- Ruthenium-containing SBA-12 catalysts for anisole hydrodeoxygenation
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Hexagonally ordered mesoporous silica SBA-12 catalysts containing various amounts of Ru (1 or 3 wt.percent) were obtained by wet impregnation. These catalysts were thoroughly characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM)
- Feliczak-Guzik, Agnieszka,Szczyglewska, Paulina,Jaroniec, Mietek,Nowak, Izabela
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- Evaluation of the Arrhenius Parameters for the Thermal Isomerization of a Gaseous Ion. The Temperature Dependence of the Cyclohexylium Ion Unimolecular Rearrangement
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Gas-phase isomerization of cyclohexylium ion (1), obtained via protonation of cyclohexene and of bicyclohexane and via hydride-ion abstraction from cyclohexane by CnH5(1+) (n = 1,2) and by s-C3H7(1+) ions, has been investigated by a radiolytic technique in CH4 and C3H8 in the pressure range from 106 to 1480 Torr.Temperature-dependence studies in the temperature interval from 310 to 353 K have provided the activation parameters of the thermal rearrangement of 1 into 1-methylcyclopentylium ion (2) in CH4 at 750 Torr and in C3H8 at 1480 Torr.Least-squares analysis of the two mutually consistent sets of data leads to an activation energy of 7.4 +/- 1 kcal mol-1 and to a preexponential factor of 1E12+/-1.3 s-1.These values represent the first estimates of the activation parameters of a unimolecular isomerization of a gaseous ion thermally equilibrated with the bath gas, i.e., under conditions which allow meaningful comparison with solution kinetics.The results support previous evidence for the existence of gaseous 1, providing a quantitative evaluation of the energy barrier for its rearrangement into 2.The more extensive formation of 2 from the protonation of bicyclohexane than that of cyclohexene is consistent with the long-postulated protonated-cyclopropane route in the branching rearrangement of cycloalkylium ions.
- Attina, Marina,Cacace, Fulvio,Marzio, Annito di
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- Chemoselective and Tandem Reduction of Arenes Using a Metal–Organic Framework-Supported Single-Site Cobalt Catalyst
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The development of heterogeneous, chemoselective, and tandem catalytic systems using abundant metals is vital for the sustainable synthesis of fine and commodity chemicals. We report a robust and recyclable single-site cobalt-hydride catalyst based on a porous aluminum metal–organic framework (DUT-5 MOF) for chemoselective hydrogenation of arenes. The DUT-5 node-supported cobalt(II) hydride (DUT-5-CoH) is a versatile solid catalyst for chemoselective hydrogenation of a range of nonpolar and polar arenes, including heteroarenes such as pyridines, quinolines, isoquinolines, indoles, and furans to afford cycloalkanes and saturated heterocycles in excellent yields. DUT-5-CoH exhibited excellent functional group tolerance and could be reusable at least five times without decreased activity. The same MOF-Co catalyst was also efficient for tandem hydrogenation–hydrodeoxygenation of aryl carbonyl compounds, including biomass-derived platform molecules such as furfural and hydroxymethylfurfural to cycloalkanes. In the case of hydrogenation of cumene, our spectroscopic, kinetic, and density functional theory (DFT) studies suggest the insertion of a trisubstituted alkene intermediate into the Co–H bond occurring in the turnover limiting step. Our work highlights the potential of MOF-supported single-site base–metal catalysts for sustainable and environment-friendly industrial production of chemicals and biofuels.
- Antil, Neha,Kumar, Ajay,Akhtar, Naved,Begum, Wahida,Chauhan, Manav,Newar, Rajashree,Rawat, Manhar Singh,Manna, Kuntal
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supporting information
p. 1031 - 1040
(2022/01/19)
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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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- 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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- 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 0094-0095; 0123-0126; 0128-0130
(2021/05/29)
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- Catalytic role of metals supported on SBA-16 in hydrodeoxygenation of chemical compounds derived from biomass processing
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Hydrodeoxygenation (HDO) carried out at high temperatures and high hydrogen pressures is one of the alternative methods of upgrading pyrolytic oils from biomass, leading to high quality biofuels. To save energy, it is important to carry out catalytic proc
- Szczyglewska, Paulina,Feliczak-Guzik, Agnieszka,Jaroniec, Mietek,Nowak, Izabela
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p. 9505 - 9517
(2021/03/16)
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- Supported nickel catalysts for anisole hydrodeoxygenation: Increase in the selectivity to cyclohexane
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The hydrodeoxygenation (HDO) of anisole was performed with Ni catalysts supported on SBA-15 silica and protonated titanate nanotubes (PTN), in order to determine the effect of the support's nature and the method of incorporation of Ni species on the catalytic activity and selectivity in HDO. Catalysts with 10 wt.percent of Ni were prepared by two methods: deposition-precipitation with urea (DP) and the classical incipient wetness impregnation (IM). Characterization of the catalysts was performed by nitrogen physisorption, temperature programmed reduction, temperature programmed desorption of ammonia, high resolution transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, XPS and O2 chemisorption. The obtained results show that the support's nature and the preparation method had a strong influence on the dispersion of the supported Ni species and their HDO performance. Catalysts with larger metallic Ni particles showed higher ability for hydrogenation of anisole and higher intrinsic activity (TOF) than those with smaller Ni particles. On the other side, the use of the PTN support and the DP with urea preparation method resulted in catalysts with increased acidity and improved selectivity for the formation of deoxygenated products (cyclohexane).
- Vargas-Villagrán,Flores-Villeda,Puente-Lee,Solís-Casados,Gómez-Cortés,Díaz-Guerrero,Klimova
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- Anionic Amphiphilic Cyclodextrins Bearing Oleic Grafts for the Stabilization of Ruthenium Nanoparticles Efficient in Aqueous Catalytic Hydrogenation
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Oleic succinyl β-cyclodextrin was proved to be efficient for the stabilization of ruthenium nanoparticles (NPs) in aqueous medium. These NPs were characterized by FTIR spectroscopy and transition electron microscopy (TEM). The catalytic activity of these NPs was evaluated in the aqueous hydrogenation of petrosourced and biosourced unsaturated compounds such as benzene and furfural derivatives. The catalytic system can be easily recycled and reused up to nine runs without any loss of activity and selectivity, demonstrating its robustness.
- Cocq, Aurélien,Léger, Bastien,No?l, Sébastien,Bricout, Hervé,Djeda?ni-Pilard, Florence,Tilloy, Sébastien,Monflier, Eric
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p. 1013 - 1018
(2019/12/27)
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- Selective hydrogenation of lignin-derived compounds under mild conditions
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A key challenge in the production of lignin-derived chemicals is to reduce the energy intensive processes used in their production. Here, we show that well-defined Rh nanoparticles dispersed in sub-micrometer size carbon hollow spheres, are able to hydrogenate lignin derived products under mild conditions (30 °C, 5 bar H2), in water. The optimum catalyst exhibits excellent selectivity and activity in the conversion of phenol to cyclohexanol and other related substrates including aryl ethers.
- Chen, Lu,Van Muyden, Antoine P.,Cui, Xinjiang,Laurenczy, Gabor,Dyson, Paul J.
