A new method of converting squalene, which is produced by microalgae and also found in shark livers to vehicle or jet fuel, has been developed by Prof. Keiichi Tomishige and Dr. Yoshinao Nakagawa from Tohoku University's Department of Applied Chemistry, and Dr. Hideo Watanabe from the University of Tsukuba.
This study is part of a research project titled "Next-generation Energies for Tohoku Recovery. Task 2: R&D on using algae biofuels." The project attempts to make use of oil-producing algae in wastewater treatment. The result will help to expand the utilisation of oil that is produced from wastewater.
This new method uses a highly dispersed ruthenium catalyst supported on cerium oxide.
Squalane – which is easily obtained from squalene – reacts with hydrogen over this catalyst, producing smaller hydrocarbons.
The produced hydrocarbons are composed of only branched alkanes with simple distribution and do not contain toxic aromatics. These molecules have high stability and low freezing points. These features are very different from the hydrocarbons obtained by conventional petroleum refinery.
Squalene is a "heavy oil" range of hydrocarbon. It is currently gathered from the livers of deep sea sharks and used as a component of cosmetics. However, wastewater-derived squalene is not suitable for such sensitive uses and has little demand. Most uses of oil, such as fuels, require reforming.
This catalytic system makes good use of the squalene's branched structure, while conventional methods are suitable to straight-chain molecules in petroleum. In the future, this catalytic conversion method can be applied to real wastewater samples and other important algal hydrocarbons, such as those from Botryococcus braunii.
Branched hydrocarbons are good components for fuels because of the high octane number, low freezing point and good stability. Other noble metal catalysts were also tested, but the results were inferior to the sub-nanometer-sized ruthenium on cerium oxide catalyst in terms of activity and selectivity.
The conventional catalyst, the combination of platinum and strong solid acid, produces a very complex mixture of products because of acid-catalysed isomerization. In this catalyst system, the deposition of carbonaceous solid on the catalyst is negligible, while it is often problematic in many catalytic reactions in petroleum refinery. The catalyst was reusable 4 times without loss of performance.
The detailed results of the research will be published later this June in the journal "ChemSusChem."