Optimization of hydrogen production by photocatalytic steam methane reforming over lanthanum modified Titanium (IV) oxide using response surface methodology

Abstract

In this study, the optimization of hydrogen production by photocatalytic steam methane reforming over Lanthanum modified TiO2 has been investigated using response surface methodology. The La/TiO2 photocatalysts were synthesized using wet impregnation method and characterized for physicochemical and photocatalytic properties by N2 physisorption, X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), and ultraviolet-visible (UV-vis) spectroscopy. The characterization shows that the La/TiO2 possesses appropriate properties to be used as photocatalysts. The photocatalysts were employed in the optimization studies of hydrogen production by photocatalytic steam methane reforming. The effects of irradiation time (10–150 min), metal loading (1–3%), methane concentration (10–50%), and steam concentration (0.5–1.5%) on the rate of hydrogen production were determined employing Box-Behnken experimental design. The application of the RSM resulted in the formulation of four models out which the quadratic model was adjudged to adequately fit the experimental data. A further statistical analysis of the quadratic model established the significance of the model with p-value far less than 0.05 and coefficient of determination (R2) of 0.975. A non-significant lack of fit obtained for the model further confirm the suitability of the quadratic model in fitting the experimental data. At the desirability function of 1, optimum conditions of 146.15 min, 2.94%, 22.83% and 1.24% for irradiation time, metal loading, methane concentration, and steam concentration, respectively resulted in the production of 2.42 μmol of hydrogen/min.