Pyrolysis of aquatic carbohydrates using CO₂ as reactive gas medium: A case study of chitin

Here in this study, the thermolysis of aquatic biopolymer (i.e., chitin)was mainly investigated as a strategic means for reinforcing the insecure supply chains of terrestrial biomass. To maximize carbon utilization in the carbon substrate and establish a sustainable pyrolysis platform, this study particularly employed CO₂ as reactive gas medium. To this end, this study laid great emphasis on elucidating the mechanistic role of CO₂ in pyrolysis of chitin. For the fundamental study, the thermolysis of chitin in CO₂ in reference to the case in N₂ was characterized thermo-gravimetrically. A series of the TGA tests signified that the homogeneous reactions between solid-state chitin and CO₂ should be excluded. However, a lab-scale pyrolysis of chitin in CO₂ demonstrated that CO₂ enhanced thermal cracking of the volatile hydrocarbon species from the thermolysis of chitin. In parallel, CO₂ reacted with the volatile hydrocarbon species to form CO. To justify such genuine mechanistic roles of CO₂, two-stage pyrolysis of chitin was conducted, and all experimental findings strongly supported the genuine mechanistic roles of CO₂.