Mechanistic insights into slow pyrolysis of hydrothermal carbon

Slow pyrolysis of fructose-derived hydrothermal carbon spheres at temperatures between 200 °C to 600 °C has been investigated using X-ray Raman spectroscopy and pyrolysis gas chromatography-mass spectrometry in combination with infrared spectroscopy, elemental analysis and thermogravimetry. This study demonstrates the application of temperature resolved X-ray Raman spectroscopy to map the evolution of carbon functionality in complex organic materials. The results show that thermolysis of the polyfuranic linking units within hydrothermal carbon occurs between 300 °C to 350 °C. At pyrolysis temperatures above 350 °C, a stable Csingle bondO species is observed. The combination of X-ray Raman and pyrolysis GCMS is used in a synergistic approach to monitor both evolving pyrolysate chemistry and bulk carbon composition. The evolution of key furanic and aromatic analytes during pyrolysis is reported. This work contributes to our understanding of the thermal stability and reactivity of these materials, which is essential for optimising their applications as catalyst supports.