Activated Carbon Fibre Monoliths for Hydrogen Storage

Porous adsorbents are currently investigated for hydrogen storage application. From a practical point of view, in addition to high porosity developments, high material densities are required, in order to confine as much material as possible in a tank device. In this study, we use different measured sample densities (tap, packing, compacted and monolith) for analyzing the hydrogen adsorption behavior of activated carbon fibres (ACFs) and activated carbon nanofibres (ACNFs) which were prepared by KOH and CO2 activations, respectively. Hydrogen adsorption isotherms are measured for all of the adsorbents at room temperature and under high pressures (up to 20 MPa). The obtained results confirm that (i) gravimetric H2 adsorption is directly related to the porosity of the adsorbent, (ii) volumetric H2 adsorption depends on the adsorbent porosity and importantly also on the material density, (iii) the density of the adsorbent can be improved by packing the original adsorbents under mechanical pressure or synthesizing monoliths from them, (iv) both ways (packing under pressure or preparing monoliths) considerably improve the storage capacity of the starting adsorbents, and (v) the preparation of monoliths, in addition to avoid engineering constrains of packing under mechanical pressure, has the advantage of providing high mechanical resistance and easy handling of the adsorbent

Impacto de la adopción de las tecnologías de información y comunicación en la productividad en ventas de la asociación de fondos contra accidentes de tránsito de la región San Martín

The following research is related to how important the Informatics an Communication Technology (ICT) is for improving productivity and competitive of the Association of Traffic Accident Founds AFOCAT San Martín, which faces an important challenge to the economic develop of San Martin region and the country in a whole, on the basis that this research shows a low level of ICT management like Internet and computing apps, which come from a poor computing technology knowledge and its multiple advantages for process, team work, economic resources improvement in relation to ratability and other benefits to the company. At the same time, the company faces a growing competence. This research has as objective to evaluate the impact of the ICT in profits and productivity in Association of Traffic Accident Founds of San Martin, establishing the association among the ICT adoption degree and the productivity of AFOCAT San Martín. Correlation descriptive investigation design was use through the statistics contrast Chi Quadrant (X2), which shows that there is not significant relation in the use of ICT computing and Internet apps adoption in AFOCAT San Martin. According to the research results, it can be established that the usage of ICT in AFOCAT San Martin is categorized as “low level of use”, having a 38% of the whole sample, in spite, when we measured the impact generated for the level of use reached in the company productivity by using computing programs and Internet, divided into 15 productivity items, a positive result in a global level was reached around 44.4% that means “Good Impact”.El presente esfuerzo documenta la importancia de las Tecnologías de la Información y la Comunicación (TIC) para mejorar la productividad y la competitividad de la Asociación de Fondos Contra Accidentes de Tránsito AFOCAT San Martín, que enfrenta un importante reto de cara al desarrollo económico de la región San Martín y del país, toda vez que el presente estudio muestra un bajo nivel de adopción de TIC mediante el uso de aplicaciones de cómputo e Internet, derivado del desconocimiento de lo que la tecnología puede hacer mejorar sus procesos, trabajo en equipo, recursos económicos relacionados con la rentabilidad de la empresa y otros beneficios, al mismo tiempo enfrenta una creciente competencia con empresas del mismo rubro con quienes compite por una mayor cuota de participación en el mercado. La investigación tiene como objetivo evaluar el impacto de la adopción de TIC en la productividad en ventas de la Asociación de Fondos Contra Accidentes de Tránsito de la Región San Martín, estableciendo la asociación existente entre el grado de adopción de TIC y la productividad en ventas en AFOCAT San Martín. Usando un diseño descriptivo correlacional a través del estadístico de contraste Chi-Cuadrado (x 2), se encontró que no existe una relación significativa en el grado de adopción de TIC mediante el uso de aplicaciones de cómputo e Internet en AFOCAT San Martín. En cuanto a los resultados obtenidos en la investigación, se puede evaluar que el grado de adopción de las TIC en AFOCAT San Martín se encuentra en la categoría de “Bajo nivel de adopción”, siendo un 38% del total de la muestra en estudio, a pesar de ello, al explorar el impacto que genera el nivel de adopción alcanzado en la empresa en la productividad en ventas mediante el uso de computadoras, programas de computación e Internet, desagregados en 15 variables de productividad, se obtiene un resultado satisfactorio a nivel general posicionándose en la categoría de “Buen impacto” con una representación del 44.4%.Tesi

