Considering the several usages of CO2, it is necessary to find a suitable CO2 purification method to satisfy each demand with low energy consumption. There are major four methods to separate CO2 from mixed gas, absorption, adsorption, membrane, and cryogenic separation. These four processes have different characteristics due to their basic separation properties. In this study, the characteristics of those processes were compared based on three performance indexes: CO2 product purity, recovery ratio, and energy consumption to find a suitable separation process for satisfying various CO2 demands. As a result, to obtain pure CO2 with a high recovery ratio and low energy consumption, it was found that vacuum pressure swing adsorption (VPSA) was the most promising among these processes and membrane separation, especially the vacuuming process was a potential candidate for getting low purity of CO2.