Activated carbon synthesis from bituminous coals by chemical activation

Jagtoyen, M.; Stewart, M.; Rathbone, Robert F.; Derbyshire, F.J.

doi:10.1016/0016-2361(93)90658-o

Cited by 2 publications

(5 citation statements)

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“…Our results agree with those of Wang et al 29 because the majority of the mineral components of our coals are quartz and kaolinite. Conversely, other authors 24 have observed that the mineral matter content of the coal is not modified by activation with KOH at ratios of KOH/C lower than 1.3, but it is noticeably increased when higher activating agent/coal ratios are used.…”

Section: Resultsmentioning

confidence: 68%

“…These results confirm the well-known ability of alkali metal hydroxides to develop the porosity of the raw material. 13,14,[17][18][19][20][21][22]24,25,30,31 The extent of the porous development reached depends on the KOH/coal ratio and the procedure used. High apparent surface areas can be obtained by selection of the appropiate conditions.…”

Section: Resultsmentioning

confidence: 99%

“…Effect of the Activating Agent/Coal Ratio (A/C). The A/C ratio widely varies in the literature. ,,,,− , In the present work the ratios 1/1 and 2/1 have been tested in several coals using different activating agents. Table compiles the results for coal UA8 activated with KOH, pyrolyzed at 700 °C, and using the WP.…”

Section: Resultsmentioning

confidence: 99%

“…The increase in N 2 surface area with the KOH/coal ratio was also observed previously. An example is the work of Jagtoyen et al 13,[23][24][25]31 Nevertheless, contradictory results have also been found; thus, Otowa et al, 30 using a much higher KOH/coal ratio, observed an increase in the N 2 surface up to a KOH/coal ratio of 4/1, while for a greater ratio (6/1) they detected a decrease of the surface area (of approximately 20%). The reason for obtaining a wider distribution of porosity with a KOH/coal ratio of 2/1 compared to 1/1 has not been previously discussed but can be inferred considering the results of Ehrburger et al, 14 previously commented on.…”

Section: Effect Of the Activating Agent/coal Ratio (A/c)mentioning

confidence: 99%

“…In the literature, several studies have been published concerning the chemical activation of coals with hydroxides. 13,14,[17][18][19][20][21][22][23][24][25][26] However, none of them accomplish a detailed study of the different variables that can influence the characteristics of the activated carbons.…”

Section: Introductionmentioning

confidence: 99%

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Activated Carbons from Spanish Coals. 2. Chemical Activation

et al. 1996

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Activated carbons from Spanish coals have been prepared by chemical activation with alkali and alkaline-earth hydroxides. The paper analyzes the following aspects: presence of water during pyrolysis, extension of the impregnation and drying processes, activating agent, temperature and time of pyrolysis, activating agent/coal ratio, coal rank, and mineral matter content. KOH and NaOH activation provides very successful results in which N 2 apparent surface areas of 2500 m 2 /g are obtained; contrarily, Ca(OH) 2 produces a small porosity development. A pyrolysis temperature of 700 °C yields activated carbons with a wider pore size distribution than those prepared at 500 °C. The pyrolysis time does not affect the microporosity development but an important reduction in the ash content is observed when the time is increased. The use of an activating agent/coal ratio of 2/1 compared to 1/1 has favorable effects: (i) a decrease in the ash content and (ii) a wider pore size distribution. The addition of a drying step before pyrolysis greatly increases the nitrogen surface area and decreases the ash content. Porosity development depends on the coal rank. Low rank coals yield activated carbons with wider pore size distributions. The chemical activation process presents the great advantage, compared to physical activation, of removing the inherent mineral matter of the coal. Activated carbons obtained by chemical activation exhibit much lower ash content than the corresponding original coals. Ash reduction, depending on the coal used, could be very noticeable; the highest reduction observed corresponds to coal UA10 (11.3% ash) that, after NaOH activation, results in an activated carbon with only 0.5% ash content.

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Section: Resultsmentioning

confidence: 68%

Section: Resultsmentioning

confidence: 99%