Complex microstructural evolution in high temperature pyrolysis of plastic and biomass

Pyrolytic carbon with controlled pore structure and high surface area from produced from recycled carbonaceous materials like biomass and plastics have significant applications such as solid fuel for power plants and reductants for metallurgical process. Understanding the detailed pathways of carbon structural evolution, yields insights into the effect of temperature on chemical and physical properties and is expected to yield efficiencies in the synthesis of these heat treated carbonaceous materials. While the effect of heat treatment temperature in determining the texture, pore size, and chemical structure of pyrolytic carbon has been well studied, the influence of precursor structure and mineral content is less understood. In the present work, the differences in structural evolution during pyrolysis using fixed bed reactors, of biomass and plastics, or between biomass with different ash contents have been studied. An in depth measurement of the resulting pyrolytic carbon in the range of 600 degrees C to 1500 degrees C, using Raman spectroscopy, XRD, surface area measurement, yield a detailed understanding of the structural evolution of char. The difference in characteristics between chars from biomass and plastics is shown to arise due to distinct structural evolution in the early stages of the pyrolysis while the presence of different alkali oxides in the chars influences the char characteristics at higher temperatures (>1000 degrees C) via a metal ion intercalation mechanism. These structural changes are directly related to changes in the measured gasification reaction of the chars.