Sistemas SCR y NSR-SCR para DeNOx en corrientes de escape diésel: Formulaciones, cinética y modelización

314 p.En esta tesis, se estudian las características físico-químicas de diferentes catalizadores Fe,Cu/ZSM-5, BETA y SSZ-13, tanto en forma granulada como monolítica, y se analiza su comportamiento NH3-SCR en la eliminación de NOx de corrientes de gases de escape de motores de mezcla pobre. También se analizan las ventajas de colocar los catalizadores SCR corriente debajo de otro catalizador modelo Pt-BaO/Al2O3 NSR para mejorar la eficiencia de eliminación de NOx a N2, eliminando el deslizamiento de amoniaco en el sistema. El catalizador Cu/CHA proporciona el mejor comportamiento, a la vez que muestra una muy elevada resistencia al envejecimiento hidrotérmico. También se propone un modelo cinético globalizado para el sistema de reacciones NO/NO2 NH3-SCR, que se verifica con un extenso conjunto de reacciones experimentales. Finalmente, se modeliza y simula el comportamiento NH3-SCR en un canal monolítico, utilizando el software Comsol Multiphysics

Evaluation of Cu/SAPO-34 Catalysts Prepared by Solid-State and Liquid Ion-Exchange Methods for NOx Removal by NH3-SCR

Cu/SAPO-34 catalysts are prepared using solid-state ion exchange (SSIE) and liquid ion exchange (LIE). SSIE is conducted by calcining a physical mixture of H-SAPO-34 zeolite and CuO nanoparticles at elevated temperatures (500-800 degrees C). The conventional LIE method is conducted by exchanging Na-SAPO-34 with Cu(COOCH3)(2) aqueous solution with a final calcination step at 500 degrees C. Catalysts were fully characterized, focusing on Cu species identification. The NH3-SCR activity is evaluated for NOx removal. Cu/SAPO-34 catalysts synthesized by SSIE at 700 degrees C achieved an optimal reaction rate, which was correlated with a higher proportion of Cu2+ ions. The activation energies of Cu/SAPO-34 catalysts prepared by SSIE and LIE with varying copper loadings are 32-38 and 42-47 kJ mol(-1), respectively. The SSIE catalysts achieve higher turnover frequency than LIE catalysts for a similar copper content, which decreases on increasing the copper loading. These results provide evidence that Cu ions exchanged into the Cu/SAPO-34 catalysts synthesized by SSIE present higher activity than those prepared by LIE for NOx removal by NH3-SCR.The authors wish to acknowledge the financial support provided by the Spanish Economy and Competitiveness Ministry (CTQ2015-67597-2-1-R) and the Basque Government (IT657-013 and IT1297-19). Also, technical support by SGIker (UPV/EHU Advanced Research Facilities) is acknowledged. The assistance of Prof. Luis Lezama during EPR analysis and interpretation is gratefully acknowledged. U.D.-L.T. and M. U. want to acknowledge UPV/EHU and the Spanish Economy and Competitiveness for the postdoc (ESPDOC16/69) and Ph.D. (BFI-2010-330) research grants, respectively

Perovskite-Based Formulations as Rival Platinum Catalysts for NO_x Removal in Diesel Exhaust Aftertreatment

NOx removal is still a technological challenge in diesel engines. NOx storage and reduction (NSR), selective catalytic reduction (SCR), and combined NSR-SCR systems are the efficient approaches for diesel exhaust aftertreatment control. However, NSR and combined NSR-SCR technologies require high noble metal loadings, with low thermal stability and high cost. Recently, perovskites have gained special attention as an efficient alternative to substituting noble metals in heterogeneous catalysis. Up to date, few studies analyzed the application of perovskites in automobile catalytic converters. This chapter overviews recent research on development of novel perovskite-based catalysts as a component of single-NSR and hybrid NSR-SCR systems for NOx removal from diesel engine exhaust gases. Results in our laboratory are compared with similar work reported in the literature by other authors. Under realistic conditions, 0.5% Pd–30% La0.5Ba0.5CoO3/Al2O3 catalyst achieves NOx-to-N2 conversion higher than 92% when is coupled with an SCR catalyst placed downstream. The results show promise for a considerably higher thermal stability and lower cost diesel exhaust treatment system

