Multicomponent Domino [4+1+1] Carbocyclization Providing an Efficient and Regioselective Strategy to Fluoren-9-ones

Concise and efficient three‐component domino [4+1+1] carbocyclization to highly substituted fluoren‐9‐one derivatives promoted by K₂CO₃ has been developed under microwave irradiation conditions. The direct bis‐cyanation and aryl amination residing in fluoren‐9‐one framework were achieved in a one‐pot operation. The reaction proceeds at fast rates and can be finished within 30 min, which makes workup convenient to give good to excellent chemical yields.     

Solvent-Free C-Benzoylation and N-Benzoylation Reactions Using Microwave Heating

An ecofriendly and efficient microwave-irradiated solvent-free benzoylation method was developed. The procedure for C-benzoylation used 50 mol% AlCl₃ as a Lewis acid catalyst at 130 °C and was completed in 10 min. The isolated yield was between 71% and 100%. N-benzoylation was conducted in a catalyst-free environment at 130 °C in 10 min. The isolated yield was between 80% and 100%.

Synthesis of Metal‐Free Phthalocyanines in Functionalized Ammonium Ionic Liquids

A convenient, fast, efficient, and ecofriendly synthesis of metal‐free phthalocyanines from various substituted phthalonitriles in different hydroxyalkylammonium ionic liquids in the presence of 1,8‐diazabicyclo‐[5,4,0]‐undec‐7‐ene (DBU) is reported in moderate yields. The effect of concentration of DBU and temperature on the synthesis of phthalocyanine in N‐(2‐hydroxyethyl)‐N,N‐dimethylbutylammonium bromide ionic liquid has been examined, and the ionic liquid has been recovered and reused conveniently.     

Microwave‐Assisted Synthesis and Characterization of CuO Nanocrystals

CuO feather‐like and flower‐like crystals have been synthesized by a fast microwave‐assisted solution approach using Cu(NO₃)₂ and NaOH. The morphology transformation of CuO could be achieved by ionic liquid 1‐n‐butyl‐3‐methyl imidazolium tetrafluoroborate ([BMIM]BF₄). With [BMIM]BF₄, flower‐like CuO were obtained, whereas without [BMIM]BF₄, feather‐like CuO were obtained. The possible formation mechanism of flower‐like CuO was discussed on the basis of experimental results. The products were characterized by XRD, FESEM/EDS, and TEM/SAED. In addition, the adsorption of [BMIM]BF₄ on flower‐like CuO was confirmed by FTIR and TG/DSC, and the band gap energies of the flower‐like CuO was estimated by UV‐vis spectra.     

New formal (3+3) cycloaddition of enaminones for forming tetracyclic indolo[2,3-b]quinolines under microwave irradiation

Concise and efficient base-promoted domino formal (3+3) cycloaddition has been established for the formation of tetracyclic indolo[2,3-b]quinoline derivatives under microwave heating. The present methodology shows attractive properties, such as the maximum efficiency of a process, short reaction periods, and operational simplicity, and it can avoid time-consuming and costly syntheses, tedious work-up and isolation of intermediate. This chemistry provides a facile and promising synthetic strategy to construction of tetracyclic indolo[2,3-b]quinoline skeleton.     

Cathode catalysts degradation mechanism from liquid electrolyte to membrane electrode assembly

Single-cell and half-cell degradation test procedures were evaluated for carbon-supported Pt/C, PtCo/C and PtNi/C catalysts. Half-cell analyses were employed to understand the effect of the number of cycles and of the scan rate over the cathode catalysts degradation under potential cycling from 0.6 to 1.2 V. The data suggested a time-dependent degradation for all three catalytic systems. Single-cell measurements were used to evaluate the impact of catalyst degradation on fuel cell performance. The measurements in both setups showed similar ECSA and ORR mass activity losses. Specific degradation mechanisms related to Pt dissolution, Pt agglomeration, and transitional metal leaching were quantified and correlated with performance losses.     

油页岩固定床热解反应器中内构件强化作用

在内构件(传热板和中心集气管)外热式固定床反应器中研究了油页岩热解产物生成特性,并与无内构件的相同常规固定床反应器内的油页岩热解行为对比,考察了两反应器中油页岩升温特性、热解产物分布、页岩油品质以及气体产物组成的变化规律.结果表明,内置传热板和中心集气管显著强化了反应器内的传热,相对于无内构件常规固定床反应器,料层升温速率提高了约2倍.对于依兰油页岩,其热解页岩油产率明显提高,最高达11.1 wt%(干燥基),明显高于无构件常规固定床反应器获得的页岩油产率.随着外加热炉温度的升高,内构件固定床反应器的页岩油产率逐渐增加,而无内构件常规固定床反应器的页岩油产率则明显降低.当外加热炉温度为1000℃时,前者页岩油产率是后者的2.3倍,并且内构件固定床反应器的热解水产率较低.两反应器中热解气产物组成相近,其H2与CH4之和占气体总量的70 vol%左右,热值为4406~5400 kcal/Nm3.     

Experimental comparison of performance and emission characteristics of 4-stroke CI engine operated with Roselle and Jatropha biodiesel blends

The environmental degradation, combined with the continuous depletion of the world's fossil fuel reserves, has forced the search for alternative fuels. This study was performed to investigate the performance of novel biodiesels in the CI engine. The experiments were performed at three different compressions ratios (16:1, 17:1, 18:1) and four loading conditions (25%, 50%, 75%, 100%). Different types of fuels such as jatropha biodiesel (JB), roselle biodiesel (RB), and ternary biodiesel (TB) were prepared and analyzed. The thermal performance of different fuels was analyzed in terms of brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), and exhaust gas temperature (EGT). The emission characteristics such as CO₂ emission, NO_x emission, and smoke emission were analyzed for all types of fuels. The results of these fuels in the engine were compared with mineral diesel (MD). The BTE was increased with increasing compression ratios and loads for all types of fuels. The BSFC was increased with increasing compression ratios but decreased with increasing loads. The increase in emission of NO_x was observed at higher compression ratios and loads. However, the CO₂ emission was decreased at higher loads and lower compression ratio. The performance curves achieved with a 20% jatropha biodiesel blend showed results that were approximate to those obtained with pure MD. The comparative analysis between different fuels showed that JB exhibit higher thermal performance as compared to other biodiesels. Therefore, JB can be a better alternative to conventional fuel.     

单原子分散的Ir-N-C燃料电池阳极抗中毒催化剂

燃料电池的阳极抗中毒研究是重要课题,探索具有超高质量活性和抗CO毒化的阳极催化剂具有显著的科学意义和应用价值。本文成功制备了Ir原子级别分散在N掺杂碳的载体上的新催化剂,并且发现该Ir-N-C对甲酸具有良好的电催化氧化性能,其质量比活性为商业Pd/C的48倍。组装了燃料电池单电池进行测试,结果显示,Ir-N-C催化剂在单电池中的质量比功率密度高达281 mW/mg,较商业Pd/C催化剂提升了3倍。同时,Ir-N-C对CO毒化的耐受性大大增强,经过14000 s的长期测试后,其活性仅衰减68%,优于商业Pd/C催化剂（衰减85%）。并且,该催化剂能够简单有效的大批量制备,为单原子催化剂的大批量制备提供了新思路。