The behaviour of coplanar cathodic and anodic band electrodes was investigated and their use for standard syntheses was proven to be considerably advantageous, when compared to other techniques. Electrode arrays were fabricated by screen printing platinum, silver or carbon inks. The inter-electrode distances were in the range 1 mm to 250μm for a constant band width of 1 mm. The mass transport was characterised for different inter-electrode distances and flow conditions. Figures compared positively with other cells. Two acceptable mathematical models were derived for the estimation of the resistance between coplanar band electrodes and were compared with results obtained experimentally or by simulation. Due to their excellent physical and chemical properties, platinum electrodes were found to be particularly well suited for the three syntheses investigated. The furan methoxylation, being carried out in a resistive solvent, was chosen to highlight the advantage of minimising the ohmic drop. It was also shown that the formation of by-product could be limited by acid neutralisation on the adjacent band. Vigorous mixing conditions were not crucial. With the 250 μm inter-electrode array, DHDMF could be produced with a current efficiency of 87%. This compared extremely well with other cells and furthermore the energy consumption could be reduced to 1.4kWh.kg<SUP>-1</SUP>, which represented a saving of at least 50%. The importance of having small ohmic losses was also encountered for the Kolbe reaction, where the applied voltage was set at high values. However the printed platinum film was too rugged and a passivation of the electrode was noticed. The advantage of having small inter-electrode distances was stressed by investigating the propylene epoxidation, which is a coupled reaction. Propylene oxide was produced at a rate of 0.12 mol.h<SUP>-1</SUP>.dm<SUP>-2 </SUP>for an energy consumption of 2.0 kWh.kg<SUP>-1</SUP>. This technique was thus found to be very competitive. Finally the possibility of using this method for the production of hypochlorite by electrolysis of sea water was investigated.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:641514 |
| Date | January 1994 |
| Creators | Belmont, Cecile |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/13940 |
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