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Title: Molecular separations with organic solvent nanofiltration
Author: See Toh, Yoong Hsiang
ISNI:       0000 0001 3534 4274
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 2008
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This thesis firstly describes the application of organic solvent nanofiltration (OSN) in the recycle of asymmetric hydrogenation catalysts through the retention of the (often) larger catalyst whilst allowing the smaller products to penneate. This improves the catalyst tum over number (TON) and the further addition of the ionic liquid (IL) CyPhoslOl markedly improves the enantiomeric excess in the asymmetric hydrogenation of dimethyl itaconate using Ru-BINAP. The high molecular weight of the catalyst and IL allows them to be simultaneously recycled using an OSN membrane. Although this work identifies significant potential to further the application of OSN in homogeneous catalyst recycle, there is a lack of commercially available OSN membranes with good chemical stability across a range of organic solvents and with the ability to separate compounds in the NF range of 200-1000 g morl. The central part of this thesis addresses these issues through the development of various integrally skinned asymmetric polyimide OSN membranes. A consistent method to describe the penneation property of the molecular weight cut off (MWCO) has been developed. This allows the detennination of membrane performance and integrity across a range of different membranes and solvents. The variation of membrane separation perfonnance across the NF range has been achieved through cfanging various membrane fonnation parameters. Crosslinking of these membranes significa~tly enhances the chemical stability allowing stable perfonnances in a range of organic solvents including polar aprotic solvents. Coupling chemical crosslinking with the fonner methodology simultaneously improves the membrane chemical stability and allows membranes to be tailored for specific separations. Finally, this work also examines some initial steps leading to the scale up of OSN membranes to pilot scale through the use of spiral bound elements.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available