生物质衍生物催化转化制喷气燃料组分的研究进展

随着我国航空业的不断发展,对喷气燃料的需求也日益增加。在石油危机和环境问题日益严重的背景下,如何可再生地利用生物质资源生产出喷气燃料组分来部分代替传统炼油得到的喷气燃料受到相关科研人员密切关注。从催化的层面入手,本文回顾了利用催化化学方法将生物质衍生物催化制备转化为喷气燃料组分的不同途径,介绍了合成高密度、高辛烷值等高品质喷气燃料组分的新型工艺路线,给出不同糖醇平台的优缺点,如：单官能团化合物平台工艺路线复杂,目的产物选择性低;糠醛和5-羟甲基糠醛平台、乙酰丙酸和γ-戊内酯平台、2-甲基呋喃平台目前工艺较为成熟,已实现工业化。在此基础上,总结分析了目前以糖醇平台催化制备喷气燃料组分的研究状况,指出解决单糖到平台化合物大规模生产问题和研发高效、水热稳定性好的加氢脱氧催化剂可能是未来该领域研究的重点。     

取代型N-烷基化反应专利技术综述

N-烷基化反应是合成精细化工中间体的一种重要工艺,其合成方法很多,所得产品可应用于诸多领域。其中,以卤代烷烃、烷基醇、羧酸酯、磺酸酯作为烷基化试剂的取代N-烷基化反应是非常有用的反应类型,也是近期专利申请的热点课题之一。本文对取代型N-烷基化反应专利技术进行了概述。     

一株中度嗜盐菌Salinicola sp.在高盐环境中的烷烃降解特性

从青海油田附近被石油污染的土壤中分离得到一株可利用原油为唯一碳源的菌株,将其命名为X4菌株。经16SrDNA分析鉴定,该菌株与中度嗜盐菌Salinicola zeshunii strain N4^T（GenBank序列号为EU056581）同源性高达99%。X4菌株的最适温度为30℃,最适盐度为8%,最适pH为6.5,最佳碳源为甘油,最佳氮源为氯化铵。该菌可产生生物乳化剂,具有较强的细胞疏水性,对正辛烷、十六烷、二甲苯等典型烃类物质具有良好的乳化能力,细胞CSH值达到60%以上。在含5%盐度的无机盐培养基中,以3g/L的柴油为唯一碳源,采用GC-MS定量分析X4菌株的烃降解特征,结果表明菌株X4培养5天后柴油的总降解率达56%,菌株X4优先降解中长链烃类;C₇～C₁₃烃类的平均降解率为64.1%,C₁₄～C₂₀烃类的平均降解率为52.3%,C₂₁～C₃₁烃类的平均降解率约26.8%。离子型表面活性剂TTAB和SDS对X4菌株生长具有较强的毒性：在浓度达到100mg/L和400mg/L时能完全抑制菌体生长;在40mg/L的浓度下,使得菌株对柴油的降解率降低到20%。而X4菌株对非离子型表活剂——吐温80和生物表面活性剂——鼠李糖脂的耐受浓度均可达400mg/L。鼠李糖脂是嗜盐菌X4菌株的合适复配表活剂。     

多孔材料烷烃/烯烃分离技术的研究

以模拟油品为原料,在小型固定床（200 mL）反应器上考察了硅胶、γ-Al₂O₃、13X分子筛、Y分子筛及ZSM-5分子筛等多孔材料对烷烃/烯烃的吸附分离性能;其中硅胶的烷烃/烯烃分离效果最好,在吸附温度为40 ℃、压力为0.5 MPa、解吸剂为正辛烷/甲基环己烷的条件下,烷烃/烯烃分离度最高达到0.81;与其他类型硅胶相比,平均孔径为4~6 nm的B型硅胶传质效果更好,吸附-脱附过程更易趋于平衡。经过焙烧和溶剂再生的吸附剂,与新鲜剂相比,分离效果没有明显的降低。     

烷烃结构异构数新的计算方法

设W_n、Q_n和X_n分别表示n-碳烷(C_nH_(2n n2)n-碳炔(C_nH_(2n-2))和n-碳烯(C_nH_(2n))的同分异构体数,作者发现了下列公式: W_n=Q_(n 2) (1-(-1)~n)/2Q_(n 3)/2-X_(n 1)并算出W_(40)=62,481,801,147,341。(Henze和Blair算出W_(40)=62,491,178,805,831)和W_(50)=1,117,743,651,746,953,270     

