Carbon Dioxide Capture by an Amine Functionalized Ionic Liquid: Fundamental Differences of Surface and Bulk Behavior

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• 作者：Inga Niedermaier ; Matthias Bahlmann ; Christian Papp ; Claudia Kolbeck ; Wei Wei ; Sandra Krick Calderón ; Mathias Grabau ; Peter S. Schulz ; Peter Wasserscheid ; Hans-Peter Steinrück ; Florian Maier
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：January 8, 2014
• 年：2014
• 卷：136
• 期：1
• 页码：436-441
• 全文大小：311K
• ISSN：1520-5126

文摘

Carbon dioxide (CO<sub>2sub>) absorption by the amine-functionalized ionic liquid (IL) dihydroxyethyldimethylammonium taurinate at 310 K was studied using surface- and bulk-sensitive experimental techniques. From near-ambient pressure X-ray photoelectron spectroscopy at 0.9 mbar CO<sub>2sub>, the amount of captured CO<sub>2sub> per mole of IL in the near-surface region is quantified to 0.58 mol, with 0.15 mol in form of carbamate dianions and 0.43 mol in form of carbamic acid. From isothermal uptake experiments combined with infrared spectroscopy, CO<sub>2sub> is found to be bound in the bulk as carbamate (with nominally 0.5 mol of CO<sub>2sub> bound per 1 mol of IL) up to 2.5 bar CO<sub>2sub>, and as carbamic acid (with nominally 1 mol CO<sub>2sub> bound per 1 mol IL) at higher pressures. We attribute the fact that at low pressures carbamic acid is the dominating species in the near-surface region, while only carbamate is formed in the bulk, to differences in solvation in the outermost IL layers as compared to the bulk situation.