(149b) A Modified Nickel-Copper Catalytic System for Enhancing Hydrogen Production in Tri-Reforming of Methane: The Role of Promoters and Synthesis Techniques

As the global energy demand surges, hydrogen has emerged as a promising alternative fuel source to lower atmospheric carbon intensity. Hydrogen is particularly attractive due to its high energy content and zero carbon emissions upon burning. One practical approach to producing hydrogen is natural gas reforming, whereby steam reforming was the most attractive commercial technology to date. The Tri-Reforming of Methane (TRM) recently emerged as an option because it will utilize CO₂ as a soft oxidant in addition to steam and oxygen, which could be considered a CO₂ utilization process. Therefore, this catalytic reforming process combines steam reforming, dry reforming, and partial methane oxidation, all in a single reactor. TRM allows tuning the operating conditions to optimize the generation of valuable syngas quality (specific ratios between the hydrogen and carbon monoxide, the gas mixture that forms the syngas). Despite its potential, TRM operates under harsh oxidizing environments and high operating conditions and is, therefore, prone to severe carbon deposition and sintering of the active metal (Chatla et al., 2020).

This study focuses on developing a bi-metallic nickel-copper system by incorporating lanthanum and cerium as promoters to enhance the catalyst’s performance. The aim is to maximize hydrogen yield and reduce the oxidation tendency of the active nickel site while maintaining high carbon resistance and stability during operation. Moreover, carbon dioxide is utilized as an oxidizing agent in the reforming processes, potentially reducing the process’s overall carbon footprint.

We compared two synthesis methods: ball milling and incipient wet impregnation (IWI). The nickel-copper system's base catalyst is fixed to an atomic ratio of 8:1 with 10% nickel loading. Incorporating promoters into the base catalyst did not significantly improve the reduction temperature. This implies that these promoters do not substantially enhance the reduction temperature. When comparing different synthesis methods, catalysts prepared via ball milling exhibited lower reduction temperatures around 392°C compared to 415°C for samples prepared by IWI. Oddly, the cerium-promoted nickel-copper system synthesized by IWI revealed only one broad reduction peak at 427.5°C for a nickel. It is suspected to be due to the formation of nickel, copper, and cerium alloys.

Further investigation with XRD and XPS is to be conducted to study the nature of the alloy. Our paper will report that the catalytic activity is being tested using a lab-scale state-of-the-art fixed bed quartz reactor system for TRM under the desired conditions. A long time-on-stream (TOS) is being conducted under inlet composition CH₄:CO₂:O₂:H₂O:H₂:CO with molar ratios of 1:1:0.3:0.4:0:0 to assess long-term stability and sustainability against carbon formation. The paper will also report the effect of reaction parameters such as gas space velocity, partial pressures, feed composition, and temperature on hydrogen selectivity, which is evaluated using online gas analysis.

Reference:

Chatla, A., Ghouri, M. M., El Hassan, O. W., Mohamed, N., Prakash, A. V., & Elbashir, N. O. (2020). An experimental and first principles DFT investigation on the effect of Cu addition to Ni/Al₂O₃ catalyst for the dry reforming of methane. Applied Catalysis A: General, 602, 117699.