Homogeneous catalysts are extremely useful tools that are extensively used in manufacturing processes, particularly in chemical and pharmaceutical processing. However, recycling and reusing such catalysts without damaging their prized chemical activity has long been considered a challenge.
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Current recycling methods are energy-intensive, and their reliance on heat destroys the catalyst’s structure while producing a significant carbon footprint. Other issues with being unable to effectively recycle catalytic waste include the environmental cost of consistent mining and increased waste production, as well as the economic impact that can have a huge impact on both manufacturing companies and consumers.
Recently, a group of researchers at the Beckman Institute for Advanced Science and Technology have developed a greener solution for recycling homogeneous catalysts. The team’s novel electrochemical approach marks a long-awaited solution to the decades-long challenge of finding an effective method for recycling homogeneous catalysts.
Currently, many industries don’t recycle homogenous catalysts at all due to the costs and the complexity of the process; they just throw them away and live with the cost.
Xiao Su, Assistant Professor of Chemical and Biomolecular Engineering, Beckman Institute for Advanced Science and Technology
“If the catalyst does get recycled, the process can be very expensive and inefficient, and the catalyst structure is often destroyed. In general, the burden is placed on the mining side, because there’s a continuous need for more of those platinum metals,” Su continued.
Electrochemical Recycling
The novel recycling method developed by the team at the Beckman Institute was focused on separating platinum and palladium homogenous catalysts, which are used in industrial chemical manufacturing processes. The redox-mediated electrochemical approach for catalyst recycling utilizes metallopolymer-functionalized electrodes for both binding and release.
This means that an electrical field is applied to the redox-mediated electrode, which is used to separate the reactive mixture as the catalyst binds to the redox-electrode. The catalyst can be released into a new mixture solution by applying an inverted electrical field to the redox-electrode.
Therefore, catalysts can be used for several cycles using the team’s novel electrochemical process and consequently limit waste production. Moreover, the team has reported that their method is less energy intensive as it does not depend on heat, unlike current conventional catalytic recycling methods.
The cool part about our recycling method is that we’re purely electrically driven... It’s a step toward making the whole manufacturing process more sustainable and having electricity driving things instead of heat.
Xiao Su, Assistant Professor of Chemical and Biomolecular Engineering, Beckman Institute for Advanced Science and Technology
Green Innovation
Moving from energy-intensive recycling methods towards a more sustainable approach not only demonstrates the capacity to make recycling catalysts more environmentally friendly but also represents wider green innovation that takes on the challenges of recycling homogeneous catalysts.
As a result of the complexity of conventional catalyst recycling methods, the recycling of catalysts is not generally considered standard practice. However, the method developed by the Beckman Institute team could help to change attitudes toward the widespread use of homogenous catalysts.
What we’re doing now is making these very powerful catalysts feasible and cheap to use for important reactions… Eventually we’d like to see an entirely zero-waste, high-energy efficiency chemical manufacturing process.
Xiao Su, Assistant Professor of Chemical and Biomolecular Engineering, Beckman Institute for Advanced Science and Technology
Moving forward, the team will push beyond a small group of platinum-group homogeneous catalysts and test their method in a broader class of metals in the hope that the novel electrochemical recycling process can prove extra utility. The results and details of their current research were published in the journal Science Advances.
References and Further Reading
Cotty, S. et al., ‘Electrochemical Recycling of Homogeneous Catalysts’, Science Advances, Vol. 8. 42. Available at: https://www.science.org/doi/10.1126/sciadv.ade3094
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