Insight into the immobilization of ionic liquids on porous carbons

Very different carbon materials have been used as support in the preparation of supported ionic liquid phase samples (SILP). Some of them have been oxidized, either strongly (with ammonium persulfate solution) or weakly (with air at 300 °C, 2 h). The purpose is to establish which properties of the supports (e.g., porosity -volume and type-, surface area, oxygen surface chemistry and morphology) determine the IL adsorption capacity and the stability (immobilization) of the supported IL phase. The ionic liquid used in this work is 1-butyl-3-methyl-imidazolium hexafluorophosphate ([bmim][PF6]). For each support, samples with different amounts of ionic liquid have been prepared. The maximum IL that can be loaded depends mainly on the total pore volume of the supports. For comparable pore volumes, the porosity type and the oxygen surface content have no influence on the IL loading. The supported IL fills most of the pores, leaving some blocked porosity. The stability of the supported IL phase (especially important for its subsequent use in catalysis) has been tested in water under general hydrogenation conditions (60 °C and 10 bar H2). In general, leaching is low but it increases with the amount of IL loaded and with the oxidation treatments of the supports.The authors thank the Spanish government for the project MAT2012-32832. M.R.B thanks the FPI scholarship grant associated to project MAT2009-07150

Factors governing the adsorption of ethanol on spherical activated carbons

Ethanol adsorption on different activated carbons (mostly spherical ones) was investigated covering the relative pressure range from 0.001 to 1. Oxygen surface contents of the ACs were modified by oxidation (in HNO3 solution or air) and/or by thermal treatment in N2. To differentiate the concomitant effects of porosity and oxygen surface chemistry on ethanol adsorption, different sets of samples were used to analyze different relative pressure ranges (below 1000 ppmv concentration and close to unity). To see the effect of oxygen surface chemistry, selected samples having similar porosity but different oxygen contents were studied in the low relative pressure range. At low ethanol concentration (225 ppmv) adsorption is favored in oxidized samples, remarking the effect of the oxidizing treatment used (HNO3 is more effective than air) and the type of oxygen functionalities created (carboxyl and anhydride groups are more effective than phenolic, carbonyl and derivatives). To analyze the high relative pressure range, spherical and additional ACs were used. As the relative pressure of ethanol increases, the effect of oxygen-containing surface groups decreases and microporosity becomes the most important variable affecting the adsorption of ethanol.Authors thank Generalitat Valenciana – Spain (PROMETEOII/2014/010), MINECO (MAT-2012-32832), MICINN – Spain and plan E (CTQ2012-3176) for financial support

Activation of a spherical carbon for toluene adsorption at low concentration

This paper complements a previous one [1] about toluene adsorption on a commercial spherical activated carbon and on samples obtained from it by CO2 or steam activation. The present paper deals with the activation of a commercial spherical carbon (SC) having low porosity and high bed density (0.85 g/cm3) using the same procedure. Our results show that SC can be well activated with CO2 or steam. The increase in the burn-off percentage leads to an increase in the gravimetric adsorption capacity (more intensively for CO2) and a decrease in bed density (more intensively for CO2). However, for similar porosity developments similar bed densities are achieved for CO2 and steam. Especial attention is paid to differences between both activating agents, comparing samples having similar or different activation rates, showing that CO2 generates more narrow porosity and penetrates more inside the spherical particles than steam. Steam activates more from the outside to the interior of the spheres and hence produces larger spheres size reductions. With both activation agents and with a suitable combination of porosity development and bed density, quite high volumetric adsorption values of toluene (up to 236 g toluene/L) can be obtained even using a low toluene concentration (200 ppmv).Generalitat Valenciana (Prometeo/2009/047 and FEDER), MICINN and plan E (CTQ2012-3176) and MINECO (MAT-2012-32832)

