Ki Jun Kim  Churl-hee Cho  Dong-Woo Cho

10.7464/ksct.2024.30.2.123

Zeolite templated carbon Methane Nitrogen Adsorption DAC of CH4

Zeolite template carbon (ZTC) was synthesized as an adsorbent to remove low-concentration CH4 from the atmosphere. The synthesis of ZTC was performed using CH4 and C2H2 as carbon precursors and their impact on adsorption was investigated. ZTC was also synthesized using Y zeolite ion-exchanged with CaCl2 and LiCl as templates to investigate the effect of using metals in ion exchange. The comparison of the carbon precursors revealed that C2H2 had a higher carbon yield than CH4. The synthesized ZTC exhibited developed micropores due to carbon deposition deep inside the micropores of the zeolite template. The kinetic diameter of C2H2 (0.33 nm) is smaller than that of CH4 (0.38 nm), which allowed for its deposition. The study compared metal precursors used for ion exchange and confirmed that the CaCl2-based ZTC developed more micropores compared to the LiCl-based ZTC. The ion-exchanged Ca inhibited pore blocking by the carbon precursor, allowing it to enter the pores. The ability of synthesized ZTC to adsorb N2 and CH4 at 298 K was investigated. The results showed that CH4 had a higher overall adsorption amount than N2. The sample synthesized using C2H2 and CaY exhibited the highest N2 and CH4 adsorption capacity. However, the sample synthesized with CH4 had the highest CH4/N2 gas uptake ratio, which is a crucial factor in designing an adsorption process. The observed difference was likely caused by the underdevelopment of ultrafine pores that are associated with N2 adsorption. This resulted in a reduction of N2 adsorption, leading to an increase in CH4/N2 separation.