Improvement of gasification performance of Eucalyptus globulus stumps with torrefaction and densification pre-treatments

•Gasification of eucalypt stumps.•Study of the biomass pre-treatments: densification, torrefaction and densification of torrefied feedstock.•Effect of biomass pre-treatments on syngas yield and quality.•Effect of biomass pre-treatments on the release of H2S and NH3.•Selection of the best biomass pre-treatments to improve gasification performance and syngas composition.