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Dumb question - what is 'white oil'?
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That's not a dumb question. White oils are clear oils with low toxicity. In the US, white oil product specifications are regulated by, e.g., 21 CFR 178.3620(b). They are used in foods, pharmaceuticals, etc.
A white oil can be made from a petroleum oil as follows. First, a lube fraction is separated from an upgraded crude oil. Some aromatics, nitrogen, and sulfur are removed using a solvent. The low-aromatics product (sometimes called a raffinate) is then dewaxed to improve lubricating properties, and treated with a hydrotreating catalyst to remove more sulfur and nitrogen. Sometimes the dewaxing precedes hydrotreating, sometimes hydrotreating is first, particularly when hydrodewaxing is used as the dewaxing step. Even a small amount of sulfur and nitrogen can ruin a hydrodewaxing catalyst.
The hydrotreated, dewaxed raffinate (sometimes called a dewaxed oil) is then treated in another catalytic processing step called hydrofinishing where most of the remaining aromatic molecules are saturated. If processed with sufficient severity, the result is a "water white" (clear) oil with low toxicity. Processing is always a balance between product quality and yield. Higher yield can be obtained at the expense of product quality, and vice versa.
White oil can also be made by hydrocracking a petroleum oil fraction, separating a lube fraction from the hydrocracked oil, hydrodewaxing, and then hydrofinishing.
Big oil companies like Chevron and ExxonMobil sell catalysts and processes for making white oil.