Feasibility of green mechanochemical synthesis for dual function materials preparation

Abstract

Dual function materials (DFMs) are key for the integrated capture of CO₂ from waste gas streams and its valorisation to valuable chemicals, such as syngas. To be able to function in commercial applications, DFMs require both high capture capacity and catalytic activity, achieved by optimising the synergistic interactions among the catalytic metals, support and adsorbent components. To obtain increased interaction, the dry milling process can be used as a sustainable, solvent free, green synthesis method. In this work, we report the performance of RuNi bimetallic DFMs supported on CeO₂-Al₂O₃ and promoted with CaO and Na₂O, synthesised by a mild-energy mechanochemical process. The materials show generally comparable, and sometimes superior, capture capacity and increased activity in Reverse Water-Gas Shift (RWGS) reaction for CO production at 650 °C compared to their counterpart prepared by a conventional impregnation method, underlining the potential of the synthesis method for highly functional DFMs. Remarkably, high activity and stability are also maintained when O₂ is present in the capture step, indicating potential for real exhaust-gases capture applications. Also, direct air capture of CO₂ is reported, further underlining the benefits of the dry milling approach for creating versatile DFMs.