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71.
Kian Hoong Chai Loong Kong Leong David Shan-Hill Wong De-Hao Tsai Sumathi Sethupathi 《中国化学会会志》2020,67(6):998-1008
The present work studied the effect of different carbon dioxide (CO2) adsorbents on Ni-based dual-function materials (DFMs) for the development of carbon capture and on-site utilization in a reactor at isothermal condition. The DFMs containing Ni functioning as a methanation catalyst with various CO2 adsorbents (i.e., CaO, MgO, K2CO3, or Na2CO3) were prepared on γ-Al2O3 through sequential impregnation. The result indicated that Ni-Na2CO3/γ-Al2O3 had the highest methanation capacity (i.e., 0.1783 mmol/g) and efficiency (i.e., 71.09%) in the CO2 adsorption–methanation test. The CO2 uptake and the subsequent methanation capacity of the Ni-Na2CO3/γ-Al2O3 increased to more than 24 times and more than 17 times, respectively, compared to Ni/γ-Al2O3. The high methanation capacity was correlated to its highest amount of weak basic sites, substantial CO2 capture capacity and capture/release efficiency, and reactivity to H2 at a lower temperature, supported by CO2-TPD, TGA analyses for adsorption or adsorption–desorption at the isothermal condition, and H2-TPRea, respectively. A continuous cyclic CO2 adsorption–methanation was performed by using the Ni-Na2CO3/γ-Al2O3 and Ni-CaO/γ-Al2O3, showing that the CO2 adsorption capacity was stabilized from third cycle onward, whereas the methanation capacity was stabilized at all cycles, indicating the high stability of the DFMs for both CO2 adsorption and subsequent methanation. This work demonstrated successful synthesis of the Ni-based, low-cost, and stable DFMs with the ability to produce methane via the direct capture of CO2. 相似文献
72.
Reactions of (N-isocyanimino)triphenylphosphorane with aromatic bis-aldehydes (isophthalaldehyde and terphthalaldehyde) in the presence of aromatic (or heteroaromatic) carboxylic acids proceed smoothly at room temperature and in neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in good yields. The reaction proceeds smoothly and cleanly under mild conditions, and no side reactions were observed.
73.
Hai‐Sen Xu Yi Luo Pei Zhen See Xing Li Zhongxin Chen Yi Zhou Xiaoxu Zhao Kai Leng In‐Hyeok Park Runlai Li Cuibo Liu Fangzheng Chen Shibo Xi Junliang Sun Kian Ping Loh 《Angewandte Chemie (International ed. in English)》2020,59(28):11527-11532
The marriage of dynamic covalent chemistry (DCC) and coordination chemistry is a powerful tool for assembling complex architectures from simple building units. Recently, the synthesis of woven covalent organic frameworks (COFs) with topologically fascinating structures has been achieved using this approach. However, the scope is highly limited and there is a need to discover new pathways that can assemble covalently linked organic threads into crystalline frameworks. Herein, we have identified branching pathways leading to the assembly of three‐dimensional (3D) woven COFs or one‐dimensional (1D) metallo‐COFs (mCOFs), where the mechanism is underpinned by the absence or presence of ligand exchange. 相似文献
74.
75.
Zhao M Wang S Bao Q Wang Y Ang PK Loh KP 《Chemical communications (Cambridge, England)》2011,47(14):4153-4155
Using concentrated nitric acid as the solvent, and water as the non-solvent, one-dimensional (1D) organic nanowires can be synthesized in a simple, one-pot process with high yield. The method has broad validity to a wide range of aromatic molecules for the synthesis of derivatized organic wires. 相似文献
76.
Ex-changing places: a highly enantioselective desymmetrization of 1,2-diols has been developed in which the catalyst utilizes reversible covalent bonding to the substrate to achieve both high selectivity and rate acceleration (see scheme, PMP=pentalmethylpiperidine, TBS=tert-butyldimethylsilyl). Induced intramolecularity is responsible for the enhanced rate, thus allowing the reaction to be performed at room temperature. 相似文献
77.
We have developed a ligand that reversibly binds to aniline substrates, allowing for the control of regioselectivity and enantioselectivity in hydroformylation. In this paper we address how the electronics of the aniline ring affect both the binding of the substrate to the ligand and the enantioselectivity in this reaction. 相似文献
78.
The 1:1 imine intermediate generated by the addition of benzyl amine to cyclobutanone is trapped by (N-isocyanimino)triphenylphosphorane in the presence of an aromatic carboxylic acid leads to the formation of the corresponding
iminophosphorane intermediate. Disubstituted 1,3,4-oxadiazole derivatives are formed via intramolecular aza-Wittig reaction of the iminophosphorane intermediate. The reactions were completed in neutral conditions at room temperature.
The disubstituted 1,3,4-oxadiazole derivatives, were produced in excellent yields. 相似文献
79.
80.
Given , a compact connected Riemannian manifold of dimension , with boundary ?M, we consider an initial boundary value problem for a fractional diffusion equation on , , with time-fractional Caputo derivative of order . We prove uniqueness in the inverse problem of determining the smooth manifold (up to an isometry), and various time-independent smooth coefficients appearing in this equation, from measurements of the solutions on a subset of ?M at fixed time. In the “flat” case where M is a compact subset of , two out the three coefficients ρ (density), a (conductivity) and q (potential) appearing in the equation on are recovered simultaneously. 相似文献