Low-Temperature Activated Direct Air Capture Methanation Using K-β″ Alumina

Abstract

400 ppm of CO 2 was captured with Ru/K 2 CO 3 on K-β″ alumina at 30 °C and was transformed into CH 4 successfully when the temperature was increased to 300 °C. K-β″ alumina was employed as the support material, and K + ions were designed to access Ru particles and induce the activation of adsorbed CO 2 . By the promotional effect, the K-β″ alumina-supported catalyst displayed a lower methanation temperature (120 °C) than the γ-Al 2 O 3 -supported one (150 °C). The K-β″ alumina-supported catalysts also exhibited high CH 4 selectivity (79%) and highly stable cyclic properties throughout the tests. Diffuse reflectance infrared Fourier transform spectroscopy revealed that K + in K-β″ alumina actively intervenes in the formation of intermediates (CO 3 2− and CO). The promotion in reactions will be due to σ → π K backdonation and can assist in their reactions to other intermediates (formate and carbonyl) at 120 °C. This implies that promotion of CH 4 intermediates' formation was aided by the conduction of K + in K-β″ alumina.

Reactive direct air capture of CO2 to C–C coupled products using multifunctional materials

“…The carbonyl vibration of formate was observed at the ∼1631 cm −1 region. 64 The Fe–CO interactions were visible in the 1800–2100 cm −1 region, which corresponds to bound CO with different forms of Fe. 65 In addition to formate and CO, there are additional bands visible for carbonates and bicarbonates in the IR spectrum.…”

Integrated CO2 capture and utilization: a review of the synergistic effects of dual function materials

“…The adsorption process of DFMs in DAC application is better operated at ambient temperature, however, the CO 2 capture capacity would be sharply reduced compared with working at high temperature. Lee et al 193 synthesized Ru/K 2 CO 3 on K-β′′ alumina based DFMs which can capture CO 2 at 30 °C with CO 2 capacity of 0.2 mmol g −1 . The working principle of Ru/K 2 CO 3 DFMs is shown in Fig.…”