Direct air capture (DAC), a technology that removes CO2 directly from the atmosphere, is increasingly recognized as a viable solution to global warming. Among various DAC methods, adsorption-based technologies are emerging as scalable and potentially low-cost options. While significant progress has been made in the development of adsorbents, there remains a gap in the research focused on the desorption mode. Among the various practical desorption strategies that have been considered, direct steam desorption is considered one of the most efficient and rapid methods for CO2 removal, primarily due to the swift heat transfer provided by condensing steam. However, challenges such as leaching of active CO2 adsorption components (like amines) and metal contamination from low-purity steam can lead to the deactivation of the adsorbent. Furthermore, when the adsorption temperature drops below zero degrees Celsius, residual water from the steam can freeze, obstructing the adsorption column. In this context, vacuum desorption presents an appealing alternative. This method operates by creating a pressure difference to desorb adsorbates, eliminating contact with a liquid medium. Nevertheless, the slow heat transfer that occurs during temperature vacuum swing adsorption (TVSA) often results in longer desorption times compared to steam desorption, thereby reducing overall productivity. In this study, we have developed an adsorbent specifically designed for vacuum desorption. The desirable characteristics for an adsorbent suitable for vacuum swing adsorption include high CO2 uptake, stability throughout the process, low pressure drop, rapid, and efficient heating. Utilizing carbonaceous materials, we fabricated an adsorbent contactor capable of electric heating through Joule heating. In comparative tests, our vacuum-assisted electrical swing adsorption (VESA) demonstrated superior desorption kinetics when compared to traditional TVSA methods. In this talk, we will discuss the fabrication of the electric heating adsorbent contactor and benefits of VESA compared to TVSA in terms of energy efficiency and process time.
