Comparison study on potential syngas produced by mild thermoconversion of microalgal residues through proton nuclear magnetic resonance and thermogravimetric analysis-fourier transform infrared spectroscopy

Abstract

This paper presented a mechanism study of syngas production through lipid-extracted microalgal residues by investigating how the structure of these residues affected the pyrolysis characteristics. The results showed that both Chlorella sorokiniana 21 and Monoraphidium 3s35 residues could be pyrolyzed efficiently at low temperatures from 120 to 380 °C, with a final residue of less than 22.75%. Hemicellulose with carboxyl groups was the main component of both microalgal residues, most likely contributing to the production of the C=O compounds and carbon monoxide (CO). A large amount of CHO, CH2O, and CH3O (60.09% in total) was observed from C. sorokiniana 21, which was 1.58 times more than that from Monoraphidium 3s35. Pyrolysis of the C. sorokiniana 21 residue yielded more C=O and CHn compounds with less activation energy (52.97–58.57 kJ mol−1) and a higher reaction rate (0.105% s−1) than that of Monoraphidium 3s35. The different pyrolysis characteristics between the two microalgal residues might be attributed to structural variations.