فهرست نشریات علمی دسترسی آزاد ایران

Microalgae, characterized by their high growth rates and photosynthetic efficiency, effectively capture anthropogenic CO2 from the atmosphere and serve as a versatile source of renewable biofuels and a wide range of bioproducts. Among thermochemical conversion methods for transforming microalgae into biofuels, supercritical water gasification (SCWG) has emerged as a clean and promising technique for processing high-moisture biomass to produce valuable gases with significant heating values, primarily methane and hydrogen. This study focuses on the kinetic modeling of marine microalgal biomass to describe the formation of gaseous products during non-catalytic SCWG. The model assumes an initial conversion of microalgal biomass into two intermediate types, namely rapidly and slowly gasified intermediates, followed by the production of gaseous components via steam reforming and decomposition pathways. Experimental data from SCWG of microalgae were used to validate the model, covering temperatures of 380 ºC and 405 ºC, biomass loadings ranging from 1-8 wt%, and reaction times between 15 and 45 minutes. By applying first-order kinetics, reaction rate constants were estimated using MATLAB software combined with a genetic algorithm. The model demonstrated a strong ability to predict gas production from microalgae biomass. As evidenced by the kinetic data, higher temperatures resulted in increased reaction rate constants, favoring gasification pathways over char formation. Sensitivity analysis and reaction rate constants indicated that hydrogen gas is mainly produced through steam reforming and water gas shift reactions, whereas methane generation primarily results from the direct decomposition of intermediates.