Hydrogenation of soybean oil with copper-chromium catalyst: Preliminary plant-scale observations

Abstract

Four commercial hydrogenations were carried out on 20,000 1b batches of soybean oil with 0.25, 0.5, and 1% fresh copper-chromite catalyst and 1% used catalyst. Hydrogenations proceeded smoothly at catalyst levels of 0.5 and 1%, but the reaction was slow at a 0.25% concentration. Kinetic, selectivity ratio$(K\frac{{Ln}}{{Lo}})$ and fatty acid compositional data were acquired during several of the hydrogenation runs. Nickel contamination, confirmed by analysis of used copper catalyst, lowered selectivity. Copper content of the oil rose during hydrogenation, but normal processing steps, particularly bleaching and winterization, removed it to below levels (0.01–0.02 ppm) detectable by direct atomic absorption spectroscopy. Both copper and chromium remaining in the oil after processing were concentrated by winterization in the stearine fraction. Organoleptic, oxidative, and room odor tests showed that oils of good stability can be produced on a commercial scale by copper hydrogenation and winterization. Information was gained regarding problems involved in the plant use of copper-chromite catalyst for hydrogenating soybean oil for edible purposes.