Effects of total pressure and CO₂ partial pressure on the physicochemical properties and reactivity of pressurized coal char produced at rapid heating rate

The effects of the total pressure (0.1–1.3 MPa) and the CO₂ partial pressure (0–0.45 MPa) on the physical structural properties, chemical structural properties and reactivity of Shenhua coal pressurized char at 1273 K were investigated in a pressurized drop tube furnace (PDTF). There were reverse-direction effects on char yield between total pressure and CO₂ partial pressure for char preparation. Porosity characteristics were performed using an ASAP2020 instrument. It was found that same-direction increment effects on BET surface and porosity between total pressure and CO₂ partial pressure for char preparation. Carbon structure and surface structure were performed by Raman and XPS methods. The results showed that both total pressure and CO₂ partial pressure can promote the transformation of small aromatic structures to large aromatic structures and increase the graphitization degree of the char. With increasing total pressure and CO₂ partial pressure, the unstable N-5 content decreased, while the N-6 and N-Q content increased.