Production of biochars by intermediate pyrolysis and activated carbons from oak by three activation methods using CO2

Biochars were produced by intermediate pyrolysis in a fixed-bed reactor, and their physicochemical properties were investigated. In addition, activated carbons were prepared by three different methods (N-2/CO2 without cooling, N-2/CO2 with cooling and direct CO2), and their properties were compared to evaluate the efficiency of the three methods. Surface areas of biochars obtained by intermediate pyrolysis at 500 and 800 degrees C were 107 and 249 m(2)/g. The maximum surface area of activated carbon (1126 m(2)/g) was obtained by the N-2/CO2 without cooling method at a final activation temperature of 900 degrees C and with a 1-h final activation time. Comparison between the N-2/CO2 methods with and without cooling showed no significant difference in terms of the surface area of activated carbon. The activated carbons produced by the direct CO2 method had a specific surface area of approximately 800 m(2)/g which appeared to be sufficiently high for commercial uses. The activated carbons produced had predominantly microporous structures (<= 1 nm). (C) 2014 Elsevier B.V. All rights reserved.