Open Access
Life cycle assessment of natural gas fuelled power plants based on chemical looping combustion technology
(Elsevier, 2019-07-30) Navajas León, Alberto; Mendiara, Teresa; Goñi, Víctor; Jiménez, Adrián; Gandía Pascual, Luis; Abad, Alberto; García Labiano, Francisco; Diego, Luis F. de; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Among the different Carbon Capture and Storage (CCS) technologies being developed in the last decades, Chemical Looping Combustion (CLC) stands out since it allows inherent CO2 capture. In the CLC process, there is a solid oxygen carrier circulating between two reactors in a cycle that allows providing the oxygen needed for combustion. In one of the reactors, named as fuel reactor, the fuel is introduced and combusted while the oxygen carrier reduction takes place. In the second reactor, named air reactor, the oxygen carrier is reoxidized in air. Different materials based on copper, nickel and iron oxides have been proposed as oxygen carriers for the CLC process. This work presents an environmental evaluation of the CLC process for natural gas based on Life Cycle Assessment (LCA). Five different oxygen carrier materials already tested in pilot plants were considered and the results compared to the conventional natural gas combustion in a gas turbine in a combined cycle without and with CO2 capture using postcombustion capture with amines. In view of the results, lower impact of the CLC process compared to the base case is expected without and with CO2 capture. The influence of several variables on the results was considered, such as temperature in the air reactor, lifetime of the oxygen carrier and possibility of recuperation of the depleted oxygen carrier. The nickel-based oxygen carriers were identified as the most adequate to be used in natural gas combustion. However, due to their toxicity, several analyses were also performed in order to identify improvements in the known oxygen carriers that can qualify them to replace nickel-based materials.
Open Access
Application of eco-design and life cycle assessment standards for environmental impact reduction of an industrial product
(MDPI, 2017) Navajas León, Alberto; Uriarte Elizaga, Leire; Gandía Pascual, Luis; Kimika Aplikatua; Institute for Advanced Materials and Mathematics - INAMAT2; Química Aplicada
Eco-design is included within the framework of the standard for “Environmental management systems—Guidelines for incorporating Eco-design” (ISO 14006:2011). Eco-design process, as defined in standard, has six steps: (i) Specify product functions; (ii) Environmental assessment of products; (iii) Strategies of improvement; (iv) Environmental objectives; (v) Product specification; and (vi) Technical solutions. Step (ii), determination of the stage or process of the product life cycle that has the highest environmental impact; this is perhaps the most controversial step because the standard does not specify which tool should be used. This lack of specification has generated some distrust with regard to eco-design, hindering its development. In order to make a trustworthy eco-design, Life Cycle Assessment (LCA) should be applied as a tool for environmental impact quantification. The main objective of this work is to apply standardised eco-design methodology for the reduction of the environmental impact of an industrial product in Spain using LCA as a tool for the environmental product assessment. LCA standardised process (ISO 14040,14044:2006) is included in the eco-design process. A glass container intended for cough syrup delivery has been selected as an industrial product to be eco-designed. Following the methodology described, the overall normalised impact decreased 35.1% when a PET container substituted a glass container. Environmental impacts have been reduced following standardised eco-design and LCA methodologies, serving as an example to industry and administration regarding how to eco-design with the confidence of obtaining reliable results
Open Access
A techno-economic and life cycle assessment for the production of green methanol from CO2: catalyst and process bottlenecks
(Elsevier, 2022) Cordero-Lanzac, Tomas; Ramirez, Adrián; Navajas León, Alberto; Gevers, Lieven; Brunialti, Sirio; Gandía Pascual, Luis; Aguayo, Andrés T.; Sarathy, S. Mani; Gascon, Jorge; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The success of catalytic schemes for the large-scale valorization of CO2 does not only depend on the development of active, selective and stable catalytic materials but also on the overall process design. Here we present a multidisciplinary study (from catalyst to plant and techno-economic/lifecycle analysis) for the production of green methanol from renewable H2 and CO2. We combine an in-depth kinetic analysis of one of the most promising recently reported methanol-synthesis catalysts (InCo) with a thorough process simulation and techno-economic assessment. We then perform a life cycle assessment of the simulated process to gauge the real environmental impact of green methanol production from CO2. Our results indicate that up to 1.75 ton of CO2 can be abated per ton of produced methanol only if renewable energy is used to run the process, while the sensitivity analysis suggest that either rock-bottom H2 prices (1.5 $ kg−1) or severe CO2 taxation (300 $ per ton) are needed for a profitable methanol plant. Besides, we herein highlight and analyze some critical bottlenecks of the process. Especial attention has been paid to the contribution of H2 to the overall plant costs, CH4 trace formation, and purity and costs of raw gases. In addition to providing important information for policy makers and industrialists, directions for catalyst (and therefore process) improvements are outlined.
