Biomass source influence on hydrogen production through pyrolysis and in line oxidative steam reforming.

Abstract

This study evaluates the potential of several biomasses differing in nature and composition for their valorization by pyrolysis and in-line oxidative steam reforming. The first task involved the fast pyrolysis of the biomasses in a conical spouted bed reactor at 500ºC, in which product yields were analyzed in detail. Then, the oxidative steam reforming of pyrolysis volatiles (gases and bio-oil) was approached in a fluidized bed reactor. The reforming experiments were performed at 600 ºC, with an steam/biomass (S/B) ratio of 3 and catalyst (Ni/Al2O3) space times of 7.5 and 20 gcat min gvol-1. Concerning equivalence ratio (ER), a value of 0.12 was selected to ensure autothermal operation. Remarkable differences were observed in H2 production depending on the type of biomass. Thus, pine wood led to a H2 production of 9.3 wt%. The lower productions obtained with rice husk (7.7 wt%) and orange peel (5.5 wt%) are associated with their higher ash and fixed carbon content, respectively, which limit the efficiency of biomass conversion to bio-oil. However, in the case of the microalga, the poor performance observed is due to the lower conversion in the reforming step toward gases due to the composition of its pyrolysis volatile stream.