Mesoporous soft solid electrolyte-based quaternary ammonium salt

Journal of Solid State Electrochemistry - A novel mesoporous soft solid electrolyte was successfully prepared from tetrabutylammonium hexafluorophosphate, propylene carbonate, and...     

[1+1] and [2+2] crown ethers derived from N,N-bis(2-hydroxyalkylbenzyl)alkylamine and their inclusion phenomena with metal ions

N,N-bis(2-hydroxyalkylbenzyl)alkylamine (HBA) is a derivative obtained from a single time ring opening of benzoxazines. For HBA with methyl group at ortho and para positions, and at N atom, the reaction between this derivative and ditosylated compound gives [1+1] dibenzo-monoaza-crowns. For HBA without methyl group at ortho position, the compound gives [2+2] macrocyclic ethers. The studies on inclusion phenomena using Pedersen’s and molar ratio techniques clarify the alkali metal ion guest inclusion to be 2:1 for [2+2] and 5:2 for [1+1] macrocycles.     

Ethylene Epoxidation in AC Dielectric Barrier Discharge Over Silver-Based Catalysts with Different Second Metals

Plasma Chemistry and Plasma Processing - This work was to investigate the effects of Ag-based catalysts and the addition of a second metal (Sn or Cu) loaded on an 0.1% wt% Ag catalyst on the...     

Influence of Operating Parameters,Al2O3 and Ni/Al2O3 Catalysts on Plasma-Assisted CO2 Reforming of CH4 in a Parallel Plate Dielectric Barrier Discharge for High H2/CO Ratio Syngas Production

Plasma Chemistry and Plasma Processing - This work aimed to investigate plasma-assisted CO2 reforming of CH4 in a parallel plate dielectric barrier discharge (DBD) system for production of high...     

Ethylene Epoxidation in an AC Dielectric Barrier Discharge Jet System

In this work, ethylene epoxidation was investigated in a dielectric barrier discharge jet (DBDJ) with a separate ethylene/oxygen feed under oxygen lean conditions. The ethylene (C₂H₄) stream was directly injected behind the plasma zone in order to reduce all undesired reactions, including C₂H₄ cracking and further reactions, while the oxygen (O₂) balanced with argon was fed through the plasma zone totally to maximize the formation of active oxygen species. The effects of various operating parameters, such as total feed flow rate, O₂/C₂H₄ feed molar ratio, applied voltage, input frequency, and C₂H₄ feed position on the ethylene epoxidation activity, were investigated to determine the optimum operating conditions for this new DBDJ system. The highest ethylene oxide (EO) selectivity (55.2 %) and yield (27.6 %), as well as the lowest power consumption (3.3 × 10^?21 and 6.0 × 10^?21 Ws/molecule C₂H₄ converted and EO produced, respectively) were obtained at a total feed flow rate of 1,625 cm³/min (corresponding to a residence time of 0.022 s), an O₂/C₂H₄ feed molar ratio of 0.25:1, an applied voltage of 9 kV, an input frequency of 300 Hz, and a C₂H₄ feed position of 3 mm behind the plasma zone. The superior activity of the ethylene epoxidation in the DBDJ system resulted from a small reaction volume as well as a separate ethylene/oxygen feed.     

Synergistic effects of a specific metal template and H-bonds in controlling macrocyclization: a simple, selective, and effective cyclization from N,N-bis(2-hydroxybenzyl)alkylamine derivatives

A macrocyclic compound obtained from a simple, selective, and effective reaction between N,N-bis(2-hydroxybenzyl)alkylamine derivatives and 1,3-bis(tosyloxy)propane is a good example of a cyclization controlled by synergistic effects of a metal template and hydrogen bonds.     

Ethylene Epoxidation in Low-Temperature AC Dielectric Barrier Discharge: Effect of Electrode Geometry

In this work, the epoxidation of ethylene under a cylindrical dielectric barrier discharge (DBD) reactor and a parallel DBD reactor was comparatively studied. The effects of important operating parameters—feed O₂/C₂H₄ molar ratio, applied voltage, input frequency, and residence time—were investigated on the reaction performance in terms of reactant conversions, product selectivities, product yields, and power consumptions per molecule of ethylene converted and per molecule of ethylene oxide produced. The optimum conditions obtained from the operating parameter investigation were used for a comparative performance evaluation of both DBD reactor systems. It was found that under the optimum conditions of each system, the cylindrical DBD system exhibited superior epoxidation performance for ethylene oxide production compared to the parallel DBD system, indicating that the electrode geometry (electrode edge length-to-electrode surface area ratio) plays a significant role in the ethylene epoxidation.     

Selective crown ether based macrocyclization: a model case study from N,N-bis(2-hydroxyalkylbenzyl)alkylamine

A model case of selective crown ether based macrocycles, i.e., [1+1] or [2+2] macrocycles, obtained from a simple reaction of N,N-bis(2-hydroxyalkylbenzyl)alkylamine, HBA, and ditosylated compounds is proposed. For HBA with the methyl group at ortho and para positions, and at N atom, 1, the reaction between this derivative and the ditosylated compound with three, four, five, or eight atom chain length gives only a [1+1] macrocycle. For HBA with the methyl group at ortho and para positions, but a cyclohexyl group at N atom, 2, the reaction gives both [1+1] and [2+2] macrocyclic types when reacting with the ditosylated compound. The present work indicates that the structure of HBA induces selective macrocyclization to provide both [1+1] and [2+2] macrocycles.     

Artificial Molecular Ratchets: Tools Enabling Endergonic Processes

Non-equilibrium chemical systems underpin multiple domains of contemporary interest, including supramolecular chemistry, molecular machines, systems chemistry, prebiotic chemistry, and energy transduction. Experimental chemists are now pioneering the realization of artificial systems that can harvest energy away from equilibrium. In this tutorial Review, we provide an overview of artificial molecular ratchets: the chemical mechanisms enabling energy absorption from the environment. By focusing on the mechanism type—rather than the application domain or energy source—we offer a unifying picture of seemingly disparate phenomena, which we hope will foster progress in this fascinating domain of science.     

Multi-stage preconcentrator/focuser module designed to enable trace level determinations of trichloroethylene in indoor air with a microfabricated gas chromatograph

This article describes the development and characterization of a multi-stage preconcentrator/focuser (PCF) module designed to be integrated with a microfabricated gas chromatograph (μGC) for autonomous, in situ determinations of volatile organic compounds. The PCF module has been optimized specifically for the determination of trichloroethylene (TCE) vapors at low- or sub-parts-per-billion concentrations in the presence of common indoor air co-contaminants in residences at risk of vapor intrusion (VI) from surrounding TCE-contaminated soil. It consists of three adsorbent-packed devices arranged in series: a pre-trap of conventional (tubular metal) design for capturing interferences with vapor pressures <3 torr; a high-volume sampler, also of conventional design, for capturing (and transferring) TCE and other compounds with vapor pressures within the range of ~3 to 95 torr; and a microfocuser (μF) consisting of a micromachined Si chamber with an integrated microheater for focusing and injecting samples into the separation module. The adsorbent masses, sampling and desorption flow rates, and heating profiles required for selective, quantitative capture and transfer/injection of TCE are determined for each of the devices, and the assembled PCF module is used to analyze a test atmosphere containing 200 parts-per-trillion of TCE and 27 relevant co-contaminants with a conventional downstream capillary column and electron-capture detector. An average TCE transfer efficiency of 107% is achieved for a 20 L air sample, with a preconcentration factor of ~800,000.