Acid vapor lets CO2 capture tech run 4,500+ hours without failures

The research team behind the acid vapor breakthrough in carbon capture technology. RICE University

Carbon capture and utilization technologies are becoming central to global efforts to combat climate change. These systems aim to trap climate-warming carbon dioxide emissions and convert them into usable chemicals or fuels.

But for the technology to become commercially viable, it needs to run reliably for thousands of hours. This is something that’s proven difficult due to persistent issues like salt buildup inside the devices.

Now, researchers at Rice University have found a surprisingly low-tech solution to a major bottleneck in electrochemical CO2 reduction systems.

Instead of using water to humidify CO2 gas before it enters the reactor, they simply bubbled the gas through a mild acid.

The result was a system that stayed stable for more than 4,500 hours, over 50 times longer than conventional setups.

Acid vapor dissolves the salt problem

At the core of the issue is potassium bicarbonate. In traditional systems, potassium ions migrate through the device and react with CO2 to form this poorly soluble salt.

It clogs gas flow channels, blocks CO2 transport, and floods electrodes, leading to premature failure.

“Salt precipitation blocks CO2 transport and floods the gas diffusion electrode, which leads to performance failure,” said Haotian Wang, associate professor of chemical and biomolecular engineering at Rice and the study’s lead author.

This typically happens in just a few hundred hours, far short of what commercial systems require.

The Rice team swapped out the standard water-based humidification with acid-based alternatives using solutions like hydrochloric, formic, or acetic acid.

These vapors altered the local chemistry just enough to prevent salt from crystallizing. Instead, the newly formed salts stayed dissolved and were carried out with the gas flow, avoiding clogs.

Thousands of hours without failure

Tests using a silver catalyst showed striking results. The lab-scale setup ran stably for over 2,000 hours. In a larger 100-square-centimeter electrolyzer, the system operated for over 4,500 hours without major issues.

By contrast, water-humidified systems failed after around 80 hours due to rapid salt buildup.

Importantly, the acid-vapor method worked across multiple catalyst types, including zinc oxide, copper oxide, and bismuth oxide, showing it can support different CO2 conversion targets.

The team also observed no significant corrosion or damage to the membranes, since acid concentrations were kept low.

Shaoyun Hao, co-first author and postdoctoral research associate, said they had hypothesized that “acid vapor could dissolve the salt and convert the low solubility KHCO3 into salt with higher solubility, thus shifting the solubility balance just enough to avoid clogging without affecting catalyst performance.”

The researchers even built transparent reactors to observe the process in real time. With water, salt crystals formed within 48 hours.

With acid vapor, salt didn’t accumulate even after hundreds of hours.

Simple and scalable at lower cost

Ahmad Elgazzar, co-first author and graduate student at Rice, said the approach offers a rare combination of durability and simplicity. “Our method addresses a long-standing obstacle with a low-cost, easily implementable solution,” he said.

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“It’s a step toward making carbon utilization technologies more commercially viable and more sustainable.”

Because the method only requires minor changes to existing humidification systems, it could be adopted in industrial-scale devices without costly redesigns.

The study is published in the journal Science.

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ABOUT THE AUTHOR

Aamir Khollam Aamir is a seasoned tech journalist with experience at Exhibit Magazine, Republic World, and PR Newswire. With a deep love for all things tech and science, he has spent years decoding the latest innovations and exploring how they shape industries, lifestyles, and the future of humanity.

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