Open Access
Effect of oxygen addition, reaction temperature and thermal treatments on syngas production from biogas combined reforming using Rh/alumina catalysts
(Elsevier, 2019) Navarro Puyuelo, Andrea; Reyero Zaragoza, Inés; Moral Larrasoaña, Ainara; Bimbela Serrano, Fernando; Bañares, Miguel A.; Gandía Pascual, Luis; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Dry reforming and partial oxidation of biogas were studied using 0.5 wt.% Rh/Al2O3 catalysts, both inhouse prepared and commercial. The effects of O2 addition on syngas yield and biogas conversion were studied at 700 C using different O2/CH4 ratios in the gas feeding stream: 0 (dry reforming), 0.12, 0.25, 0.45 and 0.50. The highest CH4 conversion, H2 yield and H2/CO molar ratio were obtained with an O2/CH4 ratio of 0.45, even though simultaneous valorization of both CH4 and CO2 could be best attained when the O2/CH4 ratio was 0.12. Increased biogas conversions and syngas yields were obtained by increasing reaction temperatures between 650 and 750 C. A detrimental influence on catalytic activity could be observed when the catalyst was subjected to calcination. Increasing the hold time of the thermal conditioning of the catalyst under inert flow altered Rh dispersion, though had no significant impact on catalyst performance in the dry reforming of methane at 700 C and 150 N L CH4/(gcat h). Characterization of spent samples after reaction by Raman spectroscopy revealed the presence of carbonaceous deposits of different nature, especially on the commercial(named as Rh com) and calcined (Rh calc) catalysts, though oxygen addition in the biogas feed significantly reduced the amount of these deposits. The Rh catalysts that had not been calcined after impregnation (Rh prep) did not present any noticeable characteristic peaks in the G and D bands. In particular, scanning transmission electron microscopy (STEM) images of the spent Rh prep sample revealed the presence of very highly dispersed Rh nanoparticles after reaction, of particle sizes of about 1 nm, and no noticeable C deposits. Combined oxy-CO2 reforming of biogas using highly dispersed and low metal-loading Rh/Al2O3 catalysts with low O2 dosage in the reactor feed can be used to effectively transform biogas into syngas.
Open Access
Rutas y retos para la valorización de biogás
(Universidad Libre (Colombia), 2017) Navarro Puyuelo, Andrea; Reyero Zaragoza, Inés; Moral Larrasoaña, Ainara; Bimbela Serrano, Fernando; Gandía Pascual, Luis; Química Aplicada; Kimika Aplikatua
Las tecnologías de digestión anaerobia para procesar corrientes residuales (fracción orgánica de residuos de vertedero, lodos de estaciones depuradoras de aguas residuales, purines, etc.) han originado un incremento de la producción de biogás. El biogás está compuesto principalmente por metano y dióxido de carbono, aunque contiene otros componentes minoritarios e impurezas que obligan a efectuar tratamientos para su purificación y acondicionamiento. Existen diversas alternativas para el aprovechamiento y la valorización de este gas, como son: su utilización directa en la generación de energía calorífica y/o eléctrica, su conversión a biometano, y la producción de gas de síntesis (H2+CO), que posteriormente permite producir combustibles líquidos y/o compuestos químicos de interés como el metanol. En este trabajo se presenta una revisión general de las alternativas de valorización de biogás, con énfasis en los procesos de reformado catalítico, tales como el reformado seco o con vapor de agua y procesos de reformado combinado incluyendo la oxidación parcial.
