Open Access
Environmental impact improvement of chitosan-based mixed-matrix membranes manufacture for CO2 gas separation by life cycle assessment
(Wiley, 2023) Echarri San Martín, Itsaso Andrea; Casado-Coterillo, Clara; Rumayor, Marta; Navajas León, Alberto; Gandía Pascual, Luis; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The environmental impacts of the manufacture of chitosan (CS) and polymeric poly(1-trimethylsilyl-1-propyne) (PTMSP) mixed-matrix membranes (MMMs) for CO2 separation by life cycle assessment (LCA) are compared. An ionic liquid of non-reported toxicity is used in CS membranes to enhance the mechanical strength, and different fillers are used to increase mechanical and functional properties: ETS-10, ZIF-8, HKUST-1, and Zeolite A. Results with the same CO2 permeation flux indicate that ETS-10/IL-CS is the membrane manufacture with highest impacts due to its lower permeability. When comparing impacts with same permeation areas, the polymeric one is the membrane with highest impacts. Biopolymer and polymer manufacture are the components with highest contribution to the total environmental impacts of each membrane. To decrease all their impacts below fossil polymer membrane for the same CO2 permeation flux, CS membranes permeabilities should be improved by a numerical factor of 1000, 100, and 2 for the ETS-10, ZIF-8, and HKUST-1/IL-CS MMMs, respectively.
Embargo
How bimetallic CoMo carbides and nitrides improve CO oxidation
(Elsevier, 2023) Villasana, Yanet; García Macedo, Jorge A.; Navarro Puyuelo, Andrea; Reyero Zaragoza, Inés; Lara, Hugo; Bimbela Serrano, Fernando; Gandía Pascual, Luis; Brito, Joaquin L.; Méndez, Franklin J.; Institute for Advanced Materials and Mathematics - INAMAT2
CO elimination is an important step for the proper management of gaseous effluents from various processes, thus avoiding adverse impacts on the environment and human health. In this study, different bimetallic Al2O3-supported CoMo catalysts have been developed, characterized, and tested in the CO oxidation reaction, based on their respective oxides, carbides, and nitrides phases. The parent CoMo-oxide catalyst (CoMo) was prepared by impregnation and then transformed to its carburized (CoMoC) and nitrided (CoMoN) forms using temperatureprogrammed reaction methods under controlled atmospheres of CH4/H2 and NH3, respectively. The catalytic results demonstrate that the CoMoC catalyst exhibits higher activity compared to its CoMoN counterpart, and both are more active than the parent CoMo catalyst. Furthermore, the reduction temperature and space velocity were key process factors, which notably influenced activity and kinetic parameters, while the increase of reduction time does not seem to improve catalytic behavior. These results were associated with a better metal dispersion, and relatively higher reduction grade and metallic surface area on the carbides and nitrides, opening the possibility that new adsorption sites may be created. The catalytic results compare favorably with other nonnoble metal catalysts, such as Cr-, Cu-, Fe-, and Ni-based samples, and highlight the potential of using carbides and nitrides as alternative formulations to enhance the performance of CO oxidation.
Open Access
Exploring a low-cost valorization route for amazonian cocoa pod husks through thermochemical and catalytic upgrading of pyrolysis vapors
(American Chemical Society, 2023) Villasana, Yanet; Armenise, Sabino; Ábrego, Javier; Hablich, Karina; Bimbela Serrano, Fernando; Cornejo Ibergallartu, Alfonso; Gandía Pascual, Luis; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Ecuador as an international leader in the production of cocoa beans produced more than 300 000 tons in 2021; hence, the management and valorization of the 2 MM tons of waste generated annually by this industry have a strategic and socioeconomic value. Consequently, appropriate technologies to avoid environmental problems and promote sustainable development and the bioeconomy, especially considering that this is a megadiverse country, are of the utmost relevance. For this reason, we explored a low-cost pyrolysis route for valorizing cocoa pod husks from Ecuador’s Amazonian region, aiming at producing pyrolysis liquids (bio-oil), biochar, and gas as an alternative chemical source from cocoa residues in the absence of hydrogen. Downstream catalytic processing of hot pyrolysis vapors using Mo- and/or Ni-based catalysts and standalone γ-Al2O3 was applied for obtaining upgraded bio-oils in a laboratory-scale fixed bed reactor, at 500 °C in a N2 atmosphere. As a result, bimetallic catalysts increased the bio-oil aqueous phase yield by 6.6%, at the expense of the organic phase due to cracking reactions according to nuclear magnetic resonance (NMR) and gas chromatography–mass spectrometry (GC–MS) results. Overall product yield remained constant, in comparison to pyrolysis without any downstream catalytic treatment (bio-oil ∼39.0–40.0 wt % and permanent gases 24.6–26.6 wt %). Ex situ reduced and passivated MoNi/γ-Al2O3 led to the lowest organic phase and highest aqueous phase yields. The product distribution between the two liquid phases was also modified by the catalytic upgrading experiments carried out, according to heteronuclear single-quantum correlation (HSQC), total correlation spectroscopy (TOCSY), and NMR analyses. The detailed composition distribution reported here shows the chemical production potential of this residue and serves as a starting point for subsequent valorizing technologies and/or processes in the food and nonfood industry beneficiating society, environment, economy, and research.
