Making biodiesel from dirty old cooking oil just got easier

A global team including researchers from The University of Western Australia has developed a powerful, low-cost method for recycling used cooking oil and agricultural waste into biodiesel, and turning food scraps and plastic rubbish into high-value products.

The method, published today in Nature Catalysis, harnesses a new type of ultra-efficient catalyst that can make low-carbon biodiesel and other valuable complex molecules out of diverse, impure raw materials, even when containing up to 50 per cent contaminants.

The material is so tough that it could double the productivity of manufacturing processes for transforming waste into high-value chemical products.

To make this possible, the team designed a porous ceramic sponge containing different specialised active sites within pores of different sizes.

Molecules initially enter the material through large pores where they undergo a first chemical reaction, and then proceed into smaller pores where a second reaction occurs to form the desired product.

It is the first time that a multi-functional catalyst material has been developed that can perform several chemical reactions in sequence within a single catalyst particle, and is a potential game changer for the US $34 billion global catalyst market.

The material is also cheap and easy to manufacture, using no precious metals, and requires little more than a large container, some gentle heating and stirring.

The research team used UWA’s world-leading magnetic resonance facilities to characterise the new material.

Co-author Dr Neil Robinson from UWA’s Department of Chemical Engineering said that magnetic resonance methods provided a unique approach for porous materials characterisation.

“Using the specialist facilities here at UWA we were able to look inside the pore structure of this fascinating new material in a totally non-destructive manner,” Dr Robinson said.

“By watching the behaviour of liquid molecules in and around the material, it was possible to show that the different pore structures were well-connected, and that liquid outside of the material preferentially enters the large pores first, before moving into the smaller pores.

“These observations were crucial in showing that molecules can reach the different active sites within this material, and do so in the right order.”

The material provides a low-cost approach that could reduce reliance on fossil fuel-derived diesel, a process that is particularly important in developing countries, where it is the primary fuel used to power household electricity generators

The research was funded by the Australian Research Council with collaborators from RMIT University, University College London, University of Manchester, University of Plymouth, Aston University, Durham University and University of Leeds.