Vegetable oil refining
Vegetable oil refining is a process to transform vegetable oil into fuel by hydrocracking or hydrogenation. Hydrocracking breaks big molecules into smaller ones using hydrogen while hydrogenation adds hydrogen to molecules. These methods can be used for production of gasoline, diesel, and propane. Produced diesel fuel is known as green diesel or renewable diesel.
The majority of plant and animal oils are vegetable oils which are triglycerides—suitable for refining. Refinery feedstock includes canola, algae, jatropha, salicornia and tallow. One type of algae, Botryococcus braunii produces a different type of oil, known as a triterpene, which is transformed into alkanes by a different process.
Comparison to biodiesel
Based on its feedstock green diesel could be classified as biodiesel; however, based on the processing technology and chemical formula green diesel and biodiesel are different products. The chemical reaction commonly used to produce biodiesel is known as transesterification. Vegetable oil and alcohol are reacted, producing esters, or biodiesel, and the coproduct, glycerol.
When refining vegetable oil, no glycerol is produced, only fuels. Refined diesel can be produced that is chemically identical to diesel fuel and does not have the problems specific to transesterified biodiesel. Any blending ratio can be used, and no modifications or checks are required for any diesel engine.
Some commercial examples of vegetable oil refining are NExBTL, H-Bio, the ConocoPhilips process, and the UOP/Eni Ecofining process. Neste Oil is the largest manufacturer, producing 2 million tons annually (2013). Neste Oil completed their first NExBTL plant in the summer 2007 and the second one in 2009. Petrobras planned to use 256 megalitres (1,610,000 bbl) of vegetable oils in the production of H-Bio fuel in 2007. ConocoPhilips is processing 42,000 US gallons per day (1,000 bbl/d) of vegetable oil.
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- University Of Wisconsin / College Of Engineering (2005, June 6). Green Diesel: New Process Makes Liquid Transportation Fuel From Plants. ScienceDaily. Retrieved August 10, 2010
- Renewable Diesel Primer. Retrieved August 10, 2010