phenolic compounds could also afford the corresponding alkanes with yields higher than 85%. Moreover, Ni2P-Al2O3 exhibited high hydrodeoxygenation activity in the deconstruction of more complex wood structures, including lignin oil and real lignin. Among the two different types of Ni sites of Ni(1) and Ni(2) in Ni2P, density functional theory (DFT) calculations showed that the Ni(2) site, highly exposed on the Ni2P-Al2O3 surface, possesses a stronger ability to break C-OH bonds during the hydrodeoxygenation of guaiacol in comparison with the Ni(1) site.
- Chen, Guanyi,Diao, Xinyong,Ji, Na,Jia, Zhichao,Li, Changzhi,Li, Xinxin,Liu, Caixia,Liu, Qingling,Lu, Xuebin,Ma, Longlong,Song, Chunfeng,Wang, Shurong,Zhao, Yujun
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p. 1338 - 1356
(2022/02/07)
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- One-step conversion of lignin-derived alkylphenols to light arenes by co-breaking of C-O and C-C bonds
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The conversion of lignin-derived alkylphenols to light arenes by a one-step reaction is still a challenge. A 'shortcut' route to transform alkylphenols via the co-breaking of C-O and C-C bonds is presented in this paper. The catalytic transformation of 4-ethylphenol in the presence of H2 was used to test the breaking of C-O and C-C bonds. It was found that the conversion of 4-ethylphenol was nearly 100%, and the main products were light arenes (benzene and toluene) and ethylbenzene under the catalysis of Cr2O3/Al2O3. The conversion of 4-ethylphenol and the selectivity of the products were significantly influenced by the reaction temperature. The selectivity for light arenes reached 55.7% and the selectivity for overall arenes was as high as 84.0% under suitable reaction conditions. Such results confirmed that the co-breaking of the C-O and C-C bonds of 4-ethylphenol on a single catalyst by one step was achieved with high efficiency. The adsorption configuration of the 4-ethylphenol molecule on the catalyst played an important role in the breaking of the C-O and C-C bonds. Two special adsorption configurations of 4-ethylphenol, including a parallel adsorption and a vertical adsorption, might exist in the reaction process, as revealed by DFT calculations. They were related to the breaking of C-O and C-C bonds, respectively. A path for the hydrogenation reaction of 4-ethylphenol on Cr2O3/Al2O3 was proposed. Furthermore, the co-breaking of the C-O and C-C bonds was also achieved in the hydrogenation reactions of several alkylphenols. This journal is
- Di, Yali,Li, Guangyu,Li, Zhiqin,Liu, Weiwei,Qiu, Zegang,Ren, Xiaoxiong,Wang, Ying
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p. 2710 - 2721
(2022/02/21)
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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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- 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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- Bimetallic RuPd nanoparticles in ionic liquids: Selective catalysts for the hydrogenation of aromatic compounds
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Bimetallic RuPd nanoparticles (NPs) immobilized in ionic liquids (ILs) were shown to be a highly active medium for the selective hydrogenation of benzene and phenol under mild conditions (4 bar H2, 60 °C) in a biphasic system (n-heptane/IL). The equimolar combination of Ru and Pd into a bimetallic particle generated a synergistic catalyst that allowed the selective production of cyclohexane (>99% selectivity, 94% conversion) and cyclohexanol (99% selectivity, >98% conversion) from the reduction of benzene and phenol, respectively. Moreover, the catalytic results revealed that the activity and selectivity are dependent on the Ru?:?Pd ratio into the bimetallic NPs.
- Abarca, Gabriel,Goncalves, Wellington D. G.,Albuquerque, Brunno L.,Dupont, Jairton,Prechtl, Martin H. G.,Scholten, Jackson D.
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supporting information
p. 98 - 103
(2021/01/11)
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- Direct synthesis of a high-density aviation fuel using a polycarbonate
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High-density cyclic hydrocarbons were first synthesized with high carbon yields by a one-pot transfer hydrodeoxygenation of a polycarbonate (PC) using isopropanol as the solvent and hydrogen donor at the same time. RANEY nickel was found to be an effective catalyst for the conversion of the PC in isopropanol. Over it, the pure PC pellet was completely converted to a mixture of C6-C15oxygenates, aromatics and cycloalkanes after the reaction was carried out at 463 K for 1 h. The catalytic performance of RANEY Ni was further improved after the introduction of solid acids as co-catalysts. Among the investigated solid acids, ultrastable Y (USY), a commercial acidic zeolite, demonstrated the best promotion effect, which can be explained by its larger pore size and suitable acidity. Under the optimized conditions, an ～75% carbon yield of C6-C15cyclic hydrocarbons was achieved from the one-pot transfer hydrodeoxygenation of a chopped DVD disk under the co-catalysis of RANEY Ni and USY. According to our measurement, the C6-C15cyclic hydrocarbon mixture as obtained has a high density (0.94 g mL?1), good volumetric net heat of combustion (NHOC) (41.5 MJ L?1) and low freezing point (202 K-188 K). In real applications, it can be used as a potential substitute for currently used high-density aviation fuels.
- Wang, Lulin,Han, Fengan,Li, Guangyi,Zheng, Min,Wang, Aiqin,Wang, Xiaodong,Zhang, Tao,Cong, Yu,Li, Ning
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supporting information
p. 912 - 919
(2021/02/09)
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- Aromatic compound hydrogenation and hydrodeoxygenation method and application thereof
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The invention belongs to the technical field of medicines, and discloses an aromatic compound hydrogenation and hydrodeoxygenation method under mild conditions and application of the method in hydrogenation and hydrodeoxygenation reactions of the aromatic compounds and related mixtures. Specifically, the method comprises the following steps: contacting the aromatic compound or a mixture containing the aromatic compound with a catalyst and hydrogen with proper pressure in a solvent under a proper temperature condition, and reacting the hydrogen, the solvent and the aromatic compound under the action of the catalyst to obtain a corresponding hydrogenation product or/and a hydrodeoxygenation product without an oxygen-containing substituent group. The invention also discloses specific implementation conditions of the method and an aromatic compound structure type applicable to the method. The hydrogenation and hydrodeoxygenation reaction method used in the invention has the advantages of mild reaction conditions, high hydrodeoxygenation efficiency, wide substrate applicability, convenient post-treatment, and good laboratory and industrial application prospects.
