1-(5-溴-2-羟基苯基)乙酮苯甲酰腙的合成及晶体结构

由1-(5-溴-2-羟基苯基)乙酮和苯甲酰肼通过缩合反应,合成新的芳香酰腙化合物:1-(5-溴-2-羟基苯基)乙酮苯甲酰腙.通过X射线单晶衍射对该化合物进行晶体结构的表征.研究表明,该酰腙为单斜晶系,空间群为P2(1)/n,晶胞学数据a=0.737 61(15)nm,α=90°,b=2.827 0(6)nm,β=116.928(12)°,c=0.860 89(13)nm,γ=90°.V=1.600 5(5)nm3,Z=4,μ=2.570mm-1,Dc=1.383mg/m3,F(000)=672,R1=0.067 6[I2σ(I)],wR2=0.187 7.     

Effect of initial solution apparent pH on nano-sized nickel catalysts in p-nitrophenol hydrogenation

The effect of initial solution apparent pH (pH_a) on nano-sized nickel in the catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated in detail. Experimental results show that the catalytic activity of the nano-sized nickel shows a strong dependence on the initial solution pH_a, and is the highest at the initial solution pH_a 4.8. At lower or higher pH_a values the nano-sized nickel will obviously deactivate, but the deactivation mechanisms are fully different. With respect to the former, the nickel dissolution and the strong adsorption of the complex compound of nickel ion and p-nitrophenol on the surface of nano-sized nickel are the main reasons. The severe agglomeration of nickel particles also causes the deactivation of nickel used at the initial solution pH_a 1.6. For the latter the main reasons are the formation of nickel hydroxide surface species and the decrease of p-nitrophenol adsorption on the hydrogenation sites.     

氧还原催化剂Fe-N/C的制备及催化性能

将乙炔黑、六次甲基四胺和六水三氯化铁混合研磨,经800℃热处理制备出氧阴极还原催化剂Fe-N/C。采用X射线衍射对催化剂结构进行表征,用电化学线性扫描法对其催化活性和稳定性进行了评价。实验考察了热处理温度和热处理时间对催化剂性能的影响。结果表明该催化剂制备的最佳催化条件为:热处理温度800℃下保温2 h。铁单质的存在和热处理温度对Fe-N/C催化剂的催化活性和稳定性影响较大,单质铁有助于催化活性位的形成。     

A comprehensive mathematical model of a serial composite process for biomass and coal Co-gasification

A comprehensive mathematical model to simulate a serial composite process for biomass and coal co-gasification has been built. The process is divided into combustion stage and gasification stage in the same gasifier, it is a new process for the co-gasification of biomass and coal. The model is based on reaction kinetic, hydrodynamics, mass and energy balances, it is a one-dimensional, K-L three-phase, unsteady state model. The model is divided into two sub-models, one is the combustion sub-model, the other is the coal-biomass serial gasification sub-model. Combustion sub-model includes coal pyrolysis, dense phase combustion, and dilute phase combustion model. Gasification sub-model includes biomass pyrolysis, dense phase coal gasification, dense phase biomass gasification, and dilute phase gasification model. The model studies the effects of key parameters on gasification properties, including gasification temperature, S/B, B/C, and predicts the composition of product gas and gas calorific value along the reactor's axis at different time. The model predictions agree well with experimental results and can be used to study and optimize the operation of the process.     

First-principles rational design of M-doped LiBH4(010) surface for hydrogen release: Role of strain and dopants (M=Na,K, Al,F, or Cl)

To overcome the important challenges of facilitating dehydrogenation in the complex metal hydride, LiBH₄, the structural and chemical effects were considered using the strain (−3% − +3%) and five dopants (M = Na, K, Al, F, or Cl). The desorption energies of a hydrogen molecule decreased with increasing tensile strain on the LiBH₄(010) surface. The tensile strain was useful for promoting the dehydrogenation process by weakening the B-H interactions. Among the dopants examined, the most favorable dopant to enhance dehydrogenation was Al. The ranking of dopants for hydrogen release was Al > Cl > F > Na > K. Remarkably, codoping of Al and Cl was more effective for hydrogen release than the single doping of Al or Cl with the lowest hydrogen desorption energy. These methods that destabilize metal hydrides are practical for tuning the hydrogen release of LiBH₄ hydrides. These studies will provide efficient means for designing excellent hydrides for hydrogen release.     

Insights into the visible light photocatalytic activity of S-doped hydrated TiO2

Cationic doping of TiO₂ anatase with sulphur represents a facile method to improve catalytic and photocatalytic activity for hydrogen production and extend the action spectrum of TiO₂ into the visible light region. However, there is a lot of misunderstanding when trying to explain the experimental findings and suggest theoretical models. In the present computational research work, novel theoretical models are put forward representing fully hydroxylated small anatase nanoparticles with S(IV) and S(VI) doping in various surface positions and in the bulk. It was found that sulfur in the doped anatase nanoparticles preserves its typical coordination geometries of trigonal pyramid for S(IV) and tetrahedron for S(VI). Doping in the anatase surface is much more energetically favorable compared to doping in the bulk. Doping with S(IV) causes decrease of the band gap from 3.22 to 2.65 eV while S(VI) doping could decrease E_g only to 2.96 eV. Location of photogenerated electrons and holes depends strongly on the position of dopant atoms and their valent state. Contrary to some experimental works, no strong and extended visible light absorption bands could be found with cationic doped hydroxylated anatase nanoparticles. However, improved charges separation is observed indeed and causes improved photocatalytic hydrogen production.     

