Boosting CO2 adsorption and selectivity in metal-organic frameworks of MIL-96(Al) via second metal Ca coordination

Hussein Rasool Abid; Zana Hassan Rada; Yuan Li; Hussein A Mohammed; Yuan Wang; Shaobin Wang; Hamidreza Arandiyan; Xiaoyao Tan; Shaomin Liu

doi:10.1039/d0ra00305k

Boosting CO₂ adsorption and selectivity in metal-organic frameworks of MIL-96(Al) via second metal Ca coordination

RSC Adv. 2020 Feb 25;10(14):8130-8139. doi: 10.1039/d0ra00305k. eCollection 2020 Feb 24.

Authors

Hussein Rasool Abid^{1

2}, Zana Hassan Rada¹, Yuan Li³, Hussein A Mohammed¹, Yuan Wang⁴, Shaobin Wang⁵, Hamidreza Arandiyan⁶, Xiaoyao Tan³, Shaomin Liu¹

Affiliations

¹ WA School of Mines: Minerals, Energy and Chemical Engineering, Curtin University WA 6102 Australia hussein.abid@curtin.edu.au Shaomin.Liu@curtin.edu.au.
² Environmental Department, Applied Medical Science, University of Karbala Karbala 56001 Iraq.
³ Department of Chemical Engineering, Tianjin Polytechnic University Tianjin 300387 China liyuan@tjpu.edu.cn.
⁴ School of Chemistry, Faculty of Science, The University of New South Wales Sydney New South Wales 2052 Australia.
⁵ School of Chemical Engineering, University of Adelaide SA 5005 Australia.
⁶ Laboratory of Advanced Catalysis for Sustainability, School of Chemistry, The University of Sydney Sydney 2006 Australia.

Abstract

Aluminum trimesate-based MOF (MIL-96-(Al)) has attracted intense attention due to its high chemical stability and strong CO₂ adsorption capacity. In this study, CO₂ capture and selectivity of MIL-96-Al was further improved by the coordination of the second metal Ca. To this end, a series of MIL-96(Al)-Ca were hydrothermally synthesised by a one-pot method, varying the molar ratio of Ca²⁺/Al³⁺. It is shown that the variation of Ca²⁺/Al³⁺ ratio results in significant changes in crystal shape and size. The shape varies from the hexagonal rods capped in the ends by a hexagonal pyramid in MIL-96(Al) without Ca to the thin hexagonal disks in MIL-96(Al)-Ca4 (the highest Ca content). Adsorption studies reveal that the CO₂ adsorption on MIL-96(Al)-Ca1 and MIL-96(Al)-Ca2 at pressures up to 950 kPa is vastly improved due to the enhanced pore volumes compared to MIL-96(Al). The CO₂ uptake on these materials measured in the above sequence is 10.22, 9.38 and 8.09 mmol g^-1, respectively. However, the CO₂ uptake reduces to 5.26 mmol g^-1 on MIL-96(Al)-Ca4. Compared with MIL-96(Al)-Ca1, the N₂ adsorption in MIL-96(Al)-Ca4 is significantly reduced by 90% at similar operational conditions. At 100 and 28.8 kPa, the selectivity of MIL-96(Al)-Ca4 to CO₂/N₂ reaches up to 67 and 841.42, respectively, which is equivalent to 5 and 26 times the selectivity of MIL-96(Al). The present findings highlight that MIL-96(Al) with second metal Ca coordination is a potential candidate as an alternative CO₂ adsorbent for practical applications.