气固色谱中分子热运动能的作用

Action of Molecular Kinetic Energy on a Gas-solid Chromatography

用麦克斯韦(M axwell)能量分布和能量均分原理推导溶质迁移速度方程,研究了N2-GDX-101气固色谱体系中5种烷烃的迁移速度、迁移活化能和迁移中溶质分子热运动的作用.得到的迁移活化能可以很好地解释溶质的迁移速度.研究结果表明,溶质分子的转动、振动能量显著地影响迁移活化能.用统计热力学的估算验证的计算结果表明,迁移活化能明显小于脱附焓.溶质迁移时可能远未达到解吸脱附的状态.流动相驱动的溶质迁移可能主要为吸附状态下的滑移.

The migration velocity, the migratory activation energy and the action of molecular motion on migration were researched for five alkanes in the gas-solid chromatography of N2/GDX-101 system. Maxwell distribution of energy which originally shows the molecule fraction of molecular translation energy exceeding E, was used for expressing the time fraction of the translation energy exceeding E. The kinetic energy of rotation and vibration was expressed by the times of kT/2 in the light of the principle of equiparation of energy, to modify the ideal equation. The migratory activation energy （E） which is calculated with the rate equation, could well explain the migration velocity. The kinetic energy of rotation and vibration observably influences E. These properties were also authenticated with the estimate of statistical thermodynamics. The calculation showed that E was obviously smaller than the desorption enthalpy （△HDesorption）. The solute migration might not reach the state of desorption. The solute driven by mobile phase should mainly slip under the state of adsorption.