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81.
82.
Shraddha G. Mahamulkar Ivana Císaov Ullrich Jahn 《Advanced Synthesis \u0026amp; Catalysis》2015,357(4):793-799
Alkyldiphenylphosphine oxides typically undergo α‐deprotonation with alkyllithium reagents. Here, the lithiation of differentially branched alkyldiphenylphosphine oxides was investigated and a diverse, but predictable reactivity was found. γ‐Branched derivatives undergo selective directed ortho‐metalation (DoM) using butyllithium and TMEDA as an additive. With decreasing degree of γ‐branching α‐lithiation becomes predominant. The ortho‐phosphinoyllithium intermediates are subject to functionalization and C C bond forming reactions, thus providing a convenient approach to new phosphine oxides and phosphine‐borane complexes, which have a good potential for an approach to new ligands for catalysis.
83.
Kasper T. Møller Mathias Jørgensen Jacob G. Andreasen Jørgen Skibsted Zbigniew Łodziana Yaroslav Filinchuk Torben R. Jensen 《International Journal of Hydrogen Energy》2018,43(1):311-321
A new potassium tetraamidoboranealuminate, K[Al(NH2BH3)4], has been synthesized by a mechanochemical reaction between KAlH4 and NH3BH3. The compound, K[Al(NH2BH3)4], crystallizes in a triclinic unit cell with space group symmetry P?1. The crystal structure consists of [K(NH2BH3)6]5? octahedra which facilitate the bridging between K+ in 1D chains, while also bridging K+ to Al3+ to connect the 1D chains in a 3D network. Thermal analysis reveals that K[Al(NH2BH3)4] decomposes in two exothermic steps at T ~ 94 and 138 °C and releases primarily hydrogen. The total gas release amounts to ~6.0 wt% H2. The decomposition products are investigated ex situ by powder X-ray diffraction, infrared spectroscopy, and 11B and 27Al NMR and identified as KBH4 and amorphous phases, possibly BN3, N2BH, and/or NBH2 whereas aluminum is found in four-, five-, and six-fold coordination. Unfortunately, the decomposed sample shows no hydrogen absorption at T = 260 °C and p(H2) = 110 bar. 相似文献
84.
We characterize the electrochemical stability of the organic semiconductor Dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) in aqueous solutions. Electrochemical stability of DNTT in solution is validated by cyclic voltammetry and demonstrated by solution gating of DNTT organic field effect transistors (OFETs). Then, we investigate the response time of DNTT OFETs to ammonia, a common blood gas. For bare OFETs, the response time to ammonia is 1–2s only. The exact response time depends on the DNTT film morphology; the fastest response is obtained for pronounced 3D (Volmer-Weber) growth. By comparing OFETs with and without a semipermeable parylene-C encapsulation layer, the influence of the capping on the response time is investigated. An encapsulation layer of 86 nm prolongs the response time to 100s, indicating that parylene-C acts as an efficient diffusion barrier for ammonia. 相似文献
85.
Several techniques are available for dealing with the waste sludge produced in biological waste water treatment. A biological approach uses aquatic worms to consume and partially digest the waste sludge. In our concept for a worm reactor, the worms (Lumbriculus variegatus) are immobilised in a carrier material. For correct sizing and operation of such a worm reactor, the effect of changes in dissolved oxygen (DO) concentration, ammonia concentration, temperature and light exposure were studied in sequencing batch experiments. DO concentration had an effect on both sludge consumption rate and sludge reduction efficiency. Sludge consumption rate was four times higher at DO concentrations above 8.1 mg/L, when compared to DO concentrations below 2.5 mg/L. Sludge reduction was 36 and 77% at these respective DO concentrations. The effect is most likely the result of a difference in gut residence time. An increase in unionised ammonia concentration drastically decreased the consumption rate. Ammonia is released by the worms at a rate of 0.02 mg N/mg TSS digested; therefore, replacing the effluent in the worm reactor is required to maintain a low ammonia concentration. The highest sludge consumption rates were measured at a temperature around 15 °C, whilst the highest TSS reduction was achieved at 10 °C. Not exposing the worms to light did not affect consumption or digestion rates. High temperatures (above 25 °C) as well as low DO concentrations (below 1 mg/L) in the worm reactor should be avoided as these lead to significant decreases in the number of worms. The main challenges for applying the worm reactor at a larger scale are the supply of oxygen to the worms and maintaining a low ammonia concentration in the worm reactor. Applying a worm reactor at a waste water treatment plant was estimated to increase the oxygen consumption and the ammonia load by 15-20% and 5% respectively. 相似文献
86.
