Comparison of CO2 and steam gasification reactivity of algal and woody biomass chars

This study undertook gasification reactivity measurement of an algal biomass (Chlorella sp.) char prepared in two different reactors with two gasifying agents (CO2 and steam) and compared that with similar measurements on woody biomass (commercial wood mix) char in a thermo-gravimetric analyser at three different temperatures. In general, the woody char from entrained flow reactor showed higher reactivity during gasification. At 800 °C and 950 °C, similar reactivity was exhibited by algal char from thermo-gravimetric analyser whereas at 1100 °C, the woody char became more reactive than the algal char. For algae, the char prepared in entrained flow reactor showed lower reactivity than the char from thermo-gravimetric analyser. The scanning electron microscope images of the char samples showed significant difference in morphology with respect to the char preparation condition and species. For chars of both the species, a temperature of 800 °C and time of around 20 min are found to be sufficient to accomplish most conversion; this information is of practical relevance.

► First study on gasification reactivity of algal char from entrained flow reactor
► Reactivity of the algal and woody chars was studied under CO2 and steam.
► Reactivity was evaluated at three different temperatures.
► Structure of algal and woody chars from different reactors was compared.
► Structural information was used to interpret the reactivity of chars.