Production of Pure Hydrogen through Thermocatalytic Methane Decomposition Using NiO-MgO Catalysts Promoted by Chromium and Copper Prepared via Mechanochemical Method

Abstract

The burning of fossil fuels enhanced the greenhouse gas emissions in the atmosphere and caused serious environmental problems; so, it is necessary to find a replacement energy source. Hydrogen is considered one of the clean and viable energy carriers. Thermocatalytic methane decomposition (TMD) allows the production of COx-free H2 and solid carbon with excellent attributes and high potential. In this study, 50NiO-MgO (50 wt.% NiO and 50 wt.% MgO) and Cu- and Cr-doped samples were synthesized via the mechanochemical route. Structural characteristics of the fresh and spent catalysts were analyzed by different analysis methods. The results demonstrated that the specific surface area improved by introducing chromium to the catalyst formulation. Between all of the samples, the 50NiO-MgO-15Cr2O3 (50 wt.% NiO, 35 wt.% MgO, and 15 wt.% Cr2O3) showed the higher BET surface area with an amount of 38.3 m2/g. The performance of 50NiO-MgO and Cr- and Cu-doped catalysts was tested in the thermocatalytic methane decomposition. The obtained result showed that the Cr-doped sample possessed higher methane conversion with the amount of 65% at 575°C and much better lifetime due to its positive impact on the reducibility of the catalyst. Also, the influence of GHSV (gas hourly space velocity) was investigated on the catalytic performance of this sample which was chosen as the optimum catalyst.