Activated Carbon Fibers with a High Heteroatom Content by Chemical Activation of PBO with Phosphoric Acid

Abstract

The preparation of activated carbon fibers (ACFs) by phosphoric acid activation of poly(p-phenylene benzobisoxazole) (PBO) fibers was studied, with particular attention to the effects of impregnation ratio and carbonization temperature on porous texture. Phosphoric acid has a strong effect on PBO degradation, lowering the temperature range at which the decomposition takes place and changing the number of mass loss steps. Chemical analysis results indicated that activation with phosphoric acid increases the concentration of oxygenated surface groups; the resulting materials also exhibiting high nitrogen content. ACFs are obtained with extremely high yields; they have well-developed porosity restricted to the micropore and narrow mesopore range and with a significant concentration of phosphorus incorporated homogeneously in the form of functional groups. An increase in the impregnation ratio leads to increases in both pore volume and pore size, maximum values of surface area (1250 m(2)/g) and total pore volume (0.67 cm(3)/g) being attained at the highest impregnation ratio (210 wt % H(3)PO(4)) and lowest activation temperature (650 °C) used; the corresponding yield was as large as 83 wt %. The obtained surface areas and pore volumes were higher than those achieved in previous works by physical activation with CO(2) of PBO chars.

Carbonfasern: Präkursor‐Systeme, Verarbeitung, Struktur und Eigenschaften

“…stellten durch chemische Aktivierung mit Phosphorsäure schließlich auch aktivierte CF aus PBO her. Spezifische Oberflächen von 1250 m 2 g −1 konnten erzielt werden 204. Bei einer alternativen Vorgehensweise wurde CO 2 als Aktivator verwendet, dies führte zu spezifischen Oberflächen bis 943 m 2 g −1 205…”

Imine-Linked Polymer Based Nitrogen-Doped Porous Activated Carbon for Efficient and Selective CO2 Capture

“…In the physical activation, the precursor materials are carbonized at high temperatures with a flow of gases (CO 2 or steam), while in chemical activation the precursors are first impregnated or physically mixed with chemical agents and then heated at the target temperature under inert atmosphere. To improve the porosity of the activated carbons, many activation parameters are to be taken into consideration, such as carbonization temperature, the type of activation agent, the weight ratio between activation agents and the sample, and the time of carbonization held at the target temperature1113 etc., all of which have their own significance in the development of porosity of activated carbons. But it is still unclear which factor has the largest effect on controlling the porosity in activated carbons.…”

Development and Environmental Applications of Activated Carbon Cloths

“…The precursors mostly examined have included cellulose and regenerated cellulose (mainly, viscous rayon), polyacrylonitrile (PAN), pitch, polyimides, aramids, polyvinyl alcohol, and phenolicbased materials [19,75,[77][78][79][80][81][82][83][84][85][86][87][88][89][90][91][92]. Recently, the preparation of microporous activated carbon fibers from poly (p-phenylene benzobisoxazole) has also been reported [93,94]. For physical activation of a given precursor, experimental variables involved in the pyrolysis and gasification stages, such as heating rate, temperature, activating gas, gas flow rate, and degree of burn-off, have been examined.…”