Hydrogen production and structure evolution mechanism during thermochemical conversion of microalgae pellet in molten hydroxide salts

By comparing the temperature evolution, gas release characteristics, and structure evolution of pellet with and without molten salt, and combining with char alkalization experiments, the regulatory mechanism of molten salt on the reaction pathways and hydrogen production behavior of microalgae pellet was systematically analyzed.

The results indicate that the molten salt significantly enhances the internal heat transfer efficiency of the pellet, with a central heating rate reaching 177°C/s, effectively alleviating thermal hysteresis. Meanwhile, the molten salt promoted pellet pore development through penetration, erosion, and catalytic effects, resulting in a porosity increase of 53.2%–104.3% after 10 s of reaction. It also significantly enhanced the conversion efficiency, with the dominant reaction pathway shifting to char gasification after only70 s.