Biodiesel production method could reduce fuel’s drawbacks

A new method of producing biodiesel from microalgae aims to overcome some of the previous drawbacks of the fuel.

Using a novel catalyst, the researchers at the Technical University of Munich were able to produce saturated hydrocarbons suitable for use as high-grade fuels in vehicles.

For the production of biofuels, microalgae are an interesting alternative to conventional oil-containing crops such as soybean and rapeseed.

‘They grow significantly faster than land-based biomass, have a high triglyceride content and, unlike the terrestrial cultivation of oilseed plants, their use for fuel production does not compete with food production,’ said project lead Johannes Lercher of Munich.

Previously known methods for refining oil from microalgae suffer from various disadvantages. The resulting fuel either has too high an oxygen content and poor flow at low temperatures, or a sulphur-containing catalyst may contaminate the product. However, other catalysts are still not efficient enough.

The Munich scientists developed a new process, for which they have developed a novel catalyst: nickel on a porous support made of zeolite HBeta. They have used this to achieve the conversion of raw, untreated algae oil under mild conditions (260°C, 40-bar hydrogen pressure).

After an eight-hour reaction, the researchers obtain 78 per cent liquid alkanes with octadecane (C18) as the primary component. The main gas-phase side products are propane and methane.

‘The products are diesel-range saturated hydrocarbons that are suitable for use as high-grade fuels for vehicles,’ Lercher said.