Recent Results on Fast Flow Gas-Phase Partial Oxidation of Lower Alkanes

Recent experimental results and kinetic modeling of fast flow gas-phase oxidation of methane and other lower alkanes to methanol and other oxygenates are discussed,alongside with prospects and possible areas for applications of the processes.     

REE AND Sr, Nd, Pb ISOTOPIC GEOCHEMISTRY OF HUANGYISHAN BASALT, KUANDIAN, LIAONING, NORTHEAST CHINA

In the light of major element geochemistry, mineral chemistry and REE and isotopic data, the small but apparent isotopic differences between the Cenozoic volcanic rocks east and west of the Tancheng-Lujiang fault are believed to be caused by the mixing and metasomatism of crustal and mantle material in tho mantle source region in response to Pacific plate subduction. The presence of phlogopite and pargasite in mantle xenoliths lends strong support to mantle metasomatism.     

Effects of H/D-isotope substitution and temperature on the volume characteristics of tetra-n-butylammonium bromide dissolved in methanol and its D-isotopomers

Densities of Buⁿ ₄NBr solutions in MeOH, MeOD, and CD₃OH were measured at salt concentrations of up to 1.5 solvomolality units (nearly 2.63·10^–2 mole fraction) at 278.15, 288.15, 298.15, 308.15, and 318.15 K. The limiting partial molar volumes of Buⁿ ₄NBr dissolved in these alcohols were calculated. The isotope effects in the volume characteristics of the stoichiometric mixture of ions, [Buⁿ ₄N⁺ + Br^–], are mainly due to the vibrational changes in the solvent structure upon deuteration of different molecular fragments. Structural transformations in infinitely dilute solution of Buⁿ ₄NBr in methanol are governed by non-specific solvation of the symmetrical Buⁿ ₄N⁺ cation.     

STUDY OF Cu-Mu CATALYST FOR THE SYNTHESIS OF METHYL FORMATE AND METHANOL FROM SYNTHESIS GAS

将一种新型的ＣｕＭｎ催化剂用于由合成气合成甲酸甲酯和甲醇，该催化剂表现出良好的反应活性和甲酸甲酯选择性。考察了反应温度、合成气压力及催化剂制备方法等对合成甲酸甲酯和甲醇的反应活性及选择性的影响。在反应条件下，产物收率最高达６０．１０ｇ／（Ｌ·ｈ），产物甲酸甲酯的选择性很高。用ＢＥＴ、ＸＲＤ及ＸＰＳＡｕｇｅｒ等测试方法对催化剂的比表面、晶相组成以及铜、锰在催化剂中的价态进行了表征，并探讨了催化剂失活的原因。     

Recent Progress in Direct Partial Oxidation of Methane to Methanol

The direct conversion of methane to methanol has attracted a great deal of attention for nearly a century since it was first found possible in 1902, and it is still a challenging task. This review article describes recent advancements in the direct partial oxidation of methane to methanol. The history of direct oxidation of methane and the difficulties encountered in the partial oxidation of methane to methanol are briefly summarized. Recently reported developments in gas-phase homogeneous oxidation, heterogeneous catalytic oxidation and liquid phase homogeneous catalytic oxidation of methane axe reviewed.     

Excess enthalpies of solution of some primary and secondary alcohols in sodium dodecylsulfate micellar solutions

