A study on growth and pyrolysis characteristics of microalgae using Thermogravimetric Analysis-Infrared Spectroscopy and synchrotron Fourier Transform Infrared Spectroscopy.

This two-part study firstly investigated Tetraselmis suecica grown in different CO ₂ (0.04-15%v/v) concentration through indoor and outdoor cultivation systems. A high CO ₂ concentration led to a high lipid content, and low nitrogen and oxygen content, which are desirable for transport fuel production. Pyrolysis characteristics were investigated by TG-IR and synchrotron IR microscopy. The results show Tetraselmis suecica grown in 10%CO ₂ had the highest decomposition rate corresponding to more volatile products produced during the main thermal cracking stage and derived from protein-and lipid-corresponding functional groups. Moreover, a high reaction temperature and CO ₂ concentration resulted in a low retention of surface functional groups. The nitrogen functional groups initially decomposed at a temperature range of 250-300°C and still remained at 550°C, while the lipid-corresponding functional groups completely disappeared at a temperature range of 400-500°C. Besides, the decomposition of chemical components followed the order of carbohydrate, protein and lipid.
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