Hydrogen Porduction By Steam Reforming Of Phenol Over Mesoporous MgO Supported Ni Catalyst

In this paper, a mesoporous MgO supported nickel based catalyst with high surface area and small Ni nanoparticles was synthesized and investigated for hydrogen production by steam reforming of biomass oil model compound-phenol.We synthesized four different solid solutions using impregnation method and coprecipitation method. Thereinto, the solid solutions which were obtained by commercial MgO impregnation and mesoporous MgO impregnation method were marked as NiO/M and NiO/Mm, respectively; the ones which were obtained by commercial coprecipitation and hydrothermal coprecipitation were marked as NiO-M, NiO-Mm, respectively. Afterwards, the four solid solutions were characterized with XRD, N2 adsorption/desorption, H2-TPR and TEM, respectively. Subsequently, the reduced Ni-M, Ni-Mm, Ni/M and Ni/Mm catalysts were investigated by catalyzing phenol steam reforming for producing hydrogen. The used catalysts were characterized by XRD, TG and TEM.The results indicated that the NiO/Mm solid solution which was obtained by mesoporous MgO impregnation method had the highest surface area(60.6 m~2/g) and largest pore diameter(10.1 nm), in addition, the BET surface area of Ni O/Mm is about 2.1 times that of NiO/M(29.1 m~2/g). Besides, the small and uniform Ni nanoparticles of Ni/Mm were narrowly distributed in the range of 5~6 nm.To compare the catalytic activity and stability of different catalysts with different methods on the steam reforming of phenol, the Ni/Mm with 15.8 wt% Ni content exhibited the highest catalytic activity and longer-term catalytic stability in steam. The reaction was carried out at 450 oC, liquid flow rate = 5.2 mL/h and S/C = 20 mol/mol, the results showed that phenol conversion of 87.3%, hydrogen selectivity of 89.7% and hydrogen yield of 54.7%, respectively. Compared to Ni/M catalyst under the same Ni loading condition, the H2 selectivity and the yield of hydrogen were enhanced by 29.3% and 29.3% respectively. In addition, the hydrogen selectivity and yield of the Ni/Mm catalyst were almost stable up to 15 h on stream and remained at around 82.1% and 49.5%, respectively.The results of used catalyst indicated that the Ni/Mm catalyst still maintained mesoporous channels and the nickel particle size remained unchanged during 15 h on stream. Besides, no obvious deposits or formation of carbon whiskers were observed on the used catalyst surface.Consequently, among the prepared four Ni-based catalysts, we adopted Ni catalyst supported mesoporous MgO using impregnation method for hydrogen production by steam reforming of phenol and exhibited the highest catalytic activity and longer-term catalytic stability in steam.