Sorbent design for CO2 capture under different flue gas conditions

CO2 capture by solid sorbents is a physisorption process in which the gas molecules are adsorbed in a different porosity range, depending on the temperature and pressure of the capture conditions. Accordingly, CO2 capture capacities can be enhanced if the sorbent has a proper porosity development and a suitable pore size distribution. Thus, the main objective of this work is to maximize the CO2 capture capacity at ambient temperature, elucidating which is the most suitable porosity that the adsorbent has to have as a function of the emission source conditions. In order to do so, different activated carbons have been selected and their CO2 capture capacities have been measured. The obtained results show that for low CO2 pressures (e.g., conditions similar to post-combustion processes) the sorbent should have the maximum possible volume of micropores smaller than 0.7 nm. However, the sorbent requires the maximum possible total micropore volume when the capture is performed at high pressures (e.g., conditions similar to oxy-combustion or pre-combustion processes). Finally, this study also analyzes the important influence that the sorbent density has on the CO2 capture capacity, since the adsorbent will be confined in a bed with a restricted volume.The authors thank the Generalitat Valenciana and FEDER (project PROMETEO/2009/047) for financial support

Effect of the stabilisation time of pitch fibres on the molecular sieve properties of carbon fibres

The stabilisation of pitch fibres (PFs) is the most important step for their subsequent use in the preparation of carbon fibres (CFs) and their resulting characteristics. The present work studies the influence that the stabilisation time has on the porosity of the CFs, and on the subsequent properties as carbon molecular sieve (CMS). The increase of the stabilisation time carried out at 573 K, from 2 to 8 h favours their CMS properties producing a decrease in the microposity accessible to N2, which gets completely blocked after 6 and 8 h, while the narrow microporosity (V-DR CO2) remains accessible. Adsorption kinetic studies with CH4 and CO2 were performed to assess the possibility of using these CFs as CMS by comparing them with Takeda 3A CMS. The results suggest that there is an optimal stabilisation time which allows the preparation of CFs from an abundant raw precursor with properties similar to Takeda 3A CMS.MCYT (PPQ2003-03884)

Gas Storage Scale-up at Room Temperature on High Density Carbon Materials

In relation to the current interest on gas storage demand for environmental applications (e.g., gas transportation, and carbon dioxide capture) and for energy purposes (e.g., methane and hydrogen), high pressure adsorption (physisorption) on highly porous sorbents has become an attractive option. Considering that for high pressure adsorption, the sorbent requires both, high porosity and high density, the present paper investigates gas storage enhancement on selected carbon adsorbents, both on a gravimetric and on a volumetric basis. Results on carbon dioxide, methane, and hydrogen adsorption at room temperature (i.e., supercritical and subcritical gases) are reported. From the obtained results, the importance of both parameters (porosity and density) of the adsorbents is confirmed. Hence, the densest of the different carbon materials used is selected to study a scale-up gas storage system, with a 2.5 l cylinder tank containing 2.64 kg of adsorbent. The scale-up results are in agreement with the laboratory scale ones and highlight the importance of the adsorbent density for volumetric storage performances, reaching, at 20 bar and at RT, 376 g l-1, 104 g l-1, and 2.4 g l-1 for CO2, CH4,and H2, respectively.Generalitat Valenciana and FEDER (project PROMETEO/2009/047)

Spherical activated carbons for the adsorption of a real multicomponent VOC mixture

The objective of this work is to study the adsorption of a multicomponent gaseous mixture (acetaldehyde, formaldehyde, 2-propenal, 1,3-butadiene and benzene) in which the components are present at different concentration on spherical activated carbons (SACs). Attention is paid to the influence of the carbons’ properties on such adsorption, especially their porosities and distributions. For this purpose, a series of spherical activated carbons were prepared by physical activation with CO2 of a commercial spherical carbon. Their physico-chemical properties were characterized by N2 and CO2 isotherms, temperature programmed desorption and scanning electron microscopy. Measurements of the adsorption of the volatile organic compounds (VOC) mixture on SACs were performed in a flow-typed fixed bed system at room temperature under atmospheric pressure. Regarding porosity, our results show that, for this particular mixture, SACs with narrow micropore size distribution and moderate porous texture development (surface area in the range of 1000 m2/g or even lower) exhibit higher multicomponent adsorption capacities than others with much larger porosities. This can be explained considering that the VOC present in larger concentration in the mixture, aldehydes, present low adsorption affinities and their adsorption is enhanced in adsorbents with narrow micropore size distribution.The authors would like to thank Philip Morris International (PMI) for financial support