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

Zhang, Kang; Kim, Woo-Jae; Park, Ah-Hyung Alissa · Nat Commun · 2020

basic_science · Level V

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Abstract

Current thermochemical methods to generate H<sub>2</sub> include gasification and steam reforming of coal and natural gas, in which anthropogenic CO<sub>2</sub> emission is inevitable. If biomass is used as a source of H<sub>2</sub>, 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<sub>2</sub> are limited. In this study, a catalytic alkaline thermal treatment of brown seaweed is investigated to produce high purity H<sub>2</sub> with substantially suppressed CO<sub>2</sub> formation making the overall biomass conversion not only carbon-neutral but also potentially carbon-negative. High-purity 69.69 mmol-H<sub>2</sub>/(dry-ash-free)g-brown seaweed is produced with a conversion as high as 71%. The hydroxide is involved in both H<sub>2</sub> production and in situ CO<sub>2</sub> capture, while the Ni/ZrO<sub>2</sub> catalyst enhanced the secondary H<sub>2</sub> formation via steam methane reforming and water-gas shift reactions.

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