Open Access
Renewable hydrocarbon production from waste cottonseed oil pyrolysis and catalytic upgrading of vapors with Mo-Co and Mo-Ni catalysts supported on γ-Al2O3
(MDPI, 2021) Alves Melo, Josué; Santana de Sá, Mirele; Moral Larrasoaña, Ainara; Bimbela Serrano, Fernando; Gandía Pascual, Luis; Wisniewski, Alberto; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In this work, the production of renewable hydrocarbons was explored by the means of waste cottonseed oil (WCSO) micropyrolysis at 500◦C. Catalytic upgrading of the pyrolysis vapors was studied using α-Al2O3, γ-Al2O3, Mo-Co/γ-Al2O3, and Mo-Ni/γ-Al2O3 catalysts. The oxygen removal efficiency was much lower in non-catalytic pyrolysis (18.0%), whilst γ-Al2O3 yielded a very high oxygen removal efficiency (91.8%), similar to that obtained with Mo-Co/γ-Al2O3 (92.8%) and higher than that attained with Mo-Ni/γ-Al2O3 (82.0%). Higher conversion yields into total renewable hydrocarbons were obtained with Mo-Co/γ-Al2O3 (61.9 wt.%) in comparison to Mo-Ni/γ-Al2O3 (46.6%). GC/MS analyses showed a relative chemical composition of 31.3, 86.4, and 92.6% of total renewable hydrocarbons and 58.7, 7.2, and 4.2% of oxygenated compounds for non-catalytic bio-oil (BOWCSO), BOMoNi and BOMoCo, respectively. The renewable hydrocarbons that were derived from BOMoNi and BOMoCo were mainly composed by olefins (35.3 and 33.4%), aromatics (31.4 and 28.9%), and paraffins (13.8 and 25.7%). The results revealed the catalysts’ effectiveness in FFA decarbonylation and decarboxylation, as evidenced by significant changes in the van Krevelen space, with the lowest O/C ratio values for BOMoCo and BOMoNi (O/C = 0–0.10) in relation to the BOWCSO (O/C = 0.10–0.20), and by a decrease in the presence of oxygenated compounds in the catalytic bio-oils.
Open Access
Oxidative steam reforming of glycerol. A review
(Elsevier, 2021) Moreira, Rui; Bimbela Serrano, Fernando; Gandía Pascual, Luis; Ferreira, Abel; Sánchez, José Luis; Portugal, Antonio; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This review article presents the state-of-the-art on the catalytic oxidative steam reforming (OSR) of glycerol to produce syngas. Concerning the different technologies proposed for the catalytic OSR of glycerol, the following key points can be highlighted: (1) the robustness is much higher than other reforming technologies, (2) several catalysts can work with low deactivation, some of which can recover almost full activity by suitable regeneration, (3) syngas production by catalytic OSR of glycerin is higher than with concurrent technologies, (4) their scaling-up remains an unrealized task, (5) the thermodynamics of the process has been sufficiently covered in the literature, (6) there is a significant lack of kinetic and mechanistic studies that could help gaining deeper insight on the process, (7) novel concepts and reactor designs must be proposed for their development at larger scales, (8) new catalyst formulations must be developed for attaining higher resistance against oxidation and (9) process intensification could help developing them at larger scales.
Open Access
Clean syngas production by gasification of lignocellulosic char: state of the art and future prospects
(Elsevier, 2021) Moreira, Rui; Bimbela Serrano, Fernando; Gil-Lalaguna, Noemí; Sánchez, José Luis; Portugal, Antonio; Institute for Advanced Materials and Mathematics - INAMAT2
Using lignocellulosic char instead of the original biomass avoids the need for costly cleaning and conditioning stages of the producer gasification gas. However, lignocellulosic char gasification has been less extensively studied than gasification of lignocellulosic biomass, and a review of published works on this topic was missing. In this review the present status of char gasification technologies and their future prospects are critically discussed, including possible research opportunities. To date, most studies on char gasification have been performed in thermogravimetric analyzers (TGA) or TGA-like experimental setups. The major setback of TGA and TGA-like equipment is that they do not mimic the actual reaction conditions occurring in gasification reactors, which impedes a direct extrapolation of the findings during the scale-up of different gasification technologies. For this reason, in this literature review focus was put on studies undertaken in industrially relevant reactors, both in batch and continuous configurations. Overall, char gasification can be deemed a valid alternative for clean syngas production, contributing to an integral valorization of lignocellulosic residues within different biorefinery schemes. Of these, process intensification by microwave heating offers interesting opportunities for research and scaling-up, though efforts must be directed toward developing continuous microwave-assisted gasification processes.
