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Investigations of Fe−MAl2O4 (M=Ca,Mg,Sr,Ba) Catalysts for Catalytic Decomposition of Methane

Samuel B. Portillo, Joshua Sellers, and Fanxing Li*

  • *Contact author: fli5@ncsu.edu
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PRX Energy 5, 043002 – Published 13 October, 2026

DOI: https://doi.org/10.1103/jjfg-4jst

Abstract

Catalytic decomposition of methane is a more sustainable alternative for hydrogen production compared to established technologies like steam methane reforming and coal gasification. This study reports iron-based catalysts supported on MAl2O4 (M=Ca,Mg,Sr,Ba) prepared via a ball-milling or one-pot modified Pechini (sol-gel) method. The synthesized catalysts were evaluated for their CDM performance in the range of 750–800 °C. In general, we show that ball-mill synthesis leads to higher CDM activities than sol-gel synthesized samples, which undergo quick deactivation. Raman spectroscopy and H2-TPR indicate that synthesizing the Fe−MAl2O4 catalysts via the sol-gel method results in iron coordination with cations (i.e., M) and with alumina to decrease iron’s reducibility and its overall catalytic activity. For the ball-mill synthesized samples, we find that a 30 wt% Fe−CaAl2O4 catalyst tested at optimized reaction conditions of Tred=700 °C, Trxn=750 °C, yCH4=0.9, and GHSV=1.25  L·g−1·h−1 obtained a competitive carbon yield of 17.86gC/gFe(5.06gC/gCat). TEM and SEM of the spent product indicate that the carbon product forms primarily via a tip-growth mechanism, with both filamentous and nano-onion-type carbon being generated. Raman spectroscopy of the spent product determined most of the carbon formed on the ball-milled Fe−MAl2O4 catalysts was graphitic in nature with ID/IG ratios ranging between 0.400 and 0.500. Overall, ball-milling appears to be a simple yet effective strategy to prepare dispersed iron catalysts for CDM.

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This article appears in the following collection:

PRX Energy collection on carbon capture, utilization, and storage

This PRX Energy Collection showcases the latest advances and ideas in carbon capture, utilization, and storage, including modeling, materials- and chemistry-based research, techno-economic analysis, and more. This collection amplifies advancements related to Sustainable Development Goals #7 and #13.

The guest editors for this Collection are Maria Escudero-Escribano of Catalan Institute of Nanoscience and Nanotechnology, Ewa Marek of University of Cambridge, and Jesús Velázquez of University of California-Davis.

Every article in this Collection was subjected to a rigorous peer review process, upholding the high standards applied to all papers. The PRX Energy editorial team managed the peer review and made all editorial decisions.

Popular Summary

Hydrogen can help reduce industrial emissions but producing it from methane typically releases substantial amounts of carbon dioxide. An alternative is to split methane into hydrogen and solid carbon, avoiding direct carbon dioxide formation. The challenge is finding inexpensive catalysts that sustain this process. Here, the authors investigated iron catalysts supported on four different metal aluminates and found that a simple preparation method, mechanically mixing materials through ball milling, outperformed a more elaborate solution-based method. The solution-based preparation bound iron more strongly to the surrounding material, making it harder to activate and causing the catalysts to deactivate quickly. Ball milling produced more active catalysts, with an iron–calcium aluminate formulation delivering promising performance. The reaction also produced predominantly graphitic carbon. These findings identify a straightforward route to preparing effective iron catalysts for producing hydrogen alongside potentially useful solid carbon products.

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PRX Energy 5, 043002– Published 13 October, 2026
  • Received 27 May 2026
  • Revised 21 August 2026
  • Accepted 10 September 2026
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