Parametric study and optimization of bio-hydrogen production using steam reforming of glycerol and biodiesel fuel mixtures

Abstract

The increasing global energy demand, scarcity of fossil fuels, and climate change have encouraged the use of renewable energy sources to decrease the reliance on fossil fuels and reduce the environmental impacts. Liquid biofuels have received noticeable attention lately as renewable feedstock for hydrogen production. Since the ever-growing production of biodiesel leads to an accumulated surplus of glycerol in the world market with a low commercial value, research is focused on finding alternative methods to make use of glycerol with the aim of upgrading the biodiesel business and improving its economic feasibility. The main objective of the current study is to perform a parametric analysis and optimization of bio-hydrogen production via steam reforming of the glycerol and biodiesel mixtures. A simulation model for steam reforming of glycerol/biodiesel mixture was developed using Aspen Plus software. The simulation results were validated with experimental data. The comparison showed a good agreement between the simulation and experimental results. A parametric study was carried out to investigate the effects of the gasification temperature (500–800 °C), steam-to-fuel ratio (SFR) (6–12), and biodiesel-to-glycerol ratio (BGR) (0–20%) on the composition of the syngas fuel. The response surface methodology (RSM) with conjunction of central composite design (CCD) was used in this study to optimize the steam fuel reforming process. The simulation results showed that the reformer temperature was found to significantly affect hydrogen production compared to the SFR and BGR. A quadratic equation developed in this study for the hydrogen versus the three input factors (temperature, SFR, BGR) fits very well with the predicted value obtained from the simulation (R2 = 0.99). The optimized operating conditions of the reformer for maximum bio-hydrogen production (66.06 mol%) are as follows: reformer temperature of 689.27 °C, SFR of 9.87, and BGR of 5.63%. This research study brings clear evidence for the research community as well as industry that bio-hydrogen can be successfully produced via steam reforming of glycerol and biodiesel mixtures.