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Paragraph 0094-0097; 0100-0104
(2021/05/29)
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- Pt and Ru Catalysts Based on Porous Aromatic Frameworks for Hydrogenation of Lignin Biofuel Components
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Abstract: A platinum catalyst and a ruthenium catalyst were synthesized from a porousaromatic framework, namely PAF-30. The catalyst properties were examined inhydrogenation of phenol and guaiacol at 80–250°C and at a hydrogen pressure of30 atm in the presence of various solvents. Significant effects of the reactionmedium, process conditions, and catalyst morphology on the reaction mechanismwere demonstrated. Reaction conditions optimal for complete conversion of phenoland guaiacol to hydrogenation products were selected for both catalysts. [Figure not available: see fulltext.]
- Cherednichenko, K. A.,Kalinina, M. A.,Karakhanov, E. A.,Kulikov, L. A.,Makeeva, D. A.,Maximov, A. L.
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p. 711 - 720
(2021/08/03)
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- Improved Hydrodeoxygenation of Phenol to Cyclohexane on NiFe Alloy Catalysts Derived from Phyllosilicates
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A phyllosilicate-derived NiFe/SiO2 catalyst (NiFe/SiO2?AE) was successfully prepared by the ammonia evaporation method and applied in the hydrodeoxygenation of phenol to cyclohexane. Another two catalysts were also prepared for a comparison by impregnation (NiFe/SiO2?IM) and deposition-precipitation (NiFe/SiO2?DP) methods, respectively. It was found that Ni?Fe alloy, the active sites for the hydrogenolysis of C?O bond, can be obtained by the reduction of NiFe2O4 (IM) or phyllosilicate (DP and AE) by H2. The AE strategy can generate more phyllosilicate structure, which improves the dispersion of both Ni?Fe alloy and metallic Ni sites and allows the formation of more interface between these two kinds of sites as well. Therefore, the NiFe/SiO2?AE exhibits a significantly high catalytic performance in the HDO of phenol to cyclohexane. Moreover, the turnover frequency of Ni?Fe alloy sites over NiFe/SiO2?AE catalysts is much higher than those of other two catalysts. It is suggested that the enhanced synergy between the two kinds of active sites in the adsorption of C?O groups and hydrogen molecules ensures the superior intrinsic activity in HDO process.
- Han, Qiao,Wang, Hui,Rehman, Mooeez Ur,Shang, Xin,Chen, Haijun,Ji, Na,Tong, Xinli,Shi, Hui,Zhao, Yujun
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supporting information
p. 5069 - 5076
(2021/12/14)
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- Tunable selectivity of phenol hydrogenation to cyclohexane or cyclohexanol by a solvent-driven effect over a bifunctional Pd/NaY catalyst
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Hydrogenation of phenol is an important strategy to produce cyclohexane or cyclohexanol as both of them are raw materials for the synthesis of nylon-6 and nylon-66. Herein, we report a novel method for the selective hydrogenation of phenol to cyclohexane or cyclohexanol over a bifunctional Pd/NaY catalyst by regulating the solvent polarity. It was found that solvent polarity has a strong influence on the hydrogenation reaction mechanism. Under the identical conditions, 100% selectivity to cyclohexane could be obtained when reacting inn-octane (nonpolar solvent), while 92.3% selectivity to cyclohexanol was achieved in EtOH (polar solvent). The polarity of the solvent not only affects the competitive adsorption capacity but also the adsorption manner of phenol over the acid sites and the Pd nanoparticles in the Pd/NaY catalyst. DFT calculations show that different solvents have an almost negligible effect on the reaction energy barriers but highly affect the hydration reaction of cyclohexanol if the trace amount of water formed could not be timely removed from the catalytic system. This solvent-driven catalysis exhibits good recyclability, showing great promise for industrial applications. These findings not only provide new insights into the hydrogenation mechanism of phenolics, but also might help to develop facile strategies for the selective conversion of other phenolics into desired products.
- Xia, Heng,Tan, Hongzi,Cui, Hongyou,Song, Feng,Zhang, Yuan,Zhao, Rongrong,Chen, Zhe-Ning,Yi, Weiming,Li, Zhihe
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p. 1881 - 1887
(2021/03/29)
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- Supported Pt-Ni bimetallic nanoparticles catalyzed hydrodeoxygenation of dibenzofuran with high selectivity to bicyclohexane
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Catalytic hydrodeoxygenation (HDO) is one of the most effective methods to upgrade the oxygen-containing compounds derived from coal tar to valuable hydrocarbons. Herein, an efficient bimetallic catalyst Pt1Ni4/MgO was prepared and applied in the HDO of dibenzofuran (DBF). High yield (95%) of the desired product bicyclohexane (BCH) was achieved at 240 °C and 1.2 MPa of H2. Superior catalytic performance could be ascribed to the “relay catalysis” of Pt sites and Ni sites, and the reaction pathway is proposed as well. Scale-up experiment and recyclability test were also performed, which demonstrated the recyclability and promising potential application of Pt1Ni4/MgO.
- Cai, Chun,Wu, Pengyu
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- Catalyzed transfer hydrogenation by 2-propanol for highly selective PAHs reduction
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Catalytic hydrogenation of mono-, di- and trinuclear aromatic compounds has been studied under hydrogen transfer conditions at 150 °C and 82 °C in 2-PrOH as a hydrogen donor and with Raney nickel as a catalyst. In contrast to conjugated or condensed aromatic rings, isolated ones demonstrated low reactivity in transfer hydrogenation (TH) that can be used to increase the hydrogenation selectivity of the reaction. So, naphthalene and biphenyl are partially hydrogenated into tetralin and cyclohexylbenzene, respectively, with excellent conversion (≥ 96 %) and selectivity (≥ 98 %) for 5–6 h at 82 °C. Increasing the reaction temperature to 150 °C results expectedly in the hydrogenation of second aromatic ring, which occurs slowly enough. Only 8 % of decaline and 42 % of dicyclohexyl, correspondingly, were obtained after 5 h at 150 °C. At the same time, TH of trinuclear anthracene and phenanthrene at 150 °C resulted in the formation of deeper hydrogenated octahydro-anthracenes and -phenanthrenes, respectively.
