High-Efficiency Copper Catalyst Converts CO₂ into Acetaldehyde
A newly developed catalyst now promises a more sustainable route to acetaldehyde from captured carbon dioxide, potentially replacing petrochemical processes.
Acetaldehyde has long been an essential building block for a range of products, including perfumes, pharmaceuticals and plastics. Currently, it is typically made using the “Wacker process”, which relies on ethylene derived from oil and natural gas combined with strong acids such as hydrochloric acid. This petrochemical-based method carries a significant carbon footprint and is becoming increasingly unsustainable, prompting researchers to look for alternative ways to produce acetaldehyde without depleting fossil resources.
A Petrochemical Concern
The Wacker process has been used for nearly six decades and is widely recognised for its reliability and effectiveness. However, its heavy dependence on petrochemicals is at odds with efforts to reduce carbon emissions and minimise environmental impact. According to scientists investigating cleaner processes, acetaldehyde production must shift towards more environmentally responsible methods that address growing concerns over climate change.
In parallel, the chemical sector is exploring the electrochemical reduction of carbon dioxide (CO₂) into valuable products. Since CO₂ is a major greenhouse gas emitted through industrial processes, capturing and utilising it for chemical synthesis provides a two-fold benefit: it avoids further atmospheric CO₂ accumulation while cutting back on fossil feedstocks.
A Promising Alternative
One popular route under examination involves using copper-based catalysts. Copper holds particular interest because of its ability to convert CO₂ into carbon-based products, but it often suffers from low selectivity, yielding a spectrum of chemicals rather than a specific compound. A public-private consortium now claims to have addressed this issue with a new catalyst design, making it more selective for acetaldehyde production.
Researchers led by Cedric David Koolen in the group of Andreas Züttel at EPFL, Jack K. Pedersen at the University of Copenhagen, and Wen Luo at Shanghai University have reported a copper-based catalyst that delivers a remarkable 92% selectivity for acetaldehyde. They have published their findings in Nature Synthesis, suggesting that this breakthrough could herald a shift away from the Wacker process. “The Wacker process effectively hasn’t changed in the past 60 years. It is still based on the same basic chemistry. The time was ripe for a green breakthrough,” says Koolen.
The team’s success lies in fabricating tiny clusters of copper particles, each around 1.6 nanometres, using a technique called spark ablation. By carefully managing the size of these copper clusters and stabilising them on carbon supports, the researchers ensured a stable, reusable catalyst. In testing, they achieved the high selectivity at a relatively low voltage, which promises efficiency gains for industrial upscaling.
Outlook for Industry
Further experiments revealed that the new catalyst retains its form even after extended operation. “What was really surprising to us was that the copper remained metallic, even after removal of the potential and exposure to air,” says co-lead author Wen Luo. “. “Copper usually oxidizes like crazy, especially copper that small. But in our case, an oxide shell formed around the cluster protecting the core from further oxidation. And this explains the recyclability of the material. Fascinating chemistry.”
In addition, advanced computational modelling informed the catalyst’s design by pinpointing how copper atoms bind CO₂ and steer it towards acetaldehyde. “The great thing about our process is the fact that it can be applied to any other catalysts system,” says co-lead author Jack K. Pedersen. “With our computational framework, we can quickly screen clusters for promising characteristics. If it’s for CO₂ reduction, or water electrolysis, with spark ablation we can produce the new material with ease and directly test it in the lab. This is so much faster than your typical test-learn-repeat cycle.”
This copper-based catalyst may open the door to industrial methods that rely far less on petrochemicals, while simultaneously reducing carbon emissions. As acetaldehyde is a crucial precursor for many chemicals, including those in agriculture and health care, the environmental and economic benefits of a sustainable route could resonate across multiple sectors. If these findings are successfully scaled up, they could help re-shape the way manufacturers obtain acetaldehyde and usher in a new era of cleaner chemical processes.