Open Access
Encuesta de satisfacción de un proyecto de mejora de calidad del servicio aragonés de salud
(Universidad de Murcia, 2015) Bimbela Serrano, María Teresa; Bimbela Serrano, Fernando; Bernués Vázquez, Luis; Ciencias; Zientziak
Introducción: Según el informe de 2008 del Sistema Nacional de Salud, existe un 4,7% de los usuarios que opina que el sistema sanitario debería rehacerse por completo y casi un 27%, que es necesario introducir cambios importantes para su mejora. Hipótesis: El desarrollo de un programa específico de control de peso para pacientes obesos en Atención Primaria mejora la calidad de la actuación percibida por el paciente de Atención Primaria. Objetivos: Valorar la influencia de un proyecto de mejora de calidad de Atención Primaria en los resultados globales de una encuesta de satisfacción de los usuarios de dicha Zona Básica de Salud. Material y Métodos: Estudio prospectivo de intervención cuasiexperimental centrado en el tratamiento de la obesidad en Atención Primaria realizado desde Enero de 2012 a Diciembre 2013, en cuya evaluación final se realizó una encuesta autoadministrada de Satisfacción de los usuarios y se comparó con los resultados obtenidos con el mismo cuestionario por el Servicio Aragonés de Salud en dicha Zona Básica de Salud. Para el análisis estadístico de estos datos se empleó el programa informático SPSS.15. Resultados principales: Se observa un aumento destacable en los apartados ‘Interés del personal de enfermería’, ‘Satisfacción de los cuidados sanitarios’ (medicina y enfermería) y ‘Solución dada a problemas’. No hubo aspectos negativos y el 100% de los encuestados expresó una satisfacción general y un 88% destacó el aspecto de la paciencia del profesional hacia los pacientes. Conclusión: El proyecto de mejora de calidad realizado con pacientes crónicos de la consulta de enfermería de Atención Primaria, ha sido valorado muy satisfactoriamente, llegando a mejorar la puntuación de los resultados globales del Sistema Aragonés de Salud en esta Zona Básica de Salud.
Open Access
Application of a modeling tool to describe fly ash generation, composition, and melting behavior in a wheat straw fired commercial power plant
(MDPI, 2020) Funcia, Ibai; Bimbela Serrano, Fernando; Gil, Javier; Gandía Pascual, Luis; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Ash behavior is a key operational aspect of industrial-scale power generation by means of biomass combustion. In this work, FactSage™ 6.4 software was used to develop and assess three models of wheat straw combustion in a vibrating grate-fired commercial boiler of 16 MWth, aiming to describe the inorganic elements release as well as fly ash melting behavior and composition. Simulations were carried out solving four consecutive calculation stages corresponding to the main plant sections. Chemical fractionation was adopted in order to distinguish between reactive, inert and partially reactive biomass fractions. The developed models allow take into account different levels of partial reactivity, values of the temperature for each sub-stage on the grate, and ways to apply entrained streams based on data from the elemental analyses of the fly ashes. To this end, two one-week experimental campaigns were conducted in the plant to carry out the sampling. It has been found that considering chemical fractionation is indispensable to describe the entrainment of solid particles in the gas stream. In addition, the best results are obtained by adopting a small reactivity (2%) of the inert fraction. As for fly ash composition, the concentrations of the major elements showed good agreement with the results from the chemical analyses. In the case of S and Cl, calculations revealed a match with gas cooling effects in the superheaters as well as an entrainment effect. The melting behavior together with the presence of KCl and K2SO4 condensates, point out at possible corrosion phenomena in walls at temperatures of 700–750 °C.
Open Access
Extraction of phenolic compounds from populus salicaceae bark
(MDPI, 2022) Autor, Elsa; Cornejo Ibergallartu, Alfonso; Bimbela Serrano, Fernando; Maisterra Udi, Maitane; Gandía Pascual, Luis; Martínez Merino, Víctor; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate
Lignocellulosic residues have the potential for obtaining high value-added products that could be better valorized if biorefinery strategies are adopted. The debarking of short-rotation crops yields important amounts of residues that are currently underexploited as low-grade fuel and could be a renewable source of phenolic compounds and other important phytochemicals. The isolation of these compounds can be carried out by different methods, but for attaining an integral valorization of barks, a preliminary extraction step for phytochemicals should be included. Using optimized extraction methods based on Soxhlet extraction can be effective for the isolation of phenolic compounds with antioxidant properties. In this study, poplar bark (Populus Salicaceae) was used to obtain a series of extracts using five different solvents in a sequential extraction of 24 h each in a Soxhlet extractor. Selected solvents were put in contact with the bark sample raffinate following an increasing order of polarity: n-hexane, dichloromethane, ethyl acetate, methanol, and water. The oily residues of the extracts obtained after each extraction were further subjected to flash chromatography, and the fractions obtained were characterized by gas chromatography coupled with mass spectrometry (GC–MS). The total phenolic content (TPC) was determined using the Folin–Ciocalteu method, and the antioxidant activity (AOA) of the samples was evaluated in their reaction with the free radical 2,2-Diphenyl-picrylhydrazyl (DPPH method). Polar solvents allowed for higher individual extraction yields, with overall extraction yields at around 23% (dry, ash-free basis). Different compounds were identified, including hydrolyzable tannins, phenolic monomers such as catechol and vanillin, pentoses and hexoses, and other organic compounds such as long-chain alkanes, alcohols, and carboxylic acids, among others. An excellent correlation was found between TPC and antioxidant activity for the samples analyzed. The fractions obtained using methanol showed the highest phenolic content (608 g of gallic acid equivalent (GAE)/mg) and the greatest antioxidant activity.
