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Carratala-Abril J.,Grupo de Materiales Carbonosos y Medio Ambiente | Lillo-Rodenas M.A.,Grupo de Materiales Carbonosos y Medio Ambiente | Linares-Solano A.,Grupo de Materiales Carbonosos y Medio Ambiente | Cazorla-Amoros D.,Grupo de Materiales Carbonosos y Medio Ambiente
Chemical Engineering Science | Year: 2010

Regeneration of activated carbons (ACs) after their use for benzene and toluene removal at low concentration was studied in an oxygen-containing atmosphere, analysing the effect of porosity of the adsorbent. Attention was paid to the effect of regeneration cycles on the adsorption capacity and surface chemistry of the AC. Results show that ACs with large mesopore volumes, together with wide micropore size distributions, are desired to achieve complete regeneration at low temperatures (250-300 °C). The effect of successive regeneration cycles under an oxygen-containing atmosphere indicates that 250 °C is suitable for regeneration of most benzene-exhausted adsorbents, whereas for toluene the process requires higher temperatures (300-350 °C). The experiments show that in the case of benzene, regeneration efficiencies remain essentially constant with the number of cycles and the achieved regeneration efficiencies are close to 100%. The slight differences in regeneration efficiencies can be explained considering changes in microporosity and surface chemistry of the AC with the cycles. For regeneration of toluene-saturated AC, the regeneration percentage only remains constant for one AC, whereas some decrease is observed for the rest. This decrease can be explained, in general, by a reduction in the narrow micropore volume with cycling. © 2009 Elsevier Ltd. All rights reserved.


Vilaplana-Ortego E.,Grupo de Materiales Carbonosos y Medio Ambiente | Lillo-Rodenas M.A.,Grupo de Materiales Carbonosos y Medio Ambiente | Alcaniz-Monge J.,Grupo de Materiales Carbonosos y Medio Ambiente | Cazorla-Amoros D.,Grupo de Materiales Carbonosos y Medio Ambiente | Linares-Solano A.,Grupo de Materiales Carbonosos y Medio Ambiente
Fuel Processing Technology | Year: 2010

The paper provides interesting evidences that a low softening point isotropic petroleum pitch can be used as a good carbon precursor for the preparation of activated carbons. The activation is carried out by KOH and/or NaOH and the resulting activated carbons present well developed porosity. Such hydroxide activations can be done directly on the pristine petroleum pitch (P) or on the pitch that has been submitted to an air stabilisation followed by a N2 heat treatment (TAN). In general, KOH activation produces better results than NaOH, both in terms of porosity and yield, the results obtained for the activation of TAN being impressive because of the good porosity developments and high yields reached. The different treatments carried out over the petroleum pitch precursor clearly show that they significantly influence the extent of microporosity development. This is due to different changes occurring in the porous structure of the precursor as a function of the treatment carried out. The efficiency of the activation process increases as the mesophase content of the precursor decreases, as well as the mesophase formation during the activation process is avoided. © 2009 Elsevier B.V. All rights reserved.

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