Feb
26
Going Straight from Farm To Diesel Fuel Tank
February 26, 2009 | Leave a Comment
A UK team that started with the University of Newcastle added the Universities of Cambridge and Manchester to an effort to design and engineer an idea of making a single catalyst for processing raw vegetable oils into diesel fuel. News this week has it that BP Plc will add its support to the research.
Plant oils contain various amounts of fatty acids that corrode metals, which need to be removed or neutralized. The Universities are working toward a design that uses a single catalyst with a reactor that can do the processing in a single continuous flow step.
Dr. Karen Wilson of York University is the principal investigator leading a wide spread multidisciplinary team while Dr. Adam Lee a senior lecturer in physical chemistry at Cambridge is handling the public information and descriptions. Lee explains, “Synthetic chemistry has dominated in the area of transportation fuels. Manufacturers add large amounts of chemicals such as sodium hydroxide or sodium methoxide, which are soluble materials that can catalyze reactions, but these catalysts can’t be recovered. We’re trying to combine our materials knowledge with reactor designs using flow systems rather than the batch reactors currently used for biodiesel production. These have several disadvantages: you can’t easily separate the products until the end of the reaction so you can’t have continuous production, the mixing can be poor and the materials can pose hazards.”
The concept was born at Newcastle who has filed a patent application. The goal is to develop a solid catalyst porous to the size of plant oil molecules with very high surface areas for the catalyst molecules. Using computational engineering the team will seek to design interconnecting pores to allow the oil to pass through in contact with the catalysts. The structures to be built are known as mesostructure solids and the team will be designing a second generation that has pore sizes larger to accommodate the viscosity of plant oils.
Plant oil poses a challenge with their long chain molecules. The team expects to use silica for the structure as its thermally and chemically stabile. Silica can also tolerate the active catalyst sites whether strongly base or acid.
The idea is for the catalyst to perform two chemical reactions in one — neutralize the free fatty acids and simultaneously esterify the plant oil triglycerides into biodiesel. The acids will be converted into an ester, a non-corrosive molecule that would be burnt off in the vehicle engine. The researchers ideal hope is to devise catalysts that have basic sites and acidic sites in the same material, so the acidic sites will esterify the undesired contaminants and the basic sites will perform the transesterification to make the biodiesel. Another solution would be set up a two-bed system, where the plant oils are pushed through a catalyst bed to deal with the fatty acids then moved on to biodiesel creation.
Lee says, “With these porous silicas, you could put down nanoparticles of something such as magnesium oxide, which is a nice solid base. Alongside those, you could anchor a range of solid acids, such as sulphated zirconias or polyoxyl methylates. These could be grafted into the same particle so you can have a crystallite of silica that contains solid base and acid sites geographically separated so they can attack each kind of molecule coming through.”
Another point is the variation of plant oils. Jatropha is an early target raw oil. Lee says, “The oil composition will vary with the type of plant it comes from, so the trick will be to find a catalyst that enjoys working with jatropha oil.” A project goal is to make a catalyst tailored to feedstocks such as jatropha, which grows on scrubland in arid conditions and does not compete with food crops. Yet by the end of the project the team hopes to have a suite of catalysts tuned to handle different feedstocks, an operating reactor system in which to use the catalyst and a semi-pilot scale sized operation to make the catalysts.
Long term the project plans to have portable reactor designs that allow farmers to make biofuels. A solid-catalyst system would make possible a reactor made with a 2 meter long pipe and a few of grams of catalyst bed, where plant oils could be poured in at the top and biodiesel would come out at the bottom.
Quite an idea for all that unused land across the planet. It would also offer a cash crop to countless subsistence farmers. Over time these kinds of ideas will surely raise the standards of living across lot of the world’s population while cutting into fossil based fuel market share.
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