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p. 3069 - 3073
(2020/06/17)
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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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- Chemoselective hydrogenation of heteroarenes and arenes by Pd-Ru-PVP under mild conditions
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Monometallic (Pd, Ru or Rh) and bimetallic (Pd0.5-Ru0.5) alloy NPs catalysts were examined for the hydrogenation of quinoline. Pd-Ru alloy catalyst showed superior catalytic activity to the traditional Rh catalyst. The characterization of Pd0.5-Ru0.5 catalysts, HAADF-EDX mapping and XPS analysis suggested that the alloy state of PdRu catalysts remained unchanged in the recovered catalyst. Furthermore, the catalyst was highly selective for the hydrogenation of different arenes. This journal is
- Abe, Naoya,Chaudhari, Chandan,Ikeda, Yasuyuki,Kitagawa, Hiroshi,Kusuda, Kohei,Matsumura, Syo,Nagaoka, Katsutoshi,Nishida, Yoshihide,Sato, Katsutoshi,Terada, Kenji,Toriyama, Takaaki,Yamamoto, Tomokazu
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p. 44191 - 44195
(2020/12/25)
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- Highly Efficient Cleavage of Ether Bonds in Lignin Models by Transfer Hydrogenolysis over Dual-Functional Ruthenium/Montmorillonite
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Cleavage of ether bonds is a crucial but challenging step for lignin valorization. To efficiently realize this transformation, the development of robust catalysts or catalytic systems is required. In this study, montmorillonite (MMT)-supported Ru (denoted as Ru/MMT) is fabricated as a dual-functional heterogeneous catalyst to cleave various types of ether bonds through transfer hydrogenolysis without using any additional acids or bases. The prepared Ru/MMT material is found to efficiently catalyze the cleavage of various lignin models and lignin-derived phenols; cyclohexanes (fuels) and cyclohexanols (key intermediates) are the main products. The synergistic effect between electron-enriched Ru and the acidic sites on MMT contributes to the excellent performance of Ru/MMT. Systematic studies reveal that the reaction proceeds through two possible reaction pathways, including the direct cleavage of ether bonds and the formation of intermediates with one hydrogenated benzene ring, for all examined types of ether bonds, namely, 4-O-5, α-O-4, and β-O-4.
- Xue, Zhimin,Yu, Haitao,He, Jing,Zhang, Yibin,Lan, Xue,Liu, Rundong,Zhang, Luyao,Mu, Tiancheng
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p. 4579 - 4586
(2020/06/21)
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- Selective hydrogenation of fluorinated arenes using rhodium nanoparticles on molecularly modified silica
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The production of fluorinated cyclohexane derivatives is accomplished through the selective hydrogenation of readily available fluorinated arenes using Rh nanoparticles on molecularly modified silica supports (Rh?Si-R) as highly effective and recyclable catalysts. The catalyst preparation comprises grafting non-polar molecular entities on the SiO2 surface generating a hydrophobic environment for controlled deposition of well-defined rhodium particles from a simple organometallic precursor. A broad range of fluorinated cyclohexane derivatives was shown to be accessible with excellent efficacy (0.05-0.5 mol% Rh, 10-55 bar H2, 80-100 °C, 1-2 h), including industrially relevant building blocks. Addition of CaO as scavenger for trace amounts of HF greatly improves the recyclability of the catalytic system and prevents the risks associated to the presence of HF, without compromising the activity and selectivity of the reaction.
- Bordet, Alexis,Emondts, Meike,Kacem, Souha,Leitner, Walter
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p. 8120 - 8126
(2020/12/28)
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- Formation of Cyclopropanes via Activation of (γ-Methoxy)alkyl Gold(I) Complexes with Lewis Acids
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Treatment of the gold 3-methoxy-3-phenylpropyl complex (P)AuCH2CH2CH(OMe)Ph [P = P(t-Bu)2o-biphenyl] with AlCl3 at -78 °C led to the immediate (≤5 min) formation of a 4:1 mixture of phenylcyclopropane and (1-methoxypropyl)benzene in 86 ± 5% combined yield. Lewis acid activation of the stereochemically pure isotopomer erythro-(P)AuCH2CHDCH(OMe)Ph led to the formation of cis-2-deuterio-1-phenylcyclopropane in 84 ± 5% yield as a single stereoisomer, which established that cyclopropanation occurred with inversion of the γ-stereocenter. Similarly, ionization of the stereochemically pure cyclohexyl gold complex cis-(P)AuCHCH2CH(OMe)CH2CH2CH2 at -78 °C formed bicyclo[3.1.0]hexane in 82% ± 5% yield, which validated a low energy pathway for cyclopropanation involving inversion of the α-stereocenter. Taken together, these observations are consistent with a mechanism for cyclopropane formation involving backside displacement of both the Cγleaving group and the Cα (L)Au+ fragment via a W-shaped transition state.
- Kim, Nana,Widenhoefer, Ross A.
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p. 3160 - 3167
(2020/09/12)
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- Low-Temperature Catalytic Hydrogenolysis of Guaiacol to Phenol over Al-Doped SBA-15 Supported Ni Catalysts
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Selective hydrogenolysis of aromatic carbon-oxygen (Caryl?O) bonds is a key strategy for the generation of aromatic chemicals from lignin. However, this process is usually operated at high temperatures and pressures over hydrogenation catalysts, resulting in a low selectivity for aromatics and an extra consumption of hydrogen. Here, a series of Al-doped SBA-15 mesoporous materials with different Si/Al molar ratios (Al-SBA-15) were prepared via a post-synthesis method using NaAlO2 as the Al source, and then Al-SBA-15 supported Ni catalysts (Ni/Al-SBA-15) were prepared by a deposition-precipitation method using urea as the hydrolysis reagent. The prepared supports and catalysts were extensively characterized using various techniques such as XRD, N2 adsorption/desorption, TEM, 27Al NMR, NH3-TPD, XPS, H2-TPR, and pyridine-FT-IR, and the catalysts were evaluated in the hydrogenolysis of the Caryl?O bond in guaiacol and lignin derived compounds under mild conditions. The effects of the Si/Al ratio in catalyst and reaction parameters on guaiacol conversion and product distribution were investigated in detail, associated with solvent effect. The incorporation of Al into the framework of SBA-15 can improve the Lewis acidity and the dispersion of the supported Ni particles and yet modulate the metal-support interactions, which are propitious to the hydrogenolysis of the Caryl?O bond in guaiacol. The catalyst Ni/Al-SBA-15 with a Si/Al molar ratio of 10 shows the best performance with a guaiacol conversion of 87.4 % and a phenol selectivity of 76.9 % under the mild conditions conducted, because of its proper acidity, suitable metal-support interactions, and high dispersion of the active species. The present study would stimulate research and development in multi-functional catalysts for the generation of valuable chemicals from biomass.