Open Access
Life cycle assessment of power-to-methane systems with CO2 supplied by the chemical looping combustion of biomass
(Elsevier, 2022) Navajas León, Alberto; Mendiara, Teresa; Gandía Pascual, Luis; Abad, Alberto; García Labiano, Francisco; Diego, Luis F. de; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Power-to-methane (PtM) systems may allow fluctuations in the renewable energy supply to be smoothed out by storing surplus energy in the form of methane. These systems work by combining the hydrogen produced by electrolysis with carbon dioxide from different sources to produce methane via the Sabatier reaction. The present work studies PtM systems based on the CO2 supplied by the chemical looping combustion (CLC) of biomass (PtM-bioCLC). Life- cycle- assessment (LCA) was performed on PtM-bioCLC systems to evaluate their environmental impact with respect to a specific reference case. The proposed configurations have the potential to reduce the value of the global warming potential (GWP) climate change indicator to the lowest values reported in the literature to date. Moreover, the possibility of effectively removing CO2 from the atmosphere through the concept of CO2 negative emissions was also assessed. In addition to GWP, as many as 16 LCA indicators were also evaluated and their values for the studied PtM-bioCLC systems were found to be similar to those of the reference case considered or even significantly lower in such categories as resource use-depletion, ozone depletion, human health, acidification potential and eutrophication. The results obtained highlight the potential of these newly proposed PtM schemes.
Open Access
Outstanding performance of rehydrated Mg-Al hydrotalcites as heterogeneous methanolysis catalysts for the synthesis of biodiesel
(Elsevier, 2018) Navajas León, Alberto; Campo Aranguren, Idoia; Moral Larrasoaña, Ainara; Echave, Javier; Sanz, Oihane; Montes, Mario; Odriozola, José A.; Arzamendi Manterola, Gurutze; Gandía Pascual, Luis; Química Aplicada; Kimika Aplikatua; Institute for Advanced Materials and Mathematics - INAMAT2
There is still a need for active, selective and stable heterogeneous catalysts for the synthesis of biodiesel. In this work, magnesium-aluminium hydrotalcites with Mg/Al molar ratios within the 1.5–5 range were synthesized by coprecipitation and used as transesterification catalysts for the synthesis of biodiesel. The mixed oxides obtained after calcination recovered the hydrotalcite structure in the form of meixnerite after rehydration in boiling water. The solids were characterized by XRD, TGA, N2 adsorption-desorption, and SEM. Basic properties were assessed by means of Hammett indicators and CO2-TPD. Rehydrated materials with the highest Mg/Al ratios showed some distinctive features: low surface area, well defined flake-like crystals, high basicity and strong basic sites with H_ values above 11. They were also the most active catalysts allowing to achieve 51–75% sunflower oil methanolysis conversion after 8 h of reaction under mild conditions (60 °C, 1 atm), methanol/oil molar ratio of 12 using between 2 and 6 wt% of catalyst. The conversion increased up to 96% (92% fatty acid methyl esters yield) using 2 wt% catalyst and methanol/oil molar ratio of 48. Catalyst leaching was not a serious problem with these solids that could be reutilized maintaining very good activities. A general accordance between solids basic properties and their catalytic performance has been observed. These results are among the best reported in the literature for heterogeneous methanolysis catalysts and have been attributed to the high basicity of the rehydrated solids and the presence of strong and accessible basic sites probably consisting in interlayer hydroxide anions at the edges of the crystals.
Open Access
Catalytic performance of bulk and Al₂O₃-supported molybdenum oxide for the production of biodiesel from oil with high free fatty acids content
(MDPI, 2020) Navajas León, Alberto; Reyero Zaragoza, Inés; Jiménez Barrera, Elena; Romero Sarria, Francisca; Llorca Piqué, Jordi; Gandía Pascual, Luis; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
Non-edible vegetable oils are characterized by high contents of free fatty acids (FFAs) that prevent from using the conventional basic catalysts for the production of biodiesel. In this work, solid acid catalysts are used for the simultaneous esterification and transesterification with methanol of the FFAs and triglycerides contained in sunflower oil acidified with oleic acid. Molybdenum oxide (MoO₃), which has been seldom considered as a catalyst for the production of biodiesel, was used in bulk and alumina-supported forms. Results showed that bulk MoO3 is very active for both transesterification and esterification reactions, but it suffered from severe molybdenum leaching in the reaction medium. When supported on Al₂O₃, the MoO₃ performance improved in terms of active phase utilization and stability though molybdenum leaching remained significant. The improvement of catalytic performance was ascribed to the establishment of MoO₃Al₂O₃ interactions that favored the anchorage of molybdenum to the support and the formation of new strong acidic centers, although this effect was offset by a decrease of specific surface area. It is concluded that the development of stable catalysts based on MoO₃ offers an attractive route for the valorization of oils with high FFAs content.
