La Anunciación del Monasterio de Caleruega (Burgos): contextualización en la Baja Edad Media peninsular

The Annunciation from the Monastery of Santo Domingo of Caleruega, founded by Alfonso X the Wise, has remained virtually forgotten by the Spanish historiography. Isolated behind the walls of the cloister, the sculpture group presents a particularity that hasn’t been properly analyzed for too long: the Virgin is pregnant. The amount of recorded examples of the same nature shows that this kind of representations was common in some kingdoms of the Iberian Peninsula during the Late Middle Ages. From an essentially iconographic perspective, but without giving up further approaches, this paper provides an in-depth study on the singularity of the Annunciation from Caleruega. At the same time, it becomes the starting point for a comprehensive analysis of this variant of the Angelic Salutation.La Anunciación del Monasterio de Santo Domingo de Caleruega, fundado por Alfonso X el Sabio, ha permanecido prácticamente olvidada por la historiografía nacional. Aislado tras los muros de la clausura, el grupo escultórico presenta una particularidad que, durante mucho tiempo, no fue analizada convenientemente: la Virgen está embarazada. La cantidad de ejemplos contabilizados de la misma naturaleza demuestra que esta clase de representaciones fue habitual, durante la Baja Edad Media, en algunos reinos de la península ibérica. Con un enfoque fundamentalmente iconográfico pero sin renunciar a otra clase de aproximaciones, el presente artículo pretende estudiar en profundidad la singularidad de la Anunciación calerogana que, al mismo tiempo, se convierte en el punto de partida para un análisis global de esta variante de la Salutación Angélica

Methanol dehydration over ZrO2 supported-activated carbons

Resumen comunicación congreso internacionalDME is playing an important role due to its potential use as an alternative fuel in diesel engines. The use of this fuel produces lower NOx emissions, and less engine noise compared to traditional diesel fuels. Moreover, this compound is used as building block for many value-added chemicals such as lower olefins. DME is usually produced via catalytic dehydration of methanol over a solid acid. The use of activated carbons in catalytic processes, acting directly as catalyst and as catalyst support, is focussing much attention. They can be obtained from different types of lignocellulosic waste, producing not only an environmental but an economical profit. In this sense, the preparation of activated carbons with phosphoric acid produces catalytic supports with certain surface acidity, which have shown high activity for alcohol dehydration. In this study, ZrO2 supported activated carbons were prepared from an industrial byproduct as lignin for the methanol dehydration to DME. The activated carbon was prepared by chemical activation with H3PO4, using Alcell® lignin as precursor. The impregnation ratio value (H3PO4/lignin) used was 3. The impregnated sample was activated under N2 flow at 500 ºC for 2h, washed and dried. The activated carbon was loaded with different amounts of ZrO(NO3)2, dried at 120ºC for 24h, and calcined in air at 250ºC for 2h, obtaining ZrO2 loadings of 5 and 10%, respectively. For the sake of comparison, pure ZrO2 was also used. Catalytic tests were performed at atmospheric pressure in a fixed bed reactor, at different space times and partial pressures. The activated carbon (ACP) prepared shows a well-developed porous structure, with an apparent surface area higher than 2000 m2/g, and a high contribution of mesoporosity. After metal loading, a maximum decrease of 20% in all structural parameters of the ACP was observed.The results show that ZrO2 loading produces an enhancing in the catalytic activity of the carbon materials compared to the parent activated carbon (0.1 g·s/μmol, PCH3OH= 0.02 atm in helium and 350 ºC). In this sense, a methanol conversion of 25% was observed with the addition of 10% w/w ZrO2 (ACP-10Zr), at steady state conditions (Figure 1). ACP shows negligible conversion, at the same conditions and for pure ZrO2 the methanol conversion was of 10%. Very high selectivity to DME (~100%) was found at temperatures lower than 350 ºC. The methanol conversion increases with temperature, reaching a value of 67% at 475ºC, but a slight decrease in DME selectivity is observed, resulting in a higher production of light hydrocarbons, mainly CH4. The results suggest that the addition of only a 10% of ZrO2 over an activated carbon prepared by chemical activation with H3PO4 enhances significantly the performance of the catalyst, compared to pure ZrO2.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Kinetic study of methanol dehydration over Zro2 supported-activated carbons

