Production of Biodiesel From Vegetable Oil

Production of Biodiesel From Vegetable Oil

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I’m professor Scott Williams and I serve as the managing director of the Omaha biofuels cooperative. The co-op is partnering
with Metropolitan Community College to develop biofuels capabilities here in Omaha, to consult on biofuels implementation and to provide education about biofuels. Today I’m going to be discussing and demonstrating the production of biodiesel from vegetable oil. Even though the reaction has a complicated sounding name it’s fairly easy and straightforward to demonstrate. As you can see here, most of the equipment can be found around the house. The reaction involves three main ingredients or reactants: Vegetable oil. Methanol or methyl alcohol, also known as wood alcohol, sourced from a common gasoline fuel additive. And a catalyst, which is lye, often used in homemade soap making. Both methanol and lye should be used with appropriate precaution including personal protective equipment. Methanol is volatile flammable and toxic with contact on skin. Lye is highly caustic, dissolves many materials, and also produces chemical burns immediately on contact with skin. I’ll be wearing along sleeve lab coat, goggles, and laboratory gloves. The recipe used today will be two
hundred milliliters of cooking oil, fifty milliliters of methyl alcohol, and
four grams of the catalyst lye. To start we need to warm up the cooking oil, which I have already begun here, using a modified mister biofuel. Now that the oil is nearly
warm enough, we can start with the other reactants. We’ll add a weigh boat to the scale
and tare, or reset the scale to zero, and then weigh out four grams of the catalyst lye. Next we’ll measure fifty milliliters of the methyl alcohol into our flask. Next we’ll dissolve the catalyst into the
methanol making the meth oxide solution. The dissolution reaction is exothermic,
meaning it produces and gives off heat. At a larger scale it can even produce
dangerously high levels of heat, getting to above the point of boiling for methanol, which is a hundred and forty degrees Fahrenheit, significantly lower than the boiling point of water. We’re going to use a magnetic stir plate to help provide mixing. In the base is a motor attached to a magnet. The magnet can magnetically couple to a magnetic stir bar and when the motor rotates, the stir bar
rotates, providing mixing. Next we dissolve the catalyst into the methanol, making a meth oxide solution. It takes about three minutes for all of the lye to dissolve into the methanol, forming the meth oxide solution. Now that the lye is mostly dissolved in
methanol, we can remove the stir bar We’ll measure out two hundred milliliters
of the heated cooking oil into our reaction vessel. Today we’re using a mason jar. We’ll place the jar on the mixing plate, and add a stir bar. To make the reaction happen we need heat, which we provided by adding it to the oil, and mixing which we get from the
magnetic plate, and time. We need to make the reaction happen with heat but it’s
critically important to make sure the temperature is not above the boiling
point of the methanol, or else a violent eruption can take place when we mix the reactants. For this we’re using a standard digital kitchen thermometer. As I mentioned previously, the boiling point of the methanol is one hundred and forty eight degrees Fahrenheit, so we just need to stay below that with the cooking oil. Before we react the methoxide with the oil, let’s talk briefly about the chemistry that we’ll see taking place. The vegetable oil and methyl alcohol are going to undergo a reaction called transesterification It sounds complicated,but the name is fairly straightforward. “Trans” means cross, “ester”is the name of a specific type of chemical bond in the vegetable oil, and “ification” is the process of making. So transesterification is the process of crossing and making ester bonds. The vegetable oil and methyl alcohol will cross cut each other’s chemical bonds and form new chemical bonds. We’ll be left with biodiesel, technically called fatty acid methyl esters, FAME, biodiesel, and glycerol, which is also known as glycerin. Glycerol is water-soluble, but is not soluble in the oily biodiesel, so it’ll fall down to the bottom. The two phases can’t mix, like oil
and water, so they separate. Here’s where the really good stuff happens. We’ll mix
the methoxide solution and the heated cooking oil and watch the reaction happen. Initially we can see the amber colored
oil getting lighter as we mix in a colorless liquid. As the reaction takes place, the glycerol that has been cut away from the vegetable oil will start to appear. glycerol from used cooking oil is significantly dark, darker than the vegetable oil, and it’ll make the entire mixture start to appear dark. Now that we’ve given enough heat, mixing, and time for the reaction to take place, we’ll stop the mixing. We need to let the glycerol settle down to the bottom. Glycerol has had time to separate and settle out of the biodiesel leaving two distinct layers clearly visible. In about 24 hours settling time, the biodiesel would appear completely clear, and all of the glycerol would be down at the bottom. With a valve at the bottom of the container, we can drain away the glycerol and leave just the free biodiesel on the top. The by-product glycerol can be useful in the process of making soaps. The last step would be to wash away any residual reactants or contaminants in the biodiesel, such as soap. Then the final fuel is ready to use. Biodiesel is a drop-in replacement for petroleum diesel in any diesel engine application: cars, vans, trucks, trams, trains, semi-trucks, generators, even heating applications. Biodiesel burns cleaner at the tailpipe, emitting less soot and less air pollutants. With no sulfur in the fuel, there’s no sulfur oxides released from the tail pipe which can contribute to smog and acid rain. Since biodiesel is produced from bio sources, it’s a net zero carbon cycle. There are no contributions of CO2 as greenhouse gas that can cause global climate change. Biodiesel can be made from recycled
sources, including used cooking oil, and can be produced domestically, even locally,
right where it’s needed and used. Stay in touch with Metropolitan Community College and the Omaha Biofuels Cooperative to keep learning more.

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