The question has shifted from whether solid sorbents can work in direct air capture (DAC) technologies to which solid sorbents are more economically advantaged. Determining this is challenging due to the influence of many different yet interconnected sorbent properties on the cost of CO₂ capture. Existing DAC economic models oversimplify sorbent stability by treating it as a simple replacement rate, neglecting crucial factors such as capacity loss rate and form. To address this challenge, we have developed an economic model that accounts for sorbent degradation in DAC processes. By factoring in capacity loss over time, our model provides a more accurate estimate of the cost associated with DAC and highlights the optimum time for sorbent replacement. We then identified sorbent characteristics and process features that minimize both the carbon footprint and the cost of captured CO₂. To further investigate the interplay of sorbent properties and DAC cost, we constructed a series of alkyl- and epoxy-functionalized polyamine sorbents. The sorbents’ CO₂ uptake, heat of adsorption and capacity fade were adjusted via a one-step modification, varying the proportions of primary, secondary, and tertiary amines. We then integrated the experimentally-measured parameters, including the form of degradation, into our economic model to probe which combination of sorbent properties results in the lowest cost of DAC for a fixed operating condition. The results provide guidelines and priorities for sorbent performance metrics that will yield the most cost-effective DAC technologies.

中文翻译：

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调整吸附剂特性以降低直接空气捕获的成本


问题已经从固体吸附剂是否可以在直接空气捕获（DAC）技术中发挥作用，转变为固体吸附剂在经济上更具优势。由于许多不同但相互关联的吸附剂特性对 CO ₂ 捕获成本的影响，确定这一点具有挑战性。现有的 DAC 经济模型将吸附剂稳定性视为简单的替代率，从而过于简化了吸附剂的稳定性，忽略了容量损失率和形式等关键因素。为了应对这一挑战，我们开发了一个经济模型来解释 DAC 工艺中吸附剂的降解。通过考虑随时间推移的容量损失，我们的模型可以更准确地估计与 DAC 相关的成本，并突出显示吸附剂更换的最佳时间。然后，我们确定了吸附剂特性和工艺特征，可最大限度地减少碳足迹和捕获 CO 的成本 ₂ 。为了进一步研究吸附剂性能和 DAC 成本之间的相互作用，我们构建了一系列烷基和环氧官能化的聚胺吸附剂。吸附剂的 CO ₂ 吸收、吸附热和容量衰减通过一步修改来调整，改变伯胺、仲胺和叔胺的比例。然后，我们将实验测量的参数（包括降解形式）整合到我们的经济模型中，以探讨哪种吸附剂特性组合可以在固定操作条件下实现最低的 DAC 成本。结果为吸附剂性能指标提供了指导方针和优先事项，从而产生最具成本效益的 DAC 技术。