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用 5 0 0MHz超导核磁共振仪测定了 36个碳氢燃料油的1 HNMR谱 ,获得各类氢的相对含量。假设碳氢燃料由直链烷烃和直链烷基苯两种模型化合物构成 ,由1 HNMR结果和相对分子质量计算了相应的基团组成数。采用斜式沸点计测定燃料在不同温度下的泡点蒸气压 ,根据Clausius Clapeyron方程计算了燃料的蒸发焓和蒸发熵。以基团贡献法为桥梁 ,把微观的1 HNMR结构信息与宏观的蒸发性质联系起来 ,给出一个预测碳氢燃料蒸发焓的基团贡献表达式 ,检验结果表明偏差为 +5 4 %～ - 5 9% (平均 2 1% )。用此表达式预测了 17个纯烃和石油馏分的蒸发焓 ,偏差为 +8 5 %～ - 10 1% (平均 3 3% )。
The 1 H NMR spectra of 36 hydrocarbon fuel oils were measured with a 500 MHz superconducting nuclear magnetic resonance apparatus to obtain the relative contents of various types of hydrogen. It is assumed that the hydrocarbon fuel consists of two model compounds, straight-chain alkanes and straight-chain alkylbenzenes, and the corresponding group composition numbers are calculated from 1 H NMR results and relative molecular weights. The bubble point vapor pressure of the fuel at different temperatures was measured using a tilt-type boiling point meter. The enthalpy of vaporization and the entropy of evaporation of the fuel were calculated according to the Clausius Clapeyron equation. Using the group contribution method as a bridge, the microscopic 1 H NMR structural information is linked with the macroscopic evaporation properties to give a group contribution expression for predicting the enthalpy of vaporization of hydrocarbon fuels. The test results show that the deviation is +5 4% ~ - 59% (average 21%). Using this expression, the enthalpies of evaporation of 17 pure hydrocarbons and petroleum fractions were predicted with a deviation of +8 5% -101% (average 33%).