Syngas production by CO2/O2 gasification of aquatic biomass

In the gasification of an aquatic biomass with He/CO2/O2, the effects of the concentration of CO2 and O2 in the gasifying agent and the feeding rate on the gasification behavior were investigated using a downdraft fixed-bed gasifier at 900°C. Using CO2/O2 as the gasifying agent led to an increase in the conversion to gas and the syngas (CO+H2) content because the gasification of char with CO2 (C+CO2→2CO) and the decomposition of tarry compounds were promoted. Increasing CO2 content led to the increase in the conversion to gas and CO content and the decrease in the H2 content. With increasing O2 content, contents of CO and H2 increased while the conversions to gas remained almost constant. Especially with CO2/O2=45/55vol.%, the conversion to gas was 94.0C-mol% and the syngas content exhibited a maximum value of 69.7vol.%. As the feeding rate was decreased, contents of CO and H2 decreased while the conversion to gas remained almost constant. The nitrogen atoms in the feedstock were mainly converted to form N2. H2S and COS were the main sulfurous gases. The sulfur content in the char was much higher than that in the feedstock. •Using CO2/O2 as the gasifying agent led to an increase in the syngas content.•Increasing CO2 led to the increase in CO content and decrease in H2 content.•Increasing O2 led to the increase in the syngas content.•Increasing gas residence time led to the decrease in the syngas content.•The sulfur content in the char was much higher than that in feedstock.