Herein, we explore the intrinsic ability of cellulose dissolved in NaOH(aq) to reversibly capture CO₂. The stability of cellulose solutions differed significantly when adding CO₂ prior to or after the dissolution of cellulose. ATR-IR spectroscopy on cellulose regenerated from the solutions, using ethanol, revealed the formation of a new carbonate species likely to be cellulose carbonate. To elucidate the interaction of cellulose with CO₂ at the molecular level, a ¹³C NMR spectrum was recorded on methyl α-D-glucopyranoside (MeO-Glcp), a model compound, dissolved in NaOH(aq), which showed a difference in chemical shift when CO₂ was added prior to or after the dissolution of MeO-Glcp, without a change in pH. The uptake of CO₂ was found to be more than twice as high when CO₂ was added to a solution after the dissolution of MeO-Glcp. Altogether, a mechanism for the observed CO₂ capture is proposed, involving the formation of an intermediate cellulose carbonate upon the reaction of a cellulose alkoxide with CO₂. The intermediate was observed as a captured carbonate structure only in regenerated samples, while its corresponding NMR peak in solution was absent. The reason for this is plausibly a rather fast hydrolysis of the carbonate intermediate by water, leading to the formation of CO₃²⁻, and thus increased capture of CO₂. The potential of using carbohydrates as CO₂ capturing agents in NaOH(aq) is shown to be simple and resource-effective in terms of the capture and regeneration of CO₂.

中文翻译：

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低温下溶于NaOH（aq）的纤维素的CO ₂捕获能力

在这里，我们探讨了溶解在NaOH（aq）中的纤维素可逆地捕获CO ₂的内在能力。当在纤维素溶解之前或之后添加CO ₂时，纤维素溶液的稳定性显着不同。使用乙醇对从溶液中再生的纤维素进行的ATR-IR光谱分析表明，形成了一种新的碳酸盐物质，可能是碳酸纤维素。为了阐明纤维素与CO ₂在分子水平上的相互作用，在溶解于NaOH（aq）的模型化合物甲基α - D-吡喃葡萄糖苷（MeO-Glcp）上记录了¹³ C NMR光谱。 CO ₂时的化学位移在溶解MeO-Glcp之前或之后加入水，pH不变。当在溶解MeO-Glcp后将CO ₂添加到溶液中时，发现CO ₂的吸收高出两倍以上。总之，提出了用于观察到的CO ₂捕获的机制，该机制涉及在纤维素醇盐与CO ₂反应时形成中间碳酸纤维素。仅在再生样品中观察到该中间体为捕获的碳酸盐结构，而在溶液中不存在其相应的NMR峰。原因可能是碳酸酯中间体被水相当快地水解，导致形成CO ₃ ^2-，从而增加了对CO的捕集。₂。在NaOH（aq）中使用碳水化合物作为CO ₂捕获剂的潜力显示出就CO ₂的捕获和再生而言既简单又节省资源。