- Wang, Qiuyue,Chen, Yufang,Yang, Guanheng,Deng, Ping,Lu, Xinqing,Ma, Rui,Fu, Yanghe,Zhu, Weidong
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p. 4930 - 4938
(2020/08/26)
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- Influence of Hydrogen Bond Donating Sites in UiO-66 Metal-Organic Framework for Highly Regioselective Methanolysis of Epoxides
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A Zr(IV)-based UiO-66 metal-organic framework (MOF) (named 1) was synthesized by employing 1-(aminomethyl)naphthalene-2-ol appended terephthalate linker and Zr(IV) salt via solvothermal method and subsequently characterized. Furthermore, the potential efficiency of activated (named 1′) form of as-synthesized MOF was investigated as an organocatalyst for the ring-opening of epoxide by methanol. The catalytic performance of 1 and 1′ was studied in the methanolysis of styrene oxide as a model substrate and the activity of 1′ was also examined with various alcohols. Under the optimized reaction conditions, the catalytic performance of 1′ reached 96 % conversion of styrene oxide to its corresponding product with 98 % regioselectivity. The reusability and stability of the catalyst were proved by recycling up to four runs in the methanolysis of styrene oxide. The Lewis acidity originating from metal nodes and hydrogen bond donating (HBD) sites in the linker is distributed homogeneously throughout the framework, thus playing crucial role in the activation of epoxide with easy accessibility.
- Anbu, Nagaraj,Biswas, Shyam,Das, Aniruddha,Dhakshinamoorthy, Amarajothi,Sk, Mostakim
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- Raney nickel-catalyzed hydrodeoxygenation and dearomatization under transfer hydrogenation conditions—Reaction pathways of non-phenolic compounds
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Catalytic reduction of oxygen-containing aromatic compounds has been studied under transfer hydrogenation (TH) conditions at 150 °C in 2-PrOH as a hydrogen donor. Raney nickel is used as a heterogeneous catalyst. The reaction of aromatic non-phenolic carbonyl compounds is most likely to proceed through the pathway “aromatic ketone (aldehyde)→aromatic alcohol→alkylaromatics→saturated alkylcyclohexane”. One of the main reactions under the TH conditions is a hydrodeoxygenation (HDO) process. Unexpectedly, the hydrodeoxygenation of aromatic ketones to alkylaromatics (C[dbnd]O → CH2) occurs faster than of corresponding aromatic alcohols (HC–OH → CH2) that means either additional reaction pathway of its hydrodeoxygenation missing for the corresponding aromatic alcohols or specific interaction of OH functionality with Raney nickel surface obstructing (hindering) the further reduction. Benzaldehyde is shown to be less reactive than the aromatic ketones under the same reaction conditions. The main reason is proposed to be carbon monoxide release resulted from the decarbonylation of the aldehyde. Carbon monoxide demonstrates a poisoning effect on Raney nickel surface that is evidenced in the catalyzed TH reaction of acetophenone. The HDO reaction of anisole under the same reaction conditions was a little slowly than of oxygen-containing non-phenolic aromatics.
- Philippov,Chibiryaev,Martyanov
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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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- Cobalt-Nanoparticles Catalyzed Efficient and Selective Hydrogenation of Aromatic Hydrocarbons
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The development of inexpensive and practical catalysts for arene hydrogenations is key for future valorizations of this general feedstock. Here, we report the development of cobalt nanoparticles supported on silica as selective and general catalysts for such reactions. The specific nanoparticles were prepared by assembling cobalt-pyromellitic acid-piperazine coordination polymer on commercial silica and subsequent pyrolysis. Applying the optimal nanocatalyst, industrial bulk, substituted, and functionalized arenes as well as polycyclic aromatic hydrocarbons are selectively hydrogenated to obtain cyclohexane-based compounds under industrially viable and scalable conditions. The applicability of this hydrogenation methodology is presented for the storage of H2 in liquid organic hydrogen carriers.
- Murugesan, Kathiravan,Senthamarai, Thirusangumurugan,Alshammari, Ahmad S.,Altamimi, Rashid M.,Kreyenschulte, Carsten,Pohl, Marga-Martina,Lund, Henrik,Jagadeesh, Rajenahally V.,Beller, Matthias
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p. 8581 - 8591
(2019/09/12)
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- Ru/hydroxyapatite as a dual-functional catalyst for efficient transfer hydrogenolytic cleavage of aromatic ether bonds without additional bases
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Cleavage of aromatic ether bonds is a key step for lignin valorization, and the development of novel heterogeneous catalysts with high activity is crucial. Herein, bifunctional Ru/hydroxyapatite has been prepared via ion exchange and subsequent reduction. The obtained Ru/hydroxyapatite could efficiently catalyze the cleavage of various compounds containing aromatic ether bonds via transfer hydrogenolysis without additional bases. Systematic studies indicated that the basic nature of hydroxyapatite and electron-enriched Ru sites resulted in the high activity of the catalyst. A mechanism study revealed that the direct cleavage of aromatic ether bonds was the main reaction pathway.
- Hua, Manli,Song, Jinliang,Xie, Chao,Wu, Haoran,Hu, Yue,Huang, Xin,Han, Buxing
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p. 5073 - 5079
(2019/09/30)
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- Hydrodeoxygenation of anisole over different Rh surfaces
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The cleavage of the alkoxy (Ar–O–R) ether bond present in anisole is an interesting hydrodeoxygenation (HDO) reaction, since this asymmetric group contains two different C–O bonds, Caryl–O or Calkyl–O, which could potentially cleave. Recent work on the HDO of anisole over Pt, Ru, and Fe catalysts has shown that a common phenoxy surface intermediate is formed on all three metals. The subsequent reaction path of this intermediate varies from metal to metal, depending on the metal oxophilicity. Over the less oxophilic Pt, phenol is the only primary product. By contrast, on the more oxophilic Fe catalyst, the sole primary product is benzene instead of phenol. On Ru, with intermediate oxophilicity, both benzene and phenol are primary products. In this contribution, we have investigated Rh catalysts of varying surface nanostructures. A combination of experimental measurements and computational calculations was used to explore the effects of varying metal coordination number, an additional parameter that can be used to control the oxophilicity of a metal. The results confirm that metal oxophilicity is a good descriptor for HDO performance of metal catalysts and it can be controlled via selection of metal type and/or metal extent of coordination. Small Rh metal clusters with low coordination metal sites are more active for the deoxygenation pathway but also quickly deactivated while large clusters with high coordination sites are more active toward hydrogenation and more stable.
- Duong, Nhung N.,Aruho, Darius,Wang, Bin,Resasco, Daniel E.
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p. 1721 - 1730
(2019/11/11)
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- Ruthenium Catalysts on ZSM-5/MCM-41 Micro-Mesoporous Support for Hydrodeoxygenation of Guaiacol in the Presence of Water
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A ruthenium-containing catalyst on ZSM-5/MCM-41 micro-mesoporous aluminosilicate support was synthesized. The micro-mesoporous support and supported catalyst were characterized by low-temperature nitrogen desorption/adsorption, temperature-programmed ammonia desorption, transmission electron microscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction with hydrogen, and energy-dispersive X-ray fluorescence analysis. Ru/ZSM-5/MCM-41 has high specific surface area (392 m2 g?1) and high acidity (1087 μmol g?1); the mean ruthenium particle size is 1.7 nm. The catalyst was studied in hydrodeoxygenation of a modelbio-oil compound, guaiacol, in the presence of water at a hydrogen pressure of 5 MPa and temperatures in the interval 130–290°C. The catalyst obtained exhibits high activity in guaiacol hydrodeoxygenation: The conversion was 90%, and the selectivity with respect to cycloalkanes was 64% in 3-h reaction performed at a hydrogen pressure of 5 MPa and a temperature of 230°C.