- Philippov,Chibiryaev,Martyanov
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- STRONGLY LEWIS ACIDIC METAL-ORGANIC FRAMEWORKS FOR CONTINUOUS FLOW CATALYSIS
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Lewis acidic metal-organic framework (MOF) materials comprising triflate-coordinated metal nodes are described. The materials can be used as heterogenous catalysts in a wide range of organic group transformations, including Diels-Alder reactions, epoxide-ring opening reactions, Friedel-Crafts acylation reactions and alkene hydroalkoxylation reactions. The MOFs can also be prepared with metallated organic bridging ligands to provide heterogenous catalysts for tandem reactions and/or prepared as composites with support particles for use in columns of continuous flow reactor systems. Methods of preparing and using the MOF materials and their composites are also described.
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-
Paragraph 0166; 0168
(2021/02/26)
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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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- Ordered macroporous Co3O4-supported Ru nanoparticles: A robust catalyst for efficient hydrodeoxygenation of anisole
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A three-dimensional ordered macroporous Co3O4 (OM-Co3O4) supported Ru catalyst was developed for the efficient hydrodeoxygenation (HDO) of anisole. It is revealed that small-sized Ru nanoparticles evenly distributed over the surface of OM-Co3O4 with large quantities of oxygen vacancies could strongly capture Ru0 species, thereby resulting in strong Ru-Co3O4 interactions. Compared with commercial Co3O4 supported Ru catalyst, Ru/OM-Co3O4 displays a better catalytic HDO performance, with a high cyclohexane yield of 92.4% at 250 °C and 0.5 MPa hydrogen pressure after 5 h on stream. Such a significant efficiency of Ru/OM-Co3O4 is mainly attributed to both high dispersion of Ru0 species and an enhanced formation of surface defects, as well as the unique macroporous framework of OM-Co3O4 support.
- Wang, An,Shi, Yisheng,Yang, Lan,Fan, Guoli,Li, Feng
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- The Effect of Sulfonate Groups in the Structure of Porous Aromatic Frameworks on the Activity of Platinum Catalysts Towards Hydrodeoxygenation of Biofuel Components
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Abstract: Platinum catalysts based on porous aromatic frameworks (PAF-30 and PAF-30–SO3H) have been synthesized. Properties of the obtained catalysts have been assessed via hydrogenation of guaiacol, veratrole, and pyrocatechol at 250°С and hydrogen pressure 3.0 MPa in isopropanol medium. It has been shown that the presence of acidic sites in the catalyst significantly increases the yield of deoxygenation products. The effect of the substrate structure on the rate of its hydrodeoxygenation and the mechanism of the occurring processes have been studied. [Figure not available: see fulltext.]
- Kalinina,Kulikov,Cherednichenko,Maximov,Karakhanov
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p. 1061 - 1070
(2021/09/06)
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- Bipyridinium and Phenanthrolinium Dications for Metal-Free Hydrodefluorination: Distinctive Carbon-Based Reactivity
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The development of novel Lewis acids derived from bipyridinium and phenanthrolinium dications is reported. Calculations of Hydride Ion Affinity (HIA) values indicate high carbon-based Lewis acidity at the ortho and para positions. This arises in part from extensive LUMO delocalization across the aromatic backbones. Species [C10H6R2N2CH2CH2]2+ (R=H [1 a]2+, Me [1 f]2+, tBu [1 g]2+), and [C12H4R4N2CH2CH2]2+ (R=H [2 a]2+, Me [2 b]2+) were prepared and evaluated for use in the initiation of hydrodefluorination (HDF) catalysis. Compound [2 a]2+ proved highly effective towards generating catalytically active silylium cations via Lewis acid-mediated hydride abstraction from silane. This enabled the HDF of a range of aryl- and alkyl- substituted sp3(C?F) bonds under mild conditions. The protocol was also adapted to effect the deuterodefluorination of cis-2,4,6-(CF3)3C6H9. The dications are shown to act as hydride acceptors with the isolation of neutral species C16H14N2 (3 a) and C16H10Me4N2 (3 b) and monocationic species [C14H13N2]+ ([4 a]+) and [C18H21N2]+ ([4 b]+). Experimental and computational data provide further support that the dications are initiators in the generation of silylium cations.
- Burton, Katherine I.,Elser, Iris,Waked, Alexander E.,Wagener, Tobias,Andrews, Ryan J.,Glorius, Frank,Stephan, Douglas W.
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supporting information
p. 11730 - 11737
(2021/07/16)
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- Synergistic effect of Ni-Co alloying on hydrodeoxygenation of guaiacol over Ni-Co/Al2O3 catalysts
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The hydrodeoxygenation (HDO) of guaiacol was investigated in a batch reactor using Ni-Co/γ-Al2O3 catalysts prepared by co-impregnation method. The structural and physicochemical properties of the catalysts were investigated using BET, XRD, H2-TPR, FT-IR, and NH3-TPD. The characterization results revealed that the formation of various Ni-Co composite species strongly depend on the Ni/Co mole ratio, total metal loadings, and the calcination/reduction temperature. The 6.1Ni3.05CoAl (Ni/Co = 1:2) catalyst seeds the formation of NiCo2O4 spinel structure and subsequent formation of Ni-Co alloy, which represents as specific active site for direct demethoxylation/deoxygenation reaction. The synergistic interaction of Ni-Co enhances the selectivity of benzene. The benzene selectivity of 35.2 % and cyclohexane selectivity of 59.1 % with complete conversion of guaiacol (98.9 %) were achieved with the 3.05Ni6.1CoAl catalyst at 575 K. A tentative reaction pathway is proposed based on the product distribution accomplished during HDO reaction. The structural property was correlated with activity to explore the mechanistic insights.
