Characteristics and catalytic properties of Ni/CaAlOx catalyst for hydrogen-enriched syngas production from pyrolysis-steam reforming of biomass sawdust

Abstract

The production of hydrogen-enriched syngas from the thermo-chemical conversion of biomass was studied using Ni/CaAlOx catalysts prepared by co-precipitation method. The effect of Ca addition with different molar ratios of Ca:Al (1:3, 1:2, 1:1, 2:1, 3:1) on the properties and catalytic behavior in relation to syngas production and the coke formation on the surface of the catalysts were investigated. Catalysts were characterized by BET, XRD, TPR, SEM, and TEM. The SEM and TEM results showed that rod-shaped nano-particles were highly dispersed on the surface of the catalyst. The particle size of NiO was slightly affected with the increase of Ca content in the catalyst. It appeared that the selectivity of CO was increased and the selectivity of CO2 was reduced with the increase of Ca addition to the catalyst. For example, CO2 concentration was reduced from 20 to 12vol.%, when the molar ratio of Ca/Al was increased from 1:3 to 3:1 for the Ni/CaAlOx catalyst; it is suggested that the water gas shift reaction was inhibited and CO2 reforming reactions were promoted in the presence of the catalyst with higher Ca content. The CO/H2 molar ratio could be manipulated by changing the Ca content in the catalyst, while the H2 concentration remained almost constant (around 45vol.%). Thus, using the Ni/CaAlOx catalyst developed in this work could provide a promising route to control the syngas composition, which is an important factor for syngas applications.