Hydrogen production from steam reforming of ethanol with nano-Ni/SiO2 catalysts prepared at different Ni to citric acid ratios using a sol–gel method

Abstract: Steam reforming of ethanol to produce hydrogen was carried out using a two-stage reaction system with several nano-Ni/SiO2 catalysts prepared at different citric acid (CA) contents using the sol–gel process. The fresh (non-calcined and calcined) catalysts and the reacted catalysts were analysed using surface area and pore size analysis, Fourier-transform infrared (FTIR) spectroscopy, thermo-gravimetry analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that a meso-structured material was produced at Ni:CA ratios lower than 1:0.5; and the pore volume of the catalyst was increased when more citric acid was used during the sol–gel preparation. Gas and hydrogen yield were observed to be increased when the Ni:CA ratio was reduced from 1:0.5 to 1:3.0; however, gas concentration was slightly changed for the catalysts prepared at different Ni:CA ratios. In addition, coke formation was increased from 0.7 to 7.5wt.% when the Ni:CA ratio decreased from 1:0.5 to 1:3.0. It was also found that the Ni/SiO2 catalyst prepared at the low CA content (Ni:CA=0.5) was non-stable during the ethanol steam reforming process; since sintering was obtained as observed using TEM analysis of the used catalyst. [ABSTRACT FROM AUTHOR]