14^th World Bioenergy Congress and Expo

https://bioenergy.insightconferences.comBacteria can manufacture supported nano-catalysts from solutions of precious metals (PMs), waste leachates and industrial processing solutions as an economic alternative to the use of primary-sourced PM catalysts in high volume/low value applications. Metal deposition occurs via nucleation of soluble metal ions to cellular ligands followed by enzymatically-catalysed growth of nanoparticles (NPs), to form templated, structured nanomaterial. This can self-immobilize onto a carrier for easy catalyst recovery, multiple re-use and in continuous-flow processes. Monometallic structures like Pd-NPs have multiple applications but faster reactions and higher selectivity can be achieved with a second metal to make alloys or core-shell nano-patterned structures. The second metal coupling is abiotic; importantly, no live bacteria remain in the material, while the catalysts can be made directly from highly acidic leachates in order to ‘bio-refine’ precious metal (PM) scraps, overcoming the economic barrier to use of PMs for large or sacrificial operations. Examples will describe the use of such neo-catalysts in fuel cells and also applications in upgrading of intermediates produced in the thermochemical processing of organic materials to a platform chemical and fuel precursor; the use of catalysts bio-refined from road dusts in the catalytic upgrading of heavy fossil oils (reduced viscosity, levels of impurities and coking)1 and in the catalytic hydrodeoxygenation of pyrolysis oil from biomass  2. Throughout, the bio-derived catalysts performed comparably to commercial catalysts and favourable oil distillation curves were obtained. In addition, when upgrading 5-hydroxymethyl furfural extracted from biomass hydrolysate the commercial catalyst was ineffective although a bio-Pd/Ru equivalent achieved the conversion. For economy at scale, similar results were obtained using ‘second life’ bacteria left over from another bioprocess, while the catalysts were bio-refined from PMs from high volume wastes (road dusts). The latter has been subjected to a life cycle assessment showing process viability at scale.