Rapeseed Acid Oil

About This Product

Rapeseed acid oil is the split soapstock from chemically refined rapeseed oil, including the low-erucic varieties often traded as canola. Refineries neutralise crude or degummed rapeseed oil with caustic soda; the soaps and entrained oil separated in that step are acidulated, usually with sulphuric acid, and the oil phase is recovered as a dark, high-FFA product. Its character follows the rapeseed crop: a low share of saturated fatty acids and a high share of oleic acid, with moderate linoleic and linolenic acid. That composition makes it attractive for colder markets. Rapeseed methyl ester has long been the reference biodiesel in northern and central Europe because its low saturates give a favourable cold filter plugging point, and ester made from rapeseed acid oil broadly inherits that behaviour. Iodine value typically falls around 100–120 g I2/100 g, usually within the EN 14214 limit without heavy blending. The trade-off is sulphur. Rapeseed contains glucosinolates, whose sulphur-bearing breakdown products can partly follow the oil into the soapstock, and acidulation with sulphuric acid adds to that load. Chlorophyll from the seed can also concentrate in the soapstock and is removed with bleaching earth. For FAME, FFA of typically 50–80 % requires acid esterification or glycerolysis before transesterification, and many producers distil the ester to meet the 10 mg/kg sulphur limit. For HVO and HEFA-SPK (SAF), the C18-rich profile converts efficiently into diesel- and jet-range paraffins, and sulphur is removed in the hydrotreater at the cost of extra hydrogen; phosphorus, metals, chlorophyll-derived compounds and sulphate should still be reduced in pretreatment. Typical contract parameters are TFM (often 90–95 % or more), MIU (commonly up to 3–5 %), FFA as % oleic acid, iodine value, sulphur, phosphorus and, for HVO, sodium, calcium, magnesium, iron and chloride. Ask which sulphur method the laboratory uses: ultraviolet fluorescence methods designed for low levels give more reliable results than general elemental screening. Rapeseed acid oil is not named in Annex IX of the Renewable Energy Directive. Under RED III it is treated as a processing residue by some authorities and as a co-product by others, and some aviation schemes restrict acid oils. Confirm the category and the certificate scope for the specific lot with your certification body, and make sure the documents identify the originating refinery and can be booked cleanly in your mass-balance system. Rapeseed acid oil is usually liquid at ambient temperature and moves in flexitanks (with liner compatibility confirmed), lined or stainless ISO tanks and bulk parcels; light heating helps discharge in winter. In an enquiry, state your TFM, MIU, FFA and sulphur basis, the conversion route, volume, packaging, delivery terms and documentation needs.