A porous carbon foam prepared from liquefied birch sawdust

Carbon foam was prepared by submitting birch sawdust to liquefaction, resinification, foaming, carbonization, and activation steps. The foam was characterized by TG and DTG, XRD, SEM, and nitrogen adsorption at 77 K. A mechanism for the formation of the porous carbon foam was proposed. Solid non-graphitized lightweight carbon foams with specific surface areas of 534-555 m(2)/g and cell sizes of 100-200 mu m were obtained, depending on the carbonization or activation temperature used. The intermediate liquefied birch-based resin foam exhibits thermal stability superior to liquefied wood and inferior to phenolic resin, and decomposes rapidly in two stages, at 285.7 and 412.9 degrees C, respectively. Further activation of the carbon foam in a stream of nitrogen above 800 degrees C improves the pore structure and homogeneity of the cell size significantly. The matrix of the foams contains a large number of micropores, and the microstructure becomes more ordered as the activation temperature is increased.