Homogeneous Catalyst Recycling and Separation of a Multicomponent Mixture Using Organic Solvent Nanofiltration

Abstract

In homogeneous catalysis, the application of organic solvent nanofiltration (OSN) has become a well‐known alternative to common recycling methods. Even though some OSN membranes are commercially available, their classification and the scope of application have to be determined for the specific solvent mixture. The commercial membrane Evoniks DuraMem® 300 was tested in a mixture of ethanol, ethyl acetate, and cyclohexane with magnesium triflate as possible catalyst. The cross permeate fluxes were measured for two transmembrane pressures and the hydrodynamic radii of the components were determined. Some of the components in the ternary mixture are retained, which makes the membrane also suitable for fractioning thereof.

Development of Thin-Film Composite Membranes for Nanofiltration at Extreme pH

“…The pore size is defined so that the nonharmful monovalent salts could pass through the membranes, while micropollutants and heavy metals would be easily retained . The NF process has been successfully applied to numerous separation processes in industrial scales. − However, the low stability of NF membranes remains a drawback and often hinders their application in a broader range, where the solution to be filtered can damage the membrane. , This is a critical issue because most of the effluents in chemical factories are often at extreme pH and highly corrosive. − Conventional polymer NF membranes quickly lose their performance upon contact with either acidic or alkaline solutions . Hence, the need for developing highly robust materials for membrane fabrication is rapidly emerging, and this could be achieved by carefully engineering the chemistry of materials.…”

Recycling and Separation of Homogeneous Catalyst from Aqueous Multicomponent Mixture by Organic Solvent Nanofiltration

“…19 F nuclear magnetic resonance (NMR) spectroscopy was used for the quantification of the catalyst. This has been established as a very reliable and robust measurement method during earlier experiments [1].…”

“…Schnoor et al showed a linear correlation between the EtOAc fraction and the size of the molecules in the mixtures. This size can be described by the hydrodynamic radius [1]. This correlation would explain the reduced permeability of all the components for high molar fractions of EtOAc since large molecules permeate more slowly through the membrane.…”

“…In a previous paper, Schnoor et al have looked at the idea to use organic solvent nanofiltration (OSN) for this separation [1]. During the investigation of the esterification of acetic acid with ethanol with homogeneous catalysts, to produce higher alcohols, different methods were tried for the recycling of the catalysts.…”

Recycling of Catalysts from Surfactant Systems

“…Furthermore, the most used reactants in organic synthesis are hydrophobic, and in the absence of the surfactant, the system is comparable with a conventional reaction medium. For such systems, besides extraction, solvent resistant nanofiltration is one way to recycle the catalyst in its active state [29].…”