- Roldugina,Glotov,Isakov,Maksimov,Vinokurov,Karakhanov
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p. 1170 - 1178
(2019/10/22)
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- Catalytic Hydrogenolysis of Substituted Diaryl Ethers by Using Ruthenium Nanoparticles on an Acidic Supported Ionic Liquid Phase (Ru@SILP-SO3H)
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Catalytic hydrogenolysis of diaryl ethers is achieved by using ruthenium nanoparticles immobilized on an acidic supported ionic liquid phase (Ru@SILP-SO 3 H) as a multifunctional catalyst. The catalyst components are assembled through a molecular approach ensuring synergistic action of the metal and acid functions. The resulting catalyst is highly active for the hydrogenolysis of various diaryl ethers. For symmetric substrates such as diphenyl ether, hydrogenolysis is followed by full hydrodeoxygenation producing the corresponding cycloalkanes as the main products. For unsymmetric substrates, the cleavage of the C-O bond is regioselective and occurs adjacent to the unsubstituted phenyl ring. As hydrogenation of benzene is faster than hydrodeoxygenation over the Ru@SILP-SO 3 H catalyst, controlled mixtures of cyclohexane and substituted phenols are accessible with good selectivity. Application of Ru@SILP-SO 3 H catalyst in continuous-flow hydrogenolysis of 2-methoxy-4-methylphenoxybenzene is demonstrated with use of commercial equipment.
- Rengshausen, Simon,Etscheidt, Fabian,Gro?kurth, Johannes,Luska, Kylie L.,Bordet, Alexis,Leitner, Walter
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p. 405 - 412
(2019/02/26)
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- Polysilane-Immobilized Rh-Pt Bimetallic Nanoparticles as Powerful Arene Hydrogenation Catalysts: Synthesis, Reactions under Batch and Flow Conditions and Reaction Mechanism
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Hydrogenation of arenes is an important reaction not only for hydrogen storage and transport but also for the synthesis of functional molecules such as pharmaceuticals and biologically active compounds. Here, we describe the development of heterogeneous Rh-Pt bimetallic nanoparticle catalysts for the hydrogenation of arenes with inexpensive polysilane as support. The catalysts could be used in both batch and continuous-flow systems with high performance under mild conditions and showed wide substrate generality. In the continuous-flow system, the product could be obtained by simply passing the substrate and 1 atm H2 through a column packed with the catalyst. Remarkably, much higher catalytic performance was observed in the flow system than in the batch system, and extremely strong durability under continuous-flow conditions was demonstrated (>50 days continuous run; turnover number >3.4 × 105). Furthermore, details of the reaction mechanisms and the origin of different kinetics in batch and flow were studied, and the obtained knowledge was applied to develop completely selective arene hydrogenation of compounds containing two aromatic rings toward the synthesis of an active pharmaceutical ingredient.
- Miyamura, Hiroyuki,Suzuki, Aya,Yasukawa, Tomohiro,Kobayashi, Shu
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supporting information
p. 11325 - 11334
(2018/09/06)
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- Titanium(III)-Oxo Clusters in a Metal-Organic Framework Support Single-Site Co(II)-Hydride Catalysts for Arene Hydrogenation
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Titania (TiO2) is widely used in the chemical industry as an efficacious catalyst support, benefiting from its unique strong metal-support interaction. Many proposals have been made to rationalize this effect at the macroscopic level, yet the underlying molecular mechanism is not understood due to the presence of multiple catalytic species on the TiO2 surface. This challenge can be addressed with metal-organic frameworks (MOFs) featuring well-defined metal oxo/hydroxo clusters for supporting single-site catalysts. Herein we report that the Ti8(μ2-O)8(μ2-OH)4 node of the Ti-BDC MOF (MIL-125) provides a single-site model of the classical TiO2 support to enable CoII-hydride-catalyzed arene hydrogenation. The catalytic activity of the supported CoII-hydride is strongly dependent on the reduction of the Ti-oxo cluster, definitively proving the pivotal role of TiIII in the performance of the supported catalyst. This work thus provides a molecularly precise model of Ti-oxo clusters for understating the strong metal-support interaction of TiO2-supported heterogeneous catalysts.
- Ji, Pengfei,Song, Yang,Drake, Tasha,Veroneau, Samuel S.,Lin, Zekai,Pan, Xiandao,Lin, Wenbin
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p. 433 - 440
(2018/01/17)
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- Ruthenium nanoparticles ligated by cholesterol-derived NHCs and their application in the hydrogenation of arenes
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Herein we present ruthenium nanoparticles (Ru-NPs) stabilized with two rigid NHC ligands derived from cholesterol. The obtained nanoparticles were fully characterized and applied in the hydrogenation of various aromatic compounds under mild conditions. Interestingly, the more bulky ligand gives a slightly lower ligand coverage and a faster catalyst.
- Rakers, Lena,Martínez-Prieto, Luis M.,López-Vinasco, Angela M.,Philippot, Karine,Van Leeuwen, Piet W. N. M.,Chaudret, Bruno,Glorius, Frank
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p. 7070 - 7073
(2018/07/05)
-
- Effect of the Crystallographic Phase of Ruthenium Nanosponges on Arene and Substituted-Arene Hydrogenation Activity
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Identifying crystal structure sensitivity of a catalyst for a particular reaction is an important issue in heterogeneous catalysis. In this context, the activity of different phases of ruthenium catalysts for benzene hydrogenation has not yet been investigated. The synthesis of hcp and fcc phases of ruthenium nanosponges by chemical reduction method has been described. Reduction of ruthenium chloride using ammonia borane (AB) and tert-butylamine borane (TBAB) as reducing agents gave ruthenium nanosponge in its hcp phase. On the other hand, reduction using sodium borohydride (SB) afforded ruthenium nanosponge in its fcc phase. The as prepared hcp ruthenium nanosponge was found to be catalytically more active compared to the as prepared fcc ruthenium nanosponge for hydrogenation of benzene. The hcp ruthenium nanosponge was found to be thermally stable and recyclable over several cycles. This self-supported hcp ruthenium nanosponge shows excellent catalytic activity towards hydrogenation of various substituted benzenes. Moreover, the ruthenium nanosponge catalyst was found to bring about selective hydrogenation of aromatic cores of phenols and aryl ethers to the respective alicyclic products without hydrogenolysis of the C?O bond.
- Ghosh, Sourav,Jagirdar, Balaji R.
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p. 3086 - 3095
(2018/05/29)
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- Synergistic effects of Ru and Fe on titania-supported catalyst for enhanced anisole hydrodeoxygenation selectivity
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The hydrodeoxygenation (HDO) of bio-oil is considered among the most promising techniques for upgrading pyrolysis bio-oils to biofuels. However, its commercial application is challenging because of the complexity of the reaction. In particular, minimizing the hydrogen consumption in HDO is a main concern. In this study, ruthenium supported on mesoporous TiO2 (Ru/meso-TiO2) catalysts were prepared with various Fe loadings for this reaction, using anisole as a model substrate. Analytical techniques, such as transmission electron microscopy, CO chemisorption, and X-ray photoelectron spectroscopy, revealed that the addition of Fe increased the number of oxygen vacancies, reaching a maximum when the Fe loading was 1 wt.%. H2 consumption can be reduced by performing HDO reaction at high temperatures. The Ru/meso-TiO2 without Fe converted anisole mainly to methoxycyclohexane, indicating that hydrogenation (HYD) is the dominant reaction pathway. The addition of Fe remarkably promotes the conversion and selectivity of the catalyst. The reaction path could be drastically changed from HYD to direct deoxygenation (DDO) by the addition of a proper amount of Fe. This change can be assigned to the synergism between Ru particles and Fe species on the surface of meso-TiO2 support. The catalyst with 1 wt.% Fe exhibited the highest conversion and benzene selectivity due to its largest number of oxygen vacancies, indicating that it utilized a minimum amount of H2.
