Catalytic hydrothermal gasification of microalgae for producing hydrogen and methane-rich gas

ABSTRACT

We report herein the production of H₂ and CH₄ from the catalytic hydrothermal gasification of microalgae. All reactions were performed at 430°C for 1 h using a batch reactor. The effects of catalyst, water density, and initial feedstock on the mole fractions and yields of H₂ and CH₄ were examined. The catalytic yields of H₂ and CH₄ increased 2–3 and 3–9 times higher than their yields without catalysts, respectively. Pt/C and Ru/C catalysts produced the highest mole fractions and yields of H₂, which were 43.11% and 5.75 mmol/g and 42.01% and 5.97 mmol/g, respectively. In contrast, Pd/C and Rh/C catalysts produced the highest mole fractions and yields of CH₄, which were 35.24% and 6.17 mmol/g and 31.39% and 7.19 mmol/g, respectively. When the water density was increased, the H₂ content in the gaseous products decreased, and the H₂ yield initially increased and subsequently decreased the peak value. The mole fraction and yield of CH₄ always increased with increasing water density, indicating that the methanation reaction preferentially occurs at high water density. Fatty acids derived from algae contributed to the production of CH₄. Protein and carbohydrate-based feedstocks preferentially produced H₂. A synergistic effect was observed among the biochemical components of algae during the gasification of algae.

KEYWORDS:

• Hydrothermal gasification
• microalgae
• methane
• noble metal catalyst
• water density
• hydrogen

Funding

The authors gratefully acknowledge the financial support provided by the Program for New Century Excellent Talents in University (NCET-13-775) and the National Science Foundation of China (21106034).

Additional information

Funding

The authors gratefully acknowledge the financial support provided by the Program for New Century Excellent Talents in University (NCET-13-775) and the National Science Foundation of China (21106034).