THE ELECTROCHEMICAL HYDROGENATION OF EDIBLE OILS IN A SOLID POLYMER ELECTROLYTE REACTOR - I - REACTOR DESIGN AND OPERATION

A new electrochemical method has been devised and tested for the moder ate temperature/atmospheric pressure hydrogenation of edible oils, fat ty acids, and fatty acid methyl esters. The method employed a solid po lymer electrolyte (SPE) reactor, similar to that used in H-2/O-2 fuel cells, with water as the source of hydrogen. The key component of the reactor was a membrane-electrode-assembly, composed of a RuO2 powder a node and either a Pt-black or Pd-black powder cathode that were hot-pr essed as thin films onto the opposing surfaces of a Nafion cation-exch ange membrane. During reactor operation at a constant applied current, water was back-fed to the RuO2 anode, where it was oxidized electroch emically to O-2 and HC Protons migrated through the Nafion membrane un der the influence of the applied electric field and contacted the Pt o r Pd cathode, where they were reduced to atomic and molecular hydrogen . Oil was circulated past the back side of the cathode and unsaturated triglycerides reacted with the electrogenerated hydrogen species. The SPE reactor was operated successfully at a constant applied current d ensity of 0.10 A/cm(2) and a temperature between 50 and 80 degrees C w ith soybean, canola, and cottonseed oils and with mixtures of fatty ac ids and fatty acid methyl esters. Reaction products with iodine values in the range of 60-105 were characterized by a higher stearic acid co ntent and a lower percentage of trans isomers than those produced in a traditional hydrogenation process.