Reduction of CO2 with KBH4 in solvent-free conditions
Reduction of CO2 with KBH4 in solvent-free conditions
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DOI：
10.1016/j.ijhydene.2016.04.052
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发表时间：
2016-08
影响因子：
7.2
通讯作者：
C. Picasso;D. Safin;I. Dovgaliuk;F. Devred;D. Debecker;Haiwen Li;J. Proost;Y. Filinchuk
中科院分区：
文献类型：
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作者：
C. Picasso;D. Safin;I. Dovgaliuk;F. Devred;D. Debecker;Haiwen Li;J. Proost;Y. Filinchuk
在有机和无机化学中，金属氧化物通常用作还原剂。迄今为止，硼氢化钾（KBH 4）将醛和酮还原为醇的能力因其在空气和碱性溶液中的高稳定性而闻名。利用金属硼氢化物将CO2转化为甲酸盐和甲醇硼化合物是近年来的研究热点。在本工作中，我们研究了KBH 4和CO2在机械化学和热诱导条件下的固-气非催化反应，同时生成甲酰基氢硼酸钾K[HxB（OCHO）4 −x]（x= 1-3）作为主要产物。通过机械化学方法获得的固-气金属硼氢化物-CO2反应产物三甲酰基氢硼酸钾K[HB（OCHO）3]的第一个晶体结构得到了阐明。采用热重分析、质谱和红外光谱相结合的方法，研究了KBH 4固体与CO2在室温至500 °C的反应过程，揭示了在三步增质反应中氢气、甲醇和一氧化碳的生成。变温原位同步辐射X射线粉末衍射在CO2压力下揭示了一个新的结晶中间相的形成与一个身份不明的组合物，但在单斜空间群结晶，KBO 2在第二和第三步骤，分别。气相色谱法的不断变化的物种下CO2流揭示了第一次形成的甲醇和甲烷在无水条件下。
Metal hydrides have been commonly used as reducing agents in organic and inorganic chemistry. Until today, the capability of potassium borohydride (KBH4) to reduce aldehydes and ketones to alcohols has been known for its advantage of high stability on air and in alkaline solutions. Conversion of CO2to formates and boron methoxide compounds by metal borohydrides has been recently studied. In this work we investigated the solid–gas non-catalytic reaction between KBH4and CO2under both mechanochemical and thermal-induced conditions with the simultaneous formation of potassium formylhydroborates, K[HxB(OCHO)4 −x] (x= 1–3), as main products. The first crystal structure of a product of solid–gas metal borohydride – CO2reaction, potassium triformylhydroborate, K[HB(OCHO)3], obtained mechanochemically, was elucidated. The evolution of the reaction between solid KBH4and CO2was monitored by a combination of thermogravimetric analysis coupled with mass spectrometry and infrared spectroscopy from room temperature to 500 °C, revealing the generation of hydrogen, methanol and carbon monoxide in a three-step mass increase reaction. Variable temperaturein situsynchrotron X-ray powder diffraction under CO2pressure revealed the formation of a new crystalline intermediate phase with an unidentified composition but crystallizing in a monoclinic space group, and KBO2during the second and third steps, respectively. Gas chromatography of evolving species under CO2flow revealed for the first time the formation of methanol and methane in water-free conditions.