- Phan, Tuan Ngoc,Ko, Chang Hyun
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p. 219 - 226
(2017/09/06)
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- Palladium-Catalyzed Reductive Insertion of Alcohols into Aryl Ether Bonds
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Palladium on carbon catalyzes C?O bond cleavage of aryl ethers (diphenyl ether and cyclohexyl phenyl ether) by alcohols (R?OH) in H2. The aromatic C?O bond is cleaved by reductive solvolysis, which is initiated by Pd-catalyzed partial hydrogenation of one phenyl ring to form an enol ether. The enol ether reacts rapidly with alcohols to form a ketal, which generates 1-cyclohexenyl?O?R by eliminating phenol or an alkanol. Subsequent hydrogenation leads to cyclohexyl?O?R.
- Wang, Meng,Gutiérrez, Oliver Y.,Camaioni, Donald M.,Lercher, Johannes A.
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p. 3747 - 3751
(2018/03/21)
-
- Metallic nickel supported on mesoporous silica as catalyst for hydrodeoxygenation: effect of pore size and structure
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Catalytic hydrodeoxygenation (HDO) of anisole, a methoxy-rich lignin-derived bio-oil model compound, was carried out over a series of Ni-containing (5, 10, 20, and 30?wt%) catalysts with commercial silica and ordered mesoporous silica SBA-15 as support. Both supports and catalysts were characterized by N2 adsorption–desorption isotherms, X-ray diffraction, CO chemisorption, and transmission electron microscopy (TEM). Catalytic reaction was performed at 250?°C and 10?bar H2 pressure. Depending on the catalyst support used and the content of active metal, the catalytic activity and product distribution changed drastically. Increase of the nickel loading resulted in increased anisole conversion and C6 hydrocarbon (benzene and cyclohexane) yield. However, loading more Ni than 20?wt% resulted in a decrease of both conversion and C6 yield due to agglomeration of Ni particles. In addition, Ni/SBA-15 samples exhibited much stronger catalytic activity and selectivity toward C6 hydrocarbon products compared with Ni/silica catalysts. The differences in catalytic activity among these catalysts can be attributed to the effect of the pore size and pore structure of mesoporous SBA-15. SBA-15 can accommodate more Ni species inside channels than conventional silica due to its high pore volume with uniform pore structure, leading to high HDO catalytic activity.
- Jang, Min Su,Phan, Tuan Ngoc,Chung, Im Sik,Lee, In-Gu,Park, Young-Kwon,Ko, Chang Hyun
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p. 3723 - 3735
(2018/04/02)
-
- Guaiacol Hydrogenation in an Aqueous Medium in the Presence of a Palladium Catalyst Supported on a Mesoporous Dendrimer-Containing Polymer
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Guaiacol hydrogenation in an aqueous medium in the presence of a palladium catalyst supported on a mesoporous dendrimer-containing polymer and the effect of addition of sulfuric acid to the catalyst system have been studied. It has been found that the main hydrogenation product is 2-methoxycyclohexanol. After the addition of sulfuric acid to the catalyst system, the reaction mechanism significantly changes and cyclohexanol becomes the main hydrogenation product.
- Karakhanov,Boronoev,Filippova, T. Yu.,Maksimov
-
p. 407 - 411
(2018/05/28)
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- AN ECO-FRIENDLY PROCESS FOR HYDROGENATION OR/AND HYDRODEOXYGENATION OF ORGANIC COMPOUND USING HYDROUS RUTHENIUM OXIDE CATALYST
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The invention discloses aneco-friendly process for hydrogenation (alkenealkene, carbonyl compound and aromatic) and hydrodeoxygenation (methoxy phenols) of organic compound using hydrous ruthenium oxide (HRO) and its supported form as a recyclable heterogeneous catalyst in aqueous medium with good yield of desired compounds (70-100%) under mild reaction conditions. The invention also discloses hydrogenation of organic compound such as alkene, carbonyl compound and substituted aromatic and also for the processes that involve hydrodeoxygenation, for example, lignin derived aromatic (methoxy phenols).
- -
-
Page/Page column 15; 22
(2017/08/01)
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- Enhancement of C–O bond cleavage to afford aromatics in the hydrodeoxygenation of anisole over ruthenium-supporting mesoporous metal oxides
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Mesoporous TiO2, Al2O3, silica (SBA-15), and nonporous conventional TiO2 (P25) were used as supports for Ru catalysts in the hydrodeoxygenation (HDO) of anisole. The catalytic reaction was performed in a batch reactor at 200?°C and 5–30?bar H2 pressure. It was shown that the selectivity of this catalytic system towards benzene strongly depended on the H2 pressure, being higher at low pressure. Moreover, significant differences in the product distribution were observed for these catalysts suggesting the strong influence of the nature of supports on controlling the reaction pathway. The SBA-15-supported Ru catalyst (Ru/SBA-15) catalyzed the reaction primarily by the hydrogenation (HYD) pathway. The mesoporous-Al2O3-supported Ru (Ru/meso-Al2O3) promoted the reaction via the HYD and demethylation pathways simultaneously. Mesoporous-TiO2-supported Ru (Ru/meso-TiO2) and P25-supported Ru (Ru/P25) promoted higher yield of benzene, indicating its high selectivity for the direct deoxygenation (DDO) route. The use of meso-TiO2 facilitated the spillover effect, leading to the formation of numerous Ti3+ defect sites and oxygen vacancies. As a result, Ru/meso-TiO2 with anatase phase exhibited higher selectivity for the DDO pathway compared to nonporous P25 with a mixed rutile and anatase phase. The results indicated that the phase and mesoporous structure of TiO2 plays an important role in promoting its interaction with Ru particles and in selecting the HDO reaction pathway.
- Phan, Tuan Ngoc,Park, Young-Kwon,Lee, In-Gu,Ko, Chang Hyun
-
-
- Enhanced Hydroconversion of Lignin-Derived Oxygen-Containing Compounds Over Bulk Nickel Catalysts Though Nb2O5 Modification
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A series of bimetallic Nb–Ni oxide catalysts with different Nb/Ni molar ratio have been prepared by chemical precipitation method. XRD, Raman and XPS results indicate that amorphous Nb2O5 species exist in the samples with a Nb/Ni ratio about 0.087. The as-synthesized bimetallic Nb–Ni oxides effectively promote the dispersion of NiO active components, as a result effectively inhibit the agglomeration of NiO particles. Ni0.92Nb0.08O sample with the largest surface area of 173?m2/g mainly consists of fold-like nanosheets and the amorphous Nb2O5 species are well-dispersed all over the bulk NiO. After the reduction in hydrogen, the Nb-promoted bulk nickel catalysts display better catalytic performance for hydrodeoxygenation of lignin-derived anisole to biofuels than bulk Ni catalyst. The selectivity to deoxygenated products with using Ni0.92Nb0.08 catalyst increases 2.5 fold to that with bulk Ni catalyst at 160 °C and 3?MPa H2, as a result of the synergistic effect between amorphous Nb2O5 species and metal Ni active sites. In addition, with further increase in the reaction temperature to 200 °C, deoxygenation almost goes quantitatively. Graphical Abstract: High-specific-surface-area Nb–Ni oxides are prepared by using chemical precipitation, and display excellent HDO performance for lignin-derived compounds. Selectivity to deoxygenated products increases 2.5 folds over Ni0.92Nb0.08 than over bulk Ni catalyst. [Figure not available: see fulltext.].