- Raikwar, Deepak,Majumdar, Saptarshi,Shee, Debaprasad
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- Production of alkoxyl-functionalized cyclohexylamines from lignin-derived guaiacols
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The transformation of renewable lignin-based platform chemicals into value-added nitrogen-containing compounds is an emerging strategy for lignin utilization. However, multi-reactive sites on these platform chemicals make it challenging to control the product selectivity, thereby resulting in limited success. In this work, we developed the reductive-coupling of guaiacol, a typical lignin-based platform chemical, with amines and H2 to synthesize methoxy-functionalized cyclohexylamines. It was demonstrated that Pd/C was a very efficient catalyst for this kind of reaction, and high yields of the target products can be obtained. Notably, this methodology can be applied for the reductive-coupling of various guaiacol analogues with amines to synthesize alkoxyl-functionalized cyclohexylamines with high yields. A mechanism study revealed that the reaction occurred through the generation of 2-methoxycyclohexanone and its subsequent reductive amination. This journal is
- Han, Buxing,He, Mingyuan,Mei, Xuelei,Song, Jinliang,Wu, Haihong,Wu, Wei,Xu, Caiyun,Xu, Jiao,Zhang, Kaili,Zheng, Bingxiao
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supporting information
p. 8441 - 8447
(2021/11/17)
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- Catalytic transfer hydrogenation of 4-O-5 models in lignin-derived compounds to cycloalkanes over Ni-based catalysts
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There is an urgent need to develop a selective hydrogenolysis of Caryl-O bonds in lignin to produce valued-added chemicals and fuels. Recently, hydrogen has been used in the hydrogenation reaction, which hides inevitable danger and is not economical. Therefore, isopropanol, as a hydrogen-donor solvent, is employed for aryl ether hydrogenolysis in lignin models over nickel supported on a carbon nanotube (CNT). Except for aromatic ether (4-O-5), the Ni/CNT catalyst is also found to be suitable for alkyl-aryl ether (α-O-4 and β-O-4) cleavage in control experiments. The physicochemical characterizations were carried out by means of H2-temperature-programmed reduction, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. The catalyst can be magnetically recovered and efficiently reused for five consecutive recycling tests in the transfer hydrogenation of aromatic ethers. A mechanism study indicated that the hydrogenolysis cleavage of the ether bond is the first step in the reaction process, and hydrogenation of aromatic rings is only a successive step in which phenol and benzene are intermediate states and are then further hydrogenated. Furthermore, it has been demonstrated that aryl groups play an important role in the hydrogenation of phenol in the competitive catalytic hydrogenation reaction of phenol.
- Chen, Changzhou,Liu, Peng,Xia, Haihong,Zhou, Minghao,Jiang, Jianchun
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p. 582 - 591
(2020/12/01)
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- Rational design of oligomeric MoO3 in SnO2 lattices for selective hydrodeoxygenation of lignin derivatives into monophenols
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Novel Mo-Sn bimetallic oxide catalysts with highly dispersed oligomeric MoO3 in SnO2 lattices, which were synthesized by the co-precipitation method and pretreated by anhydrous ethanol, were first employed in the hydrodeoxygenation of various lignin derivatives to produce monophenols with high activity and selectivity. In comparison with the pure α-MoO3 and the previous reported catalysts, the α-2Mo1Sn exhibited superior activity in the hydrodeoxygenation of guaiacol, with full conversion and 92.5% phenol yield at 300 °C under 4 MPa initial H2 pressure in n-hexane for 4 h. According to comprehensive characterizations and catalytic measurements, the excellent performance of α-2Mo1Sn was ascribed to the formation of abundant Sn-O-Mo-OV interfacial sites, which possessed strong Mo-Sn interaction with enhanced surface area, electron-donating group binding ability, Lewis acidity, and redox ability. It was demonstrated that over the present α-2Mo1Sn catalyst system, the Sn-O-Mo-OV interfacial sites could greatly facilitate the adsorption and activation of Caromatic-OCH3 and Caromatic-CH3 bonds, and thus significantly promote the demethoxylation and demethylation reaction to produce phenol. This work figures out the rational design of MoO3-based catalyst and displays a clear potential for the selective hydrodeoxygenation of lignin derivatives into monophenols.
- Diao, Xinyong,Ji, Na,Jia, Zhichao,Jiang, Sinan,Li, Tingting,Liu, Caixia,Liu, Qingling,Lu, Xuebin,Song, Chunfeng,Wang, Zhenjiao
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p. 234 - 251
(2021/08/19)
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- Synergistic effect for selective hydrodeoxygenation of anisole over Cu-ReOx/SiO2
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Selective hydrodeoxygenation (HDO) of lignin derived oxygenated aromatic compounds has great significance for lignin utilization and chemicals production. Hereby, bifunctional catalysts of Cu-MOx/SiO2 (M = Re, Mo or W) were prepared to study the synergistic effect of Cu and MOx on the performance of anisole HDO. Characterizations indicated that Cu interacted strongly with the second metal species. As a result, more efficient sites exposed on catalysts surface, and metal dispersion and surface properties both were improved. Besides, adsorption strength for both oxygen atom and aromatic ring in reactant were all adjusted due to Cu-MOx interaction. Bimetallic catalyst Cu-ReOx/SiO2 showed the highest HDO activity, while Cu-MoOx/SiO2 and Cu-WOx/SiO2 both preferred transmethylation because of their prominent acid properties. The Cu-ReOx composition was found to evidently affect the anisole conversion and selectivity of benzene, toluene and xylene (BTX). The highest BTX yield of 50.5 % could be achieved when Cu/Re ratio was 3.
- Wang, Xiaofei,Zhou, Wei,Wang, Yue,Huang, Shouying,Zhao, Yujun,Wang, Shengping,Ma, Xinbin
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p. 223 - 234
(2020/04/27)
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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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- 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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- Hydrodeoxygenation of Lignin-Derived Aromatic Oxygenates Over Pd-Fe Bimetallic Catalyst: A Mechanistic Study of Direct C–O Bond Cleavage and Direct Ring Hydrogenation
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Hydrodeoxygenation of lignin-derived phenols could be achieved generally with three reaction pathways: tautomerization, direct ring hydrogenation and direct C–O bond cleavage. The former pathway has been extensively studied over Pd/Fe catalyst in liquid-phase reaction, however, the contribution of the latter two is yet subject to further investigations. In this report, a comparative study of direct C–O bond cleavage and direct ring hydrogenation reaction pathways is presented on Pd/Fe, Fe and Pd/C catalysts using diphenyl ether as modelling compound. Despite its much higher activation energy than direct ring hydrogenation, direct C–O bond cleavage is dominant over Pd/Fe with much higher rates than the monometallic analogues due to the synergic catalysis of Pd–Fe. Based on this study and our previous results, the detailed reaction network for HDO of diphenyl ether is proposed. Graphic Abstract: [Figure not available: see fulltext.]
