Acetaldehyde, a vital chemical used in a wide range of products such as perfumes, plastics, and pharmaceuticals, is traditionally produced using ethylene, a petrochemical. However, with increasing environmental concerns surrounding the use of fossil fuels, there is growing pressure on the chemical industry to find greener alternatives. Currently, acetaldehyde is produced through the Wacker process, a method that relies on ethylene derived from oil and natural gas, combined with strong acids like hydrochloric acid. While effective, this process has a large carbon footprint, is resource-intensive, and is not sustainable in the long term.

To address these challenges, scientists have been exploring the electrochemical reduction of carbon dioxide (CO2) into valuable chemicals. This approach not only reduces CO2 emissions but also creates useful products, tackling two critical environmental issues simultaneously. Among the promising solutions, copper-based catalysts have shown potential for converting CO2 into acetaldehyde. However, past attempts have faced challenges in achieving the necessary selectivity, often producing a mixture of byproducts instead of the desired acetaldehyde.

Now, a team of researchers from a public-private consortium, led by Cedric David Koolen at EPFL, Jack K. Pedersen at the University of Copenhagen, and Wen Luo at Shanghai University, has developed a novel copper-based catalyst that can efficiently and selectively convert CO2 into acetaldehyde. This breakthrough, published in Nature Synthesis, demonstrates an impressive 92% selectivity for acetaldehyde, offering a more sustainable and greener method of production. The new catalyst is not only effective but also scalable and cost-efficient, making it suitable for industrial applications and potentially replacing the traditional Wacker process.

“The Wacker process has remained largely unchanged for over 60 years, so the time was ripe for a green breakthrough,” says Koolen. To achieve this, the team used spark ablation to create tiny clusters of copper particles, each around 1.6 nanometers in size. These particles were immobilized on carbon supports to create a stable and reusable catalyst. The team then used synchrotron light sources and X-ray absorption spectroscopy to confirm that the copper clusters were effectively converting CO2 into acetaldehyde.

In laboratory tests, the copper clusters demonstrated 92% selectivity for acetaldehyde at low voltage, a key factor for energy efficiency. The catalyst also proved to be highly stable during a 30-hour stress test, maintaining its performance across multiple cycles. Researchers were particularly surprised by the copper’s ability to remain metallic throughout the process, which contributed to its longevity and recyclability.

Computational simulations revealed that the unique configuration of atoms in the copper clusters facilitated the transformation of CO2 into acetaldehyde, promoting selectivity over other byproducts like ethanol or methane. "The beauty of our process is that it can be applied to various catalytic systems, allowing us to quickly screen and test new materials for CO2 reduction or water electrolysis," says Pedersen.

This new copper-based catalyst represents a significant advancement toward greener industrial chemistry. If scaled up, it could replace the Wacker process, reducing reliance on petrochemicals and lowering CO2 emissions. Given that acetaldehyde is a building block for many chemicals, this breakthrough could transform industries ranging from pharmaceuticals to agriculture, offering a sustainable alternative for manufacturing essential chemicals.