attempts have been made to study the thermodynamic behavior of 1,3 butadiene purification columns with the aim of retrofitting those columns to more energy efficient separation schemes. 1,3 butadiene is purified in two columns in series through being separated from methyl acetylene and 1,2 butadiene in the first and second column respectively. comparisons have been made among different thermodynamic models in both ?-? and ?-? approaches with contribution of pr, tst, prsv, and pr-twu equations of state and also the uniquac and nrtl activity models. two simulators, aspen plus and aspen hysys have been employed in this study and as a final point; the simulation results from aspen hysys with contribution of the selected four equations of state have been compared against industrial data from one of commercialized and currently in process in amir kabir petrochemical company. the simulation results indicate that all the four equations could produce the reasonable results for the first column, but for the second one, the pr-twu and tst failes to separate 1,2 butadiene at the desired value. in general, the recommended models for the first column are tst and pr-twu with an average absolute deviation (aad) of 0.512 and 0.769 percent for separation of methyl acetylene and also 0.134 and 0.135 percent for temperature prediction respectively. for the second column with bottom flow rate of 61.43 kg/h, the pr eos with an average absolute deviation of 0.487 percent for temperature prediction is the promising model.