Design of experiment for hydrogen production from ethanol reforming: A state-of-the-art review

Hydrogen production from bioethanol has garnered significant research attention due to its renewability, sustainability, and net zero emission. This research aims to review two statistical optimization techniques, response surface methodology (RSM) and the Taguchi method, for hydrogen production from ethanol thermochemical conversion. The RSM model demonstrated that temperature increases hydrogen production, which peaked between 500 °C and 600 °C for ethanol steam reformation (ESR) and >700 °C for ethanol autothermal reforming (ATR) processes. Maximum hydrogen synthesis occurs at steam-to-ethanol (S/E) ratios of 3–5 mol.mol⁻¹ for both ethanol steam and autothermal reforming. Adding oxygen, a characteristic parameter of autothermal reforming, reduces hydrogen production. Ethanol autothermal reforming may be less efficient than ethanol steam reforming for hydrogen production. The impacting parameters for ethanol reforming identified by Taguchi techniques are steam-to-carbon ratio, ethanol steam reforming temperature, and water–gas shift reaction temperature, where steam-to-carbon ratio and ethanol steam reforming regulate hydrogen production substantially. The Taguchi approach reveals that an ethanol flow rate of 2 cm³.min⁻¹, a steam-to-carbon ratio of 5, and an ethanol steam reforming temperature of 500 °C are optimal reaction conditions. Optimization strategies improve biohydrogen production and make the following reaction more precise. For example, only optimization approaches can determine if a parameter should be reinforced or lowered.