Microwaving waste cooking oil into chemicals

These chemicals could be used to create plastics and pharmaceuticals

Spotted: Research into sustainable solutions needs to account for both the sourcing and the disposal of commodities. Through its repurposing of waste, recycling kills two birds with one stone – the tin you bought today could be the one you threw out yesterday. Recently, a group of researchers at Kyushu University have gone a step farther: transforming waste cooking oil into new chemicals through an energy-efficient process.

Creating complex materials requires, as a first step, the production of simpler chemical precursors. Working with microwaves together with a zeolite catalyst, the Kyushu team discovered they can produce olefins – a standard precursor used widely in plastics and pharmaceuticals – from discarded biomasses such as cooking oil.

While cooking oil has previously been considered a viable, inexpensive source from which to create essential chemicals, previous transformative methods have required temperatures of up to 600 degrees Celsius. In addition to their financial and environmental cost, such energy-intensive processes produce a side effect known as ‘coking’, the buildup of unwanted residue that reduces the lifespan of the catalyst. However, by switching to microwaves as the heating method, the researchers at Kyushu not only avoided coking but quadrupled their production of olefins.

“Microwaves interact directly with materials and can selectively deliver energy to them, enabling significant energy savings compared to conventional heat-convective processes,” explained research lead Associate Professor Shuntaro Tsubaki. And not only was carbon dioxide reduced to just 1.3 per cent of the total reaction output using this technique, but microwaves can also be powered more easily by energy sources such as solar and wind, making the process even greener.

Now, the researchers are planning to further optimise the microwave-driven processes, including by improving the yield, energy efficiency, and capacity of the system.

Written By: Duncan Whitmore