Abstract: The energy consumption of different sequences for separating multicomponent mixtures is different, which is affected by upstream reactors. Quantitative relationship between total vapor rate of each distillation sequence and reaction extent, together with its variation trend along the reaction parameters can be determined by constructing an integrated model of the reaction parameters and distillation sequence with reaction extent as an intermediate variable. Effects of inlet temperature and catalyst activity on the extents of main reactions and the total vapor rate of 5 distillation sequences were discussed through modeling analysis of a styrene unit. All sequences were simulated by the rigorous simulation model of Aspen Plus software at different inlet temperatures. The results show that the energy consumption and the operating cost are consistent with the model prediction.