Identification of key mechanics in the ruthenium catalyzed synthesis of N,N-dimethylformamide from carbon dioxide in biphasic solvent systems

The identification of crucial key factors in the homogenously catalyzed synthesis of N,N-dimethylformamide (DMF) from carbon dioxide with an integrated catalyst recycling is demonstrated in this work. All investigations were performed in a biphasic solvent system consisting of an aqueous phase and an aliphatic alcohol in order to evaluate the reaction performance with an integrated catalyst recycling. While no mass transfer limitations between both liquid phases could be identified, the main rate limiting factor for the carbon dioxide conversion could be located in the amine to carbon dioxide ratio. A conventional dosage of CO2 via pressurization led to high CO2 loadings that resulted in a low basicity and thus in poor yields up to 34% after 5 h. By adding carbon dioxide via reactive absorption into an aqueous amine phase a defined amount could be applied and the yield for the formamide increased up to 81%. (C) 2018 Elsevier Inc. All rights reserved.