The analysis and evaluation of direct air capture adsorbents on the material characterization level

Direct air capture (DAC) of carbon dioxide has been identified as a necessary negative emission technology to limit global temperature rise to 2 °C by 2100. With the research progress in DAC, an increasing number of adsorbents have been developed and investigated. This brings about the questions that what makes good adsorbents for DAC and how to characterize and compare them with different natures. In this paper, the performance parameters of state-of-art DAC adsorbents were investigated, and it is found that because of the varying test conditions, the comparison of some parameters appears to be difficult. Therefore, it is recommended that for each performance parameter, it is best to determine relatively uniform test methods. To this end, this paper selected five benchmark adsorbents and used a set of test methods as a demonstration. Key performance parameters of the adsorbents were measured. On this basis, by comparing the results with that in existing research, the characteristics of different types of adsorbents were summarized and suggestions for future material development were provided.