Enhanced CO₂ adsorption and selectivity in CNT and piperazine modified Ni-MOF-74 nanocomposites

Abstract

The rising levels of CO₂ in the atmosphere, primarily due to industrial activities, have accelerated the need for effective carbon capture technologies. While metal-organic frameworks (MOFs) like Ni-MOF-74 are promising due to their high CO₂ adsorption capacity, they face challenges such as reduced selectivity and structural instability under real-world conditions. This study addresses these limitations by synthesizing a composite material, CNT@Ni-MOF-74/PZ, where carbon nanotubes (CNTs) enhance structural stability and piperazine (PZ) introduces additional amine sites to improve CO₂ capture. The composite was synthesized via a solvothermal method and characterized using XRD, FTIR, BET, FESEM, and TGA to evaluate its structural, chemical, and thermal properties. Experimental results showed a 33 % increase in CO₂ adsorption capacity, with CNT@Ni-MOF-74/PZ achieving 6.1 mmol/g at 25 °C and 1 bar, compared to 4.5 mmol/g for unmodified Ni-MOF-74. Additionally, the CO₂/CH₄ selectivity improved significantly, attributed to the synergistic effects of CNTs and PZ. Monte Carlo simulations further validated the trends observed experimentally. These findings highlight CNT@Ni-MOF-74/PZ as a highly effective material for CO₂ capture, offering promising advancements for sustainable carbon capture technologies.