Catalytic pyrolysis of microalgae Tetraselmis suecica and characterization study using in situ Synchrotron-based Infrared Microscopy

•In situ pyrolysis using Synchrotron IR.•Direct and catalytic pyrolysis of microalgae in a quartz fixed bed reactor.•Different pyrolysis temperatures resulted in different compositions of bio-oil.•The use of zeolite catalyst can reduce the oxygen compounds in bio-oil.•Some functional groups are still present at low heating rate experiments.

In this study, the direct and catalytic pyrolysis of microalgae Tetraselmis suecica was conducted to determine the composition of bio-oil obtained. Thermogravimetric analysis showed that at high heating rate, the decomposition temperature and volatile matter evolution increased. Direct pyrolysis results identified the optimum temperature for bio-oil production to be 400 °C. The bio-oil produced from catalytic pyrolysis showed a decrease in the oxygenated compounds which indicate that the addition of zeolite catalyst (Si/Al = 30, 60) can improve the bio-oil composition. However, zeolite catalyst (Si/Al = 30) showed a higher decrease in the oxygenated compounds compared to (Si/Al = 60). Furthermore, this study found that some functional groups are still present in the char of T. suecica biomass at 550 °C (5 °C/min heating rate), while most already disappeared at 350 °C (150 °C/min heating rate) when using in situ Synchrotron-based Infrared Microscopy.