Appraisal of agroforestry biomass wastes for hydrogen production by an integrated process of fast pyrolysis and in line steam reforming

The pyrolysis and in line steam reforming of different types of representative agroforestry biomass wastes (pine wood, citrus wastes and rice husk) was performed in a two-reactor system made up of a conical spouted bed and a fluidized bed. The pyrolysis step was carried out at 500 C-degrees, and the steam reforming at 600 C-degrees with a space time of 20 g(catalyst) min g(volatiles)(-1) and a steam/biomass ratio (S/B) of 4. A study was conducted on the effect that the pyrolysis volatiles composition obtained with several biomasses has on the reforming conversion, product yields and H2 production. The different composition of the pyrolysis volatiles obtained with the three biomasses studied led to differences in the initial activity and, especially, in the catalyst deactivation rate. Initial conversions higher than 99% were obtained in all cases and the H2 production obtained varied in the 6.7-11.2 wt% range, depending on the feedstock used. The stability of the catalysts decreased depending on the feedstock as follows: pine wood >> citrus waste > rice husk. A detailed assessment of the mechanisms of catalyst deactivation revealed that coke deposition is the main cause of catalyst decay in all the runs. However, the volatile composition derived from the pyrolysis of citrus waste and rice husk involved the formation of an encapsulating coke, which severely blocked the catalyst pores, leading to catalyst deactivation during the first minutes of reaction.

Automated summary

The pyrolysis and in line steam reforming of different types of agroforestry biomass wastes were studied, and their effects on conversion, product yields and H2 production were evaluated. The composition of pyrolysis volatiles obtained from different biomasses resulted in variations in activity and catalyst deactivation rate.