利用Monte Carlo (MC) 方法,研究了一氧化碳和氢气在不同密度正己烷中的等温吸附情况.模型考虑了正己烷密度对一氧化碳和氢气在催化剂表面吸附量与吸附速率的影响.结果表明,主要有三个因素会影响溶质的吸附量:当溶剂密度低于其临界密度时,体系压力是影响溶质吸附量的主要因素；当体系处于超临界区时,超临界溶剂的溶解能力以及溶质和溶剂之间的竞争吸附是影响溶质吸附量的主要因素.在一定范围内增加溶剂的密度（压力）可以提高溶质在催化剂表面的吸附速率. 相似文献
The stability and curvature of emulsions of H2O and CO2 are reported and analyzed in terms of measurements of interfacial tension versus formulation variables, including salinity, CO2 density, temperature and pH. Among the surfactants studied are, quaternary ammonium cationic ones with perfluoropolyether tails, block copolymer ionomers and a poly (hydroxyethyl methacrylate) with polydimethylsiloxane tails, and a nonionic ethylene oxide surfactant with a fluoroalkane tail. The interfacial tension measurements were made at surfactant concentrations from 0.05 to 1.0 wt% with a variable-volume pendant drop tensiometer up to 345 bar and 363°K. As a formulation variable was varied, the system reached a balanced state characterized by a minimum in interfacial tension, a loss in emulsion stability and in some cases an inversion from a W/C to C/W emulsion. Here the Marangoni-Gibbs stabilization weakens, and also it becomes easy to bend and rupture the surfactant monolayer, causing coalescence. Except in the case of the nonionic fluorinated surfactant C8F17—SO2NEt-(CH2CH2O)12–14CH3, the crossover from the CO2-continuous (W/C) to the H2O-continuous (C/W) emulsion occurred abruptly due to clouding of the surfactant out of the CO2 phase. For PFPE-TMAA, the plot of γ versus surfactant concentration revealed both pre-micellar aggregates and a critical micro emulsion, each of which was dependent on salinity. 相似文献
The contribution of N.T. Kudryavtsev (and later his son V.N. Kudryavtsev) to the development of electrodeposition science and technology, and especially to that of chromium, is inestimable. It is a privilege on this occasion to present some considerations of the two-phase nature of chromium electroplating solutions, caused by the generation of hydrogen gas and the use of vigorous air agitation, and to discuss its influence on fluid conductivity and consequent power consumption during electrodeposition. 相似文献
Swamps and tidal flats are believed to he important natural sources of atmospheric H2S, though it is very difficult to detect the low concentrations of this trace gas above the surface of these regions. In view of this problem an air sampling device has been developed for the sampling of atmospheric H2S with chemically impregnated filters. The sulfide generated on the filter is analyzed in a washing solution employing a very sensitive fluorescence method. The quality of the method is demonstrated by comparative calibrations. The fluorescence method is calibrated in the liquid phase with standard solutions of sulfide. Furthermore the sampling and analyzing method is calibrated together by using H2S calibration gases. The detection limit of the method is shown to he 10ng/m3 STP. Data of test-measurements in ambient air and some results of field-measurements in the lower troposphere are presented. 相似文献
The effects of collision energy (Ecol) and five different modes of H2CO+ vibration on the title reaction have been studied over the center-of-mass Ecol range from 0.1 to 3.2 eV, including measurements of product ion recoil velocity distributions. Electronic structure and Rice-Ramsperger-Kassel-Marcus calculations were used to examine properties of various complexes and transition states that might be important along the reaction coordinate. Two product channels are observed, corresponding to Hydrogen Transfer (HT) and Proton Transfer (PT). Both channels are endothermic with similar onset energies of approximately 0.9 eV; however, HT dominates over the entire Ecol range and accounts for 70-85% of the total reaction cross section. Both HT and PT occur by direct mechanisms over the entire Ecol range, and have similar dependence on reactant vibrational and collision energy. Despite these similarities, and the fact that the two channels are nearly isoenergetic and differ only in which product moiety carries the charge, their dynamics appear quite different. PT occurs primarily in large impact parameter stripping collisions, where most of the available energy is partitioned to product recoil. HT, in contrast, results in internally hot products with little recoil energy and a more forward-backward symmetric product velocity distribution. Vibration is found to affect the reaction differently in different collision energy regimes. The appearance thresholds are found to depend only on total energy, i.e., all modes of vibration are equivalent to Ecol. With increasing Ecol, vibrational energy becomes increasingly effective, relative to Ecol, at driving reaction. For HT, this transition occurs just above threshold, while for PT it begins at roughly twice the threshold energy. 相似文献
Conductivity of cadmium acetate over the concentration range of 10?4 to 10?3M was measured at 25°C. The approximate dissociation constant of CdAc2 in dilute aqueous solution was estimated from the relation, α=[Λ?36.5+39√C(1+2α)]/[57.9?93√C(1+2α)]. The limiting value of log10K for the association constant of CdAc+ ion was evaluated to be 1.75 at 25°C. 相似文献
On the surface : Adsorption of O2 at the surface oxygen vacancy (SOV) sites of TiO2 reconstructs the lattice oxygen (healing SOVs), resulting in a decrease of the photocatalytic activity of oxidizing CO over vacuum‐pretreated TiO2 with increasing temperature (see scheme). Adsorption of H2 produces new SOVs at the TiO2 surface and stabilizes the photocatalytic activity.