The growing concerns about climate change and energy consumption have been the driving force in seek of alternative fuels such as DME, mainly produced via methanol dehydration over a solid acid catalyst. The use of activated carbons for this aim has been little studied up to date. Only a few studies can be found in the literature, reporting all of them materials with a low thermal stability of the acid surface groups, which results into a fast deactivation of the catalyst. In this work, the preparation of activated carbons via chemical activation with phosphoric acid, their modification with different ZrO2 loads, and their application as methanol dehydration catalysts have been studied. The catalytic results showed that the best methanol conversion and selectivity towards DME were achieved with the activated carbon prepared with an impregnation mass ratio value (H3PO4 /precursor) of 2 and an activation temperature of 800 ºC, loaded with a 7 % (wt) of ZrO2 . This catalyst exhibits high steady state methanol conversion values even at temperatures as high as 400 ºC (XCH3OH= 80%, 0.1 g·s/μmol, PCH3OH= 0.08 atm in helium), keeping a selectivity to DME higher than 96%. The effect of oxygen in the reaction atmosphere was also analysed. In this sense, an increase of 15 % in the DME yield was obtained when using air instead of helium as reaction atmosphere (350 ºC, 0.1 g·s/μmol, PCH3OH= 0.04 atm). A kinetic study has been carried out on this catalyst in which two mechanisms (Eley Rideal and Langmuir Hinshelwood) for methanol dehydration have been analysed. The models proposed also consider the presence of oxygen in the reaction media.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. MINECO (CTQ2015-68654-R). MECD (FPU13/02413)

Biomass derived activated carbon catalysts for the one-step dimethyl ether synthesis from syngas

Se trata de un resumen extendido de una comunicación a congreso internacional.In this work we study the behaviour of a carbon-based catalyst for this one-step synthesis process. Two kinds of activated carbons, prepared by chemical (with H3PO4) and physical (by CO2 partial gasification) activation of olive stones, were used as catalysts support. The main difference between the activated carbons was the presence of chemically stable phosphorus surface groups, mainly in form of C-O-PO3 groups1, on the activated carbon prepared via chemical activation. The addition of Zr to the chemically activated carbon (ACPZr) resulted in the formation of zirconium phosphate species on the carbon surface, which were capable of promoting the selective methanol dehydration to DME. Cu-Zn loading on the chemically activated carbon resulted in strong interactions between the metallic phase and the phosphate surface groups due to the formation Cu phosphate species. The bifunctional catalyst, ACPZrCuZn showed less conversion that the physical mixture. This fact is related with the presence of phosphorus species that avoids the reduction of the metal (copper).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Aspectos psicológicos y psiquiátricos de la vida en la calle.

Analizamos las repercusiones psicológicas y psiquiátricas que puede suponer el hecho de tener que vivir en la calle, tanto como factor etiológico, precipitante o descompensatorio de determinados síntomas psicopatológicos o estructuras de personalidad

Aspectos psicológicos y psiquiátricos de la vida en la calle.

Analizamos las repercusiones psicológicas y psiquiátricas que puede suponer el hecho de tener que vivir en la calle, tanto como factor etiológico, precipitante o descompensatorio de determinados síntomas psicopatológicos o estructuras de personalidad

Funcionalización superficial de carbones activos con grupos nitrogenados mediante reaciones de oxidación/reducción

La funcionalización superficial de carbones activos con grupos nitrogenados le confiere a estos materiales unas propiedades fisicoquímicas mejoradas, que los hace muy interesantes en diferentes aplicaciones. La incorporación de heteroátomos de nitrógeno a materiales carbonosos ser realiza principalmente mediante dos estrategias: partiendo de precursores que contengan nitrógeno y mediante tratamientos químicos de funcionalización con moléculas nitrogenadas, tales como amoniaco o urea [2]. En este trabajo se ha estudiado la funcionalización superficial, con diferentes grupos nitrogenados, de carbones activos obtenidos por activación química con ácido fosfórico. La incorporación de nitrógeno se ha llevado a cabo mediante un tratamiento con ácido nítrico, realizándose a continuación diferentes tratamientos de reducción, con el fin de obtener diferentes grupos funcionales de nitrógeno.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Utilización de cenizas volantes y mineralizadores como materia prima en la fabricación de cemento

In this research the process of formation of a low energy clinker is studied, when fly-ashes (rich in sulphates and lime) and fluorspar are used as raw materials (fly-ashes replaces to the tradicional raw mix partially). The availability of those fly-ashes is shown since clinker at 1.340 °C is obtained. The mineralogical composition, mineralizer capacity and temperature of formation of the new liquid phase is studied.En el presente trabajo se estudia el proceso de formación de un clínker de bajo consumo energético, empleando como materia prima cenizas volantes sulfocálcicas (en sustitución parcial del crudo tradicional) y fluorita. Se demuestra la validez de dichas cenizas volantes, obteniendo clínker a 1.340 °C. Se estudia la composición mineralógica, capacidad de mineralización y temperatura de formación de la nueva fase líquida