Tailoring activated carbons for the development of specific adsorbents of gasoline vapors

The specific adsorption of oxygenated and aliphatic gasoline components onto activated carbons (ACs) was studied under static and dynamic conditions. Ethanol and n-octane were selected as target molecules. A highly porous activated carbon (CA) was prepared by means of two processes: carbonization and chemical activation of olive stone residues. Different types of oxygenated groups, identified and quantified by TPD and XPS, were generated on the CA surface using an oxidation treatment with ammonium peroxydisulfate and then selectively removed by thermal treatments, as confirmed by TPD results. Chemical and porous transformations were carefully analyzed throughout these processes and related to their VOC removal performance. The analysis of the adsorption process under static conditions and the thermal desorption of VOCs enabled us to determine the total adsorption capacity and regeneration possibilities. Breakthrough curves obtained for the adsorption process carried out under dynamic conditions provided information about the mass transfer zone in each adsorption bed. While n-octane adsorption is mainly determined by the porosity of activated carbons, ethanol adsorption is related to their surface chemistry, and in particular is enhanced by the presence of carboxylic acid groups.This work is supported by the MICINN-FEDER, project CTM2010-18889

Carbon nanofiber-supported tantalum oxides as durable catalyst for the oxygen evolution reaction in alkaline media

9 figures, 5 tables.-- Supplementary information availableActive and durable electrocatalysts for the oxygen evolution reaction (OER), capable of replacing noble metal catalysts, are required to develop efficient and competitive devices within the frame of the water electrolysis technology for hydrogen production. In this work, we have investigated tantalum based catalysts supported on carbon nanofibers (CNF) for the first time. The effect of CNF characteristics and the catalyst annealing temperature on the electrochemical response for the OER have been analyzed in alkaline environment using a rotating ring disc electrode (RRDE). The best OER activity and oxygen efficiency were found with a highly graphitic CNF, despite its lower surface area, synthesized at 700 °C, and upon a catalyst annealing temperature of 800 °C. The ordering degree of carbon nanofibers favors the production of oxygen in combination with a low oxygen content in tantalum oxides. The most active catalyst exhibited also an excellent durability.The authors want to thank the Ministerio de Economía, Industria y Competitividad (MICINN) and FEDER for the received funding in the project of reference ENE2017-83976-C2-1-R, and to the Gobierno de Aragón (DGA) for the funding to Grupo de Investigación Conversión de Combustibles (T06_17R). J.C. Ruiz-Cornejo acknowledges DGA for his PhD grant. D. Sebastián acknowledges the MICINN for the Ramón y Cajal research contract (RyC-2016-20944).Peer reviewe

Graphene-based materials as electrodes in vanadium redox flow batteries

Work presented at the conference RedoxFlow2020, that was organized online, 9th-10th of November 2020, by Centre National de la Recherche Scientifique (France)

Recent developments of the 1 MV AMS facility at the Centro Nacional de Aceleradores

Trabajo presentado a la International Conference on Accelerator Optimization, celebrada en Sevilla (España) del 7 al 9 de octubre de 2015.Peer Reviewe

Biogas upgrading by selective adsorption onto CO2 activated carbon from wood pellets

An activated carbon from commercial pine wood pellets was obtained by means of physical activation with carbon dioxide. Carbonized sample was also prepared in order to compare both samples. Carbonization lead to a material with very low micropore volume, which was increased when physical activation was performed (W-0(N-2) from 0.00 to 0.22 cm(3)g (1) and W-0(CO2) from 0.21 to 0.31 cm(3) g (1)). After characterizing their porous texture, samples were tested as CO2 selective adsorbent in a mixture of CH4 and CO2; at first high pressure isotherms of both compounds were obtained at different temperatures to calculate the adsorbed amount of each compound at given pressure and temperature (for PINPEL20: CO2, q(sat) = 6.66 mol kg (1) and Delta H-ads = 28.4 kJ mol (1); CH4, q(sat) = 3.36 mol kg (1) and Delta H-ads = 19.0 kJ mol (1)). Variations on isosteric heat of adsorption with uptake were also analysed (it was increased with uptake in the case of CO2 and the opposite tendency was found for CH4). Selectivity resulted larger for the activated sample (2.9 versus 1.9 at 1 bar and 30 degrees C), so this one was chosen to perform dynamic adsorption experiments. Breakthrough curves demonstrated the outstanding performance of sample as CO2 selective adsorbent in both single component experiments (Breakthrough time 995 s for CH4 and 1545 s for CO2) and competitive adsorption (950 s for CH4 and 1373 s for CO2). Activated sample showed an excellent behaviour as CO2 selective adsorbent for biogas upgrading

Fitting Carbon Gels and Composites for Environmental Processes

International audienc