Abstract: As a critical carbon reduction technology, CO₂ purification technology has been widely applied in carbon-intensive industries such as coal-fired power plants and cement factories, making significant contributions to mitigating the greenhouse effect and inhibiting global warming. The existing gas separation technologies, including gas drying technology, adsorption separation technology, chemical absorption technology, and membrane separation technology, are systematically summarized, and their application effects and limitations in different industrial scenarios are evaluated. Firstly, gas drying technology is mainly used to remove H₂O from gaseous products, which can effectively reduce the moisture content in the gas and create favorable conditions for subsequent CO₂ purification. Secondly, adsorption separation technology based on solid adsorbents is suitable for removing non-target gases such as N₂ and O₂. Pressure swing adsorption technology shows advantages of flexible operation and low energy consumption in removing O₂, N₂ and H₂O. For SO₂ removal, chemical absorption technology shows strong desulfurization performance, but considering its poor selectivity for different acidic gases, it may absorb ¹⁴CO₂ together and reduce purification efficiency. In contrast, adsorption separation technology shows more prominent performance in terms of efficiency and selectivity, especially for the separation of trace components in complex gas systems, which has high application potential. In addition, membrane separation technology, with its advantages of low energy consumption, modular design and easy mass production, shows significant potential in the separation of trace organic compounds in flue gas. In addition, with the rapid development of nuclear energy technology, nuclear power plants are paying increasing attention to the recovery and resource utilization of ¹⁴C from radioactive waste resin. Among them, thermal decomposition is a promising treatment method that can convert waste resin into gaseous products containing ¹⁴CO₂ for subsequent efficient recovery of ¹⁴C. The composition of gaseous products from the thermal decomposition of radioactive waste resin is analyzed, and the application requirements and practical challenges of CO₂ purification technology in dealing with such gaseous products are focused on. The research results indicate that a single gas technology can hardly simultaneously meet all the requirements of CO₂ purification from the gaseous products of waste resin thermal decomposition. Therefore, it is necessary to couple gas separation technologies according to gas composition and process conditions to fully leverage the advantages of each technology and achieve efficient separation of thermal decomposition products.