Effect of chemical activation on the cellular structure of biopitch-derived green carbon foam

Abstract

Current researches pay particular attention to cost-effective and abundant raw materials such as biomass as an alternative to fossil-derived-carbonaceous precursors. The aim of this study is to examine the usability of pyrolytic oil as a biopitch source in the foaming process and to investigate the effect of chemical activation on the characteristics of carbon foam. The elemental analysis of the biopitch supported the fact that the H/C and O/C ratios of wood-tar-based-pitch had high oxygenated and aliphatic carbons in contrast to fossil-pitches. Various basic analysis methods such as elemental analysis, X-ray diffraction, nitrogen sorption isotherms, Raman spectroscopy, scanning and transmission electron microscopy, true/bulk density and compressive strength tests were applied to analyze carbon foams. When the results of nitrogen sorption analysis were examined, it was determined that the surface area of carbon foam increased to about 31 times after activation. According to the pore size distribution graphs, the foams had regular pore distribution; additionally, the pore size in the mesopore region was determined to shift to the micropore region with activation. Compressive strength values were in the range of 0.40-1.97 MPa. Moreover, an increase in porosity values and a decrease in compressive strength values were observed due to enhancing porosity as a result of the activation process.