Sorption enhanced catalytic fast pyrolysis for the production of high-quality bio-oil from biomass

The rapid increase in the consumption of fossil fuels driven by enhanced economic activites and with that the emissions of CO2 have led to an increased focus on tackling its effect on climate change. Among the alternatives for liquid based fuels, liquid bio-fuel derived from lignocellulosic biomass is perceived to be of high potential. Fast pyrolysis is a promising technology to convert biomass into liquid fuel. However, the high oxygen content of the obtained bio-oil leads to undesirable characteristics. In-situ catalytic pyrolysis and/or downstream hydrogen based catalytic processes are often applied to deoxygenate the bio-oil. Despite the efforts in this direction, lower yields of bio-oil and a need for hydrogen from external sources still pose challenges.

Therefore in this work a novel concept of sorption enhanced catalytic fast pyrolysis for the production of high quality bio-oil from biomass has been developed. Here both deoxygenation and production of in-situ hydorgen is envisaged to overcome the challenges of the state of the art process. During biomass pyrolysis, in-situ hydrogen can be generated by controlling the water gas shift reaction equilibrium via the introduction of a CO2 sorbent. In order to promote both deoxygenation and in-situ H2 production, a combination of a catalyst and a CO2 sorbent during in-situ pyrolysis looks promising. Moreover developing or selecting a catalyst having both deoxygenation and CO2 sorption potential is another interesting option.

Overall, this work revealed that biomass can be effectively transformed into in a moderately deoxygenated bio-oil and a CO2 free and H2 rich pyrolysis gas in the presence of dolomite at a pyrolysis temperature of 500 °C. Furthermore, calculations showed that the H2 generated as a result of CO2 sorption can suffice the requirement of downstream hydrogenation process. Thus a high quailty bio-oil can be produced without the need of external hydrogen.