- Zhang, Jianghao,Sudduth, Berlin,Sun, Junming,Wang, Yong
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p. 932 - 939
(2020/09/02)
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- Emergent Self-Assembly of a Multicomponent Capsule via Iodine Capture
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Described here is a three-component self-assembly system that displays emergent behavior that differs from that of its constituents. The system comprises an all-hydrocarbon octaaryl macrocycle cyclo[8](1,3-(4,6-dimethyl)benzene (D4d-CDMB-8), corannulene (Cora), and I2. No appreciable interaction is seen between any pair of these three-components, either in cyclohexane or under various crystallization conditions. On the other hand, when all three-components are mixed in cyclohexane and allowed to undergo crystallization, a supramolecular iodine-containing capsule, ((D4d-CDMB-8)3(Cora)2)I2, is obtained. This all-hydrocarbon capsule consists of three D4d-CDMB-8 and two Cora subunits and contains a centrally bound I2 molecule as inferred from single-crystal and powder X-ray diffraction studies as well as solid-state 13C NMR and Raman spectroscopy. These analyses were complemented by solution-phase 1H NMR and UV-vis spectroscopic studies. No evidence of I2 escape from the capsule is seen, even at high temperatures (e.g., up to 418 K). The bound I2 is likewise protected from reaction with alkali or standard reductants in aqueous solution (e.g., saturated NaOH(aq) or aqueous Na2S2O3). It was also found that a mixed powder containing D4d-CDMB-8 and Cora in a 3:2 molar ratio could capture saturated I2 vapor or iodine from aqueous sources (e.g., 1.0 mM I2 in NaCl (35 wt %) or I2 + NaI(aq) (1.0 mM each)). The present system displays structural and functional features that go beyond what would be expected on the basis of a simple sum-of-the-components analysis. As such, it illustrates a new approach to creating self-assembled ensembles with emergent features.
- Yang, Yu-Dong,Chen, Xu-Lang,Sessler, Jonathan L.,Gong, Han-Yuan
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supporting information
p. 2315 - 2324
(2021/01/13)
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- Boosting homogeneous chemoselective hydrogenation of olefins mediated by a bis(silylenyl)terphenyl-nickel(0) pre-catalyst
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The isolable chelating bis(N-heterocyclic silylenyl)-substituted terphenyl ligand [SiII(Terp)SiII] as well as its bis(phosphine) analogue [PIII(Terp)PIII] have been synthesised and fully characterised. Their reaction with Ni(cod)2(cod = cycloocta-1,5-diene) affords the corresponding 16 VE nickel(0) complexes with an intramolecularη2-arene coordination of Ni, [E(Terp)E]Ni(η2-arene) (E = PIII, SiII; arene = phenylene spacer). Due to a strong cooperativity of the Si and Ni sites in H2activation and H atom transfer, [SiII(Terp)SiII]Ni(η2-arene) mediates very effectively and chemoselectively the homogeneously catalysed hydrogenation of olefins bearing functional groups at 1 bar H2pressure and room temperature; in contrast, the bis(phosphine) analogous complex shows only poor activity. Catalytic and stoichiometric experiments revealed the important role of the η2-coordination of the Ni(0) site by the intramolecular phenylene with respect to the hydrogenation activity of [SiII(Terp)SiII]Ni(η2-arene). The mechanism has been established by kinetic measurements, including kinetic isotope effect (KIE) and Hammet-plot correlation. With this system, the currently highest performance of a homogeneous nickel-based hydrogenation catalyst of olefins (TON = 9800, TOF = 6800 h?1) could be realised.
- Lücke, Marcel-Philip,Yao, Shenglai,Driess, Matthias
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p. 2909 - 2915
(2021/03/14)
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- Direct synthesis of a jet fuel range dicycloalkane by the aqueous phase hydrodeoxygenation of polycarbonate
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For the first time, propane-2,2-diyldicyclohexane, a jet fuel range C15dicycloalkane was directly produced by the aqueous phase hydrodeoxygenation (APHDO) of polycarbonate (PC). Among the investigated catalyst systems, the mixture of Rh/C and H-USY (denoted as Rh/C + H-USY) exhibited the best performance. Over it, a high yield of propane-2,2-diyldicyclohexane (94.9%) was achieved from the APHDO of pure PC pellets after a reaction was carried out at 473 K and 3.5 MPa H2for 12 h. The Rh/C + H-USY catalyst was stable under the investigated conditions. No evident deactivation was observed during three repeated cycles. When we used a chopped DVD disk (a representative of real PC wastes) as the substrate, a high yield (86.9%) of propane-2,2-diyldicyclohexane was obtained under the same reaction conditions. The propane-2,2-diyldicyclohexane as obtained had a high density (0.92 g mL?1) and a high volumetric net heat of combustion (39.6 MJ L?1). As a potential application, it can be blended into jet fuels to improve the range and payload of airplanes.
- Cong, Yu,Li, Guangyi,Li, Ning,Wang, Aiqin,Wang, Lulin,Wang, Xiaodong,Zhang, Tao
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p. 3693 - 3699
(2021/06/06)
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- Effects of Water Addition on the Conversion of o-Cresol in the Presence of In Situ Ni–Mo Sulfide Catalysts
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Abstract: Ni-Mo sulfide systems generated in situ from precursor salts were used for the hydrodeoxygenation of o-cresol. After the reaction, the catalysts were recovered and analyzed by transmission electron microscopy and X-ray photoelectron spectroscopy. It was shown that the addition of water into the reaction system affects the composition of the o-cresol conversion product due to a change in the texture and phase composition of the surface layer of the in situ sulfide particles.
