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CO2CRC CCUS Symposium 2023
CO2CRC Symposium 2023
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In-situ vapor promoted direct air CO2 capture

Oral Presentation

Oral Presentation

9:55 am

22 November 2023

Zeally - DAC Session

Direct Air Capture (DAC)

Presentation Description

Direct Air Capture (DAC), a groundbreaking concept in the realm of climate solutions, has emerged as a pivotal avenue for achieving negative emissions. By directly extracting CO2 from ambient air, DAC offers a unique advantage by addressing the root cause of increasing atmospheric CO2 levels. Among DAC methodologies, the adsorption-desorption process utilizing solid adsorbents presents notable promise. However, the large heat of adsorption requires high energy consumption for regeneration of adsorbents, significantly compromising the economic viability and productivity of DAC. 

Here, we show a vapor promoted DAC process to recover the adsorbed CO2 by in situ vapor purge using water harvested from atmosphere synergistically. The desorption of CO2 is substantially enhanced in the presence of concentrated water vapors at around 100 °C, resulting in the concurrent production of 97.7% purity CO2 and fresh water without the use of vacuum pumps. Moreover, we demonstrate a prototype of this DAC powered by sunlight, which recovers 98% of the adsorbed CO2, the highest among all other DAC technologies, and consumes 20% less thermal energy. 

In another case when 10 kPa vacuum is applied, this in situ vapor purge can achieve near complete regeneration of the chemisorbents at temperatures as low as 60 °C, producing 99% purity CO2 with a stable working capacity of 1.10-1.13 mmol/g for 45 cycles. The minimum work required for regeneration was only 1.62 MJ/kgCO2, over 37% lower than temperature-vacuum swing desorption. This low-temperature regeneration process not only reduces the energy demand but also reduces the overall cost of DAC.


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