Catalysts of Ni/α-Al2O3 and Ni/La2O3-αAl2O3 for hydrogen production by steam reforming of bio-oil aqueous fraction with pyrolytic lignin retention

This paper reports on the steam reforming, in continuous regime, of the aqueous fraction of bio-oil obtained by flash pyrolysis of lignocellulosic biomass (sawdust). The reaction system is provided with two steps in series: i) thermal step at 200 °C, for the pyrolytic lignin retention, and ii) reforming in-line of the treated bio-oil in a fluidized bed reactor, in the range 600–800 °C, with space-time between 0.10 and 0.45 gcatalyst h (gbio-oil)−1. The benefits of incorporating La2O3 to the Ni/α-Al2O3 catalyst on the kinetic behavior (bio-oil conversion, yield and selectivity of hydrogen) and deactivation were determined. The significant role of temperature in gasifying coke precursors was also analyzed. Complete conversion of bio-oil is achieved with the Ni/La2O3-αAl2O3 catalyst, at 700 °C and space-time of 0.22 gcatalyst h (gbio-oil)−1. The catalyst deactivation is low and the hydrogen yield and selectivity achieved are 96% and 70%, respectively.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The steam reforming of bio-oil aqueous fraction in a continuous system is tackled. ► La2O3 addition on the Ni/αAl2O3 catalyst leads to higher stability an H2 yield. ► La2O3 enhanced WGS reaction and coke gasification. ► With Ni/La2O3-αAl2O3 complete bio-oil conversion and H2 yield of 96% is achieved. ► Two-step reactor is effective for obtaining stable H2 yield with continuous feed.