Hashimoto Hidenori, Ozeki Hiroyuki, Yamamoto Yoshitaka, Muromachi Sanehiro
Graduate School of Environmental Science, Toho University, 2-2-1 Miyama, Funabashi-shi, Chiba 274-8510, Japan.
Research Institute for Energy Frontier (RIEF), National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
ACS Omega. 2020 Mar 23;5(13):7115-7123. doi: 10.1021/acsomega.9b03442. eCollection 2020 Apr 7.
Semiclathrate hydrates of tetra--butylammonium fluoride (TBAF) are potential CO capture media because they can capture CO at near ambient temperature under moderate pressure such as below 1 MPa. In addition to other semiclathrate hydrates, CO capture properties of TBAF hydrates may vary with formation conditions such as aqueous composition and pressure because of their complex hydrate structures. In this study, we investigated CO capture properties of TBAF hydrates for simulated flue gas, that is, CO + N gas, by the gas separation test with three different parameters for each pressure and aqueous composition of TBAF in mass fraction ( ). The CO capture amount in TBAF hydrates with = 0.10 was smaller than that obtained with = 0.20 and 0.30. The results found that gas pressure greatly changed the CO capture amount in TBAF hydrates, and the aqueous composition highly affected CO selectivity. The crystal morphology and single-crystal structure analyses suggested that polymorphism of TBAF hydrates with congruent aqueous solution may lower both the CO capture amount and selectivity. Our present results proposed that an aqueous solution with = 0.20 is advantageous for the CO capture from flue gas compared to near congruent solutions of TBAF hydrates ( = 0.30) and dilute solution ( = 0.10).
四丁基氟化铵（TBAF）的半笼形水合物是潜在的CO捕获介质，因为它们可以在接近环境温度、中等压力（如低于1 MPa）下捕获CO。除其他半笼形水合物外，由于TBAF水合物的结构复杂，其CO捕获性能可能会随形成条件（如水相组成和压力）而变化。在本研究中，我们通过气体分离试验，针对TBAF的每种压力和质量分数（ ）的水相组成的三个不同参数，研究了TBAF水合物对模拟烟道气（即CO + N气体）的CO捕获性能。质量分数 = 0.10的TBAF水合物中的CO捕获量小于质量分数 = 0.20和0.30时的捕获量。结果发现，气体压力极大地改变了TBAF水合物中的CO捕获量，水相组成对CO选择性有很大影响。晶体形态和单晶结构分析表明，具有全等水溶液的TBAF水合物的多晶型可能会降低CO捕获量和选择性。我们目前的结果表明，与TBAF水合物的近全等溶液（ = 0.30）和稀溶液（ = 0.10）相比，质量分数 = 0.20的水溶液有利于从烟道气中捕获CO。
