Pyrolysis of microalgae over Ni/Al-SBA-15 and Ni/Ga-SBA-15 catalysts prepared using a low-acidity solvent and ultrasonic-assisted sol-gel method

The study investigates the catalytic pyrolysis of Spirulina platensis with Ni/Al-SBA-15 and Ni/Ga-SBA-15 catalysts synthesized with a low-acidity solvent and an ultrasonication-assisted sol-gel method. The catalysts showed a notable reduction in the activation energy of the S. platensis pyrolysis compared to non-catalytic pyrolysis, as calculated by the Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose methods. Ni/Ga-SBA-15 showed better activity than Ni/Al-SBA-15 in reducing the active pyrolysis temperature and activation energy, probably due to its higher acidity. At 450 degrees C, pyrolysis-gas chromatography-mass spectrometry showed that the catalysts facilitated the thermal and catalytic degradation of proteins, carbohydrates, lipids, and chlorophylls into smaller compounds. However, both catalysts also facilitated the formation of nitrogen-containing compounds, including alkyl nitriles, which could affect the quality of the pyrolysis products. This study demonstrates the potential of Nimodified SBA-15 catalysts to improve the thermochemical conversion of S. platensis via the pyrolysis route while underlining the need for optimization of pyrolysis conditions to minimize undesired products.