Open Access
Reaction monitoring by ultrasounds in a pseudohomogeneous medium: triglyceride ethanolysis for biodiesel production
(MDPI, 2022) Reyero Zaragoza, Inés; Gandía Pascual, Luis; Arzamendi Manterola, Gurutze; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The sound propagation speed measurement us is used for monitoring triglyceride ethanol-ysis in a broad range of reaction conditions (mainly, temperature: 23–50◦C; ethanol/oil: from 6 to 24 mol/mol). Experimentally, us slightly increased with the reaction time in all cases as a result of the contribution of its dynamic mixture components. Nomoto’s expression for homogeneous mixtures offered suitable us estimation but with values notably higher than the experimental ones due to the resistance to sound propagation offered by the ethanol/oil interphase (non-homogeneous medium). Our strategy was based on both the comparison of the experimental us values and the theoretical ones correlated by means of triglyceride conversion and on the estimation of the sound speed of oil/ethanol that could emulate the resistance offered by the interphase. The evolution of the reactions was predicted quite well for all the experiments carried out with very different reaction rates. Nev-ertheless, at the beginning of the reaction, the estimated conversion (outside of industrial interests) showed important deviations. The presence of the intermediate reaction products, diglycerides, and monoglycerides could be responsible for those deviations.
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
Highly selective CO formation via CO2 hydrogenation over novel ceria-based high-entropy oxides (HEOs)
(Elsevier, 2025-03-01) Cortázar, María; Lafuente Adiego, Marta; Navarro Puyuelo, Andrea; García, Xènia; Llorca Piqué, Jordi; Reyero Zaragoza, Inés; Bimbela Serrano, Fernando; Gandía Pascual, Luis; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In the present study, new ceria-based high-entropy oxides (HEOs) were investigated as CO2 hydrogenation catalysts. The nominal composition was (Ce0.5Ni0.1Co0.1Cu0.1Zn0.1Mg0.1)Ox and the synthesis was accomplished through the citrate complexing sol-gel method. Characterization techniques utilized including ICP-AES, in situ XRD and in situ XPS, SEM-EDS, HR-TEM and HAADF-STEM, Raman spectroscopy, H2-TPR, CO2-TPD and N2 physical adsorption. The physicochemical characterization and the catalytic results revealed that the conditions of the thermal treatments at which the oxides were subjected critically determined the catalytic performance, especially the CO2 hydrogenation products selectivities. Calcination in air and/or reduction in hydrogen conducted at temperatures below 500 °C led to active but poorly selective catalysts that produced both methane and CO with significant yields. This was mainly attributed to the presence of metallic Cu, Ni and Co on the catalysts that appeared to be supported on ceria doped with the rest of the formulation elements. In contrast, thermal treatments at 750 °C favored the formation of a rocksalt entropy-stabilized (NiCoCuZnMg)Ox HEO supported on ceria that has stood out for showing an excellent selectivity towards the reverse water¿gas shift (RWGS) reaction. This catalyst led to CO selectivities of almost 100 % over a very wide range of reaction temperatures (300-700 °C). Long-term stability tests (100 h) showed only a slight decrease in CO2 conversion, while CO selectivity remained stable at nearly 100 % at 400 °C. XRD characterization of the used catalysts evidenced that, whereas the basic catalyst structure remained, some metallic copper exsolved during reduction and reaction period. These results are relevant and very promising, opening a door to the development of new catalysts for the valorization of CO2 through the RWGS reaction, thus expanding the low-temperature limit at which this process can be carried out selectively.
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
Oak wood extracts applied to the grapevine. An alternative to obtain quality Garnacha wines
(Elsevier, 2018) Jiménez Moreno, Nerea; Moler Cuiral, José Antonio; Urmeneta Martín-Calero, Henar; Suberviola Ripa, Julián; Cibriain Sabalza, Félix; Gandía Pascual, Luis; Ancín Azpilicueta, Carmen; Química Aplicada; Kimika Aplikatua; Institute for Advanced Materials and Mathematics - INAMAT2; Estadística e Investigación Operativa; Estatistika eta Ikerketa Operatiboa
Open Access
Life cycle assessment in higher education: design and implementation of a teaching sequence activity
(MDPI, 2024) Navajas León, Alberto; Echarri San Martín, Itsaso Andrea; Gandía Pascual, Luis; Pozuelo, Jorge; Cascarosa, Esther; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
The latest studies show that to achieve the Sustainable Development Goals on education, there must be a focus on adequately training higher education students. In this work, we present a study about the Life Cycle Analysis of knowledge of products and processes of engineering students. This aspect is very relevant in engineering education since it has direct implications on sustainability. The first step was to identify what the learning problems were, and taking them into account, a specific teaching sequence was designed and implemented over three academic years. Two activities, on an increasing level of complexity, of the application of Life Cycle Assessment are shown in this paper. The first one is the Life Cycle Analysis comparison between two steel and polypropylene pieces. The second one is the Life Cycle Analysis comparison between three different ends of life of a polypropylene piece: mechanical recycling, incineration, and landfill. Data on the evolution of students' marks while solving a ¿one step more difficult project¿ throughout these courses have been collected. The results show a generalized learning by the students about Life Cycle Analysis.
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.