Chinese experts have made a groundbreaking move to decarbonise one of the world’s most emissions-heavy industries by developing a new catalytic process that could transform cement production.

The Dalian Institute of Chemical Physics researchers, also called Huawusuo, a part of the Chinese Academy of Sciences, harnessed steel waste and methane to slash CO₂ emissions by up to 80%. 

 

According to the team, calcium carbonate (CaCO₃) decomposition, which accounts for about 60% of total carbon emissions during cement production, has posed a significant challenge ever since the industry’s inception. 

Despite two centuries of equipment upgrades – from rudimentary kilns to modern dry-process systems – the core chemistry of cement remained carbon-intensive due to the need for high-temperature thermal decomposition.

While existing strategies to lower emissions have focused on using alternative fuels like biomass or hydrogen and improving energy efficiency, until now, none have truly disrupted the root chemical mechanism. 

Turning steel waste and methane into a sustainable innovation

To tackle the issue, the team led by Zhenggang Liu, PhD, and Rui Lu, PhD, both from the Dalian Institute of Chemical Physics, proposed a novel strategy that uses the iron naturally present in cement raw materials to develop a catalytic system.

Inspired by the metallic composition of steel industry byproducts – ironmaking slag, steelmaking slag, and dust and sludge – the team engineered a simulated steel-derived solid waste composed of iron (Fe), aluminum (Al), and zinc (Zn).

When placed in a methane atmosphere alongside CaCO₃, this system triggered a co-thermal reaction that broke down the calcium carbonate and produced valuable syngas, a mixture of hydrogen and carbon monoxide used in energy and chemical industries. 

This process uses solid waste from the steel industry as a catalyst to facilitate the reaction between calcium carbonate (CaCO₃) and methane (CH₄) under a CH₄ atmosphere, producing calcium oxide (CaO) and syngas (CO and H₂). Image: Science China Press.

The process is even more exciting because the catalytic materials do not need to be removed after the reaction. They can instead be directly incorporated into the cement clinker, a material that forms the basis of cement production, aligning seamlessly with existing production lines and reducing waste. 

Separately, the study identified two distinct reaction pathways behind the process. The direct one involves adsorbed methane interacting with the carbon-oxygen bond at the calcium-iron interface, producing carbon monoxide and hydrogen.

The second one, in contrast, includes CaCO₃ decomposing first into CaO and CO₂, with the CO₂ then reacting with activated methane. Adding aluminium and zinc enhances the catalyst’s surface area and the distribution of active iron oxide sites, further improving performance.

Paving the way for low-carbon cement production

Preliminary findings show that the process cuts carbon emissions by about 80% compared to traditional calcium carbonate decomposition, presenting a promising route for deep decarbonisation in cement production.

Additionally, life cycle analysis (LCA) showed promising environmental gains if the method is scaled industrially. With cement accounting for roughly 8% of global CO₂ emissions, such a significant emissions reduction, without overhauling entire plants, could be a game changer. 

The researchers believe this work not only addresses the urgent challenge of decarbonising the cement industry but also underscores the untapped potential of industrial waste as a driver of sustainable innovation.

“As the world grapples with the challenges of climate change, this breakthrough could pave the way for a greener, more sustainable future for cement industry,” they said in a press release. 

The study has been published in the journal National Science Review.