GB1042923A - Hydrogenation of fatty oils - Google Patents

Abstract

Fats and fatty oils are selectively hydrogenated by agitating the oil in contact with particles of a suitable hydrogenation catalyst, e.g. 0.02-0.5% low density reduced nickel on silica (see Division B1), suspended therein while passing hydrogen through the agitated mass of oil and catalyst, continuously withdrawing a stream of heated oil from the main agitated mass while retaining the catalyst within the main mass of oil, suitably by passing the withdrawn stream through a filter, and simultaneously adding fresh oil to the treated mass of oil so as to maintain constant the volume of agitated oil being treated. Hydrogen, which is generally passed into the oil below the surface and withdrawn above the surface, is normally recycled to the process; some of the hydrogen withdrawn is suitably used to pretreat the oil under reduced pressure in order to remove contaminants. At intervals, hydrogen is passed into the main agitated mass through the filter in order to clear the filter of accumulated catalyst. Suitable oils for treatment, which is generally carried out at 200-350 DEG F., with pressures from atmospheric to 75 p.s.i.g., and a residence time of 80-300 minutes, are edible oils such as soyabean oil; in such cases, if the oil has an initial iodine valve above 130, products may be obtained having an iodine value below an average of 86 and a transisomer content below 50% by weight. If similar starting oils are treated at 170-200 DEG F. for a sufficient time to reduce the iodine value to below 115, e.g. to 100-115, the trans-isomer content is then generally 15-25% by weight.ALSO:An hydrogenation catalyst comprises 2-20% nickel supported on macroporous silica beads preferably having at least 50% of the total pore volume provided by pores having a diameter greater than 0.004 m and a specific surface area of 300 m2/g. The catalyst particles, which suitably have a particle density of 0.7-1, and most preferably less than the density of the oil to be treated, have a size of 20-200 m , with the major portion in the range 45-150 m . In an example, a catalyst of 100-325 mesh and a density of 0.712 was obtained by impregnating macroporous silica beads containing silica powder with 8.6% nickel formate solution and reducing the impregnated beads with hydrogen at 1000 DEG F. for 2 hours.