Synthesis of customized zeolite X with outstanding CO2 selectivity over CH4 and N2 using facile activated spent fluid catalytic cracking catalysts

Abstract

Efficient separation of CO2 from natural gas mixtures (CO2/CH4) and flue gas (CO2/N2) is pivotal for effective carbon capture and sequestration. Utilizing adsorbents derived from solid waste provides additional benefit for the carbon capture industry. This study introduces a convenient activation method at 200 °C for SFCC. Utilizing the activated SFCC as raw material under mild hydrothermal conditions, highly crystalline zeolite X (referred to as SFCC-X-200) of commercial quality with exceptional CO2 separation ability from CH4 and N2 is obtained. The static water adsorption rate of SFCC-X-200 meets the requirements of the national standard for commercial zeolite X (GB6287-86). Moreover, the ideal adsorbed solution theory (IAST) selectivity of SFCC-X-200 for CO2 from CO2/N2 (15/85, v/v) and CO2/CH4 (50/50, v/v) mixtures is significantly higher, at 797 and 199, respectively, compared to commercial X zeolite. SFCC-X-200 demonstrates tremendous potential for separating CO2/N2 and CO2/CH4 mixtures due to its outstanding adsorption capacity and selectivity, rapid attainment of adsorption equilibrium, complete desorption at ambient temperature, and extremely low cost.