- Jin, Shaohua,Guan, Weixiang,Tsang, Chi-Wing,Yan, Dickson Y. S.,Chan, Cho-Yin,Liang, Changhai
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p. 2215 - 2224
(2017/07/25)
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- An efficient Pt nanoparticle-ionic liquid system for the hydrodeoxygenation of bio-derived phenols under mild conditions
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Platinum nanoparticles (NPs) were synthesized in situ in the ionic liquid (IL) [Emim]NTf2 (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) as well as in mixtures of [Emim]NTf2 with a second IL, Lewis acid or Br?nsted acid, but in the absence of additional stabilizers. The resulting NP/IL systems catalyze the hydrodeoxygenation of a phenol under mild conditions (60 °C, 1.0 MPa H2), achieving full substrate conversion and a high deoxygenation rate (over 95%) to cyclohexane and cyclohexene. The combination of [Emim]NTf2 and [Bmim]PF6 results in the best catalytic performance. Also the transformation of other substituted phenols and dimers such as catechol, guaiacol and diphenyl ether was studied in the Pt NP/[Emim]NTf2-[Bmim]PF6 system and in most cases afforded cyclohexane in good yield.
- Chen, Lu,Fink, Cornel,Fei, Zhaofu,Dyson, Paul J.,Laurenczy, Gabor
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p. 5435 - 5441
(2017/11/24)
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- Highly selective hydrodeoxygenation of anisole, phenol and guaiacol to benzene over nickel phosphide
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Ni2P supported catalysts have extensively been studied for various hydrodeoxygenation (HDO) reactions. However, the main products are cyclohexane or cyclohexanol for lignin-derived compounds HDO over these catalysts. In this study, we investigate the catalytic conversion of anisole, phenol and guaiacol to benzene over Ni2P/SiO2 by probing the reaction conditions. The results show that a lower reaction temperature and higher H2 pressure favour the hydrogenation of these model chemicals to cyclohexane, whereas a higher reaction temperature and lower H2 pressure aid the generation of benzene. The cyclohexane and benzene yields are 89.8% and 96.0% at 1.5 MPa and 573 K and 0.5 MPa and 673 K, respectively. By eliminating the influence of internal and external diffusion, the low intrinsic activation energy of 58.2 kJ mol-1 is obtained, which explains the high catalytic activity. In addition, although guaiacol HDO has a low conversion due to the space steric effect of its substituents, it presents a similar reaction pathway to obtain anisole and phenol, which is dependent on reaction conditions. The long-run evaluation experiment shows that the activity and selectivity of anisole HDO to benzene changes slightly for 36 h.
- Li, Yunhua,Fu, Juan,Chen, Binghui
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p. 15272 - 15277
(2017/03/17)
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- Reductive fractionation of woody biomass into lignin monomers and cellulose by tandem metal triflate and Pd/C catalysis
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A catalytic process for the upgrading of woody biomass into mono-aromatics, hemi-cellulose sugars and a solid cellulose-rich carbohydrate residue is presented. Lignin fragments are extracted from the lignocellulosic matrix by cleavage of ester and ether linkages between lignin and carbohydrates by the catalytic action of homogeneous Lewis acid metal triflates in methanol. The released lignin fragments are converted into lignin monomers by the combined catalytic action of Pd/C and metal triflates in hydrogen. The mechanism of ether bond cleavage is investigated by lignin dimer models (benzyl phenyl ether, guaiacylglycerol-β-guaiacyl ether, 2-phenylethyl phenyl ether and 2-phenoxy-1-phenylethanol). Metal triflates are involved in cleaving not only ester and ether linkages between lignin and the carbohydrates but also β-O-4 ether linkages within the aromatic lignin structure. Metal triflates are more active for β-O-4 ether bond cleavage than Pd/C. On the other hand, Pd/C is required for cleaving α-O-4, 4-O-5 and β-β linkages. Insight into the synergy between Pd/C and metal triflates allowed optimizing the reductive fractionation process. Under optimized conditions, 55 wt% mono-aromatics-mainly alkylmethoxyphenols-can be obtained from the lignin fraction (23.8 wt%) of birch wood in a reaction system comprising birch wood, methanol and small amounts of Pd/C and Al(III)-triflate as catalysts. The promise of scale-up of this process is demonstrated.
- Huang, Xiaoming,Morales Gonzalez, Olivia M.,Zhu, Jiadong,Korányi, Tamás I.,Boot, Michael D.,Hensen, Emiel J. M.
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p. 175 - 187
(2017/01/24)
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- Long-chain NHC-stabilized RuNPs as versatile catalysts for one-pot oxidation/hydrogenation reactions
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The synthesis and catalytic activity of long-chain NHC-stabilized RuNPs are presented. Full characterization of these novel nanostructures including surface state studies show that the ligand influences the number and the location of Ru active sites which impacts the NP catalytic activity, especially in hydrogenation reactions. The high stability and versatility of these nanosystems make them successful catalysts for both oxidation and hydrogenation reactions that can even be performed successively in a one pot-fashion.
- Martínez-Prieto,Ferry,Rakers,Richter,Lecante,Philippot,Chaudret,Glorius
-
supporting information
p. 4768 - 4771
(2016/04/09)
-
- Chemoselective hydrogenation of arenes by PVP supported Rh nanoparticles
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Polyvinylpyrrolidone-stabilized Rh nanoparticles (RhNPs/PVP) of ca. 2.2 nm in size were prepared by the hydrogenation of the organometallic complex [Rh(η3-C3H5)3] in the presence of PVP and evaluated as a catalyst in the hydrogenation of a series of arene substrates as well as levulinic acid and methyl levulinate. The catalyst showed excellent activity and selectivity towards aromatic ring hydrogenation compared to other reported transition metal-based catalysts under mild reaction conditions (room temperature and 1 bar H2). Furthermore, it was shown to be a highly promising catalyst for the hydrogenation of levulinic acid and methyl levulinate in water leading to quantitative formation of the fuel additive γ-valerolactone under moderate reaction conditions compared to previously reported catalytic systems.
- Ibrahim, Mahmoud,Poreddy, Raju,Philippot, Karine,Riisager, Anders,Garcia-Suarez, Eduardo J.
