A team from the Prairie Research Institute at the University of Illinois, with colleagues from the University of Birmingham and Aarhus University, have developed a nanosized bio-Pd/C catalyst for upgrading algal bio-oil.
Published in an open-access paper in the journal Fuel, their findings point to a cheaper, more environmentally friendly and renewable catalyst for processing that uses common bacteria and the metal palladium, which can be recovered from waste sources such as discarded electronics, catalytic converters, street sweeper dust and processed sewage.
The bio-oil produced from algae contains nitrogen and oxygen; treating it with palladium as a catalyst during processing helps remove those impurities. For the palladium to do its job, the bio-oil needs to flow past it during processing. Previous studies have shown that allowing the oil flow through porous carbon particles infused with palladium is an effective method, but those carbon particles are not cheap, said Prairie Research Institute researcher B.K. Sharma.
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. The oil can flow through the palladium-decorated bacteria masses as it does through the carbon particles.—B.K. Sharma
The bio-supported nanoparticles of palladium on bacterial biomass were prepared at the University of Birmingham. The produced Pd/biomass was air-dried and ground into powder for use.
To test the effectiveness of the new method, Sharma and his co-authors performed a variety of chemical and physical analyses to compare the performance of the bio-PD/C catalyst with a commercial Pd/C catalyst.
Bio-Pd/C resulted in similar catalytic activities as commercial Pd/C. Both bio-Pd/C and commercial Pd/C were able to decrease the O, N and S content by approx. 72%, 52% and 93% and improved the HHV from 35 MJ/kg to 41 MJ/kg under similar reaction conditions. However, carbon in bio-Pd/C possibly decomposed during the upgrading process, potentially reducing the reusability of the catalyst. However since bio-Pd/C can be biorefined from low-grade waste sources and used in oil upgrading a ‘once through’ process is acceptable, particularly since the catalyst can be retained for onward commercial reprocessing, effectively realizing a ‘second life’ per unit of primary resource mined.
In addition, since the bacteria to make bio-Pd can be sourced as spent biomass from a previous bioprocess this reduces waste disposal costs while realizing benefit as additional carbon neutral fuel.—Kunwar et al.
The work was conducted in collaboration with professors Joe Wood and Lynne Macaskie from the University of Birmingham, funded through the Birmingham-Illinois Partnership for Discovery, Engagement and Education program. The Natural Environment Research Council, UK also supported this research.
Bidhya Kunwar, Sam Derakhshan Deilami, Lynne E. Macaskie, Joseph Wood, Patrick Biller, Brajendra K. Sharma (2017) “Nanoparticles of Pd supported on bacterial biomass for hydroprocessing crude bio-oil,” Fuel, Volume 209, Pages 449-456 doi: 10.1016/j.fuel.2017.08.007