Development of catalytically reactive porous membranes for the selective hydrogenation of sunflower oil
AbstractThe main objective of this contribution was to develop and validate new catalytically reactive porous membranes for hydrogenation of edible oil in a membrane reactor. High flux polymer membranes from polyethersulfone and polyamideimide with and without inorganic alumina filler were produced on a technical membrane casting machine. These porous membranes show water fluxes of about 30,000 L/m2 h bar and oil fluxes of 900–2000 L/m2 h bar at 60 °C. The pore volumes are in the range of 5–7 mL/100 cm2 of membrane area. Large pores at high porosity were received by addition of a water soluble ethyleneoxide-propyleneoxide-b-copolymer (Pluronic® F127), that forms distinctive globules in the solution when cooled below 10 °C. The catalytic activity was obtained by two different methods: by wet impregnation of the membrane in a catalyst precursor solution (palladium acetate or hexachloroplatinate) followed by calcination, respectively, chemical reduction or by addition of ready-made supported catalysts to the membrane casting solutions. Catalytically activated membranes with different Pt-contents (0.1–1 g/m2) were applied in first membrane reactor tests to hydrogenate refined sunflower oil. Within 6 h the iodine value decreased considerably and about a half of the linoleic acid was hydrogenated, which is the major compound in sunflower oil triglycerides. The overall trans-content of the fatty acids was about 25%. Membrane performance was verified in up to 5 days of discontinuous operation.