Speaker
Description
Methane dry reforming (MDR, CH₄ + CO₂ → 2CO + 2H₂) is a promising pathway to produce syngas while reducing the net emission of two of the most harmful greenhouse gases. The industrially relevant catalyst, Ni, suffers from major drawbacks, such as carbon deposition and sintering at high reaction temperatures1.
One alternative to address these issues is the use of bimetallic catalysts2. The incorporation of copper into nickel catalysts can significantly enhance their performance3. While metallic Ni is chiefly responsible for dissociating methane—a rate-determining step—copper aids in CO₂ activation, reduces coking, and augments the reducibility of NiO, leading to more active sites. To elucidate the role of copper in this catalytic reaction, our study employed Ni nanoparticles (NPs) and NiCu NPs supported on SiO₂@Si(100). These NPs underwent a three-step process at near-ambient pressures: O₂ annealing for cleaning, H₂ annealing for reduction, and three MDR reactions at increasing temperatures (550°C, 650°C, 750°C). We used X-ray photoemission electron microscopy (XPEEM), low energy electron microscopy (LEEM), X-ray photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure spectroscopy (NEXAFS) to investigate our samples. The quasi-in-situ measurements unraveled the chemical composition, oxidation state (NEXAFS, XPEEM, XPS), and morphology (LEEM) of the NPs. Findings from our H₂ annealing experiments indicated that the activation energy for NiO NPs reduction is 1.2 ± 0.1 eV, while copper addition lowers the onset temperature for this reaction. Moreover, the presence of copper modified the oxidation state of nickel under MDR conditions. These insights pave the way for a deeper understanding of the role of copper in this bimetallic catalyst system.
- Abdullah, B., Abd Ghani, N. A. & Vo, D.-V. N. Recent advances in dry reforming of methane over Ni-based catalysts. Journal of Cleaner Production 162, 170-185 (2017).
- Bian, Z., Das, S., Wai, M. H., Hongmanorom, P. & Kawi, S. A Review on Bimetallic Nickel-Based Catalysts for CO2 Reforming of Methane. ChemPhysChem 18, 3117-3134 (2017).
- Han, K., Wang, S., Liu, Q. & Wang, F. Optimizing the Ni/Cu Ratio in Ni–Cu Nanoparticle Catalysts for Methane Dry Reforming. ACS Applied Nano Materials 4, 5340-5348 (2021).
