Presently, there is great interest in the dry methane reforming reaction (DMR reaction), as it provides a means to convert harmful greenhouse gases (CO2 and CH4) into industrially useful syngas (CO and H2). Nobel metal catalysts are particularly efficient at effecting this conversion, however, they are costly and not sustainable. It is for this reason that interest has grown in earth abundant Ni-based catalysts for DMR. Unfortunately, the Ni-based catalysts suffer coking and readily become deactivated. It has been found that the addition of cobalt improves the stability of Ni DMR catalysts and inhibits coking. There have been many reports as to why this may be the case, and the prevailing hypothesis in the present literature is that this may be due to the formation of a Ni/Co alloy.
In a recent collaborative study between the research groups of Prof. Serena DeBeer and Prof. Martin Muhler (RUB and MPI CEC Research Fellow), it was shown how a Ni/Co catalyst transforms during the reductive activation step and the subsequent DMR reaction. This was shown using scanning transmission X-ray microscopy (STXM) in a specially fabricated nanoreactor, which enabled the catalyst to be studied in real time. Interestingly, the particles start out as Ni/Co alloy materials. However, upon reduction clear elemental segregation occurs in which all the Co migrates to the center of the nanoparticles. These results thus provide the first clues as to how particle dynamics and morphology optimize catalytic activity. This study was recently highlighted as the cover article in the June 5, 2020 issue of ACS Catalysis.
Original Publication: Beheshti Askari, A., al Samarai, M., Morana, B., Tillmann, L., Pfänder, N., Wandzilak, A., Watts, B., Belkhou, R., Muhler, M., and DeBeer, S.. In Situ X‑ray Microscopy Reveals Particle Dynamics in a NiCo Dry Methane Reforming Catalyst under Operating Conditions. ACS Catalysis. https://dx.doi.org/10.1021/acscatal.9b05517