Tailored hydrotalcite-based Mg-Ni-Al catalyst for hydrogen production via methane decomposition: Effect of nickel concentration and spinel-like structures

Abstract

Thrive for the COx-free hydrogen production via methane decomposition has gained much interest owing to its feasibility and environmental friendliness. Herein, ahydrotalcite based Nickel catalyst was synthesized via co-precipitation method by varying the amount of Nickel concentration and tested for methane decomposition reaction in a fixed bed reactor. In addition, the effect of calcination temperature in the development of the spinel-like structure of as-developed catalyst was comprehensively discussed. It was found that the hydrotalcite based Nickel catalyst prepared at 40% Nickel concentration has the highest performance of above 80% conversion for 7 h of methane decomposition which was owing to its effective diffusion of carbon particles and its spinel-like structure, evidently from the XRD and FESEM analysis. The profound performance monitored here was attributed to the formation of carbon nanofibers (CNFs) on the surface of the catalyst which levitates the active Niospecies on its tips, results in more available active sites for the chemisorptions of the methane molecules. Nevertheless, the excessive of Nickel concentration leads to the detrimental methane decomposition performance, hencepromotes the formation of large particle size and successive development of bulk NiO phases during the reduction process, consequently abnegate the overall methane decomposition reaction. The aforementionedfindingsshow that the spinel-like structure is the key factor in the growth of long uniform CNFs and elevation of active sites on the fibre tips.