大豆酸化油 — Frequently Asked Questions

Typically about 115–135 g I2/100 g, reflecting soybean oil's high linoleic and linolenic acid content. The exact figure depends on how much neutral oil and other material the soapstock carried. For biodiesel, a value at the top of that range can push the finished ester towards the EN 14214 limit of 120, so many producers blend it with more saturated feedstocks.

Crude soybean oil carries a relatively large amount of phospholipids. Where a refinery neutralises without fully degumming first, or routes gums into the soapstock, phosphorus ends up in the acid oil. Phosphorus is removed by degumming and bleaching before hydrotreating and must be very low in finished biodiesel, so ask for a lot analysis and set a limit that suits your pretreatment.

After esterification and transesterification it gives a methyl ester with good cold-flow properties, but its polyunsaturated fatty acids lower oxidation stability. Producers commonly add antioxidant and manage iodine value by blending. Some also distil the ester to remove colour bodies, sulphur compounds and unsaponifiables carried over from the acid oil.

Its high FFA is acceptable for hydrotreating, but its unsaturation raises hydrogen demand compared with palm-based or animal-fat feed. Phosphorus, sodium and sulphate must be reduced in pretreatment. For SAF, its C18-rich profile suits jet-range yield once the chains have been cracked and isomerised, subject to the compliance route accepting acid oils.

It is not named in Annex IX. Some authorities treat it as a processing residue and others as a co-product with limited incentives, and soy-derived materials face specific restrictions in some markets. Confirm the classification for your destination and the certificate scope with your certification body before contracting, and check that the documents identify the originating refinery.

Give your TFM basis, maximum MIU, FFA, iodine value range, sulphur and phosphorus limits, conversion route, volume per shipment, packaging (flexitank, ISO tank or bulk), delivery point and Incoterm, and the sustainability documents you require. Named test methods for each parameter help avoid disputes when the discharge analysis is compared with the loading analysis.