温度和压力对化学反应方向和化学平衡的调控

How to Control Chemical Reaction Direction and Chemical Equilibrium by Temperature and Pressure

根据一般化学反应方程式,给出了理想气体化学反应Gibbs自由能随反应进度变化的关系式。该式由3部分组成,第1部分对应于标准压力和给定温度下,反应物和生成物摩尔生成Gibbs自由能之和随反应进度的变化,是化学反应的温度调控项;第2部分对应于压力对Gibbs自由能的贡献,是压力调控项;第3部分是混合熵的贡献,是决定化学平衡的重要因素。因此,一个化学反应,向什么方向进行,进行到什么程度,可以通过温度和压力的调控来实现。以合成氨和工业合成气为例,讨论了如何利用压力和温度的调控,实现反应方向和平衡的控制。

For a chemical reaction only containing ideal gases, Gibbs free energy, changing with the extent of reaction, was obtained. In the equation of Gibbs free energy, three items were contained. The first item was the sum of Gibbs formation energy of reactants and products, defined as the temperature-controlled item. The second item was the contribution of pressure to the Gibbs energy, named as the pressure-controlled item. The third one was the mixed entropy, which was contribution of mixing degree between the reactants and the products to the Gibbs energy. For any chemical reaction, the reaction direction and the chemical equilibrium can be controlled by temperature and pressure. Take NH3 synthesis and industrial synthesis gases for examples, how to control the reaction direction and chemical equilibrium by the temperature and pressure was discussed in detail.