On the capabilities and limitations of predictive,multi-zone combustion models for hydrogen-diesel dual fuel operation

Compared with traditional hydrocarbon fuels, hydrogen provides a high-energy content and carbon-free source of energy rendering it an attractive option for internal combustion engines. Co-combusting hydrogen with other fuels offers significant advantages with respect to thermal efficiency and carbon emissions.This study seeks to investigate the potential and limitations of multi-zone combustion models implemented in the GT-Power software package to predict dual fuel operation of a hydrogen-diesel common rail compression ignition engine. Numerical results for in-cylinder pressure and heat release rate were compared with experimental data. A single cylinder dual-fuel model was used with hydrogen being injected upstream of the intake manifold. During the simulations low (20 kW), medium (40 kW) and high (60 kW) load conditions were tested with and without exhaust gas recirculation (EGR) and at a constant engine speed of 1500 rpm. Both single and double diesel injection strategies were examined with hydrogen energy share ratio being varied from 0 to 57% and 0–42 respectively. This corresponds to a range in hydrogen air-equivalence ratios of approximately 0–0.29.The results show that for the single-injection strategy, the model captures in-cylinder pressure and heat release rate with good accuracy across the entire load and hydrogen share ratio range. However, it appears that for high hydrogen content in the charge mixture and equivalence ratios beyond the lean flammability limit, the model struggles to accurately predict hydrogen entrainment leading to underestimated peak cylinder pressures and heat release rates. For double-injection cases the model shows good agreement for hydrogen share ratios up to 26%. However, for higher energy share ratios the issue of erroneous hydrogen entrainment into the spray becomes more accentuated leading to significant under-prediction of heat release rate and in-cylinder pressure.     

A highly active and stable Fischer–Tropsch synthesis cobalt/silica catalyst with bimodal cobalt particle distribution

Silica-supported cobalt (20 wt%) catalysts were prepared by incipient wetness impregnation of silica with different cobalt nitrate solution. The catalyst prepared from dehydrated ethanol solution exhibited highest activity and very low methane selectivity. The catalyst prepared from cyclohexanol had the lowest activity and highest methane selectivity. The catalyst prepared from aqueous solution, a most conventional catalyst, exhibited moderate reaction behavior. The catalyst prepared from dehydrated ethanol had cobalt particles with two different size where the large particles showed low bulk density with cluster-like structure.     

Dynamic mechanical and thermal analysis of vinylester-resin-matrix composites reinforced with untreated and alkali-treated jute fibres

Vinylester-resin-matrix composites reinforced with untreated and 5% NaOH treated jute fibres for 4 and 8 h with different fibre loading were subjected to dynamic mechanical and thermal analysis to determine their dynamic properties as a function of temperature. For all the composites the storage modulus, E′, decreased with increase in temperature, with a significant fall in the temperature range 110°–170 °C. For the treated composites, the rate of fall, dE′/dT, had an inverse relationship with the defect concentrations in the composites. The lowest defect concentrations in the 4 h treated composites corresponded to the highest rate of fall. The glass transition temperature, T_g, of the unreinforced resin, corresponding to the loss modulus peak, was 101.2 °C, whereas that of the composites increased by nearly 28 °C on account of the restricted mobility of the resin molecules in the presence of the fibres. In the case of the treated composites, the T_g value showed a decreasing trend (128 to 125 °C). Unlike the plain resin, a tiny hump was observed in the loss modulus, E″, curves of all the composites around 166 °C, which became broader and more prominent with increase in the jute fibre content. The very high tanδ value of the resin decreased in the composites, indicating that the addition of the fibres lowered the damping capacity of the composites.     

Ablation behavior of inorganic particle-filled polybenzoxazine composite coating irradiated by high-intensity continuous laser

Further utilization of aircraft structural materials is threatened by the fact that high-intensity continuous lasers are widely used in the field of military defense. To protect the aircraft structure from laser damage, ammonium polyphosphate filled polybenzoxazine composite coatings were prepared on the substrate. The anti-laser ablation characteristics of the coatings were investigated. Results showed that the addition of the inorganic filler improved the anti-laser ablation performance of polybenzoxazine. The back-surface temperature of substrates covered with the composite coatings was more 50% lower than that in the case of a pure polybenzoxazine coating after laser ablation. Further, the residue of the composite coating could be vertically divided into three distinct regions, with the dense surface char layer and the porous pyrolysis layer acting as shielding layers for the laser beam and preventing any heat-related transformations from occurring. The addition of the inorganic particles improved the surface reflectivity of the coatings resulting in much more laser energy dissipation. The decreased pyrolysis rate ensured that the pneumatic cooling effect of pyrolysis gas was more lasting and stable, owing to which the composite coatings could act as effective thermal protection layer for longer. These results confirmed that the inorganic filler modified polybenzoxazine coating exhibits excellent anti-laser properties and are suitable for protecting structural materials from laser-related damage.