Preparation of the NiO/FeAl2O4 nanopowders and their application in CH4 thermocatalytic decomposition to produce high purity of hydrogen: Optimization of the synthesis parameters using Taguchi design of experiment

Abstract

The present research is centralized on designing and optimizing the preparation conditions of the NiO(50)/FeAl2O4 catalyst in the thermocatalytic decomposition of CH4 (TDM). The mesoporous FeAl2O4 powders were synthesized by various methods, and the supported nickel catalysts were employed in the TDM. The results showed that the catalyst supported on FeAl2O4 synthesized by the modified co-precipitation (MCOP) method possessed the best efficiency, and CH4 conversion and H2 yield were 74 and 82% at 675 °C, respectively. Taguchi L9 statistical experimental design was applied to investigate and optimize the preparation parameters, including surfactant type (CTAB, PVP, P123), pH (9, 10, 11), aging temperature (40, 60, and 80 °C), and aging time (0, 15, 30 h). The obtained outcomes revealed that the optimized sample displayed a mesoporous nanocrystalline structure with an appropriate BET area (72.6 m2 g−1) and pore volume (0.17 cm3 g−1), and its maximum methane conversion was 80.8% at 700 °C. The results indicated that the Taguchi procedure was impressive in the optimization of the synthesis parameters, and the error value between the predicted value and the actual value was lower than 4%. The physicochemical characteristics of the optimized sample were assessed based on the XRD, BET, H2-TPR, FTIR, TGA/DTA, FESEM, and TPO analyses. Furthermore, the influence of calcination temperature was investigated on the textural properties and catalytic performance of the selected catalyst. The stability experiment of the samples showed that the NiO(50)/FeAl2O4 catalyst calcined at 600 °C was utterly stable for 300 min time on stream. Also, the effect of the processing parameters (GHSV, feed composition, and reduction temperature) was evaluated on the catalyst stability and amount of the deposited carbon on the catalyst surface of the optimum NiO(50)/FeAl2O4 catalyst.