Optimization of hydrogen production by steam methane reforming over Y-promoted Ni/Al2O3 catalyst using response surface methodology

Abstract

Hydrogen production from CH4 greenhouse gas through steam methane reforming (SMR) is an essential and perfect process. In this study, Y-promoted Ni-based catalysts supported on Al2O3 were utilized in this process. The response surface method (RSM) based on optimum custom design was used to investigate the synthetic parameters for Ni-based catalyst and the operating conditions of the SMR process. Independent parameters such as reaction temperature (600, 650, and 700 °C), steam to CH4 (S/C) molar ratio (1.5, 2.5, and 3.5), Ni loading (5, 15, and 25 wt%), Y loading (0, 1.5, and 3.0 wt%), and type of support (hollow or bulk alumina) were chosen for evaluation and optimization of CH4 conversion and H2 yield utilizing RSM. The design expert software recommended two optimized catalysts for bulk and hollow structures; the best choice was 16.2 Ni-2.7Y/HS-Al at 690 °C and 3.4 S/C molar ratio for achieving the maximum CH4 conversion of 93.8% and H2 yield of 97.4%. The stability test was performed to compare the activity of optimized catalysts at their optimal temperature and S/C ratio experimentally, before and after which the synthesized catalysts were characterized via XRD, TPR, FESEM, EDX, N2 adsorption/desorption, and TPO techniques.