Advanced biofuels production by upgrading of pyrolysis bio-oil

摘要

The present work is a review on the production of bio-oils from biomass pyrolysis,rnwith special emphasis on the different catalytic methods developed so far forrnthe upgrading of this liquid fraction in order to significantly improve its properties,rnso it can be used as advanced biofuel. After a discussion of the main variablesrnand factors affecting biomass pyrolysis, a number of processes arerndescribed here for bio-oil upgrading, including catalytic pyrolysis, esterification,rnaldol condensation, ketonization, and hydrodeoxygenation (HDO). All of themrnare featured by the use of tailored catalysts that may play different roles, such asrncompleting depolymerization of biomass, promoting deoxygenation reactions,rnand favoring C C bonds formation in order to increase the proportion of componentsrnpresent in the final bio-oil within the range of liquid fuels.The reviewrnhighlights the challenges that must still be faced for biomass pyrolysis/bio-oilrnupgrading to become a commercial process. Among them, catalyst deactivationrnis a general issue to be considered as bio-oil has a strong tendency to polymerize,rnforming carbonaceous deposits on the catalysts, and contains a large share ofrnwater with acidic pH that may damage the catalyst components in liquid-phasernupgrading treatments. Likewise, process integration of bio-oil upgrading treatments,rnthrough more or less complex schemes, is an aspect that should be deeplyrnanalyzed in the future as it may be a key element determining the commercialrnfeasibility of the overall process.