Cu-zeolite catalysts for NOx removal by selective catalytic reduction with NH3 and coupled to NO storage/reduction monolith in diesel engine exhaust aftertreatment systems

[EN] Coupled NSR-SCR systems comprising a Pt-BaO/Al2O3 NSR monolith and Cu/CHA, Cu/ZSM-5 or Cu/BETA SCR catalysts are prepared and tested for NOx removal from diesel and lean burn engines exhaust gases. The Cu/zeolite catalysts are characterized by ICP-AES, XRD, N-2 adsorption-desorption, NH3-TPD and H-2-TPR. The physico-chemical characteristics of fresh catalysts and aged under 5% steam/Ar at 750 degrees C for 16 h and are compared, resulting in the Cu/CHA with much higher hydrothermal resistance to the loss of textural and structural properties. The single-SCR, single-NSR and coupled NSR-SCR catalytic performance is studied including the conversion of NO and NH3, slip of NH3, and N2O and NO2 yields. Cu/CHA presents the SCR wider temperature window, eventually 100%NO conversion from 220 to 380 degrees C, even maintained after severe aging. For application in the NSR-SCR technology, the NH3 generated in the NSR catalyst during the rich period is able to achieve higher NO conversion reducing significantly the slip of NH3 (negligible at 200 degrees C and above), very few amount of N2O at any temperature, and small production of NO2 only at higher temperatures. This improvement of activity and selectivity is particularly enhanced with the coupled NSR-Cu/CHA system, which is also maintained when the catalyst is deposited on the cordierite monolith substrate, as in the case of real application. (C) 2016 Published by Elsevier B.V.The authors wish to acknowledge the financial support by the Spanish Economy and Competitiveness Ministry [CTQ2012-32899; MAT2012-3716, and "Severo Ochoa" (SEV 2012-0267)], the Basque Government (IT657-013), and the European Union (SynCat-Match project; ERC-AdG-2014-671093). One of the authors (UDLT) acknowledge to the Basque Government for the PhD Research Grant (BFI-2010-330).De-La-Torre, U.; Pereda-Ayo, B.; Moliner Marin, M.; González Velasco, JR.; Corma Canós, A. (2016). Cu-zeolite catalysts for NOx removal by selective catalytic reduction with NH3 and coupled to NO storage/reduction monolith in diesel engine exhaust aftertreatment systems. Applied Catalysis B: Environmental. 187:419-427. https://doi.org/10.1016/j.apcatb.2016.01.020S41942718

Role of the different copper species on the activity of Cu/zeolite catalysts for SCR of NOx with NH3

The SCR of NOx with NH3 has been studied by using different Cu zeolite catalysts, prepared both with ZSM5 and BETA zeolite supports by ionic exchange or by impregnation. The catalysts were characterized by ICP-AES, N2 adsorption at −196 °C, XRD, TEM, XPS and H2-TPR. The catalysts characterization confirmed the presence of different Cu(II) species on all catalyst (CuO and Cu(II) exchanged on tetrahedral and octahedral positions of the zeolites framework). Clear evidences of Cu(I) or Cu(0) species were not obtained. CuO was more abundant in high copper-content catalysts and in ZSM5 catalysts, due to its lower ionic exchange capacity, while isolated Cu(II) ions are more abundant in low copper-content catalysts and in BETA catalysts. It was concluded that CuO catalyzes the oxidation of NO to NO2, and this favors the reduction of NOx at lower temperature (the NH3-NO2 reaction is faster than the NH3-NO reaction because NO2 is much more oxidizing than NO), whereas isolated Cu(II) ions maintain high NOx conversion at high temperatures.Financial support provided by the Spanish Ministry of Economy and Competitiveness (CTQ2012-30703), the Basque Government (IT-657-13) and the UPV/EHU (UFI11/39). One of the authors (UDLT) wants to acknowledge to the Basque Government for the PhD Research Grant (BFI-2010-330)

Effect of metal loading on the CO2 methanation: A comparison between alumina supported Ni and Ru catalysts

