Hydrogen production from pyrolysis catalytic reforming of cellulose in the presence of K alkali metal

• This paper mainly studies the influence of volatilized potassium on Ni/Al2O3 catalyst.
• The deposition amount of potassium on catalyst has no relationship with the amounts of K loaded in the cellulose sample.
• More filamentous carbon formed on the surface of 5 times used catalyst with K adding.

The inherent alkaline metals in biomass material are known to be volatile during biomass pyrolysis. However, there are very limited works about the investigation of the influence of alkaline metal on hydrogen production from downstream catalytic reforming of pyrolysis vapors. In this study, the influence of volatile K inside the cellulose sample was investigated in terms of hydrogen production and catalyst stability using a two-stage fixed-bed reaction system in the presence of a Ni/Al2O3 catalyst. When the content of K in the cellulose sample was increased from 0 to 15%, the deposition of K on the surface of the reacted catalyst was kept constant at around 0.5 wt.% in terms of the weight of the catalyst. The life time test shows that hydrogen production was around 28 (mmol g−1 cellulose) for each experiment, when the catalyst was reused 5 times using the pure cellulose sample. However, the hydrogen production was significantly reduced to 22 (mmol g−1 cellulose) after the catalyst was reused 5 times with the 2.5% K/cellulose sample. X-Ray Fluorescence analysis shows that the reduce hydrogen production might be ascribed to the increase of the K deposition on the surface of the reused catalyst.