High concentrations of carbon dioxide in natural gas occur when carbon dioxide is used for enhanced oil recovery. The separation of CO2 from the hydrocarbons in the natural gas is complicated due to the existence of an azeotrope between ethane (C2) and CO2 at the cryogenic temperatures required for distillation. The main disadvantage of the conventional process lies in its high capital investment and external energy input required to fulfill the desired purification. In addition, current process is different from conventional extractive distillation columns. Because in conventional extractive columns a third component is added to the system and solvent losses in the product streams requires a make-up stream. However, in the present book, the solvent is a mixture of C3 and heavier components in which the solvent stream is quite similar to the light key (ethane) and these distinct features of the process leads to some convergence problems. In order to address these issues, applications of reactive absorption, dividing-wall column and feed-splitting techniques are investigated for this azeotropic mixture and a comparison is made for the new processes.