Optimization of Cu/Zn/Al2O3 and Cu-Ga/Zn/Al2O3 catalysts using response surface methodology for methanol steam reforming for hydrogen production

Abstract

Methanol steam reforming (MSR) is a highly efficient method for hydrogen production that offers a high hydrogen yield at relatively low operating temperatures. However, enhancing catalyst performance is essential to improve efficiency and reduce byproduct formation. This study utilized response surface methodology (RSM) with the Box-Behnken design (BBD) to systematically optimize the key factors affecting catalyst efficiency. CuZnAl₂O₃ (CZA) and CuGaZnAl₂O₃ (CGZA) catalysts were synthesized and tested for their activity, selectivity, and stability under different reaction conditions, including temperature, steam-to-methanol ratio (S/C), and gas hourly space velocity (GHSV). The statistical model developed using BBD provided valuable insights into the interaction between these variables, allowing for the identification of optimal conditions. The highest hydrogen yield of 2.28 mol was achieved while keeping carbon monoxide formation at a minimal 0.12 % under the optimized conditions of 275 °C, a S/C ratio of 2, and a GHSV of 14,500 hr⁻¹ for CGZA catalyst. The developed model was validated through experimental trials, demonstrating strong agreement between predicted and observed values. Additionally, catalyst characterization using techniques such as XRD, BET, Raman, SEM-EDX, TEM, TGA, and XPS confirmed structural and surface modifications contributing to catalytic performance. The study highlighted the effectiveness of RSM-BBD in catalyst optimization, offering a systematic and cost-effective approach to advancing hydrogen production technologies. Moreover, the Ga-modified Cu-based catalysts showed highly promising results for efficient and stable hydrogen production via MSR, with improved resistance to coke formation and deactivation.