链烷烃临界常数与分子结构拓扑相关性研究

根据拓扑学原理 ,运用图论方法 ,用计算机对链烷烃的分子结构信息进行分析处理 ,定义了一个表征分子结构信息的内聚力指数F ,并和拓扑指数W、P一道 ,应用于微观结构与物性关系的研究之中 ,与链烷烃的临界常数进行关联拟合 ,给出了相应的定量关系式。利用所得公式能够直接由分子结构信息预测链烷烃的临界常数。     

Photoluminescence of supported vanadia catalysts: linear correlation between the vanadyl emission wavelength and the isoelectric point of the oxide support

Photoluminescence spectra of vanadium oxide supported on SiO₂, TiO₂, Al₂O₃, K‐doped Al₂O₃, ZnO and MgO were recorded. All the vanadium‐containing solids exhibit room‐temperature luminescence in the 550–700 nm region upon excitation from 250 to 400 nm. Significant spectral shifts of the emission maximum wavelength (λ_phos) depending on the acid/basic nature of the support have been observed. In this way, the higher the isoelectric point (or zero point charge, pzc) of the oxide support, the higher is the λ_phos of the supported vanadia catalysts. The linear relationship between these two properties clearly proves that the characteristics of the oxide support has a direct influence on the phosphorescence, and hence on the electronic states, of the vanadyl group. Kinetic analysis of the luminescence decay of supported catalysts has also been determined. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and Properties of 1,1-bis{[3-(<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-Dimethylamino)propyl]amido}alkane-di-<Emphasis Type="Italic">N</Emphasis>-oxides

A homologous series of new surface-active 1,1-bis{[3-(N,N-dimethylamino)propyl]amido}alkane-di-N-oxides were synthesized in the reaction of an appropriate diethyl 2-alkylmalonate with N,N-dimethylamino-1,3-propanediamine followed by oxidation with aqueous hydrogen peroxide. The adsorption isotherms of their aqueous solutions were measured and evaluated to obtain adsorption parameters: critical micelle concentration (CMC), surface excess concentration (Γ_CMC), equilibrium surface tension at the CMC (γ_CMC), cross-sectional area of the adsorbed surfactant molecule (A _CMC), efficiency of surface adsorption (pC₂₀), standard free energies of adsorption (ΔG°_ads), and micellization (ΔG°_CMC). All investigated di-amidoamines and di-N-oxides were practically non-toxic to selected bacteria and yeasts. These compounds are readily biodegradable in the Closed Bottle Test inoculated with activated sludge. Surface and biological properties showed that this group of N-oxide-type compounds has high surface activity and fulfills requirements for environmental acceptance.

Diffusion of linear paraffins in NaCaA studied by the ZLC method

The zero length column (ZLC) technique has been applied to investigate the kinetics of linear alkanes (n-hexane to n-tetradecane) in a sample of zeolite NaCaA. The diffusivity values are found to be monotonically decreasing with chain length from n-hexane to n-undecane, slightly increasing between n-undecane and n-tridecane, and eventually levelling-off at n-tetradecane. The initial monotonic decreasing trend is similar to previous ZLC studies, although the values are somewhat higher for the heavier alkanes. The values found are reasonably close to PFG-NMR results and have similar qualitative trends, but do not show a marked maximum in comparison to recent neutron spin echo (NSE) results. The difference between the infinite dilution ZLC data and the microscopic techniques can not be ascribed to the intrusion of surface resistances since partial loading experiments provide clear evidence that the measurements are controlled by internal diffusion. The activation energy of linear alkanes in NaCaA lies between 20 and 26 kJ/mol.     

The selective oxidative activation of light alkanes. From supported vanadia to multicomponent bulk V-containing catalysts

V-containing materials have been proposed as active and selective catalysts in the selective oxidative transformation of C₂–C₄ alkanes to the corresponding olefins, oxygenates and nitriles. Although vanadium ions are generally assumed as the active sites in the oxidative activation of short chain alkanes, the coordination, the oxidation state and the environment of V atoms strongly influence both the catalytic activity and the nature of the reaction products. A comparative study on the catalytic behaviour of V-containing catalysts, i.e. metal vanadates, supported vanadium oxides, V-containing microporous/mesoporous materials and multicomponent bulk Mo–V–Te(Sb)–Nb mixed metal oxides, on the alkane oxidation is presented. The influence of the structure (including the V-coordination and V-environment) and the physico-chemical properties (especially redox and acid–base characteristics) of the catalysts on their behaviour in the selective oxidation of paraffins and alkenes is discussed.