Effect of Fe-loading in iron-based catalysts for the CH4 decomposition to H2 and nanocarbons.

The catalytic CH 4 decomposition (CMD) over Fe-based catalyst is an economical and environmentally friendly way to produce Co x -free H 2 and carbon nanotubes (CNTs). The Fe-loading was varied to study its influence on the catalytic performance. The highest H 2 yield (82.25%) was obtained with a 12% Fe content where the activity of the catalyst did not decrease for 3 h on-stream. A higher Fe content causes the Fe dispersion to decrease, resulting in a reduced available surface area of active sites. Different techniques were used to characterise the fresh and spent catalysts i.e., ICP-AES, XRD, H 2 -TPR, SEM, TEM, and Raman spectroscopy. Plotting kinetic results as a function of 1/T, defines two different conversion ranges, being reaction rate controlled at low temperature and diffusion rate controlled at high temperature. For the reaction rate controlled regime, the Arrhenius equation provides an activation energy of 101.26 kJ/mol (E a) and a pre-exponential factor of 393 kmol/s (A). • Iron-based catalysts for methane decomposition to H 2 and CNTs were developed. • The highest H 2 yield (82.25%) was obtained with a 12% Fe content. • The CH 4 –C was recovered as carbon nanotubes. • The CNTs outer diameter is 60–80 nm, well-graphitized nanotubes with the interlayer spacing of 0.34 nm. • CH 4 conversion at low temperature is reaction-rate determined. [ABSTRACT FROM AUTHOR]