Feasibility of switchable dual function materials as a flexible technology for CO 2 capture and utilisation and evidence of passive direct air capture.

The feasibility of a Dual Function Material (DFM) with a versatile catalyst offering switchable chemical synthesis from carbon dioxide (CO 2 ) was demonstrated for the first time, showing evidence of the ability of these DFMs to passively capture CO 2 directly from the air as well. These DFMs open up possibilities in flexible chemical production from dilute sources of CO 2 , through a combination of CO 2 adsorption and subsequent chemical transformation (methanation, reverse water gas shift or dry reforming of methane). Combinations of Ni Ru bimetallic catalyst with Na 2 O, K 2 O or CaO adsorbent were supported on CeO 2 -Al 2 O 3 to develop flexible DFMs. The designed multicomponent materials were shown to reversibly adsorb CO 2 between the 350 and 650 °C temperature range and were easily regenerated by an inert gas purge stream. The components of the flexible DFMs showed a high degree of interaction with each other, which evidently enhanced their CO 2 capture performance ranging from 0.14 to 0.49 mol kg -1 . It was shown that captured CO 2 could be converted into useful products through either CO 2 methanation, reverse water-gas shift (RWGS) or dry reforming of methane (DRM), which provides flexibility in terms of co-reactant (hydrogen vs . methane) and end product (synthetic natural gas, syngas or CO) by adjusting reaction conditions. The best DFM was the one containing CaO, producing 104 μmol of CH 4 per kg DFM in CO 2 methanation, 58 μmol of CO per kg DFM in RWGS and 338 μmol of CO per kg DFM in DRM.