The exces enthalpies of solution of some primary and secondary alcohols in aqueous sodium dodecylsulfate micellar solutions were measured and the results were explained by considering the distribution of alcohols between aqueous and micellar phases. The distribution constant and the enthalpy of transfer (and the standard free energy and entropy of transfer) were obtained. The thermodynamic parameters for the transfer of secondary alcohols from the aqueous to the sodium dodecylsulfate (NaDS) micellar phase differ slightly from those of the corresponding primary alcohols. For both series of alcohols the additivity rule holds for free energies of transfer whereas enthalpies and entropies display convex curves. The present data are compared to those for the transfer of the same solutes from the aqueous to the dodecyldimethylamine oxide (DDAO) and dodecyltrimethylammonium bromide (DTAB) micellar phases. The role of the hydrophilic interactions between the OH group and the micelles' head groups is formulated. The thermodynamics of the branched methyl group were determined. Furthermore, the thermodynamics of solvation of primary alcohols in water, in NaDS micelles, and in octane have been calculated using reference states based on the assumption that the empty space around alcohols in the initial and final states is the same. It is shown that the solvation of alcohols in NaDS micellar phase is enthalpy driven and that the thermodynamic properties of solvation vs. the length of the alcohol tail is the same for water and NaDS micelles whereas it is different for octane. A possible explanation for this difference is that the alkyl chain of alcohols folds in octane.     

Electric field effects on roto-vibrational transitions of13CD3OH1

We used a Stark-Optoacoustic cell and hybrid waveguide resonators to perform an Infrared and Far Infrared Stark Spectroscopy study on some transitions of¹³CD₃OH. Different behaviours of the transitions in the presence of a d.c. electric field were observed. The Stark splittings of six FIR laser lines ranging from 34 to 136 MHz/kVcm^–1 were determined. The analysis of the behaviour of the IR and FIR transitions in the presence of the external electric fields gives important and exclusive information on the levels involved in the transitions.Work Supported by FAPESP, CNPq, FAEP - Brazil, and CNR - Italy.     

Electrooxidation Mechanism of Methanol at Pt-Ru Catalyst Modified GC Electrode in Electrolytes with Different pH Using Electrochemical and SERS Techniques

The electrochemical and in-situ surface-enhanced Raman spectroscopy （SERS） techniques were used to investigate the electrooxidation behavior of methanol in acidic, neutral and alkaline media at a Pt-Ru nanoparticle modified glassy carbon （Pt-Ru/GC） electrode. The results showed that methanol could be dissociated spontaneously at the Pt-Ru/GC electrode to produce a strongly adsorbed intermediate, CO. It was found that CO could be oxidized more easily in the alkaline medium than in the acidic and neutral media. The peak potential of methanol oxidation was shifted from 0.663 and 0.708 V in the acidic and neutral media to -0.030 V in the alkaline medium, which is due to that the adsorption strength of CO on the Pt surface in the alkaline medium is weaker than that in the acidic and neutral media. The final product of the methanol oxidation is CO2. However, in the alkaline medium, CO2 produced would form CO3^2- and HCO3^- resulting in the decrease in the alkaline concentration and then in the decrease in the performance of DMFC. Therefore, the performance of the alkaline DMFC is not Stable.     

改进型甲醇合成催化剂NC208的催化特性

采用ＴＰＤ、ＸＲＤ、ＢＥＴ和Ｈ２Ｓ中毒试验等方法，对比研究三组份（Ｃｕ－Ｚｎ－Ａｌ）甲醇合成催化剂Ｃ２０７和添加少量金属氧化物的改进型催化剂ＮＣ２０８．结果表明，工作态ＮＣ２０８催化剂表面Ｃｕ＋／Ｃｕ０的比值和价态稳定性大于Ｃ２０７．     

Distribution of Helium Isotopes in Western Pacific Upper Layer

3He/4He ratios in samples of sea water obtained at depths from surface to 300 m in the upper layer of the Western Pacific Ocean were measured by a mass spectrometer VG5400. The lateral and vertical distribution of He isotopes in the studied area was discussed in detail on the basis of 3He/4He ratios. Excess and depleted 3He. in relation to δ3He value of surface water in equilibrium with air has been discussed in the area, which may be mainly attributed to the incorporation of the North Pacific Intermediate Water with the Equatorial Upwelling and the exchange of water masses between the South China Sea and the Western Pacific, respectively. The present work in Western Pacific has also indicated that He isotopes may be used as a tracer for mixing processes of water masses and oceanic circulation.