Development of zeolitic imidazolate framework-67 functionalized Co-Al LDH for CO2 adsorption

The effective capture of CO2 has become increasingly important for environment protection. In this work, LDH@ ZIF-67 composite was synthesized through in-situ growth of ZIF-67 on the surface of Co-Al LDH for CO2 adsorption. The as-synthesized LDH@ ZIF-67 composite was characterized by different techniques and the results confirmed that the successful formation of ZIF-67 on the surface of Co-Al LDH. The CO2 adsorption performance of the adsorbents was measured by thermogravimetric analysis and volumetric method, respectively. After introducing ZIF-67 onto the Co-Al LDH's surface, the CO2 adsorption capacity of LDH@ ZIF-67 could be as high as 22.16 mg/g at 30 degrees C, which was 88% of the capacity of pure ZIF-67 and much higher than that of Co-Al LDH. More importantly, the material showed rapid adsorption kinetics with ultrahigh selectivity for CO2 over N-2. The kinetic data were analyzed by pseudo-first order model, pseudo-second order model, Avrami model and the intraparticle diffusion model, respectively. It was found that the behaviors of CO2 adsorption could be best described by Avrami's kinetic model. Moreover, the LDH@ ZIF-67 composite could be regenerated and the efficiency retained more than 94% up to 5 cycles of the regeneration.