Production of micro- and mesoporous carbons by pyrolysis of the lithium salts of aromatic acids

As a new process for the production of micro- and mesoporous carbon materials, the thermal decomposition of the lithium salts of aromatic acids (terephthalic acid, 1,3,5-benzenetricarboxylic acid, and 1,2,4,5-benzenetetracarboxylic acid) was followed by TGA, MS, SEM, TEM, elemental analysis, and N2 adsorption. The lithium salt of terephthalic acid was decomposed at temperatures above 550 °C and then converted into a composite of amorphous carbon and microcrystalline lithium carbonate (600-700 °C) or oxide (800-900 °C). The amorphous carbons produced by washing out the lithium compounds showed surface areas of 480-780 m2 g−1, and the micro- and mesopore volumes attained 0.27 and 0.93 cm3 g−1, respectively, at the pyrolytic temperature of 850 °C. The mesopores were distributed from ca. 20 to 100 nm in size, and the distribution was independent of the pyrolytic temperatures. The pore size was, however, increased when larger-size crystals of the lithium salt were employed as the starting material. Both porous carbons prepared from the lithium salts of 1,3,5-benzenetricarboxylic acid and 1,2,4,5-benzenetetracarboxylic acid showed similar surface areas and pore size distributions to those from terephthalic acid.