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p. 19368 - 19373
(2016/12/16)
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- Acid-catalysed carboxymethylation, methylation and dehydration of alcohols and phenols with dimethyl carbonate under mild conditions
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Dimethyl carbonate (DMC) chemistry has been extended to include acid-catalysed reactions of different aliphatic alcohols and phenols. For the first time, p-toluenesulfonic acid (PTSA), H2SO4, AlCl3 and FeCl3 have been shown to aid carboxymethylation for primary aliphatic alcohols at catalytic loadings with quantitative conversion and selectivity. For carboxymethylation of secondary alcohols, stoichiometric PTSA and catalytic AlCl3 both gave quantitative conversion and selectivity. Stoichiometric FeCl3 and H2SO4 promoted dehydration of linear aliphatic alcohols. Additionally FeCl3 catalysed methylation of cyclohexanol, whilst AlCl3 resulted in methylation of phenolic compounds. This research expands the range of potential application for DMC in green chemistry.
- Jin, Saimeng,Hunt, Andrew J.,Clark, James H.,McElroy, Con Robert
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supporting information
p. 5839 - 5844
(2016/11/06)
-
- Pd@MIL-101 as an efficient bifunctional catalyst for hydrodeoxygenation of anisole
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A series of highly porous acidic metal-organic framework MIL-101 supported Pd nanoparticles materials with different Pd contents were prepared through a simple sol-gel method. The obtained heterogeneous catalytic material Pd@MIL-101 was comprehensively characterized by powder X-ray diffraction (PXRD), N2 adsorption, FTIR spectroscopy of pyridine adsorption (Py-IR) and transmission electron microscopy (TEM). The intact crystallinity of MIL-101 was found before and after the Pd loading process, and Pd nanoparticles with diameter of 2-3.5 nm were found homogeneously dispersed in MIL-101. The bifunctional Pd@MIL-101 catalyst exhibits good activity in hydrodeoxygenation (HDO) of anisole. It has been shown that the reaction temperature and the Pd content play important roles in the activity toward oxygen-removal. The catalyst after reaction at a high temperature of 240 °C revealed that the Pd nanoparticles tended to migrate to the external surface of the MOF materials and form larger aggregates.
- Ren, Hangxing,Li, Chuang,Yin, Dongdong,Liu, Jinxuan,Liang, Changhai
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p. 85659 - 85665
(2016/10/12)
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- Selective hydrodeoxygenation of lignin-derived phenols to alkyl cyclohexanols over a Ru-solid base bifunctional catalyst
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Cyclohexanol and alkyl cyclohexanol are important chemical intermediates. It is meaningful to prepare cyclohexanols from non-fossil-based biomass. Here we report Ru/ZrO2-La(OH)3, a metal-solid base bifunctional catalyst, to show its excellent performance on the partial hydrodeoxygenation of lignin-derived phenols. Guaiacol could be converted to cyclohexanol with a 91.6% yield in water. Alkyl phenols with one or two methoxy groups were converted into alkyl cyclohexanols with yields over 86.9%. The catalyst had good activity of removing a methoxy group and retaining a hydroxyl group. In this catalyst, Zr and La interacted with each other to form a mixed (hydr)oxide, thus making ZrO2-La(OH)3 a stable support. Ru was highly dispersed on the ZrLa support. The pathway from guaiacol to cyclohexanol was investigated and proposed as two parallel ways, demethoxylation followed by hydrogenation (I), the saturation of the aromatic ring through hydrogenation and then demethoxylation through direct hydrogenolysis (II).
- Xu, Guang-Yue,Guo, Jian-Hua,Qu, Yan-Chao,Zhang, Ying,Fu, Yao,Guo, Qing-Xiang
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p. 5510 - 5517
(2016/10/21)
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- An investigation on the aqueous-phase hydrodeoxygenation of various methoxy-substituted lignin monomers on Pd/C and HZSM-5 catalysts
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Aqueous phase catalytic upgrading of lignin monomers to hydrocarbons via hydrodeoxygenation (HDO) has been explored using a combination of Pd/C and HZSM-5 catalysts under 2 MPa of H2 (ambient temperature). Model monomers with varying numbers of methoxy groups, including phenol, anisole, guaiacol and 2,6-dimethoxy-phenol, were chosen as lignin model compounds. Mechanistic studies revealed cascade and parallel reaction pathways via hydrogenation and dehydration (hydrolysis) processes, which were catalyzed by Pd/C and HZSM-5, respectively. Hydrogenation was preferred at lower temperature, whereas higher temperature was favorable for the removal of oxygen-containing functional groups. The effect of methoxy groups on the HDO of these monomers was also investigated systematically. Basically, the conversion of multi-substituted monomers was tougher than that of mono-substituted ones, due to steric constraint and the inhibition of the electron-donating hydroxyl group. The selectivities to cyclohexane from phenol and anisole were improved significantly by increasing the temperature to 413 K. However, cyclohexanone was preferably produced over cyclohexane when using model compounds with multi-substituents (guaiacol and 2,6-dimethoxy-phenol), even at temperatures above 513 K. Comparative experiments were also conducted on the HDO of 1,2-cyclohexanediol with or without the presence of phenol, which clearly suggested that the further HDO of guaiacol and 2,6-dimethoxy-phenol was inhibited, probably due to the strong interactions between cyclohexanediol molecules and Br?nsted acid sites.
- Zhang, Cong,Qi, Jingbo,Xing, Jing,Tang, Si-Fu,Song, Liang,Sun, Yuanyuan,Zhang, Chuanhui,Xin, Hongchuan,Li, Xuebing
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p. 104398 - 104406
(2016/11/17)
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- Mapping reactivities of aromatic models with a lignin disassembly catalyst. Steps toward controlling product selectivity
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Copper-doped porous metal oxides catalyze the one-pot disassembly of biomass-derived lignin via C-O bond hydrogenolysis and hydrodeoxygenation in supercritical methanol. This catalytic system cleanly converts lignin as well as lignocellulose composites, such as sawdust, to organic liquids with little or no formation of intractable tars or chars. However, this catalyst based on Earth-abundant components also catalyzes less desirable aromatic ring hydrogenations and various methylations that contribute to the diversity of products. In this context, we undertook a quantitative experimental and computational evaluation of model reactions relevant to the reductive disassembly of lignin by this catalyst system in order to determine quantitatively the rates of desirable and less desirable chemical steps that define the overall product selectivities. Global fitting analysis methods were used to map the temporal evolution of key intermediates and products and to elucidate networks that provide guidelines regarding the eventual fates of reactive intermediates in this catalysis system. Phenolic compounds display multiple reaction pathways, but substrates such as benzene, toluene, and alkyl- and alkoxy-substituted aromatics are considerably more stable under these conditions. These results indicate that modifying this catalytic system in a way that controls and channels the reactivity of phenolic intermediates should improve selectivity toward producing valuable aromatic chemicals from biomass-derived lignin. To this end we demonstrate that the O-methylating agent dimethyl carbonate can intercept the phenol intermediate formed from hydrogenolysis of the model compound benzyl phenyl ether. Trapping the phenol as anisole thus gave much higher selectivity towards aromatic products.
- Bernt, Christopher M.,Bottari, Giovanni,Barrett, Jacob A.,Scott, Susannah L.,Barta, Katalin,Ford, Peter C.
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p. 2984 - 2994
(2016/05/24)
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- Rhodium-catalyzed electrochemical hydrodefluorination: A mild approach for the degradation of fluoroaromatic pollutants
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Many fluoroorganic compounds are toxic and persistent, and achieving their efficient degradation under mild conditions is currently a challenge. Herein, we developed a new electrochemical hydrodefluorination (HDF) system based on rhodium electrocatalyst for the degradation of fluoroaromatic (FA) pollutants. The HDF system realized the rapid degradation of 18 representative FAs to form nonfluorinated organics and F- under mild conditions (room temperature and pressure, water medium, air atmosphere, without the use of hazardous reagents). This study may provide a new promising alternative for the practical treatment of waste water containing FA pollutants.
