Sunlight gives biodiesel by-product a second life as hydrogen and valuable chemicals

Sunlight can covert glycerol, a low value product of biodiesel production into hydrogen and higher value chemicals

A photocatalyst based on zinc indium sulfide, modified with very small amounts of nickel and cobalt, increased the hydrogen evolution rate and the production of glyceraldehyde and dihydroxyacetone

The research team used X-ray absorption spectroscopy and infrared microspectroscopy at the Australian Synchrotron to observe the catalytic reactions in real time

Australian researchers and international collaborators have demonstrated a solar-driven approach to convert glycerol, a low-value by-product of biodiesel production, into hydrogen and higher-value chemicals. Using advanced techniques at Australian Synchrotron, they revealed how the catalyst changes while it was working.

The study, led by researchers at the University of New South Wales, investigated a process known as photoreforming, in which light energy is used to drive chemical reactions to simultaneously produce hydrogen and transform organic feedstocks into useful products. The research was published in Applied Catalysis B: Environment and Energy.

Glycerol is produced in large quantities by the growing biodiesel industry, with approximately 100 kilograms generated for every tonne of biodiesel. Crude glycerol can be worth as little as US$0.11 per kilogram.  Chemicals can be produced from it, such as glyceraldehyde and dihydroxyacetone, which have applications in the chemical and pharmaceutical industries, valued at approximately US$75 and US$150 per kilogram, respectively.

Dr Denny Gunawan from UNSW said the opportunity was to use sunlight not only to produce hydrogen, but also to extract greater value from an existing industrial by-product.

“Rather than using an expensive feedstock simply to produce hydrogen, photoreforming gives us the opportunity to do two useful things at once; generate hydrogen and convert a low-value by-product into more valuable chemicals,” said Dr Gunawan.