Development of a high density carbonaceous adsorbent from compressed wood

In order to improve adsorption capacity per unit volume of carbonaceous adsorbent, a method that decreases macropore volume was investigated. Sapwood of Japanese cedar (C. japonica) was compressed under three different pressures, 1, 2 and 3x10(3) kgf/cm(2), and the compressed wood carbonized at 600 degreesC. The total volume (V-HG) of all pores in the range of 30 nm to 13 mum in diameter was decreased by two-thirds and apparent density increased threefold. However, at all three pressures, there was little change in total volume (V-N2) Of all pores of less than 30 nm in diameter or in specific surface area. Next, the compressed wood charcoal was crushed into pellets, inserted in a rotary kiln and activated with steam at 850 degreesC for various periods of time. Activation yield decreased linearly with increasing activation time, and showed a good linear relationship with iodine adsorption capacity. These relations were not affected by compression treatment. This result indicates that the formation of micropores by steam reaction is not affected by macropore volume. Activated carbon of double density can thus be produced by compression treatment. (C) 2001 Elsevier Science Ltd. All rights reserved.