Alkaline thermal treatment of seaweed for high-purity hydrogen production with carbon capture and storage potential

Current thermochemical methods to generate H(2) include gasification and steam reforming of coal and natural gas, in which anthropogenic CO(2) emission is inevitable. If biomass is used as a source of H(2), the process can be considered carbon-neutral. Seaweeds are among the less studied types of biomass with great potential because they do not require freshwater. Unfortunately, reaction pathways to thermochemically convert salty and wet biomass into H(2) are limited. In this study, a catalytic alkaline thermal treatment of brown seaweed is investigated to produce high purity H(2) with substantially suppressed CO(2) formation making the overall biomass conversion not only carbon-neutral but also potentially carbon-negative. High-purity 69.69 mmol-H(2)/(dry-ash-free)g-brown seaweed is produced with a conversion as high as 71%. The hydroxide is involved in both H(2) production and in situ CO(2) capture, while the Ni/ZrO(2) catalyst enhanced the secondary H(2) formation via steam methane reforming and water-gas shift reactions.