- Xu, Yinghua,Ma, Hongxing,Ge, Tingjie,Chu, Youqun,Ma, Chun-An
-
-
- Ruthenium Nanoparticles Stabilized in Cross-Linked Dendrimer Matrices: Hydrogenation of Phenols in Aqueous Media
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Novel catalysts consisting of ruthenium nanoparticles encapsulated in cross-linked matrices based on the poly(propylene imine) dendrimers of the 1st and 3rd generations have been synthesized with a narrow particle size distribution (3.8 and 1.0 nm, respectively). The resulting materials showed high activity for the hydrogenation of phenols in aqueous media (specific catalytic activity reached turnover frequencies of 2975h-1 with respect to hydrogen uptake). It has been shown that the use of water as a solvent leads to a 1.5 to 50-fold increase in the reaction rate depending upon the nature of the substrate. It has been established that unlike the traditional heterogeneous catalysts based on ruthenium, during the hydrogenation of dihydroxybenzenes, the hydrogenation rate decreases in the order: resorcinol>hydroquinoneacatechol. The maximum specific activity for resorcinol was a turnover frequency of 243150h-1 with respect to hydrogen uptake. The catalyst based on the dendrimer of the 3rd generation containing finer particles has significantly inferior activity to the catalyst based on the dendrimer of the 1st generation by virtue of steric factors, as well as the need for prereduction of the ruthenium oxide contained on the surface. These catalysts showed resistance to metal leaching and may be reused several times without loss of activity.
- Maximov, Anton,Zolotukhina, Anna,Murzin, Vadim,Karakhanov, Edward,Rosenberg, Edward
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p. 1197 - 1210
(2015/04/14)
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- Hydrogenation of arenes, nitroarenes, and alkenes catalyzed by rhodium nanoparticles supported on natural nanozeolite clinoptilolite
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Abstract Nanozeolite clinoptilolite supported rhodium nanoparticles (Rh/NZ-CP) has been prepared and characterized by a variety of techniques, including XRD, BET, TEM, EDX, ICP-OES and XPS analysis. This nanomaterial contains 2 wt% Rh in the range of 5-20 nm metallic nanoparticles distributed on nanozeolite. The catalytic performance of Rh/NZ-CP was evaluated by the hydrogenation of arenes, nitroarenes, and alkenes under moderate reaction conditions. The prepared nanocatalyst can be facilely recovered and reused many times without significant decrease in activity and selectivity. The high catalytic activity, thermal stability and reusability, simple recovery and eco-friendly nature make present catalyst as a unique catalytic system, which is particularly attractive in green chemistry.
- Baghbanian, Seyed Meysam,Farhang, Maryam,Vahdat, Seyed Mohammad,Tajbakhsh, Mahmood
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p. 128 - 136
(2015/07/15)
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- Transition metal nanoparticles stabilized by ammonium salts of hyperbranched polystyrene: effect of metals on catalysis of the biphasic hydrogenation of alkenes and arenes
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Abstract Hyperbranched polystyrene bearing ammonium salts (HPS-NR3+Cl-) behaves as an excellent stabilizer of ruthenium, rhodium, iridium, palladium, and platinum nanoparticles from 1 to 3 nm in size uniformly dispersed in the polymer matrix. The catalytic performance of the resulting metal-polymer composites, M@HPS-NR3+Cl-, is dependent on the metal. This dependence was investigated by assessing the hydrogenation of alkenes and arenes. The utility of M@HPS-NR3+Cl- as reusable catalysts in aqueous/organic biphasic systems was demonstrated by examining the catalysis of the hydrogenation of aromatic compounds containing various functional groups by Ru@HPS-NR3+Cl-.
- Gao, Lei,Kojima, Keisuke,Nagashima, Hideo
-
supporting information
p. 6414 - 6423
(2015/08/18)
-
- New Route to Stabilize Ruthenium Nanoparticles with Non-Isolable Chiral N-Heterocyclic Carbenes
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Ru nanoparticles (RuNPs) stabilized by non-isolable chiral N-heterocyclic carbenes (NHCs), namely SIDPhNp ((4S,5S)-1,3-di(naphthalen-1-yl)-4,5-diphenylimidazolidine) and SIPhOH ((S)-3-((1S,2R)-2-hydroxy-1,2-diphenylethyl)-1-((R)-2-hydroxy-1,2-diphenylethyl)-4,5-dihydro-3H-imidazoline), have been synthesized through a new procedure that does not require isolation of the free carbenes. The obtained RuNPs have been characterized by state-of-the-art techniques and their surface chemistry has been investigated by FTIR and solid-state MAS NMR upon the coordination of CO, which indicated the presence of free and reactive Ru sites. Their catalytic activity has been tested in various hydrogenation reactions involving competition between different sites, whereby interesting differences in selectivity were observed, but no enantioselectivity.
- Martnez-Prieto, Luis Miguel,Ferry, Anglique,Lara, Patricia,Richter, Christian,Philippot, Karine,Glorius, Frank,Chaudret, Bruno
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p. 17495 - 17502
(2016/01/25)
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- Hydrodeoxygenation of anisole as bio-oil model compound over supported Ni and Co catalysts: Effect of metal and support properties
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Hydrodeoxygenation (HDO) is considered one of the most promising routes to convert the pyrolysis bio-oils produced from lignocellulose into biofuels very similar to those derived from petroleum. This work reports results obtained in the catalytic HDO of anisole over non-conventional hydrotreating catalysts based on metallic Ni and Co supported on micro-mesoporous carriers of different acidity. Anisole has been chosen as representative of those compounds, containing a methoxy-phenyl group, which are abundant in lignocellulose pyrolysis bio-oils. The effect of both metal phase and support properties on their performance as HDO catalysts has been studied. With this aim, three supports with different textural and acidic properties have been employed: hierarchical ZSM-5, mesostructured pure silica SBA-15 and mesostructured Al-SBA-15. The reactions have been carried out in a stainless steel high pressure batch reactor at 220 °C and with 50 bar of pure hydrogen. The interaction of the metallic species (Ni or Co) with the porous supports, as well as their dispersion, is strongly affected by the support nature and the presence of Al. Thus, it has been found a synergetic effect between the acid sites of the supports and the metallic active phases, which favors and enhances the HDO of anisole. In the case of the acidic supports, Ni-based catalysts (Ni/Al-SBA-15 and Ni/h-ZSM-5) show larger anisole conversions compared to Co-based materials. The strong interaction with the acidic supports of the latter hinders the total Co reduction prior to the reaction, being probably the major reason of their lower activity. Hydrodeoxygenation, hydrodearomatization and isomerization reactions take place extensively over Ni/h-ZSM-5, revealing it is a promising catalyst for bio-oil processing in order to attain high quality fuel production.
- Sankaranarayanan, Thangaraju M.,Berenguer, Antonio,Ochoa-Hernández, Cristina,Moreno, Inés,Jana, Prabhas,Coronado, Juan M.,Serrano, David P.,Pizarro, Patricia
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p. 163 - 172
(2015/04/22)
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