- Kniazeva,Kuchinskaya,Erasheva
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p. 682 - 687
(2021/04/09)
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- Ruthenium complex immobilized on supported ionic-liquid-phase (SILP) for alkoxycarbonylation of olefins with CO2
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In this study, the heterogeneously catalyzed alkoxycarbonylation of olefins with CO2based on a supported ionic-liquid-phase (SILP) strategy is reported for the first time. An [Ru]@SILP catalyst was accessed by immobilization of ruthenium complex on a SILP, wherein imidazolium chloride was chemically integrated at the surface or in the channels of the silica gel support. An active Ru site was generated through reacting Ru3(CO)12with the decorated imidazolium chloride in a proper microenvironment. Different IL films, by varying the functionality of the side chain at the imidazolium cation, were found to strongly affect the porosity, active Ru sites, and CO2adsorption capacity of [Ru]@SILP, thereby considerably influencing its catalytic performance. The optimized [Ru]@SILP-A-2 displayed enhanced catalytic performance and prominent substrate selectivity compared to an independent homogeneous system under identical conditions. These findings provide the basis for a novel design concept for achieving both efficient and stable catalysts in the coupling of CO2with olefins.
- Xia, Shi-Ping,Ding, Guang-Rong,Zhang, Rui,Han, Li-Jun,Xu, Bao-Hua,Zhang, Suo-Jiang
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p. 3073 - 3080
(2021/05/05)
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- Light-Promoted Transfer of an Iridium Hydride in Alkyl Ether Cleavage
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A catalytic, light-promoted hydrosilylative cleavage reaction of alkyl ethers is reported. Initial studies are consistent with a mechanism involving heterolytic silane activation followed by delivery of a photohydride equivalent to a silyloxonium ion generated in situ. The catalyst resting state is a mixture of Cp*Ir(ppy)H (ppy = 2-phenylpyridine-κC,N) and a related hydride-bridged dimer. Trends in selectivity in substrate reduction are consistent with nonradical mechanisms for C-O bond scission. Irradiation of Cp*Ir(ppy)H with blue light is found to increase the rate of hydride delivery to an oxonium ion in a stoichiometric test. A comparable rate enhancement is found in carbonyl hydrosilylation catalysis, which operates through a related mechanism also involving Cp*Ir(ppy)H as the resting state.
- Fast, Caleb D.,Schley, Nathan D.
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supporting information
p. 3291 - 3297
(2021/10/12)
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- Synthesis of cyclohexanol and ethanol via the hydrogenation of cyclohexyl acetate with Cu2Znx/Al2O3catalysts
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Cyclohexanol (CHOL), as a value-added chemical, has attracted much attention due to its huge application market. The hydrogenation of cyclohexyl acetate (CHA), derived from the esterification of acetic acid and cyclohexene, not only provides a novel route to yield CHOL and ethanol (EtOH), but also rationally utilizes excess acetic acid. In this work, a series of Zn-promoted Cu/Al2O3 catalysts were prepared via a deposition-precipitation method for the liquid-phase hydrogenation of CHA to yield CHOL and EtOH. As a result, the addition of Zn species with an optimal amount greatly improved the activity and selectivity to CHOL and EtOH. A Cu2Zn1.25/Al2O3 catalyst, which contained 16.2 wt% Cu and 9.6 wt% Zn, exhibited superior catalytic performance with 93.9% conversion of CHA and 97.2% selectivity to EtOH along with 97.1% selectivity to CHOL in a batch reactor. The Cu2Zn1.25/Al2O3 catalyst also showed excellent stability and there was no deactivation after five runs. Based on detailed characterization, it was revealed that the addition of Zn species increased the dispersion of Cu particles, adjusted the strength and amount of acid sites, and changed the electronic properties of Cu species and thus the ratio of Cu+/(Cu0 + Cu+).
- Li, Kefan,Li, Xiaohong,Qi, Yuanyuan,Song, Tongyang,Wu, Peng,Zhu, Zhirong
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p. 7035 - 7046
(2021/11/16)
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- Exploiting the radical reactivity of diazaphosphinanes in hydrodehalogenations and cascade cyclizations
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The remarkable reducibility of diazaphosphinanes has been extensively applied in various hydrogenations, based on and yet limited by their well-known hydridic reactivity. Here we exploited their unprecedented radical reactivity to implement hydrodehalogenations and cascade cyclizations originally inaccessible by hydride transfer. These reactions feature a broad substrate scope, high efficiency and simplicity of manipulation. Mechanistic studies suggested a radical chain process in which a phosphinyl radical is generated in a catalytic cycle via hydrogen-atom transfer from diazaphosphinanes. The radical reactivity of diazaphosphinanes disclosed here differs from their well-established hydridic reactivity, and hence, opens a new avenue for diazaphosphinane applications in organic syntheses.
- Cheng, Jin-Pei,Yang, Jin-Dong,Zhang, Jingjing
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p. 4786 - 4790
(2020/06/18)
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- Metal–Acid Synergy: Hydrodeoxygenation of Anisole over Pt/Al-SBA-15
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Hydrodeoxygenation (HDO) is a promising technology to upgrade fast pyrolysis bio-oils but it requires active and selective catalysts. Here we explore the synergy between the metal and acid sites in the HDO of anisole, a model pyrolysis bio-oil compound, over mono- and bi-functional Pt/(Al)-SBA-15 catalysts. Ring hydrogenation of anisole to methoxycyclohexane occurs over metal sites and is structure sensitive; it is favored over small (4 nm) Pt nanoparticles, which confer a turnover frequency (TOF) of approximately 2000 h?1 and a methoxycyclohexane selectivity of approximately 90 percent at 200 °C and 20 bar H2; in contrast, the formation of benzene and the desired cyclohexane product appears to be structure insensitive. The introduction of acidity to the SBA-15 support promotes the demethyoxylation of the methoxycyclohexane intermediate, which increases the selectivity to cyclohexane from 15 to 92 percent and the cyclohexane productivity by two orders of magnitude (from 15 to 6500 mmol gPt?1 h?1). Optimization of the metal–acid synergy confers an 865-fold increase in the cyclohexane production per gram of Pt and a 28-fold reduction in precious metal loading. These findings demonstrate that tuning the metal–acid synergy provides a strategy to direct complex catalytic reaction networks and minimize precious metal use in the production of bio-fuels.
