A new study presents a breakthrough method that slashes cement-related CO2 emissions by up to 80 % using methane and steel waste as part of a catalytic reaction.
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In traditional cement manufacturing, the decomposition of carbonates is the main driver of emissions, accounting for about 60 % of the industry’s total CO2 output.
Even after two centuries of technological progress, from early vertical kilns to today’s advanced dry-process systems, the core challenge remains: the high-temperature decomposition of calcium carbonate is constrained by fundamental thermodynamic and kinetic limitations.
Most current decarbonization efforts focus on enhancing energy efficiency or switching to alternative low-carbon fuels like biomass and hydrogen. While these strategies help, they don’t directly address the chemical heart of the problem—the decomposition of calcium carbonate. As a result, a large portion of the sector’s carbon footprint remains difficult to eliminate through conventional means.
A Novel Approach: Methane and Steel Waste as Allies
A research team has introduced a novel strategy that taps into the iron content naturally present in cement raw materials to form a catalytic system. By using metal elements such as iron, aluminum, and zinc—mimicking the composition of steel-making waste—they’ve developed a method for co-thermal conversion of CaCO3 with methane (CH4) in a methane-rich environment.
What makes this approach especially promising is its practicality: the catalyst materials don’t need to be separated after the reaction—they can be directly incorporated into the cement clinker.
Meanwhile, the process also produces syngas, a valuable byproduct. Initial results show a striking reduction in carbon emissions, around 80 % lower than those from conventional CaCO3 decomposition. This opens the door to significantly deeper emissions cuts in cement production.
How it Works: Reaction Mechanism
The team outlined two key reaction pathways. In the first—called the direct reaction—adsorbed methane interacts with carbon-oxygen bonds at the calcium-iron interface, producing carbon monoxide (CO) and hydrogen (H2). In the second, CaCO3 first decomposes into CaO and CO2; the released CO2 then reacts with activated methane to form CO and H2.
Experimental data confirms that the direct pathway is the dominant one. The simulated catalyst, designed to resemble steel waste, relies on iron oxides as active sites. Adding aluminum and zinc was found to improve the surface area and dispersion of these sites, optimizing the surrounding environment and boosting catalytic efficiency.
A Pathway to a Greener Future
A life cycle analysis (LCA) of this process showed substantial carbon savings in modeled industrial applications, highlighting its environmental advantages. Beyond reducing emissions, this research showcases the untapped potential of industrial waste—in this case, steel slag—as a resource for cleaner manufacturing.
By integrating steel-derived waste into cement production, the approach offers a practical, scalable, and cost-effective solution for a sector under increasing pressure to decarbonize. As climate change demands urgent action across industries, innovations like this one offer a glimpse into a more sustainable future for cement.
The research was published in National Science Review (NSR). Zhenggang Liu and Rui Lu from the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, are listed as co-first authors. Rui Cai and Fang Lu served as the study’s co-corresponding authors.
Journal Reference:
Liu, Z., et al. (2025). Carbon emission reduction in cement production catalyzed by steel solid waste. National Science Review. doi.org/10.1093/nsr/nwaf109.