Abstract:
Global warming and GHGs have been a topic of increasing concern due to their adverse effects on our environment. Methane is the second largest GHG emitted into the atmosphere. To reduce methane emissions, it is imperative that methane be consumed in most environmentally friendly way. This can be achieved by converting methane into hydrogen via methane cracking. Methane cracking is the only process that produces H2 from methane without the production of COx. Multiple simple oxides have been studied as catalyst supports for methane cracking, but no study has been conducted using complex oxides like perovskites even though they are economical and are stable in harsh catalytic conditions. This work focuses on the use and impact of a double perovskite oxide as a catalyst support, its performance and stability in methane cracking environment. Therefore, a double perovskite Sr2TiFeO6-δ (STF) was synthesized using glycine-nitrate combustion method. Afterwards, STF was calcined at 900 °C and was then impregnated with cobalt by dispersing STF in cobalt nitrate solution and then evaporating the mixture to obtain 2.5, 5.0, 7.5, and 10.0 wt. % cobalt loaded STF. All the cobalt loaded STF compositions were then calcined at 850 °C. All the fresh catalyst compositions (0, 2.5, 5.0, 7.5, and 10 wt. % Co/STF) were analyzed using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and N2 absorption-desorption. The same techniques were also used to analyze the spent 5% Co/STF catalyst, except for N2 absorption-desorption. The results showed that STF and Co/STF possessed a double perovskite structure but SrCoO3-δ impurity was detected for 7.5 and 10% Co/STF. Slight peak shifting and an increase in X-ray diffractograms was seen which was attributed to cobalt being doped into the deficient B-sites of STF lattice. Surface morphology results revealed that STF and Co/STF possessed porous structures which was confirmed by N2 adsorption-desorption results. Experimental results revealed that 5% Co/STF performed the best for methane cracking and spent catalyst analysis revealed the formation of carbon nanotubes and exsolution of the catalyst. The results showed that perovskites are excellent supports for methane cracking as excellent stability and high methane conversion were achieved.
