591-21-9Relevant academic research and scientific papers
One-pot dual catalysis for the hydrogenation of heteroarenes and arenes
Chatterjee, Basujit,Kalsi, Deepti,Kaithal, Akash,Bordet, Alexis,Leitner, Walter,Gunanathan, Chidambaram
, p. 5163 - 5170 (2020/09/07)
A simple dinuclear monohydrido bridged ruthenium complex [{(η6-p-cymene)RuCl}2(μ-H-μ-Cl)] acts as an efficient and selective catalyst for the hydrogenation of various heteroarenes and arenes. The nature of the catalytically active species was investigated using a combination of techniques including in situ reaction monitoring, kinetic studies, quantitative poisoning experiments and electron microscopy, evidencing a dual reactivity. The results suggest that the hydrogenation of heteroarenes proceeds via molecular catalysis. In particular, monitoring the reaction progress by NMR spectroscopy indicates that [{(η6-p-cymene)RuCl}2(μ-H-μ-Cl)] is transformed into monomeric ruthenium intermediates, which upon subsequent activation of dihydrogen and hydride transfer accomplish the hydrogenation of heteroarenes under homogeneous conditions. In contrast, carbocyclic aryl motifs are hydrogenated via a heterogeneous pathway, by in situ generated ruthenium nanoparticles. Remarkably, these hydrogenation reactions can be performed using molecular hydrogen under solvent-free conditions or with 1,4-dioxane, and thus give access to a broad range of saturated heterocycles and carbocycles while generating no waste.
Selective hydrogenation of fluorinated arenes using rhodium nanoparticles on molecularly modified silica
Bordet, Alexis,Emondts, Meike,Kacem, Souha,Leitner, Walter
, p. 8120 - 8126 (2020/12/28)
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.
Effects of steam on toluene hydrogenation over a Ni catalyst
Atsumi, Ryosuke,Kobayashi, Keisuke,Xieli, Cui,Nanba, Tetsuya,Matsumoto, Hideyuki,Matsuda, Keigo,Tsujimura, Taku
, (2019/12/23)
The catalytic toluene hydrogenation over Ni/SiO2 was carried out using H2 or a H2/H2O mixture. The toluene conversion and MCH selectivity were evaluated under partial steam pressures 0?10 kPa, at H2/t
Titanium(III)-Oxo Clusters in a Metal-Organic Framework Support Single-Site Co(II)-Hydride Catalysts for Arene Hydrogenation
Ji, Pengfei,Song, Yang,Drake, Tasha,Veroneau, Samuel S.,Lin, Zekai,Pan, Xiandao,Lin, Wenbin
, p. 433 - 440 (2018/01/17)
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.
Effect of the Crystallographic Phase of Ruthenium Nanosponges on Arene and Substituted-Arene Hydrogenation Activity
Ghosh, Sourav,Jagirdar, Balaji R.
, p. 3086 - 3095 (2018/05/29)
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.
Nanoscale Ziegler catalysts based on bis(acetylacetonate)nickel in the arene hydrogenation reactions
Titova, Yuliya Yu.,Schmidt, Fedor K.
, p. 105 - 114 (2017/09/05)
The turnover frequencies of catalytic systems based on Ni(acac)2–AlEt3 or AlEt2(OEt) in the hydrogenation of benzene and its methyl-substituted homologs (toluene, three isomers of xylene, and 1,3,5-trimethylbenzene) have been determined at temperatures of 80–120 °C, initial PH2 = 15 bar, and different ratios of Al/Ni. The size and nature of the nanoparticles forming in the systems based on Ni(acac)2–AlEt3 or AlEt2(OEt) under the benzene hydrogenation condition shave been resolved by high-resolution electron microscopy and X-ray microanalysis. This study included the performance of competitive hydrogenation reactions of benzene with toluene or three xylene isomers. The relative adsorption constants of toluene and three xylene isomers have been determined and the stereochemistry of the hydrogen addition to the arene ring has also been elucidated.
One-step hydroprocessing of fatty acids into renewable aromatic hydrocarbons over Ni/HZSM-5: Insights into the major reaction pathways
Xing, Shiyou,Lv, Pengmei,Wang, Jiayan,Fu, Junying,Fan, Pei,Yang, Lingmei,Yang, Gaixiu,Yuan, Zhenhong,Chen, Yong
, p. 2961 - 2973 (2017/02/05)
For high caloricity and stability in bio-aviation fuels, a certain content of aromatic hydrocarbons (AHCs, 8-25 wt%) is crucial. Fatty acids, obtained from waste or inedible oils, are a renewable and economic feedstock for AHC production. Considerable amounts of AHCs, up to 64.61 wt%, were produced through the one-step hydroprocessing of fatty acids over Ni/HZSM-5 catalysts. Hydrogenation, hydrocracking, and aromatization constituted the principal AHC formation processes. At a lower temperature, fatty acids were first hydrosaturated and then hydrodeoxygenated at metal sites to form long-chain hydrocarbons. Alternatively, the unsaturated fatty acids could be directly deoxygenated at acid sites without first being saturated. The long-chain hydrocarbons were cracked into gases such as ethane, propane, and C6-C8 olefins over the catalysts' Br?nsted acid sites; these underwent Diels-Alder reactions on the catalysts' Lewis acid sites to form AHCs. C6-C8 olefins were determined as critical intermediates for AHC formation. As the Ni content in the catalyst increased, the Br?nsted-acid site density was reduced due to coverage by the metal nanoparticles. Good performance was achieved with a loading of 10 wt% Ni, where the Ni nanoparticles exhibited a polyhedral morphology which exposed more active sites for aromatization.
