November 2, 2020
Dr Neil Robinson and Prof Mike Johns from the Fluid Science and Resources Research Group at The University of Western Australia (UWA) found significant success this week as part of a large, international project published in the journal Nature Catalysis.
The article describes a powerful and low-cost method for recycling waste biomass into value-added chemicals using a new, ultra-efficient catalyst material. This catalyst can make low-carbon biodiesel and other valuable and complex molecules from diverse, impure raw materials containing up to 50% contaminants.
The material is so tough that it could double the productivity of manufacturing processes for transforming waste into high-value chemical precursors.
To make this possible, the team designed and synthesised a hierarchically porous silica scaffolding containing spatially segregated active sites within pores of different sizes. It is the first time that a multi-functional catalyst material has been developed that can perform several chemical reactions in sequence within a single catalyst particle, and is potential game changer for the $US 34 billion global catalyst market.
The material is also cheap and easy to manufacture, using no precious metals, and requires little more than a large container, some gentle heating and stirring.
Reagent molecules initially enter the material through large macropores where they undergo a first chemical reaction, and then proceed into smaller mesopores where a second reaction occurs to form the desired product.
To characterise this new material, the project made extensive use of the world-leading nuclear magnetic resonance (NMR) facilities available within the Fluid Science and Resources Research Group at UWA.
Using state-of-the-art low-field NMR relaxation measurements, Dr Neil Robinson was able to carefully characterise the connectivity of the different pore structures, and to observe the preferred route that molecules take when moving into the material.
“Magnetic resonance methods provide a unique approach for porous materials characterisation” remarked Dr Robinson.
“Using the specialist facilities here at UWA, we were able to ‘look inside’ the pore structure of this fascinating new material in a totally non-destructive manner.
“By watching the behaviour of liquid molecules in and around the material, it was possible to show that the different pore structures were well-connected. We were also able to see that liquid outside of the material preferentially enters the large pores first, before moving into the smaller pores.
“This information was crucial in confirming the desired structural characteristics of the silica scaffold, and that reagents can reach the different active sites in the required order.”
The material provides a low-cost approach that could reduce reliance on fossil fuel-derived diesel, a process that is particularly important in developing countries, where diesel is the primary fuel used to power household electricity generators.
‘A spatially orthogonal hierarchically porous acid-base catalyst for cascade and antagonistic reactions’, with collaborators from RMIT University, University College London, University of Manchester, University of Plymouth, Aston University, Durham University and University of Leeds, is published in Nature Catalysis (DOI: 10.1038/s41929-020-00526-5).
This work was funded by the Australian Research Council.