Open Access
Catalytic hydroprocessing of lignin β-O-4 ether bond model compound phenethyl phenyl ether over ruthenium catalysts
(Springer, 2017) Gómez Monedero, B.; Faria, J.; Bimbela Serrano, Fernando; Ruiz, M. P.; Química Aplicada; Kimika Aplikatua
The catalytic hydroprocessing of phenethyl phenyl ether (PPE), a model compound of one of the most significant ether linkages within lignin structure, β-O-4, has been studied. Reactions were carried out using two ruthenium-based catalysts, supported on different materials: 3.8 wt.% Ru/C and 3.9 wt.% Ru/Al2O3. Aiming at studying the reaction mechanism, experiments were carried out at 150 °C and 25 bar in H2 atmosphere, with varying feed to catalyst mass ratios and reaction time. Differences between the relative importance of the steps of the mechanism were observed when using those two catalysts. The most significant finding was the predominance of the cleavage of Cβ-O bonds compared to the cleavage of the Caryl-O when using Ru/Al2O3 as catalyst; whereas with Ru/C, the two routes were nearly equivalent. It has been observed that the kinetic model describes the general tendencies of consumption and formation of the different products, but some over/under estimation of concentrations occurs. Finally, the effect of temperature was also explored by carrying out reactions at 100 and 125 °C, observing that decreasing temperature from 150 to 125 or 100 °C favored the dimer hydrogenation route versus the hydrogenolysis of the ether bonds.
Open Access
Production of aromatic compounds by catalytic depolymerization of technical and downstream biorefinery lignins
(MDPI, 2020) Cornejo Ibergallartu, Alfonso; Bimbela Serrano, Fernando; Moreira, Rui; Hablich Alvarracin, Karina Lissett; García Yoldi, Íñigo; Maisterra Udi, Maitane; Portugal, Antonio; Gandía Pascual, Luis; Martínez Merino, Víctor; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua, PC036-037 Biovalorización; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Lignocellulosic materials are promising alternatives to non-renewable fossil sources when producing aromatic compounds. Lignins from Populus salicaceae., Pinus radiata and Pinus pinaster from industrial wastes and biorefinery effluents were isolated and characterized. Lignin was depolymerized using homogenous (NaOH) and heterogeneous (Ni-, Cu-or Ni-Cu-hydrotalcites) base catalysis and catalytic hydrogenolysis using Ru/C. When homogeneous base catalyzed depolymerization (BCD) and Ru/C hydrogenolysis were combined on poplar lignin, the aromatics amount was ca. 11 wt.%. Monomer distributions changed depending on the feedstock and the reaction conditions. Aqueous NaOH produced cleavage of the alkyl side chain that was preserved when using modified hydrotalcite catalysts or Ru/C-catalyzed hydrogenolysis in ethanol. Depolymerization using hydrotalcite catalysts in ethanol produced monomers bearing carbonyl groups on the alkyl side chain. The analysis of the reaction mixtures was done by size exclusion chromatography (SEC) and diffusion ordered nuclear magnetic resonance spectroscopy (DOSY NMR).31P NMR and heteronuclear single quantum coherence spectroscopy (HSQC) were also used in this study. The content in poly-(hydroxy)-aromatic ethers in the reaction mixtures decreased upon thermal treatments in ethanol. It was concluded that thermo-solvolysis is key in lignin depolymerization, and that the synergistic effect of Ni and Cu provided monomers with oxidized alkyl side chains.