Homogeneous Hydrogenation of CO2 to Methyl Formate Utilizing Switchable Ionic Liquids

作者：Yadav Mahendra; Linehan John C; Karkamkar Abhijeet J; van der Eide Edwin; Heldebrant David J^*

来源：Inorganic Chemistry, 2014, 53(18): 9849-9854.

DOI：10.1021/ic501378w

Combined capture of CO2 and subsequent hydrogenation allows for base/methanol-promoted homogeneous hydrogenation of CO2 to methyl formate. The CO2, captured as an amidinium methyl carbonate, reacts with H-2 with no applied pressure of CO2 in the presence of a catalyst to produce sequentially amidinium formate, then methyl formate. The production of methyl formate releases the base back into the system, thereby reducing one of the flaws of catalytic hydrogenations of CO2: the notable consumption of one mole of base per mole of formate produced. The reaction proceeds under 20 atm of H-2 with selectivity to formate favored by the presence of excess base and lower temperatures (110 degrees C), while excess alcohol and higher temperatures (140 degrees C) favor methyl formate. Known CO2 hydrogenation catalysts are active in the ionic liquid medium with turnover numbers as high as 5000. It is unclear as to whether the alkyl carbonate or CO2 is hydrogenated, as we show they are in equilibrium in this system. The availability of both CO2 and the alkyl carbonate as reactive species may result in new catalyst designs and free energy pathways for CO2 that may entail different selectivity or kinetic activity.

• 出版日期2014-9-15