Open Access
Innovative catalyst integration on transparent silicone microreactors for photocatalytic applications
(Elsevier, 2022) Pellejero, Ismael; Clemente, Alberto; Navajas León, Alberto; Vesperinas Oroz, José Javier; Urbiztondo, Miguel A.; Gandía Pascual, Luis; Institute for Advanced Materials and Mathematics - INAMAT2; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Reproducible and controllable incorporation and immobilization of catalysts and other active particles onto silicone microreactor channels is still challenging. In this work, we present an innovative fabrication protocol to attain affordable, custom-designed photocatalytic microreactors in a fast and simple manner. In this protocol, a 3D-printed ABS microreactor mold is first dip-coated with the photocatalyst, and subsequently, the catalytic layer is transferred onto the microchannel walls by indirect immobilization during the silicone casting and scaffold removal step. Serpentine-shaped microreactors have been satisfactorily fabricated with Au@POM-impregnated TiO2 nanoparticles (Au@POM/TiO2; Au 0.18 % w/w, POM: H3PW12O40) as the integrated photocatalytic layer. The suitability of our fabrication method has been validated on the basis of the excellent photocatalytic performance shown by the microreactors in a model test reaction such as the continuous-flow photoreduction of 4-nitrophenol to 4-aminophenol with NaBH4 and monitored by UV-Vis spectroscopy.
Open Access
Mesoporous Sn-in-MCM-41 catalysts for the selective sugar conversion to methyl lactate and comparative life cycle assessment with the biochemical process
(American Chemical Society, 2022) Iglesia, Óscar de la; Sarango, Miryan; Munárriz Tabuenca, Mikel; Malankowska, Magdalena; Navajas León, Alberto; Gandía Pascual, Luis; Coronas, Joaquín; Téllez, Carlos; Ciencias; Zientziak; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The use of biomass for the production of energy and higher added value products is a topic of increasing interest in line with growing environmental concerns and circular economy. Mesoporous material Sn-In-MCM-41 was synthesized for the first time and used as a catalyst for the transformation of sugars to methyl lactate (ML). This catalyst was characterized in depth by various techniques and compared with Sn-MCM-41 and In-MCM-41 catalysts. In the new Sn-In-MCM-41 material, both metals, homogeneously distributed throughout the mesoporous structure of MCM-41, actuate in a cooperative way in the different steps of the reaction mechanism. As a result, yields to ML of 69.4 and 73.9% in the transformation of glucose and sucrose were respectively reached. In the case of glucose, the ML yield 1.5 and 2.6 times higher than those of Sn-MCM-41 and In-MCM-41 catalysts, respectively. The Sn-In-MCM-41 catalyst was reused in the transformation of glucose up to four cycles without significant loss of catalytic activity. Finally, life cycle assessment comparison between chemical and biochemical routes to produce ML allowed us to conclude that the use of Sn-In-MCM-41 reduces the environmental impacts compared to Sn-MCM-41. Nevertheless, to make the chemical route comparable to the biochemical one, improvements in the catalyst and ML synthesis have to be achieved.
Open Access
Three-dimensional printing of acrylonitrile butadiene styrene microreactors for photocatalytic applications
(American Chemical Society, 2020) Cabrera Barrios, Aarón; Pellejero, Ismael; Oroz Mateo, Tamara; Salazar, Cristina; Navajas León, Alberto; Fernandez Acevedo, Claudio; Gandía Pascual, Luis; Institute for Advanced Materials and Mathematics - INAMAT2; Gobierno de Navarra / Nafarroako Gobernua, PC003-004; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Miniaturization is a key aspect for many technological applications and the use of microreactors is an excellent solution for the intensification of chemical processes for a variety of applications. However, standard microfabrication requires large facilities and intricate fabrication protocols, and consequently it is not easily available, generally resulting in high production costs. Herein, we present a very cheap, fast and easy microreactor design for photocatalytic applications based on direct fused filament 3D printing as a facilitating and widespread technology. The microreactor consists of three bodies directly printed in ABS (Acrylonitrile Butadiene Styrene): a main body with a serpentine microchannel pattern where the photocatalyst is placed, a top holder with a transparent polymer window, and a base to clamp the parts. Several microreactor units were coated with TiO2 doped with Cu (2.4 wt.%) nanoparticles synthesized by FSP (Flame Spray Pyrolysis) and tested for the photocatalytic degradation of two water pollutants showing excellent performance.