- Durndell, Lee J.,Hunns, James A.,Isaacs, Mark A.,Lee, Adam F.,Parlett, Christopher M. A.,Shivhare, Atal,Wilson, Karen
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- One-Pot Conversion of Lignin into Naphthenes Catalyzed by a Heterogeneous Rhenium Oxide-Modified Iridium Compound
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The direct transformation of lignin into fuels and chemicals remains a huge challenge because of the recalcitrant and complicated structure of lignin. In this study, rhenium oxide-modified iridium supported on SiO2 (Ir-ReOx/SiO2) is employed for the one-pot conversion of various lignin model compounds and lignin feedstocks into naphthenes. Up to 100 percent yield of cyclohexane from model compounds and 44.3 percent yield of naphthenes from lignin feedstocks are achieved. 2 D HSQC NMR spectroscopy before and after the reaction confirms the activity of Ir-ReOx/SiO2 in the cleavage of the C?O bonds and hydrodeoxygenation of the depolymerized products. H2 temperature-programmed reduction, temperature-programmed desorption of NH3, IR spectroscopy of pyridine adsorption, X-ray photoelectron spectroscopy, X-ray absorption fine structure analysis, and control experiments reveal that a synergistic effect between Ir and ReOx in Ir-ReOx/SiO2 plays a crucial role in the high performance; ReOx is mainly responsible for the cleavage of C?O bonds, whereas Ir is responsible for hydrodeoxygenation and saturation of the benzene rings. This methodology opens up an energy-efficient route for the direct conversion of lignin into valuable naphthenes.
- Li, Xinxin,Zhang, Bo,Pan, Xiaoli,Ji, Jianwei,Ren, Yujing,Wang, Hua,Ji, Na,Liu, Qiying,Li, Changzhi
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p. 4409 - 4419
(2020/03/04)
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- Facile benzene reduction promoted by a synergistically coupled Cu-Co-Ce ternary mixed oxide
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Hydrogenation of aromatic rings promoted by earth-abundant metal composites under mild conditions is an attractive and challenging subject in the long term. In this work, a simple active site creation and stabilization strategy was employed to obtain a Cu+-containing ternary mixed oxide catalyst. Simply by pre-treatment of the ternary metal oxide precursor under a H2atmosphere, a Cu+-derived heterogeneous catalyst was obtained and denoted as Cu1Co5Ce5Ox. The catalyst showed (1) high Cu+species content, (2) a uniform distribution of Cu+doped into the lattices of CoOxand CeO2, (3) formation of CoOx/CuOxand CeO2/CuOxinterfaces, and (4) a mesoporous structure. These unique properties of Cu1Co5Ce5Oxendow it with pretty high hydrogenation activity for aromatic rings under mild conditions (100 °C with 5 bar H2), which is much higher than that of the corresponding binary counterparts and even exceeds the performance of commercial noble metal catalysts (e.g.Pd/C). The synergetic effect plays a crucial role in the catalytic procedure with CeO2functioning as a hydrogen dissociation and transfer medium, Cu+hydrogenating the benzene ring and CoOxstabilizing the unstable Cu+species. This will unlock a new opportunity to design highly efficient earth-abundant metal-derived heterogeneous catalystsviainterface interactions.
- Chen, Hao,Dai, Sheng,Fu, Jie,Jie, Kecheng,Lin, Wenwen,Yang, Shi-Ze,Yang, Zhenzhen,Zhang, Zihao
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p. 5766 - 5771
(2020/06/22)
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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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- Metal-organic frameworks containing nitrogen-donor ligands for efficient catalytic organic transformations
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Metal-organic framework (MOFs) compositions based on nitrogen donor-based organic bridging ligands, including ligands based on 1,3-diketimine (NacNac), bipyridines and salicylaldimine, were synthesized and then post-synthetically metalated with metal precursors, such as complexes of first row transition metals. Metal complexes of the organic bridging ligands could also be directly incorporated into the MOFs. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
- -
-
Page/Page column 41-43; 44-47
(2020/06/03)
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- Iron-Catalyzed Direct Julia-Type Olefination of Alcohols
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Herein, we report an iron-catalyzed, convenient, and expedient strategy for the synthesis of styrene and naphthalene derivatives with the liberation of dihydrogen. The use of a catalyst derived from an earth-abundant metal provides a sustainable strategy to olefins. This method exhibits wide substrate scope (primary and secondary alcohols) functional group tolerance (amino, nitro, halo, alkoxy, thiomethoxy, and S- A nd N-heterocyclic compounds) that can be scaled up. The unprecedented synthesis of 1-methyl naphthalenes proceeds via tandem methenylation/double dehydrogenation. Mechanistic study shows that the cleavage of the C-H bond of alcohol is the rate-determining step.
- Landge, Vinod G.,Babu, Reshma,Yadav, Vinita,Subaramanian, Murugan,Gupta, Virendrakumar,Balaraman, Ekambaram
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p. 9876 - 9886
(2020/09/03)
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- The role of acid and metal sites in hydrodeoxygenation of guaiacol over Ni/Beta catalysts
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Hydrodeoxygenation (HDO) of guaiacol over Ni metal supported on zeolites (H-Beta and H-ZSM-5) with different Si/Al ratios (12.5, 25, 175) and different metal loadings (2.3-23.4 wt%) was investigated in order to elucidate the role of catalyst acidity and the structure of Ni in the HDO reaction. Results show that the deoxygenation activity and product selectivity depend on the choice of support (acidity, pore size), level of metal loading, and reaction conditions. Guaiacol was deoxygenated in the presence of hydrogen with a maximum cyclohexane yield of 76% at a guaiacol conversion level of 100% over 15.7 wt% Ni/Beta-12.5 catalyst. Compared to Ni/ZSM-5 catalysts, Ni/Beta catalysts with mesopores facilitated the formation of coupling products (1,1′-bicyclohexyl). Under differential reaction conditions, we observed a linear relationship between deoxygenation activity and concentration of acid sites. Over catalysts containing small Ni particles, cyclohexane was formed as a result of a consecutive reduction of guaiacol to catechol and cyclohexane. At higher Ni-loading and consequently larger Ni particles, the selectivity towards cyclohexane increases with increased Ni loading. A higher concentration of nickel hydrides compared to smaller Ni sites was observed by H2-TPD and H2-FTIR over larger Ni species, and the nickel hydrides are believed to be crucial intermediates in the hydrogenation reaction. The 15.7 wt% Ni/Beta (Si/Al = 12.5) exhibits a promising HDO activity due to its good synergistic effect of hydrogenation and deoxygenation functions (high concentration nickel hydrides of and acid sites). In addition, based on the product distribution over catalysts containing mainly small Ni species and the Ni nanoparticles, two different reaction pathways were proposed, and the role of the acid sites and metal sites for each reaction route was discussed.
