液态烷烃制备研究进展

介绍了目前液态烷烃制备中应用较广的石油分馏提取、费托合成等传统方法,综述了以生物质为原料,经水解、脱水、醇醛缩合、脱水加氢等反应制备液态烷烃的新工艺,以及生物体内天然存在的烷烃代谢路径,并对液态烷烃制备工艺的发展方向进行展望。     

Microporous and mesoporous materials with isolated vanadium species as selective catalysts in the gas phase oxidation reactions

The preparation of V-containing micro- and mesoporous (silicates, aluminosilicates and aluminophosphates) materials as well as the nature of V species incorporated in framework positions is reviewed. In addition, the catalytic performance of V-silicalite, VAPO-5 and V-MCM-41 in the gas phase selective oxidation of hydrocarbons has also been compared.     

烷烃在分子筛孔中吸附和扩散的分子模拟

用巨正则系综蒙特卡罗(grand canonical monte carlo,GCMC)和构型偏倚蒙特卡罗(configurational-bias monte carlo,CB- MC)相结合的模拟方法,研究300 K下,烷烃(甲烷、乙烷、丙烷、丁烷)在ISV、MEL型分子筛上的吸附,饱和吸附量的大小顺序为:甲烷>乙烷>丙烷>丁烷。模拟甲烷-乙烷、乙烷-丙烷混合物在分子筛(ISV、MOR、MEL型)中的吸附分离,结果甲烷-丙烷比乙烷-丙烷混合物更易分离。采用分子动力学(molecular dynamics,MD)模拟方法,研究甲烷在MEL、MOR分子筛上的扩散系数,分别为2.76-3.86 m~2·s~(-1)、3.14-13.30 m~2·s~(-1),烷烃在分子筛中的扩散与吸附相关,且扩散系数的大小与分子筛的结构有关。模拟所得的有关吸附扩散性质的数据对于化工生产、研发和设计具有指导意义。     

Viscosity of binary mixtures. IV. Triethylamine with alkanes and monoalkylamines at 303.15 and 313.15 K

Viscosities and densities of seven binary mixtures of n-hexane, n-octane, isooctane, n-propylamine, n-butylamine, n-hexylamine, and n-octylamine with triethylamine have been measured at 303.15 and 313.15 K. Deviations of viscosities from a linear dependence on the mole fraction and values of excess Gibbs energy of activation G ^*E of viscous flow are attributable to the H-bonding and to the size of the alkylamine and alkane molecules.     

低温低碳烷烃和氮双元液态混合物密度的推算

将一个饱和液体状态方程(TONG方程)应用于已知的双元液体混合物密度的推算,温度为105K～140K,该混合物的组分是低碳烷烃和氮,它们都是液化天然气(LNG)的主要成分。此模型方程利用纯组分数据来预测液化天然气低温下密度而被检验。本方法的优点是使用简便。     

Prediction of Fluid Mixture Transport Properties by Molecular Dynamics

Equilibrium molecular dynamics simulations of mixtures of n-decane with methane, ethane, and carbon dioxide and of the mixture carbon dioxide–ethane were performed using the anisotropic united atoms model for n-decane and one-and two-center Lennard–Jones models for the light components. The Green–Kubo relations were used to calculate the viscosity, thermal conductivity, and inter- and intradiffusion. Viscosities are predicted with a maximum deviation of 30% at low gas concentrations and less than 10% deviation at high gas concentrations. The viscosity and thermal conductivity are less sensitive to the cross interactions than the diffusion coefficients, which exhibit deviations between models and with experiments of up to 60%.     

Temperature dependence of the surface tension for binary mixtures ofn-butanenitrile +n-alkanes

The differential capillary-rise method was used to determine the orthobaric surface tension of binary liquid mixtures ofn-butanenitrile mixed withn-pentane,n-hexane, andn-heptane, throughout the composition range. at 293.15, 303.15, 313.15, 323.15, 333.15. and 343.15 K. Furthermore, the system withn-hexane was also studied al 263.15 K. i.e., 19 K above its upper critical solution temperature, over the whole composition range. For each binary system the surface tension changes regularly with both temperature and composition between the values of the pure components. The results are discussed in terms of deviations from surface ideality and related to the large positive deviations observed for bulk properties of the same systems.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

Volatile Components in Blue Crab (Callinectes sapidus) Meat and Processing By-Product

Volatile components in fresh-picked blue crabmeat and processing byproduct were compared by simultaneous steam distillation-solvent extraction/gas chromatography/mass spectrometry (SDE/GC/MS). Compounds were identified in crabmeat (771 and by-product (80) of which 58 were common to both. Some compounds 154) were identified for the first time in crab. Trimethylamine, four alkanes (C15–C17, C19), and indole were highest (> 50 ng/g)) in crabmeat, while trimethylamine, carbon disulfide, dimethyltrisulfide, two alkanes (C15 and C17), geranylacetone, and 1–dodecanol were highest in by-product. Of compounds from both samples, 23 were higher in by-product and 7 were higher in the meat. Crab processing by-product may be a good source for volatile flavor recovery.     

碳化钨催化剂上烷烃异构化研究进展

综述了用于长链烷烃异构化的碳化钨催化剂的研究进展。介绍了催化剂的制备方法和异构化反应机理。分析了此类催化剂今后的发展趋向和应用前景。     

The melting points of ultralong paraffins and their homologues

Because of the recent availability of the melting points of several ultralong normal paraffins, the melting behavior of normal paraffins has been investigated. Taking the melting point of polyethylene to represent the melting point of an ultralong paraffin, a new function has been established to represent the melting points of alkanes from the carbon number 32 onwards. Adopting the same value for the limiting melting point of an ultralong paraffin, equations are derived for the melting points of several homologous series.Nomenclature a A constant to be determined - b A constant to be determined - m Number of methylene groups in the molecule - n Number of carbon atoms in the molecule - n ^* Number of carbon atom above which Eq. (6) is applicable - T ₀ Temperature constant, K - T _c Critical temperature, K - T _c Critical temperature of an ultralong normal paraffin, K - T _b Normal boiling point, K - T _b Normal boiling point of an ultralong normal paraffin, K - T _m Melting point, K - T _m Melting point of an ultralong paraffin, K - Standard deviation {[(T _m (obsd)–T _m (calc)]²/(No. points–No. parameters)}^0.5