The hydrogenation of CO2 into CH4 from H2 produced by renewable energy is considered an interesting alternative in order to promote the development of such green energies. In the present work, the effect of Ni and Ru loadings on the catalytic performance of alumina-supported catalysts is studied for CO2 methanation reaction. All catalysts were prepared by wetness incipient impregnation, characterized by several techniques (N2-physisorption, CO2-TPD, XRD, H2-chemisorption, XPS and H2-TPR) and evaluated for CO2 methanation in a fixed bed reactor at GHSV=10,000 h−1 and W/FCO2 0 = 4.7 (g cat.) h mol−1. Characterization results showed that addition of increasing loadings of Ni and Ru lead to the formation of both CO2 adsorption and H2 dissociation active sites, which are necessary to carry out CO2 hydrogenation into methane. Easily reducible ruthenium was dispersed on γ-Al2O3 in form of large agglomerates, whereas Ni was better dispersed presenting a great interaction with the support. 12% Ni and 4% Ru resulted to be the optimal contents providing metal surfaces of 5.1 and 0.6m2 g−1, T50 values of 340 and 310 °C and activity being quite stable for 24 h-on-stream. In terms of turnover frequency (TOF), 4%Ru/Al2O3 catalyst was quite more efficient than 12%Ni/Al2O3, probably due to a greater ability of ruthenium to dissociate hydrogen. The apparent activation energies for alumina supported Ni and Ru were 129 and 84 kJ mol−1, respectively.The support from the Economy and Competitiveness Spanish Ministry (CTQ2015-67597-C2-1-R and CTQ2015-67597-C2-2-R MINECO-FEDER), the Basque Government (IT657-13 and IT1297-19) and the SGIker (Analytical Services) at the University of the Basque Country are acknowledged. One of the authors (AQ) also acknowledges University of the Basque Country by his PhD grant (PIF-15/351)

Ni/LnOx catalysts (Ln = La, Ce or Pr) for CO2 methanation

The effect of the LnOx support has been studied for Ni‐based CO2 methanation catalysts. 10 wt. % nickel catalysts with LaOx, CeO2 and PrOx supports have been prepared, characterized by N2 adsorption, XRD, XRF, TG‐MS (N2‐TPD and H2‐TPR) and XPS, and have been tested for CO2 methanation. The catalytic activity follows the trend Ni/CeO2 > Ni/PrOx >> Ni/LaOx, all catalysts being very selective towards CH4 formation. The activity depends both on the nature of the catalytic active sites and on the stability of the surface CO2 and H2O species. Ni/CeO2 is the most active catalyst because (i) the Ni2+‐ceria interaction leads to the formation of the highest population of active sites for CO2 dissociation, (ii) the reduced Ni0 sites where H2 dissociation takes place are the most electronegative and active, and (iii) the stability of surface CO2 and H2O species is lowest. Ni/LaOx achieves lower activity because of the strong chemisorption of H2O and CO2, which poison the catalyst surface, and because this support is not able to promote the formation of highly active sites for CO2 and H2 dissociation. The behavior of Ni/PrOx is intermediate, being slightly lower to that of Ni/CeO2 because the formation of active sites is not so efficient and because the stability of chemisorbed CO2 is slightly higher.The authors thank the financial support of Basque Government (Consolidated Group IT657-13), Spanish Ministry of Economy and Competitiveness (Projects CTQ2015-67597-C2-1-R and CTQ2015-67597-C2-2-R), and the EU (FEDER funding). ADQ thanks the Spanish Ministry of Education, Culture and Sports (grant FPU14/01178) and AQ the University of the Basque Country (grant PIF15/351)

The environmental and social footprint of the university of the Basque Country UPV/EHU

