Unusual pre-oxidized polyacrylonitrile fibres behaviour against their activation with CO2: carbonization effect

The CF-PAN activation process with CO2 has been analysed. Activation of CF-PAN with CO2 leads to unusual results both, activation percentage evolution over the time and generated porosity development. In the explanation has been highlighted the role of the carbonization step in the CF-PAN activation process. The analysed results point to the fact that part of the released nitrogen-containing compounds during PANOX fibres carbonization are deposited on the CF surface, which affects to carbonized PAN fibres, decreasing actives sites, or acting as inhibitors of the gasification reaction.The authors thank the Generalitat Valenciana and FEDER (PROMETEO2/2014/010), and MICINN and Plan E (CTQ2012-31762) for the financial support

Carbón activado: evaluación de nuevos precursores y del proceso de activación con dióxido de carbono

Los resultados obtenidos han mostrado como el CO2 es un agente activante apropiado y muy versátil para la generación de una amplia variedad de carbones activados. De este modo, con una adecuada selección de la materia prima y el tratamiento de la misma, se puede controlar el desarrollo del tamaño de porosidad deseado durante el proceso de activación con CO2: carbones microporosos, carbones mesoporosos y carbones con meso y macroporosidad. La evaluación de dos nuevos precursores lignocelulósicos, ha resultado muy satisfactoria. Así, tanto con la cascarilla del cacao como con el hueso de níspero es posible obtener mediante activación con CO2 carbones activados con elevadas superficies y volúmenes de porosidad específicos. En el caso de la cascarilla del cacao, este precursor ha resultado ser muy interesante para la preparación de monolitos de carbón activados esencialmente microporosos con apropiadas prestaciones mecánicas sin necesidad de agente aglomerante. La materia mineral inherente de la cascarilla del cacao resulta apropiada para el desarrollo de mesoporosidad. Respecto al hueso de níspero, este precursor ha resultado muy interesante dado que permite obtener carbones superactivados tras su activación con CO2

Preparation of binderless activated carbon monoliths from cocoa bean husk

Binderless activated carbon monoliths were prepared from a new lignocellulosic precursor: cocoa bean husk. This study focussed on analysing the role of a lignocellusic-type precursor in the development of binderless carbon monoliths, and the characterisation of the porous texture and mechanical performance of the activated carbon monoliths. The results prove that an adequate combination of the macromolecular components of the cocoa bean husk (lignocellulosic molecules, gums, pectin and fats) together with a laminate macromolecular microstructure made it more suitable for obtaining binderless carbon monoliths, than other lignocellulosic precursors. In addition, the activation of these carbon monoliths gives activated carbon with a higher micropore volume and good mechanical performance.The authors would like to thank the Ministerio de Economía y Competitividad, project CTQ2015-64801-R (MINECO/FEDER), and Generalitat Valenciana and FEDER (Grant No. PROMETEO2/2014/010), for financial support

Superactivated carbons by CO2 activation of loquat stones

This work presents CO2 activation approach towards controlled preparation of superactivated carbons (SAC) from a new lignocellulosic residue: loquat stones. This study demonstrates the potential use of loquat stones as a precursor in the preparation of SAC, reaching maximum BET surface area 3500 m2/g and total micropore volume 1.84 cm3/g. Studies on CO2 activation at different temperatures reveal two interesting results: 1) Loquat stones can be activated at high temperatures, up to 1100 °C, achieving similar volumes of porosity with short maintenance times (30 min). 2) The greater facility for eliminating mineral matter content of the loquat stones, as well as the scarce presence of K in its composition. The high volumes both of total and narrow microporosity that are obtained in the activation of carbonized loquat stones can be explained both by the traces of mineral matter that they contain and the carbonaceous microstructure of its carbonized state.The authors would like to thank the Ministerio de Economia y Competitividad, project CTQ2015-64801-R (MINECO/FEDER), and Generalitat Valenciana and FEDER (Grant No. PROMETEO2/2014/010), for financial support

Development of tailored mesoporosity in carbonised cocoa bean husk

Tailored mesoporous activated carbon has been prepared from a new lignocellulosic precursor, cocoa bean husk. The study has focussed on analysing the role the mineral matter of a lignocellusic precursor plays in the development of mesoporosity in activated carbon. Three new approaches have been developed to obtain tailored mesoporosity: i) controlled demineralisation; ii) activation of mixtures of the raw and demineralised cocoa precursor; iii) incorporation of iron via ionic interchange. The results prove that each of the above methods are suitable for developing activated carbon with different pore size distributions, including highly microporous, highly micro and mesoporous and highly macroporous activated carbons. In addition, the activation mechanism of these different carbonised samples has been analysed in order to explain the differences found in the development of porosity.The authors would like to thank the Ministerio de Economía y Competitividad, project CTQ2015-64801-R (MINECO/FEDER), and Generalitat Valenciana and FEDER (Grant No. PROMETEO2/2014/010), for financial support