苯乙烯-甲基丙烯酸羟基乙酯共聚物微球固载金属卟啉催化剂的制备及其催化性能

 将酰氯化的羧基金属卟啉 (MP) 与表面含羟基的苯乙烯-甲基丙烯酸羟基乙酯共聚物微球 (P(St-co-HEMA)) 进行酯化反应, 制备了共聚物微球固载的金属卟啉催化剂 (P(St-co-HEMA)MP). 采用扫描电镜、紫外-可见光谱、红外光谱和热重等手段对微球进行了表征, 并考察了它在“金属卟啉?抗坏血酸?分子氧”体系中催化环己烷羟化反应性能. 结果表明, 共聚物微球固载的金属卟啉比非固载的金属卟啉具有更高的催化活性, 催化剂重复使用 4 次, 仍保持较高催化活性. 各共聚物微球固载的金属卟啉催化活性顺序为 P(St-co-HEMA)FeP > P(St-co-HEMA)MnP > P(St-co-HEMA)CoP.     

Improper hydrogen-bonded cyclohexane C-Hax?Yax contacts: experimental evidence from H NMR spectroscopy of suitable axial cyclohexane models

B3LYP/6-31+G(d,p) calculations predicted the presence of improper hydrogen-bonded C-H_ax?Y_ax contacts of different strength in cyclohexane derivatives;¹ it was predicted that the addition of an appropriate bridging fragment X_ax between an axial substituent Y₁ and a cyclohexane carbon would strengthen the improper hydrogen-bonded contact C-H_ax?Y₁ when the X_ax-Y₁ bond vector bisects the cyclohexane ring. To support the theoretical predictions with experimental evidence for this effect, several 2-substituted adamantane analogues with suitable improper H-bonded C-H_ax?O contacts of different strength were synthesized, as models of the corresponding cyclohexane derivatives, and their ¹H NMR spectra were recorded at 298 K. The ¹H NMR signal separation within the cyclohexane ring γ-CH₂s is increased when the B3LYP/6-31+G(d,p)-calculated strength of the H-bonded C-H_ax?O=C_ax contact interaction is increased.     

纳米碳材料负载铂催化剂在环己烷脱氢反应中的催化性能研究

制备了纳米碳材料负载铂的催化剂,通过N₂吸附、TEM、XRD技术分别对载体的BET比表面积和催化剂结构、形貌和粒径大小进行了表征。考察了不同催化剂在环己烷脱氢反应中的催化性能以及温度对纳米碳颗粒负载铂催化剂活性的影响。结果表明,锚定在不同碳载体上的铂有较好的分散性,粒径较小,粒度分布范围较窄并且具有相同的晶型结构。孔状纳米碳颗粒负载铂催化剂的活性高于碳纳米管和高比表面的活性炭负载铂催化剂,并且在低温条件下已经显示了较高的活性,尤其是中空碳颗粒负载铂催化剂在环己烷脱氢反应中显示了好的活性和稳定性。     

利用Wittig反应制备乙烷类液晶

以4-（反式4’-正烷基环己基）环己酮和氯甲醚三苯基磷盐为起始原料,经Wittig反应、水解、转型、Wittig反应和氢化反应合成了1-（3,4-二-氟苯基）-2-[反式4’-（反式4＂-正烷基环己基）环己基]乙烷类液晶,其结构经^1H NMR,^13C NMR及MS确证。纯化总收率约30％。     

Molar excess heat capacities and volumes for mixtures of alkanoates with cyclohexane at 25°C

Molar excess volumes V ^E at 25°C have been determined by vibrating-tube densimetry, as a function of mole fraction x for different series of an alkanoate (H _2m+1 C _m COOC _n H _2n+1 )+cyclohexane. Three types of alkanoates were investigated, i.e., methanoates (m=0, with n=3 and 4), ethanoates (m=1, with n=2, 3, and 4) and propanoates (m=2, with n=1, 2, and 3). In addition, a Picker flow calorimeter was used to obtain molar excess heat capacities C _p ^E at constant pressure at the same temperature. V ^E is positive for all systems and rather symmetric, with V ^E (x=0.5) amounting to almost identical values in a series of mixtures containing an alkanoate isomer of same formula (say C₄H₈O₂, C₅H₁₀O₂, or C₆H₁₂O₂). The composition dependence of C _p ^E is rather unusual in that two more or less marked minima are observed for most of the mixtures, especially when the alkanoate is a methanoate or an ethanoate. These results are discussed in terms of possible changes in conformation of both the ester and cyclohexane.     

