Researchers at the Department of Energy’s Oak Ridge National Laboratory (ORNL) have patented a new catalyst they say has outstanding performance for dry reforming of methane (DRM). The strategy may also apply to other catalysts, they believe.
The DRM reaction converts methane and carbon dioxide into syngas, a mixture of hydrogen and carbon monoxide. As such it is a platform to produce many common chemicals.
However, while the Ni-based catalysts used in the DRM reaction are highly reactive, they are prone to rapid deactivation.
The problem is that the reaction must be run at over 650°C for a significant reaction rate, but this same high temperature results in two deactivation processes – sintering which ruins the catalyst’s active sites and coking which blocks it from contacting the reactants.
According to ORNL's Felipe Polo-Garzon, who co-led a study published in Nature Communications, this deactivation makes the reaction nonviable on an industrial scale. Which is why most commercial syngas today is made by steam reforming of methane, a process that requires large amounts of water and heat and that also produces carbon dioxide.
By contrast, DRM of methane requires no water and consumes carbon dioxide and methane, two polluting greenhouse gases.
What the ORNL researchers describe in the study is a straightforward approach for anchoring dispersed Ni sites with strengthened metal-support interactions.
The Ni active sites end up embedded in dealuminated Beta zeolite, a crystalline material that contains silicon, aluminum, oxygen and nickel. The zeolite's supportive framework stabilizes the metal active sites, boosting both stability and reaction rates.
The manufacturing process for the catalyst involves solid-state grinding of dealuminated Beta zeolites and nickel nitrate, followed by calcination under finely controlled gas flow conditions.
The researchers essentially remove some atoms of aluminum and replace them with nickel.
"We're effectively creating a strong bond between the nickel and the zeolite host," Polo-Garzon said. "This strong bond makes our catalyst resistant to degradation at high temperatures."
The researchers then combined in situ X-ray absorption spectroscopy with various simulation technologies to better understand how the catalyst works.
Next up they aim to develop other catalyst formations for the DRM reaction that are stable under a broad range of conditions.
