Biomass catalytic pyrolysis over CaO microspheres: Relationship between the production of bio-oil components and CO2 capture

Abstract

Biomass catalytic pyrolysis is a promising way for the clean and even “Carbon-Negative” utilization of biomass via the in-situ upgrading bio-oil and reducing the emissions of CO2. In this work, CaO microspheres (CaO-H) prepared via hydrothermal method were used to adsorb CO2 and catalyze the reforming of bio-oil in the pyrolysis process of rice straw (RS) simultaneously. The results showed that CaO-H had the more strong basic sites compared with commercial CaO and thus the better adsorption capacity of CO2 (∼0.5 g/g CaO) at 700 °C and the stronger effect on the generation of bio-oil components and CO2. And strong relationships presented between the formation of CO2 and the composition of bio-oil. The yield of phenols and ketones can be enhanced by 37.17% and 56.76% respectively via the addition of CaO-H at the pyrolysis temperature of 650 °C, companying with the decrease of CO2 yield by 35.13%. It is also inferred that the CO2 reforming of bio-oil and the insertion of CO in CO2 into bio-oil components was strengthened during the biomass pyrolysis over CaO-H especially at the temperature of 650 °C. The possible mechanism of biomass pyrolysis over CaO-H was also proposed.