Upgrading of aromatic compounds in bio-oil over ultrathin graphene encapsulated Ru nanoparticles
Shi, Juanjuan,Zhao, Mengsi,Wang, Yingyu,Fu, Jie,Lu, Xiuyang,Hou, Zhaoyin
supporting information, p. 5842 - 5848 (2016/05/24)
Fast pyrolysis of biomass for bio-oil production is a direct route to renewable liquid fuels, but raw bio-oil must be upgraded in order to remove easily polymerized compounds (such as phenols and furfurals). Herein, a synthesis strategy for graphene encapsulated Ru nanoparticles (NPs) on carbon sheets (denoted as Ru@G-CS) and their excellent performance for the upgrading of raw bio-oil were reported. Ru@G-CS composites were prepared via the direct pyrolysis of mixed glucose, melamine and RuCl3 at varied temperatures (500-800 °C). Characterization indicated that very fine Ru NPs (2.5 ± 1.0 nm) that were encapsulated within 1-2 layered N-doped graphene were fabricated on N-doped carbon sheets (CS) in Ru@G-CS-700 (pyrolysis at 700 °C). And the Ru@G-CS-700 composite was highly active and stable for hydrogenation of unstable components in bio-oil (31 samples including phenols, furfurals and aromatics) even in aqueous media under mild conditions. This work provides a new protocol to the utilization of biomass, especially for the upgrading of bio-oil.
Aromatic ring hydrogenation catalysed by nanoporous montmorillonite supported Ir(0)-nanoparticle composites under solvent free conditions
Das, Prabin,Sarmah, Podma Pollov,Borah, Bibek Jyoti,Saikia, Lakshi,Dutta, Dipak Kumar
, p. 2850 - 2855 (2016/03/22)
Ir(0)-nanoparticles (Ir-NPs) were synthesized into the nanopores of modified montmorillonite clay by incipient wetness impregnation of IrCl3 followed by reduction with ethylene glycol. The activation of the montmorillonite clay was carried out by treatment with HCl under controlled conditions to increase the surface area by generating nanopores which act as host for the metal nanoparticles. The synthesized Ir-NP-montmorillonite composites were characterized by N2-sorption, powder XRD, SEM, EDS, TEM, XPS, etc. The composites exhibit high surface area of 327 m2 g-1 and the Ir-NPs with size around 4 nm are uniformly distributed on the support. The Ir-NPs show efficient catalytic activity in aromatic ring hydrogenation under solvent free conditions with maximum conversion up to 100% and Turn Over Frequency (TOF) up to 79 h-1. The catalyst can be easily separated by simple filtration and remained active for several runs without significant loss of catalytic efficiency.
Hydrogenation of lignin-derived phenolic compounds over step by step precipitated Ni/SiO2
Shu, Riyang,Zhang, Qi,Xu, Ying,Long, Jinxing,Ma, Longlong,Wang, Tiejun,Chen, Pengru,Wu, Qingyun
, p. 5214 - 5222 (2016/02/05)
The harsh reaction conditions for the valorization of lignin-derived phenolic compounds considerably limit the efficient utilization of the lignin derivatives. Here, we put forward a high efficient and selective hydrogenation process for phenolic compounds at a mild condition over step by step precipitated Ni/SiO2 catalyst. The properties of the Ni/SiO2 catalysts by different preparation methods were detailedly compared using various characterization measurements. Catalytic activity of the catalysts was tested by the hydrogenation of guaiacol, and the results showed that guaiacol could be completely converted into cyclohexanol with 99.9% selectivity at 120 °C, 2 MPa H2 atmosphere for 2 h. Other typical lignin-derived phenolic compounds also had excellent hydrogenation performance and great energy efficiency. Catalyst characterization results demonstrated that the high catalytic activity of the step by step precipitated Ni/SiO2 was mainly ascribed to its polyporous spherical structure, which led to the large specific surface area and high nickel dispersion. The appropriate acidity of the catalyst also promoted the catalytic performance significantly. Furthermore, the catalyst exhibited an excellent recyclability, where no significant loss of the catalytic activity was showed out after 3 runs.
