正戊烷异构化制异戊烷反应热力学分析及实验研究

摘要

In this paper, thermodynamic analysis of pentane isomerization to isopentane was carried out in detail.Thermodynamic data, including standard molar enthalpy change, standard molar Gibbs free energy change and standard equilibrium constant at various temperatures were calculated.The effects of temperature, pressure, and molar ratio of hydrogen to hydrocarbon (H2/HC) on the isomerization rate of pentane were discussed.It is found that the isomerization of pentane is an exothermic reaction, lower temperature favors the proceeding of reaction and the cracking reactions of pentane are suppressed as well.Hydrogen partial pressure has significant effect on the conversion and selectivity of pentane isomerization, overhigh hydrogen partial pressure leads to decrease of pentane conversion.The experimental study on isomerization of pentane to isopentane was conducted in a fixed-bed reactor, using C5/C6 paraffin isomerization catalyst RISO developed by Research Institute of Petroleum Processing.Results show that the experimental data agree well with the thermodynamic calculation results.However, reaction temperature, pressure and H2/HC ratio are the main factors affecting the isomerization process, it is essential to optimize these parameters for an optimum utilization of catalyst.%通过对正戊烷异构化制异戊烷反应进行热力学分析,得到不同反应温度下的标准摩尔焓变、标准摩尔吉布斯自由能变和标准平衡常数值,同时分析了反应温度、压力及氢/烃比对正戊烷异构化率的影响.结果表明,正戊烷异构化反应是放热反应,低温有利于异构化反应的进行,并且可抑制正戊烷的裂解.在异构化机理研究中发现,氢气对异构化反应的转化率和选择性有着重要的影响,过高的氢分压会使脱氢反应的平衡向反方向进行,从而降低正构烷烃的转化率.采用固定床反应器对正戊烷异构化反应热力学进行研究,所使用的催化剂为中国石化石油化工科学研究院研制的中温分子筛型异构化催化剂.结果表明,温度、压力、氢/烃比是影响正戊烷异构化反应的主要因素.温度升高促进裂解反应,导致液体收率下降；压力升高有利于异构化反应；过高的氢分压降低正戊烷的转化率.因此,三者可以互相调整、相互补偿,从而使催化剂在最佳的条件下使用.