Fig. 4: Gas formation behaviors of seaweed ATT and involved reactions.

a–c Formation behaviors of major gaseous products during the ATT reaction of brown seaweed at various reaction temperatures. a ATT, b ATT with Ni-based catalyst, and c ATT with Ni-based catalyst and secondary CO2 capture using Ca(OH)2. d Pathways of H2 generation during the ATT reaction identified based on the results given in Fig. 2a.