Hydrogen production through steam reforming of toluene over Ce, Zr or Fe promoted Ni-Mg-Al hydrotalcite-derived catalysts at low temperature

摘要

Ni-Mg-Al hydrotalcite-derived materials promoted with Ce, Zr or Fe were prepared by the co-precipitation method, which exhibited excellent performance in steam reforming of toluene (SRT) at low temperature. Especially, Fe-doped catalyst had higher catalytic activity and stability at 400 degrees C, which maintained almost 100% toluene conversion during the SRT reaction (3 h). Moreover, it also had higher hydrogen production and better selectivity for hydrogen production. The physico-chemical characterizations and model simulation indicate its high dispersion of active sites and accessibility of reactants to active sites: uniform dispersion of active sites (SEM, TEM and EDX), large specific surface area (151 m(2)/g), pore volume (0.84 cm(3)/g) and average pore diameter (22.1 nm), small crystallite size (34.9 nm), desirable Ni species reducibility (TPR), high basicity (TPD), low metal carbide formation (XPS), and good adsorption affinity with toluene (- 18.391 kJ mol(-1), DFT). Moreover, less carbon was deposited on the Fe-containing catalyst through measuring the amorphous carbon and CNTs by the TG-MS method, which was due to the tip-growth mechanism of CNTs. Considering lower toluene conversion temperature, higher hydrogen yield, and better resistance to carbon deposition, this study may be meaningful in development of SRT at low temperature.