Insight into hydroxides-activated coals: Chemical or physical activation?

• Published in: Journal of colloid and interface science Vol. 318; no. 1; pp. 35 - 41
• Main Authors: Alcañiz-Monge, J., Illán-Gómez, M.J.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.02.2008; Elsevier
• Subjects: 01 COAL, LIGNITE, AND PEAT; ACTIVATED CARBON; ACTIVATION ANALYSIS; Adsorbents; ANTHRACITE; CHEMICAL ACTIVATION; Chemistry; COAL; Colloidal state and disperse state; DESORPTION; Exact sciences and technology; General and physical chemistry; Microporosity; POROSITY; Porous materials; POTASSIUM HYDROXIDES; SODIUM HYDROXIDES; Surface physical chemistry; TEMPERATURE DEPENDENCE; Thermal analysis; Microporosity; Chemical activation; Thermal analysis; Activated carbon; Hydroxides; Activation; Porous material
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2007.10.017

The objective of this paper is to get an insight into the chemical activation mechanism using KOH and NaOH as activated agents. Three coals have been selected as carbon precursors. It was found that KOH and NaOH develop a similar narrow microporosity, independently of the coal rank, whereas only KOH generates supermicroporosity. Temperature-programmed desorption experiments, carried out with impregnated anthracite, show differences on the gas evolved during the activated carbon preparation using the two activating agents. Thus, whereas hydrogen profiles are quite similar for both activated agents, the CO and H 2O profiles are different. It is remarkable the high amount of H 2O evolved at the maximum treatment temperature for both activating agents. The results obtained allow concluding that the chemical activation is due to a combination of different process driving the development of material porosity. H 2 and H 2O evolution on the TPD experiment over AK sample.