Response surface methodology for optimizing the activity of bimetallic Ni–Co–Ce/Al2O3 catalysts in the steam methane reforming

Abstract

Hydrogen is being explored as a potential energy carrier for power and heat production, as well as energy storage, making it one of the most significant basic chemicals. In this work, steam methane reforming (SMR) over Ce-promoted Co–Ni/Al2O3 catalysts were employed to produce hydrogen, and the response surface method (RSM) based on an optimal custom method was used to examine the interplay between synthetic and operational factors affecting methane conversion, hydrogen yield and H2/CO molar ratio. Several independent factors were considered, including the catalyst Co/Ni mass ratio (0, 0.5, 1), Ce loading (0, 1.5, 3.0), operation temperature (600, 650, 700 °C), steam to methane (S/M) molar ratio (1.5, 2.5, 3.5), and support type (bulk and hollow Al2O3). Among the two determined optimized results in Design Expert, the hollow 0.17Co–Ni-1.26Ce@Al2O3 catalyst was the best choice, depicting 96.20% methane conversion, 96.89% hydrogen yield and 6.57H2/CO molar ratio. The stability test of both hollow and bulk optimized catalysts was compared in optimal conditions (S/M molar ratio and temperature) over a 12-h SMR reaction. The physical properties and morphology of the optimized catalysts were determined before and after the steam reforming reaction using FESEM, XRD, N2 physisorption, TPR, and TGA analyses.