Waste electronics used to produce cheaper, greener biofuel catalyst

A photomicrograph of the palladium and bacteria catalyst. Image courtesy of Lynne Macaskie
A photomicrograph of the palladium and bacteria catalyst. Image courtesy of Lynne Macaskie

A new catalyst made from palladium metal and bacteria could make the production of biofuels cleaner and greener, according to researchers from the University of Illinois Prairie Research Institute.

Biofuels are costly to produce because the precursor product, bio-oil, must be processed before it is sent to the refinery to be turned into liquid fuel. To try and improve this part of the process, Illinois Sustainability Technology Centre researcher B.K. Sharma, along with his co-authors, has identified and tested a new processing method.

"Bio-oil forms from the same chemical reaction that forms petroleum," Sharma said. "But what takes millions of years naturally in the ground takes only minutes in the lab using a process that is very similar to pressure cooking."

The team’s study, which has been published in the journal Fuel, points to a cheaper, environmentally friendly and renewable catalyst for processing that uses common bacteria and palladium – a metal which can be recovered from waste sources such as discarded electronics, catalytic converters, street sweeper dust and processed sewage.

Bio-oil produced from algae in the lab contains impurities like nitrogen and oxygen. Treating it with palladium as a catalyst during the processing phase helps remove these impurities to meet clean air requirements, Sharma explained in a press release.

The innovative method also saves money by taking away the need to use costly carbon particles during processing.

“Instead of using commercially produced carbon particles, we can use bacteria cell masses as a sort of biologic scaffolding for the palladium to hold on to," Sharma said. "The oil can flow through the palladium-decorated bacteria masses as it does through the carbon particles."

Sharma’s team performed a number of tests to compare the quality of the liquid biofuel produced by their new processing treatment with that made using a commercially produced catalyst.

"We found our product to be as good or even slightly better," Sharma said. "We were able to remove the oxygen and nitrogen impurities at a comparable rate, and yielded the same volume of product using our cheaper, greener catalyst as is observed using the more expensive commercial catalyst."

However, the team also admit that the downside of their palladium-on-bacteria catalyst is that it needs to undergo processing to be reused. This is not the case with the commercially available catalyst, which can be repeatedly reused without extensive processing.  

"It is a minor caveat," Sharma said. "The fact that we have shown the potential of making refinery-ready crude oil from algae bio-oil using a catalyst that can be prepared from low-grade recycled metals and green and economical bacterial biomass proves that this is a very promising advancement. In addition, this bio-catalyst would work equally well in petrochemical processing."

A photomicrograph of the palladium and bacteria catalyst. Image courtesy of Lynne Macaskie