Sorption enhanced steam reforming (SESR) of raw bio-oil with Ni based catalysts: Effect of sorbent type, catalyst support and sorbent/catalyst mass ratio

Abstract

[EN] This work analyzes the effect of sorbent type (dolomite or CaO/mayenite), catalyst type (Ni/Al2O3 obtained upon reduction of a NiAl2O4 spinel or Ni/CeO2 prepared by wet-impregnation) and sorbent/catalyst ratio (4, 10 and 20) in the sorption enhanced steam reforming (SESR) of a real raw bio-oil. The experiments were performed in a continuous reaction system with two units: a thermal treatment unit at 500 ◦C for real bio-oil volatilization and controlled deposition of pyrolytic lignin, and a fixed-bed reactor for the SESR on line of the remaining oxygenates at 600 ◦C with steam-to carbon (S/C) ratio of 2.6. Furthermore, the causes of the unavoidable catalyst deactivation have been determined by several techniques. The sorbent activity for oxygenates decomposition/cracking reactions competes with the catalyst activity for reforming reactions and affects the morphology and location of the coke, thus affecting the catalyst stability. The combination of dolomite (less active for oxygenates decomposition than CaO/mayenite) and Ni/Al2O3 catalyst (with higher activity for real bio-oil reforming than Ni/ CeO2) is the better choice. With space time of 0.15 gcatalyst⋅h/goxygenates, a dolomite/NiAl2O4 mass ratio of 10 allows producing a gas stream with almost 100% H2 for 30 min with high stability.