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Ethylenediamine (EDA) is a crucial chemical raw material and fine chemical intermediate. Compared with the industrial approach of ammonolysis of 1,2-dichloroethane, the catalytic amination of ethylene glycol (EG) is an economical and environmentally benign route that will be the future trend for EDA synthesis. Herein, we systemically review the recent progress in direct and indirect catalytic conversion of EG to EDA. Furthermore, different types of catalysts are discussed: (i) supported metal and multimetallic catalysts, (ii) solid acid catalysts, and (iii) other active catalysts (e.g., ionic liquids and metal complexes). Finally, we conclude with the frontiers and future prospects of the catalytic synthesis of EDA from EG and monoethanolamine, providing readers a snapshot of this field.
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Exploring the ring-opening polymerization (ROP) mechanism of benzoxazines is a fundamental issue in benzoxazine chemistry. Though some research papers on the topic have been reported, the ROP mechanism of mono-benzoxazines is still elusive. The key point for mechanistic studies is to determine and characterize the structure and formation pathways of the products generated in ROP. In this paper, the ROP of a vanillin-furfurylamine-based benzoxazine and a mono-azomethine derivative is studied with differential scanning calorimetry, fourier transform infrared spectroscopy, nuclear magnetic resonance, and electrospray ionization mass spectrometry, respectively. The results show that the products consist of a range of cationic species, zwitterions, fragments, and series of cyclic and linear oligomers of varying molecular sizes. It is proposed that both mono-benzoxazines undergo thermally activated cationic ring-opening oligomerization via zwitterion intermediates. Upon thermal induction, multi-bond-cleavage takes place to form various zwitterionic intermediates, which react with a monomer, a fragment, or a second zwitterion by several pathways to generate cyclic and linear oligomers.
Asunto(s)
Benzoxazinas , Furanos , Benzoxazinas/química , PolimerizacionRESUMEN
In this work, a multifunctional oxygen deficient titanium oxynitride skeleton featuring a Co-metal-decorated three-dimensional ordered macroporous (3DOM) structure embedded with N-doped carbon nanotubes (Co@TiOxNy/N-CNTs) is fabricated as a sulfur host for lithium-sulfur (Li-S) batteries. The unique 3DOM framework provides abundant space for sulfur accommodation and effective pathways for electrolyte infiltration. The robust titanium oxynitride skeleton also ensures good structural integrity during the repeated charge/discharge cycling. Meanwhile, the introduction of oxygen defects not only improves the intrinsic conductivity of the TiO2 skeleton but also enhances its capability for lithium polysulfide (LiPS) trapping. The N-CNTs embedded in the macroporous framework form an ultra-high conductive network and also provide rich micropores for sulfur distribution and physical confinement. The highly dispersed Co nanoparticles uniformly anchored on TiOxNy and N-CNTs act as electrocatalysts promoting the conversion of LiPSs. Attributed to these features, the Co@TiOxNy/N-CNTs/S electrode presents good rate capability and excellent cycling performance. Even under a sulfur loading of 6.34 mg cm-2 and a low electrolyte to sulfur ratio (E/S = 8 µL mg-1), a high area capacity of 5.05 mA h cm-2 can be achieved after 50 cycles. The flexible pouch cell also delivers an impressive discharge capacity of 972 mA h g-1 after 100 cycles under a sulfur loading of 4 mg cm-2. This work offers a rational strategy for the design of advanced sulfur cathodes for Li-S batteries.
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In the direct synthesis of 2-propylheptanol (2-PH) from n-valeraldehyde, a second-metal oxide component Co3O4 was introduced into NiO/Nb2O5-TiO2 catalyst to assist in the reduction of NiO. In order to optimize the catalytic performance of NiO-Co3O4/Nb2O5-TiO2 catalyst, the effects of the Ni/Co mass ratio and NiO-Co3O4 loading were investigated. A series of NiO-Co3O4/Nb2O5-TiO2 catalysts with different Ni/Co mass ratios were prepared by the co-precipitation method and their catalytic performances were evaluated. The result showed that NiO-Co3O4/Nb2O5-TiO2 with a Ni/Co mass ratio of 8/3 demonstrated the best catalytic performance because the number of d-band holes in this catalyst was nearly equal to the number of electrons transferred in hydrogenation reaction. Subsequently, the NiO-Co3O4/Nb2O5-TiO2 catalysts with different Ni/Co mass ratios were characterized by XRD and XPS and the results indicated that both an interaction of Ni with Co and formation of a Ni-Co alloy were the main reasons for the reduction of NiO-Co3O4/Nb2O5-TiO2 catalyst in the reaction process. A higher NiO-Co3O4 loading could increase the catalytic activity but too high a loading resulted in incomplete reduction of NiO-Co3O4 in the reaction process. Thus the NiO-Co3O4/Nb2O5-TiO2 catalyst with a Ni/Co mass ratio of 8/3 and a NiO-Co3O4 loading of 14 wt% showed the best catalytic performance; a 2-PH selectivity of 80.4% was achieved with complete conversion of n-valeraldehyde. Furthermore, the NiO-Co3O4/Nb2O5-TiO2 catalyst showed good stability. This was ascribed to the interaction of Ni with Co, the formation of the Ni-Co alloy and further reservation of both in the process of reuse.
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A novel silica-immobilized nickel and acid ionic liquid (Ni-IL/SiO2) catalyst was prepared by combining a bonding procedure with an impregnation operation and was characterized by means of X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) techniques. Its catalytic performance was evaluated for the one-pot synthesis of 2-propylheptanol (2-PH) via a sequential n-valeraldehyde self-condensation and hydrogenation reaction. As a result, Ni-IL/SiO2 showed an excellent catalytic activity for the one-pot synthesis of 2-PH, affording a 2-PH selectivity of 75.4% at a n-valeraldehyde conversion of 100% and the sum of 2-PH and pentanol selectivity reached 98.6% under the suitable reaction conditions.
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A ZrO2@C support based on t-ZrO2 embedded in amorphous carbon was obtained via the pyrolysis of a UiO-66 precursor. Highly dispersed Pd nanoparticles (NPs) were subsequently deposited onto this support, using NaOH-assisted reduction, to obtain a formic acid (FA) decomposition catalyst. This material showed a turnover frequency (TOF) for the heterogeneously-catalyzed decomposition of FA of 8588 h-1 at 60 °C, with 100% H2 selectivity. This performance is ascribed to the uniform dispersion of smaller palladium nanoparticles and a synergistic effect between the metal NPs and support. Even at 30 °C, the complete decomposition of FA was achievable in FA/SF (SF, sodium formate) solution, with a TOF as high as 1857 h-1.
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Bis(4-butoxycarbonylaminocyclohexyl) methane (H12 MDU) was prepared using dicyclohexylmethane-4,4'-diisocyanate and 1-butanol as raw materials and two solid products A and B were obtained. The structures of the two solid products were characterized separately by melting point measurement, infrared spectroscopy, elemental analysis, NMR spectrum analysis and mass spectrum analysis. The results show that both A and B are the target products H12 MDU. The solid A is trans-trans-H12 MDU while the solid B is a mixture including trans-trans-Hiz MDU and at least one of cis-trans-H12MDU and cis-cis-H12 MDU.