CO2 conversion to CO by fluidized bed biomass gasification: Analysis of operational parameters

Thermochemical conversion of CO2 with biomass to CO in fluidized bed gasifiers is promising for a sustainable carbon economy. Knowledge about this process is expanded by investigating experimental parameters influencing CO2 conversion in such a system and combining them to demonstrate effective conversion. Wood char and CO2 are fed to a lab-scale gasifier in 53 semi-continuous experiments. Six experimental parameters are varied: temperature, bed material type, initial bed-to-fuel ratio, initial fuel loading in the reactor, feed CO2 flow rate, and fuel particle size. The results are compiled in a semi-empirical model based on reaction kinetics. High temperatures and high fuel-gas contact times are favorable for increasing CO2 conversion, with the latter achieved through high initial fuel loadings in the reactor and low feed gas flow rates. Choosing olivine instead of silica sand as a bed material also results in higher CO2 conversions. The highest CO2 conversion demonstrated in this paper is 86.1%. This experiment produces a gas with 82.75% CO, 10.01% H2, and 5.90% CO2 (nitrogen-free and dry). [Display omitted] •CO2 gasification is demonstrated to convert 86% of CO2 in a fluidized bed reactor.•Temperature and contact time of CO2 and biomass strongly influence conversion.•This paper includes 53 experiments and a semi-empirical model for CO2 conversion.•CO2 conversion is investigated at low biomass conversions (differential reactor).