Department of Chemical and Biomolecular Engineering, Center for Catalytic Science and Technology, University of Delaware, 150 Academy St., Newark, DE 19716, USA.
ChemSusChem. 2012 Nov;5(11):2237-42. doi: 10.1002/cssc.201200339. Epub 2012 Aug 21.
The increased carbon dioxide concentration in the atmosphere caused by combustion of fossil fuels has been a leading contributor to global climate change. The adsorption-driven pressure or vacuum swing (PSA/VSA) processes are promising as affordable means for the capture and separation of CO₂. Herein, an 8-membered-ring zeolite ZK-5 (Framework Type Code: KFI) exchanged with different cations (H⁺, Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺) was synthesized as novel CO₂ adsorbent. The samples were characterized by SEM, energy-dispersive X-ray spectroscopy (EDAX), XRD, and gas adsorption (CO₂ and N₂). The Toth adsorption model was used to describe the CO₂ adsorption isotherms, and the isosteric heats of adsorption were calculated. CO₂ capture adsorbent evaluation criteria such as working capacity, regenerability and CO₂/N₂ selectivity were applied to evaluate the zeolite adsorbents for PSA/VSA applications. The in situ FTIR CO₂ adsorption spectra show that physisorption accounts for the largest fraction of the total CO₂ adsorbed. The CO₂ adsorption analysis shows that Mg-ZK-5 is the most promising adsorbent for PSA applications with the highest working capacity (ΔN(CO₂)=2.05 mmol g⁻¹), excellent selectivity (α(CO₂/N₂)=121), and low isosteric heat. Li-, Na- and K-ZK-5 with good working capacity (ΔN(CO₂)=1.55-2.16 mmol g⁻¹) and excellent selectivity (α(CO₂/N₂)=103-128) are promising CO₂ adsorbents for the VSA working region.
燃烧化石燃料导致大气中二氧化碳浓度增加，是全球气候变化的主要原因之一。吸附驱动的压力或真空变压（PSA/VSA）过程是一种有前途的、经济实惠的方法，可用于捕获和分离 CO₂。在此，合成了一种新型的 CO₂吸附剂，即用不同阳离子（H⁺、Li⁺、Na⁺、K⁺、Mg²⁺、Ca²⁺）交换的 8 元环沸石 ZK-5（骨架类型代码：KFI）。通过 SEM、能谱（EDAX）、XRD 和气体吸附（CO₂和 N₂）对样品进行了表征。采用 Toth 吸附模型来描述 CO₂吸附等温线，并计算了吸附热。还应用了 CO₂捕获吸附剂的评价标准，如工作容量、可再生性和 CO₂/N₂选择性，来评估 PSA/VSA 应用中的沸石吸附剂。原位 FTIR CO₂吸附光谱表明，物理吸附占总吸附 CO₂的最大部分。CO₂吸附分析表明，Mg-ZK-5 是 PSA 应用中最有前途的吸附剂，具有最高的工作容量（ΔN(CO₂)=2.05 mmol g⁻¹）、优异的选择性（α(CO₂/N₂)=121）和低的等焓。Li-、Na-和 K-ZK-5 具有良好的工作容量（ΔN(CO₂)=1.55-2.16 mmol g⁻¹）和优异的选择性（α(CO₂/N₂)=103-128），是 VSA 工作区有前途的 CO₂吸附剂。