This work has calculated the organisational environmental and social footprint of the University of the Basque Country (UPV/EHU) in 2016. First, input and output data flows of the UPV/EHU activity were collected. Next, the environmental and social impacts of the academic activity were modelled, using the Ecoinvent 3.3 database with the PSILCA-based Soca v1 module in openLCA software. In order to evaluate the environmental impacts, CML and ReCiPe LCIA methods were used. The Social Impact Weighting Method was adjusted for the assessment of specific social impacts. The modelling has identified some hotspots in the organisation. The contribution of transport (8,900 km per user, annually) is close to 60% in most of the environmental impacts considered. The life cycle of computers stands out among the impacts derived from the consumption of material products. More than half of environmental impacts are located outside the Basque Country. This work has also made it possible to estimate some of the impacts of the organisational social footprint, such as accidents at work, only some of which occur at the UPV/EHU. Traces of child labour and illiteracy have also been detected in the social footprint that supports the activity of the UPV/EHU. Some of the social and environmental impacts analysed are not directly generated by the UPV/EHU, but they all demand attention and co-responsibility. Based on the modelling performed, this work explores alternative scenarios and recommends some improvement actions which may reduce (in some cases over 30%) the environmental and social impacts of the UPV/EHU's activity. These scenarios and improvement actions will feed a process with stakeholders in the UPV/ EHU based on the Multi-criteria Decision Analysis (MCDA) methodology.To the Sustainability Directorate and the Educational Advisory Service, both belonging to the Vice-Chancellor's Office for Innovation, Social Commitment and Social Action of the University of the Basque Country UPV/EHU, in the context of the Campus Bizia Lab programme (2017/18, 18/19 and 19/20 calls) for the financing of the EHU-Aztarna project. This research has also been supported by 'Ekopol: Iraunkortasunerako Bideak' research group, recognised by the Basque Government (IT1365-19) and the University of the Basque Country UPV/EHU (GIC-18/22)

Sistemas SCR y NSR-SCR para DeNOx en corrientes de escape diésel: Formulaciones, cinética y modelización

314 p.En esta tesis, se estudian las características físico-químicas de diferentes catalizadores Fe,Cu/ZSM-5, BETA y SSZ-13, tanto en forma granulada como monolítica, y se analiza su comportamiento NH3-SCR en la eliminación de NOx de corrientes de gases de escape de motores de mezcla pobre. También se analizan las ventajas de colocar los catalizadores SCR corriente debajo de otro catalizador modelo Pt-BaO/Al2O3 NSR para mejorar la eficiencia de eliminación de NOx a N2, eliminando el deslizamiento de amoniaco en el sistema. El catalizador Cu/CHA proporciona el mejor comportamiento, a la vez que muestra una muy elevada resistencia al envejecimiento hidrotérmico. También se propone un modelo cinético globalizado para el sistema de reacciones NO/NO2 NH3-SCR, que se verifica con un extenso conjunto de reacciones experimentales. Finalmente, se modeliza y simula el comportamiento NH3-SCR en un canal monolítico, utilizando el software Comsol Multiphysics

Decoración y uso de un soporte mueble magdaleniense del abrigo de Buendía (Cuenca, España)

[EN] We present the systematic study of a blank decorated with a simple linear shape from the Buendía rockshelter, in a Magdalenian context dated at ±18000 cal BP. The blank and its decoration are studied microscopically, in order to understand the operative sequence, which includes the procurement of the blank in the surroundings, preparation of its surface prior to the graphic execution, drawing of a simple linear motif, and the subsequent modification of the surface after the drawing was made. This sequence suggests the loss of its original symbolic value. Considering the archaeological evidence associated with the decorated piece, we conclude that the symbolic action was conducted in a multifunctional context. Similar motives are reported in other Southwest European Magdalenian contexts. A better understanding of portable art operational sequences and their context will enable moving forward in our knowledge of the use and function of graphic symbolism.[ES] Se presenta el estudio integral de un soporte decorado con una forma lineal simple recuperado en el abrigo de Buendía, en un contexto magdaleniense datado en ±18000 cal BP. Se estudia el soporte y la forma decorada recurriendo al análisis microscópico a fin de comprender la cadena operativa, concretada en la captación del soporte en el ámbito cercano, la preparación de la superficie antes de la ejecución gráfica, la realización de una decoración lineal simple y la modificación posterior de la superficie tras el dibujo, lo que plantea la pérdida del valor simbólico original. Considerando las evidencias arqueológicas asociadas a la pieza decorada, se concluye que la acción simbólica se llevó a cabo en un contexto multifuncional. La búsqueda de referentes similares en el arte mueble del sudoeste europeo pone de manifiesto la existencia de motivos similares magdalenienses. La comprensión de las cadenas operativas y la contextualización del arte mueble permitirán avanzar en el conocimiento de la función y uso del simbolismo gráfico.Las excavaciones en el abrigo de Buendía fueron autorizadas y financiadas por la Dirección General de Patrimonio y Museos (Junta de Comunidades de Castilla-La Mancha) entre 2005 y 2010. Agradecemos la subvención concedida por la Society of Antiquaries of London durante las campañas de 2009 y 2010Peer reviewe