As the demand for sustainable hydrogen (H₂) production grows, catalytic decomposition of methane (CDM) has emerged as a CO2- free pathway for H2 generation, producing valuable multi-walled carbon nanotubes (MWCNTs) as byproducts. This study examines the role of fuel type in shaping the properties and performance of NiOx/AlOx catalysts synthesized via solution combustion synthesis (SCS). Catalysts prepared with citric acid, urea, hexamethylenetetramine (HMTA), and glycine exhibited varying NiO nanoparticle (NP) sizes and dispersions. Among them, the HMTA catalyst achieved the highest Ni dispersion (~ 3.2%) and specific surface area (21.6 m2/ gcat), attributed to vigorous combustion facilitated by its high pH and amino-group-based fuel. Catalytic tests showed comparable activation energy (55.7–59.7 kJ/mol) across all catalysts, indicating similar active site formation mechanisms. However, the HMTA catalyst demonstrated superior CH4 conversion (~ 68%) and stability, maintaining performance for over 160 min under undiluted CH₄, while others deactivated rapidly. MWCNT characterization revealed consistent structural properties, such as graphitization degree and electrical conductivity, across all catalysts, emphasizing that fuel type influenced stability rather than MWCNT quality. H2 temperature-programmed reduction ( H2-TPR) analysis identified moderate metal-support interaction (MSI) in the HMTA catalyst as a key factor for optimizing stability and active site utilization. These findings underscore the importance of fuel selection in SCS to control MSIs and dispersion, offering a strategy to enhance catalytic performance in CDM and other thermocatalytic applications.

Fuel-driven design of NiOxAlOx catalysts for methane decomposition through tuning of metal-support interaction
    Abstract
    1 Introduction
    2 Experimental section
        2.1 Catalyst synthesis by the SCS method
        2.2 Catalytic activity evaluation
        2.3 Characterization of catalysts
    3 Results and discussion
        3.1 Characterization of catalysts based on fuel type
        3.2 Catalytic performance of catalysts for CH4 decomposition
        3.3 Characterization of carbon byproducts derived from CDM
        3.4 The role of fuel in catalysts prepared via the SCS method
    4 Conclusion
    Acknowledgements 
    References

• Jae Hoon Kim(Chemical & Process Technology Division, Korea Research Institute of Chemical Technology (KRICT), Daejeon 34114, Republic of Korea)
• Soo Hong Lee(Chemical & Process Technology Division, Korea Research Institute of Chemical Technology (KRICT), Daejeon 34114, Republic of Korea) Corresponding author
• Nodira Urol Kizi Saidova(Chemical & Process Technology Division, Korea Research Institute of Chemical Technology (KRICT), Daejeon 34114, Republic of Korea, Advanced Materials and Chemical Engineering, University of Science and Technology (UST), Daejeon 34113, Republic of Korea)
• Shaikh Shayan Siddiqui(Chemical & Process Technology Division, Korea Research Institute of Chemical Technology (KRICT), Daejeon 34114, Republic of Korea, Advanced Materials and Chemical Engineering, University of Science and Technology (UST), Daejeon 34113, Republic of Korea)
• Ji Sun Im(Chemical & Process Technology Division, Korea Research Institute of Chemical Technology (KRICT), Daejeon 34114, Republic of Korea, Advanced Materials and Chemical Engineering, University of Science and Technology (UST), Daejeon 34113, Republic of Korea)
• So Yeong Yang(Chemical & Process Technology Division, Korea Research Institute of Chemical Technology (KRICT), Daejeon 34114, Republic of Korea, Department of Material Science and Engineering, Chungnam National University (CNU), Daejeon 34134, Republic of Korea)