Summary
In many industrial chemical processes, separation of interfering compounds is necessary to purify organic solvents. For example, in homogeneous catalysed hydroformylation carried out at high pressure, olefin educt and synthesised aliphatic product are separated using a precious metal catalyst. The subsequent thermal resolution required is very energy intensive and leads to significant losses of the precious metal ligands.
Organophilic nanofiltration - separation of low-molecular compounds of organic solvents using membranes - is an alternative separating method with major potential in terms of saving energy and raw materials and in avoiding environmentally hazardous auxiliary materials.
To implement the principle in practice, solvent-resistant membranes with sufficiently high separating capacity, practical modular systems and comprehensive process modelling are required. The aim of the research project was to achieve these necessary development advancements and demonstrate the method in a pilot process.
Results:
- It was demonstrated that the catalyst/ligand system is retained by the membrane.
- This results in high precious metal retention of up to 95% and major potential for savings on precious metals.
- The application prospects depend on further development of the PIM 1 membranes in terms of their long-term stability.
- If long-term stability and successful technical implementation can be achieved, nanofiltration processes would be possible with around 40% of the energy previously required.
- Two models were developed for simulation in organophilic nanofiltration.
- It is advantageous to carry out the process under gas pressure.
- A pilot plant was successfully operated under 17 bar synthesis gas during the project.
- The use of the membranes is not restricted to organophilic nanofiltration.
