Supporting Porous Metal–Organic Frameworks on Carboxylated-Wood Sponges for Direct Air Capture and Highly Selective CO<sub>2</sub>/CH<sub>4</sub> Separation
Xupeng Zhang, Kaiqian Li, Longxin Guo, Zhi Ping Xu, Shuduan Deng, Ying Liu, Gang Zhu
Abstract
To effectively mitigate the global warming problem caused by excessive CO 2 emissions, the implementation of direct air capture (DAC) technology has emerged as one of the most promising strategies for capturing CO 2 from the atmosphere. The key to DAC technology hinges on the development of high-performance solid sorbent materials that demonstrate high CO 2 adsorption capacity and gas separation selectivity, particularly under low CO 2 partial pressure conditions. Herein, we have successfully developed a class of MOF@carboxylated wood sponge (MOF@CWS) hybrid sorbents, capable of efficient CO 2 capture from low-concentration (less than 10,000 ppm) CO 2 sources, achieved by embedding the porous MOF into carboxylated wood sponges (CWS) substrate via an in situ growth route. Within the MOF@CWS series, the CO 2 uptake capacity of Mg-MOF-74@CWS is 3.61 and 2.65 mmol/g at 1 bar, 273 and 298 K, respectively, significantly higher than those of CWS and HKUST-1@CWS. Moreover, this material exhibited outstanding DAC performance, with the CO 2 sorption capacity at 273 K up to 0.56 mmol/g from ambient air (ca. 400 ppm of CO 2 ), surpassing most other solid sorbents. The obtained Mg-MOF-74@CWS also demonstrated exceptional CO 2 /CH 4 separation performance, primarily due to the unique pore structure and augmented interaction between the CO 2 molecules and the hybrid sorbents. The results of this study indicate that Mg-MOF-74@CWS has potential as an efficient solid sorbent for the DAC of CO 2 .