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Biodiesel Production by Mixed Solid Oxide Catalysts
KTH, School of Chemical Science and Engineering (CHE).
2014 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Biodieselproduktion genom blandoxidkatalysatorer (Swedish)
Abstract [en]

With a higher strain on existing energy sources, many of which are fossil fuels, more sustainable energy sources are needed. Therefore it would be a good idea to look into fuels that are produced from a renewable feed stock, e.g. biofuels. Of these biofuels, biodiesel is a promising choice; it is commonly produced through transesterification of oil and a shorter alcohol.

In order to produce biodiesel through transesterification, a catalyst is required. Currently the catalysis in the industry is carried out using homogeneous catalysts, making the clean-up steps for the final product, very cumbersome. Therefore it would be ideal to be able to catalyse the transesterification, heterogeneously.

To find out how well the heterogeneous catalysts perform they were tested in a lab-scale-setup. Different amounts of Li2O and MgO (5 and 10 wt.% Li2O, and 5 and 30 wt.% MgO) was added to the carriers mayenite and alumina. The catalytic activity of the materials was measured by calculating the biodiesel yield obtained by GC analysis. The best catalysts were tested for reusability by filtration. Furthermore, a kinetic study of the catalyst that proves most effective was performed.

From the various experiments it was found that MgO when applied to mayenite showed low activities, between 5.9 – 23.6% yield. However, the Li2O showed activities varying between 17 – 100% yield. The alumina proper was also found to have catalytic properties (83.7% yield), however when impregnating it with too much catalytic material the activity dropped as low as to 78.5% in one case. The bare mayenite showed no activity in biodiesel production.

The catalysts studied for reusability tests were Li2O added to mayenite and MgO added to alumina. The mayenite-based catalyst showed excellent reusability properties where both the original run and the re-run provided 100% yield. The alumina-based catalyst that was re-run dropped from 83.4% to 34.1% yield.

The kinetic study of the Li2O-impregnated mayenite showed that mass-transfer-limitations were not present in the reaction. The reaction rate constant was determined to be 0.045 [min-1]

The study has shown that alumina can catalyse the transesterification, that reusing the mayenite-based catalysts works, and that, when impregnating the alumina with Li2O and MgO, the activity increases at low impregnations, and then decreases again at higher concentrations.

Place, publisher, year, edition, pages
2014.
Keyword [en]
Rapeseed oil, transesterification, heterogeneous catalysis, alumina, mayenite
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-158562OAI: oai:DiVA.org:kth-158562DiVA: diva2:778312
Available from: 2015-01-09 Created: 2015-01-09 Last updated: 2017-08-29Bibliographically approved

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