Reaction kinetics and process simulation for biodiesel production from rapeseed oil via supercritical transesterification

As a renewable and clean energy, biodiesel has attracted increasing attention from countries worldwide. The preparation of biodiesel by supercritical transesterification has the advantages of a fast reaction rate, high conversion rate, easy product separation and purification, and simple process, and has been widely studied. This paper uses triglyceride as a rapeseed oil model compound to study the transesterification reaction kinetics between triglyceride and supercritical methanol. The reaction is a three-step reversible reaction. The experimental results show that the third step of the reaction is the control step. The reaction rate constant of each step of the reaction was obtained using the parameter estimation method. The order of the reaction rate constant is k(2)>k(1)>k(3). On this basis, the chemical process simulation software PRO/II was used to design the process flow of the supercritical methanol method for preparing biodiesel. The group contribution model UNIFAC equation was used to estimate the relevant physical property parameters. In the process simulation, a combination of NRTL and SRKM was selected. The thermodynamic method determines the appropriate operating parameters of each unit module and obtains a reasonable process flow. All product indicators meet the requirements, which provides a basis for the industrialization of supercritical methanol production of biodiesel.