Study on the pyrolysis behaviour of the macroalga Ulva prolifera

The outbreak of Ulva prolifera as a marine waste biomass costs a huge amount of manpower and sources for remediation. The effective utilisation of U. prolifera would be mutually beneficial for environmental protection and production of bio-based energy or chemicals. Herein, the pyrolysis behaviour of the main constituents in U. prolifera was investigated to provide valuable data for its further valorisation. The cleavage of thermally unstable sulphated polysaccharides initial occurred between 180 and 200 °C. Uronic acid fraction in hemicellulose degraded at 180–240 °C, releasing formic acid (FA) and oligosaccharides. The complete depolymerisation of hemicellulosic polysaccharides generated rhamnose (Rha) at 300 °C. Above 300 °C, the formation of 5-methyl furfural originated from the dehydration of Rha and the pyrolytic reactions of cellulose. Cellulose with better thermal stability slowly underwent an intermolecular dehydration process at 160 to 240 °C and needed higher temperature for full conversion. The favourable pyrolysis temperature range of the specific constituents and the corresponding detailed pyrolysis characteristics provided an opportunity to obtain value-added chemicals with high selectivity and then increased the utilisation value of U. prolifera .