Construction of a Chemical Kinetic Model of Five-Component Gasoline Surrogates under Lean Conditions

The requirements for improving the efficiency of internal combustion engines and reducing emissions have promoted the development of new combustion technologies under extreme operating conditions (e.g., lean combustion), and the ignition and combustion characteristics of fuels are increasingly becoming important. A chemical kinetic reduced mechanism consisting of 115 species and 414 elementary reactions is developed for the prediction of ignition and combustion behaviors of gasoline surrogate fuels composed of five components, namely, isooctane, n-heptane, toluene, diisobutylene, and cyclohexane (CHX). The CHX sub-mechanism is obtained by simplifying the JetSurF2.0 mechanism using direct relationship graph error propagating, rate of production analysis, and temperature sensitivity analysis and CHX is mainly consumed through ring-opening reactions, continuous dehydrogenation, and oxygenation reactions. In addition, kinetic parameter corrections were made for key reactions R14 and R391 based on the accuracy of the ignition delay time and laminar flame velocity predictions. Under a wide range of conditions, the mechanism’s ignition delay time, laminar flame speed, and the experimental and calculated results of multi-component gasoline surrogate fuel and real gasoline are compared. The proposed mechanism can accurately reproduce the combustion and oxidation of each component of the gasoline-surrogate fuel mixture and real gasoline.     

水、低碳醇与环己烷间的液-液平衡的测定与推算

用浊点法与折光分析相结合的方法测定了水-异丁醇-环己烷三元系(体系Ⅰ)30℃下的液-液平衡相图。用色谱分析方法测定了水-若干低碳醇(体系Ⅱ)及水-低碳醇-环己烷(体系Ⅲ)的液-液平衡关系。用UNIQUAC模型预测,实测值与计算值平均偏差对体系Ⅰ为0.49%(mol,下同),对体系Ⅱ为O.71%。体系Ⅲ为1.07%。     

聚碳酸亚环己酯及其制备技术研究进展

二氧化碳既(CO₂)是令人头疼的温室气体,更是有价值的碳资源,因此二氧化碳的固定和利用具有重要的理论与现实意义。以二氧化碳和环氧环己烷为原料合成的聚碳酸亚环己酯(PCHC)是一种新型的脂环类可生物降解聚酯材料,相比传统的二氧化碳-环氧烷聚合物,其机械和耐热性能更为优良,有望拓展脂肪类聚碳酸酯的使用范围。本文对PCHC的基本性能及潜在应用领域、合成工艺路线以及交替共聚反应催化剂的发展进行了综述,以期为优质PCHC材料的高效制备提供参考。     

Application of the Prigogine-Flory-Patterson theory part III. Mixtures of a bicyclic compound,benzene, cyclohexane,n-hexane with a cycloalkane,cyclohexene, a cycloalkadiene and benzene

The Prigogine-Flory-Patterson theory of liquid mixtures has been qpplied to the H _m ^E and V _m ^E for binary mixtures of a bicyclic compound, benzene, cyclohexane and n-hexane with a cycloalkane, cyclohexene, a cycloalkadiene and benzene. Furthermore the Prigogine-Flory theory has been used to predict activity coefficients at infinite dilution from the experimentally determined H _m ^E at 25°C for the mixtures cyclohexane, cyclohexene, 1,3-cyclohexadiene, 1,4-cyclohexadiene and benzene with a bicyclic compound. The predictions are compared to experimental results.     

烷基环己烷夺氢反应类的动力学研究

应用反应类过渡态理论(RC-TST)研究了氢自由基抽取烷基环己烷氢的反应类,给出了该类反应的动力学参数.通过研究该反应类中的14个代表反应,分析得到了RC-TST方法所需要的各种参数,建立了该类反应的线性能量关系式(LER).应用RC-TST/LER方法计算得到速率常数与TST/Eckart方法计算结果吻合很好,分析表明RC-TST/LER方法对于准确预测夺氢反应类的速率常数十分有效,可以节约大量计算成本.