Application Of PSA CO2 Capture Technology in The Petrochemical Industry

Adsorbent materials are the core of PSA capture technology. Currently, there are four main types of adsorbents used for PSA separation of CO2: carbon-based adsorbents, zeolite molecular sieves, amine-based adsorbents, and metal organic frameworks (MOFs). Carbon-based adsorbents are mainly composed of various activated carbons, carbon composites, and micro-mesoporous carbon materials; commonly used CO2 zeolite molecular sieves include 13X, Y-type zeolites, clinoptilolite, and 5A zeolite; the adsorption of CO2 by amine-based adsorbents is mainly chemical adsorption. Since the mechanical strength of amine materials is not high, they generally need to be loaded on a molded carrier; MOFs, as an emerging material, have a high specific surface area and flexible adjustability, but the preparation cost is relatively high, and are not suitable for large-scale actual flue gas treatment.

Carbon-based adsorbents
Carbon-based CO2 adsorbents have the advantages of high specific surface area, low price, good hydrophobicity, controllable texture, and low regeneration energy consumption. They are a promising CO2 adsorption material. The surface of carbon-based adsorbents contains different types of oxygen functional groups such as phenolic hydroxyl, carboxyl, acyl and carbonyl, which may be active centers for adsorption. The interactions involved include π-π complexation, electrostatic interaction, and electron donor-acceptor interaction. Due to the synergistic effect of different types of interactions, the adsorption behavior may be complex. However, the adsorption of CO2 by carbon-based materials is mainly weak physical adsorption, which is greatly affected by temperature. The flue gas temperature is generally between 50 and 120 degree , and the selectivity for CO2 is relatively low. The adsorption capacity drops sharply under high temperature conditions. Therefore, improving the interaction between the adsorbate and the adsorbent and the selectivity for CO2 are key points.