AbstractThe present study examined the evolution of microstructure and mechanical properties of Alloy 625 ammonia cracker tubes of heavy water production plant which had been exposed to temperatures around 600°C for 100?000 h. Detailed investigations revealed considerable modification of microstructure, significant increase of strength and loss of ductility and toughness during service and the extent of degradations were found to be sensitive to service temperature at different locations of the tube. While the increase in strength was due to precipitation of γ′′ and Ni2(Cr,Mo), the loss in ductility resulted from the presence of carbides and needle shaped δ particles at grain boundaries. When the exposed material was tested at elevated temperatures, the material softened with an attendant increase in ductility and toughness. A solution annealing treatment at 1160°C for 2 h was found to restore the microstructural as well as mechanical properties similar to that of virgin material. 相似文献
87.
Water-soluble poly(4-styrenesulfonic acid-co-maleic acid), PSSA-co-MA, stabilized ruthenium(0) and palladium(0) nanoclusters were for the first time prepared in situ from the reduction of ruthenium(III) chloride and potassium tetrachloropalladate(II), respectively, by ammonia–borane during its hydrolysis at room temperature. PSSA-co-MA stabilized ruthenium(0) and palladium(0) nanoclusters having average particle size of 1.9 ± 0.5 and 3.5 ± 1.6 nm, respectively, were isolated from the reaction solution and characterized by TEM and UV–visible electronic absorption spectroscopy. PSSA-co-MA stabilized ruthenium(0) and palladium(0) nanoclusters are highly active catalysts for hydrogen generation from the hydrolysis of ammonia–borane at low temperature. PSSA-co-MA stabilized ruthenium(0) and palladium(0) nanoclusters provide 51,720 and 8720 turnovers, respectively, in the hydrogen generation from the hydrolysis of ammonia–borane at 25 °C before deactivation. Catalytic hydrolysis of ammonia–borane is first order with respect to the catalyst concentration, but zero order with respect to the substrate concentration in the case of both ruthenium(0) and palladium(0) nanoclusters. Activation energies for the hydrolysis of ammonia–borane in the presence of PSSA-co-MA stabilized ruthenium(0) or palladium(0) nanoclusters (54 ± 2 kJ mol−1 and 44 ± 2 kJ mol−1, respectively) are smaller than most of the values reported for the same reaction in the presence of other catalyst systems. 相似文献
88.
89.
在热天平上研究了A301型铁基氨合成催化剂的还原动力学,考察了还原条件对A301型催化剂还原速率的影响,分析了氢对还原速率的反应级数在还原进行中发生的变化,以及A301型和A110-2型二种催化剂还原过程中反应级数变化规律不同的内在原因。实验结果表明:A301型催化剂具有极易还原的性能,还原速率对温度及氢浓度的变化的敏感性比A110-2型催化剂弱,其还原反应动力学方程上。文中(4)式。 相似文献
90.
舒季钊 《浙江工业大学学报》1989,(3)
用积分反应器研究了A110—2氨合成催化剂的还原速率。还原用气体系由氨分解制成的氢氮混和气。实验条件为常压~6.86MPa,温度360~500℃,空速0.098~6.86MPah~(-1)和催化剂粒径1.0~3.0mm等。实验结果表明:还原过程属动力学控制,温度是决定还原速率的主要因素,还原反应的活化能约为85kJ/mol;氢氮气中水汽含量增高会降低还原速率,但是只在还原度高时才明显;压力高可使还原速率加快。 相似文献