Enhanced CO₂ adsorption and selectivity in CNT and piperazine modified Ni-MOF-74 nanocomposites
Syed Turab Haider Zaidi, Aqeel Ahmad, Marhaina Ismail, Nik Abdul Hadi Md Nordin, Mohamad Azmi Bustam, Muhammad Usman, David Asubonteng, Syed Muhammad Wajahat ul Hasnain
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. • The composite CNT@Ni-MOF-74/PZ were successfully prepared for CO 2 capture. • Experimental results showed a 33 % increase in CO₂ adsorption capacity, with CNT@Ni-MOF-74/PZ. • The CNTs provided structural stability while piperazine added amine sites for better CO₂ adsorption capacity. • Monte Carlo simulation was performed to validate the experimental CO 2 data.