- Adesina, Adesoji,Kennedy, Eric,Li, Molly Meng-Jung,Setiawan, Adi,Stockenhuber, Michael,Yan, Penghui,Zhao, Guangyu
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p. 810 - 825
(2020/02/27)
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- An efficient bifunctional Ru-NbOPO4 catalyst for the hydrodeoxygenation of aromatic ethers, phenols and real bio-oil
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An efficient bifunctional NbOPO4 supported Ru catalyst (Ru-NbOPO4) was applied to the hydrodeoxygenation of aromatic ethers and phenols and the upgrading of bio-oil. Characterization results revealed that the Ru-NbOPO4 catalyst possessed strong acidity, including Lewis and Br?nsted acids. The Lewis acid sites originated from the Nb[sbnd]O bonding structures, including slightly distorted octahedral NbO6, regular tetrahedral NbO4 and highly distorted octahedral NbO6. In combination with the strong acidity of the Nb[sbnd]O species and excellent hydrogenation activity of the metallic Ru, the bifunctional Ru-NbOPO4 catalyst exhibited an excellent catalytic activity in the hydrodeoxygenation of aromatic ethers and phenols with different structures, and even real bio-oil to alkanes. The hydrocarbon yield after real bio-oil upgradation was up to 88.2 %. Carbon deposition and enlargement of the Ru nanoparticles resulted in slight deactivation of the catalyst. The catalytic activity could be mostly recovered after being calcined and reduced.
- Zhao, Hongye,Hu, Xun,Hao, Jianxiu,Li, Na,Zhi, Keduan,He, Runxia,Wang, Yunfei,Zhou, Huacong,Liu, Quansheng
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- Bidentate NHC-Cobalt Catalysts for the Hydrogenation of Hindered Alkenes
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Herein, we report a series of easily accessible bidentate N-heterocyclic carbene (NHC) cobalt catalysts, which enable the hydrogenation of hindered alkenes under mild conditions. The four-coordinated bidentate NHC-Co(II) complexes were characterized by X-ray diffraction, elemental analysis, ESI-HRMS, and magnetic moment measurements, revealing a distorted-tetrahedral geometry and a high-spin configuration of the metal center. The activity of the in situ formed catalytic system, which was obtained from easily available NHC precursors, CoCl2, and NaHBEt3, was identical with those of well-defined NHC-cobalt catalysts. This highlights the potential utility of this reaction system.
- Wei, Zeyuan,Wang, Yujie,Li, Yibiao,Ferraccioli, Raffaella,Liu, Qiang
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p. 3082 - 3087
(2020/10/02)
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- Hydrodeoxygenation of phenol using nickel phosphide catalysts. Study of the effect of the support
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This work studied the performance of nickel phosphide phases supported on various supports (SiO2, Al2O3, TiO2, CeO2 and CeZrO2) for the hydrodeoxygenation of phenol in gas phase at 300 °C and 1 atm. The nature of the phosphide phase obtained by the temperature programmed reduction at 700 °C depended on the type of support. Only Ni2P was formed on SiO2, TiO2, and CeZrO2, whereas the Ni12P5 was the preferred phase on Al2O3. A mixture of both Ni2P and Ni12P5 phases was obtained on CeO2. Unsupported Ni2P exhibited high selectivity to benzene (95%), indicating that the Ni2P phase is responsible for the direct deoxygenation of phenol. Ni12P5 phase promoted the formation of cyclohexanone, cyclohexane and cyclohexene. However, the supported catalysts showed lower selectivity to benzene, even when the Ni2P was the only phase present. The supports favored the formation of hydrogenation products via the tautomerization route. All catalysts only slightly deactivated with time on stream, which is likely due to the high activity of the phosphide phase.
- de Souza, Priscilla M.,Inocêncio, Carlos V.M.,Perez, Victoria I.,Rabelo-Neto, Raimundo Crisostomo,Gon?alves, Vinicius Ottonio O.,Jacobs, Gary,Richard, Frédéric,da Silva, Victor Teixeira,Noronha, Fabio B.
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p. 366 - 375
(2019/09/07)
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- Liquid-phase hydrodeoxygenation of lignin-derived phenolics on Pd/Fe: A mechanistic study
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Although Pd/Fe bimetallic catalysts have been extensively studied in vapor-phase hydrodeoxygenation of phenolics (i.e., guaiacol, cresol), little is yet known about their performance in liquid-phase reactions. In this work, we present a mechanistic study on the Pd/Fe bimetallic catalysts in liquid-phase hydrodeoxygenation of phenolics. The role of tautomerization in hydrodeoxygenation of the lignin-derived phenolics, particularly for ring saturation, is systematically studied by employing two representative modeling compounds: phenol (a molecule that is keto-enol tautomeric) and diphenyl ether (a molecule that does not allow ketol-enol tautomerization). It was found that although the addition of oxyphilic Fe inhibits the direct aromatic ring saturation reaction typically occurring on Pd, tautomerization opens another reaction pathway toward ring saturation products (i.e. cyclohexanone, cyclohexanol, cyclohexane et al.), where both tautomerization and the hydrogenation of keto isomers are significantly enhanced to produce cyclohexanol followed by direct hydrogenolysis of the cyclohexanol to cyclohexane.
- Zhang, Jianghao,Sun, Junming,Sudduth, Berlin,Pereira Hernandez, Xavier,Wang, Yong
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p. 305 - 311
(2019/01/04)
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