Advances in process intensification of direct air CO2 capture with chemical conversion

Capturing CO₂ from air (DAC) is becoming an attractive technological route to face the climate crisis. This paper reviews the existing research efforts to integrate DAC with conversion technologies to transform the captured CO₂ into chemicals or fuels. The approach can potentially lead to net zero carbon emissions, thus being of interest in a circular economy framework. A growing amount of research has been devoted to the combination of DAC with CO₂ conversion, leading to creative strategies which start to be scaled up. In this review, we have critically analysed the existing approaches by the degree of process integration. From the point of view of process intensification, the integration of both capture and reaction in the same vessel can potentially lead to equipment and energy cost savings besides other synergistic effects. In this vessel, the DAC and conversion can occur either in consecutive stages with change of feed or spontaneously in a cascade reaction without changing the conditions. As a side effect, the benefits entailed by process intensification in different levels of integration may be a decisive driving force for the widespread deployment of DAC. This paper discusses the ongoing research and perspectives to guide researchers in this promising new field.