Studies On The Process Features And Reaction Kinetics For γ-Undecalactone Preparation

For the y-Undecalactone preparation process in which n-octanol, acrylic acid are used as reactants and di-tert-butyl peroxide as initiator, the features of both main and side reactions, apparent reaction kinetics, reaction and separation coupled batch process simulation, reaction mechanism and their corresponding intrinsic kinetics have been studied systematically.Based on the knowledge about y-Undecalactone preparation, the proper experimental conditions for the study of apparent kinetics are chosen, which is the molar ratio of n[octanol]:n[acrylic acid] of6.5:1under normal pressure. Using designed experimental and analytical methods, it is proven that the main reactions between n-octanol and acrylic acid are free radical addition and esterification reaction while the side reactions are self polymerization among acrylic acid and their radicals.Based on the assumption that starting concentration of acrylic acid equals to the ending concentration of y-Undecalactone, apparent reaction kinetic model has been built in temperature range of155℃to185℃, the reaction rate is proportional to the concentration of acrylic acid and pre-exponential factor Ao is3×1010min-1while activation energy Ea is93.1kJ·mol-1. Incorporated with this apparent reaction kinetic model, RCSTR and RadFrac model in ASPEN Plus have been engaged to simulate the reaction and separation coupled batch process for y-Undecalactone preparation. Simulation results show that the calculated change of content of y-Undecalactone, steam flowrate and top fraction in the separation tower with time could fit well with experimental data, the calculated method and their data can be used as the fundamental data for the designing and optimization of separation process.Different reaction mechanisms of main and side reactions and their corresponding kinetic models have been proposed. By the results of model fitting with experimental data under different assumptions, chain initiation, propagation and termination steps in y-Undecalactone preparation have been deduced and the parameters in the corresponding intrinsic kinetic model have been regressed after some simplification and optimization.