Microwave plasma studies of Spirulina algae pyrolysis with relevance to hydrogen production

Growth of the hydrogen market has motivated increased study of hydrogen production. Understanding how biomass is converted to hydrogen gas can help in evaluating opportunities for reducing the environmental impact of petroleum-based fuels. Using an atmospheric-pressure microwave plasma reactor coupled with species-selective analysis, experiments are conducted at microwave power levels of 800, 900 and 1000 W, a reactant flow rate of 12 slm, and 1 g of dry Spirulina algae in nitrogen. At the absorbed microwave power levels used in this experiment, hydrogen gas produced is in the range of 36.75–45.13% volume fraction, 13.42–15.48 mg per minute, and 12.37–31.46 mg per gram of Spirulina algae consumed. Moreover, the selection of power levels demonstrates that 20.62–52.43% hydrogen atom mass content in dry algae is converted to hydrogen gas. In general, the effect of reaction temperatures on the gas product formation is qualitatively consistent with those produced from other biomass materials reported in literature. Overall, these results will help to expand our knowledge concerning Spirulina algae and hydrogen yield on the basis of microwave-assisted pyrolysis and reaction temperatures, which will inform the study and design of hydrogen production technologies. - Highlights: • A pyrolysis process for Spirulina algae is presented using microwave plasma. • H2, CO2 and CO are the main gas products observed in this study. • Maximum H2 gas-volume fraction of about 45% is achieved at 1 kW microwave power