Pyrolysis characteristics and kinetics of microalgae via thermogravimetric analysis (TGA): A state-of-the-art review

•A state-of-the art review on recent research activities in microalgae pyrolysis is given.•Pyrolysis characteristics and kinetics of microalgae via TGA is reviewed.•Kinetic-free, single reaction and multiple parallel reaction and distributed activation energy models are introduced.•The kinetic models predicting the thermal degradation of microalgae are examined.•Pros and cons of microalgae pyrolysis using TGA are illustrated. Pyrolysis is a promising route for biofuels production from microalgae at moderate temperatures (400–600°C) in an inert atmosphere. Depending on the operating conditions, pyrolysis can produce biochar and/or bio-oil. In practice, knowledge for thermal decomposition characteristics and kinetics of microalgae during pyrolysis is essential for pyrolyzer design and pyrolysis optimization. Recently, the pyrolysis kinetics of microalgae has become a crucial topic and received increasing interest from researchers. Thermogravimetric analysis (TGA) has been employed as a proven technique for studying microalgae pyrolysis in a kinetic control regime. In addition, a number of kinetic models have been applied to process the TGA data for kinetic evaluation and parameters estimation. This paper aims to provide a state-of-the art review on recent research activities in pyrolysis characteristics and kinetics of various microalgae. Common kinetic models predicting the thermal degradation of microalgae are examined and their pros and cons are illustrated.