Examinando por Autor "Moreno, Jovita"

Mostrando 1 - 11 de 11

Catalytic Transfer Hydrogenation of Glucose to Sorbitol with Raney Ni Catalysts Using Biomass-Derived Diols as Hydrogen Donors
(ACS, 2021) García, Beatriz; Orozco-Saumell, Ana; López Granados, Manuel; Moreno, Jovita; Iglesias, Jose
The catalytic transfer hydrogenation (CTH) of glucose to sorbitol has been studied using a wide collection of different biomass-derived alcohols and diols as hydrogen donors. Catalytic activity results reflect the feasibility to conduct this transformation in the presence of conventional, commercially available Raney Ni-type sponges as catalysts. Sacrificial diols displayed a superior performance as hydrogen donors as compared to short-chain alcohols, including secondary alcohols. Among them, terminal diols such as 1,4-butanediol and 1,5-pentanediol were revealed as excellent hydrogen donors, providing a high selectivity in the conversion of glucose into sorbitol. As for the catalysts, molybdenum promotion provided a very high catalytic activity to sponge nickel catalysts, even under mild temperature conditions. The transformation was also studied in a fixed-bed reactor under continuous-flow operation conditions. Results demonstrate that the catalysts are highly stable and able to operate for at least 550 h on stream with a high selectivity in the CTH of glucose to sorbitol.
Chromium oxide/metallocene binary catalysts for bimodal polyethylene: hydrogen effects.
(Elsevier, 2012-12) Paredes, Beatriz; Grieken, Rafael van; Carrero, Alicia; Moreno, Jovita; Moral, Alberto
Bimodal resins came up to meet application requirements: low molecular weight for good processability and high molecular weight for mechanical properties. For obtaining this bimodality there are several strategies: physical melt mixing of the two components produced separately, a single catalyst in two different serial reactors and a single reactor technology employing a tailor made catalyst and/or switching conditions. This last method has many advantages such as lower investment costs, less process complexity and intimate mixing of high and low molecular weight components (improved product quality). By means of this single reactor technology, bimodal polyethylene was synthesized using a mesostructured catalyst based on Al-SBA-15 where two active centers, chromium and metallocene, were incorporated. Ethylene polymerizations were carried out over binary catalysts (hybrid and mixed Crmetallocene) and the polyethylenes obtained were compared with those obtained with individual catalysts in order to determine the contribution of each active centre. As well, the effect on polymer properties of the partial pressure of hydrogen in the reactor was evaluated. Results indicate that the hybrid catalyst (metallocene supported over Cr-Al- SBA-15) and physical mixture (Cr-Al-SBA-15 mixed with met-Al-SBA-15) lead to bimodal polyethylenes which combine high molecular weight, crystallinity and melting point with good processability (high melt index).
Environmental analysis of Spirulina cultivation and biogas production using experimental and simulation approach
(Elsevier, 2018-12) Rodríguez, Rosalía; Espada, Juan José; Moreno, Jovita; Vicente, Gemma; Bautista, Luis Fernando; Morales, Victoria
Microalgae is constituted by different compounds, interesting for the production of a wide range of endproducts by using different technologies. Many potential possibilities have been developed under the context of a biorefinery. The aim of this work is to evaluate the environmental performance of biogas production from Spirulina (Arthrospira maxima) through LCA using experimental and simulation results. For this purpose, kinetic models for batch cultivation and anaerobic digestion (AD) were determined from experimental data. Thus, Monod kinetic model and a first order model describe well microalgal biomass growth and AD, respectively. This model was used to simulate growth of Spirulina in a continuous system by using SuperPro Designer 9.5. Calculated results were compared to continuous experimental ones, obtaining good agreement in all cases. On the other hand, the whole process (cultivation, dewatering and AD of Spirulina biomass) was also simulated and the obtained results (material and energy balances) were used to construct LCA inventory data. Thereafter, environmental impacts were quantified through CML-2001 methodology using software Gabi 6.0. LCA results show that abiotic depletion of fossil resources (ADFR) category presents the highest impact, being biomass cultivation the most important contributor (about 56%). This result is directly related to the high energy consumption required for nutrient production, which also leads to increase remarkably the global warming potential (GWP) category. Main conclusion of the work is that the total/partial substitution of mineral fertilizers as nutrient source is the key to improve the environmental performance of the studied process. In this sense, a potential alternative could be the use of nutrients from wastewater or other wast
Evaluation of bimodal polyethylene from chromium oxide/metallocene hybrid catalysts for high resistance applications
(Wiley, 2020-08) Paredes, Beatriz; Moreno, Jovita; Carrero, Alicia; van Grieken, Rafael
An interesting alternative to the industrial two-stage cascade process for the production of bimodal polyethylene, used for high resistance applications such as pressure pipes, has been developed. The key point is a binary catalytic system with chromium and metallocene sites incorporated together on AlSBA-15 mesostructured material. This hybrid catalyst is able to produce bimodal polyethylene in a single reactor. In the present work, it is shown that, in the presence of hydrogen and comonomer (1-butene or 1-hexene) in the reaction medium, the obtained polyethylenes exhibit appropriate mechanical properties for pipes manufacture, such as resistance to rapid crack propagation (RCP) and low crack growth (SCG), reaching standards for PE100 and even for PE100RC grades.
Integrated Environmental and Exergoeconomic Analysis of Biomass-Derived Maleic Anhydride
(Wiley, 2022) Blanco, Jorge; Linares, Maria; López Granados, Manuel; Agirre, Ion; Gandarias, Iñaki; Arias, Pedro Luis; Iglesia, Jose; Moreno, Jovita; García, Alicia
Life cycle analysis and exergy analysis are applied to compare the production of maleic anhydride from different feedstock, both biomass- and petrochemical-derived raw materials, in order to evaluate the sustainability of alternative biorefinery processes to conventional routes. The considered processes involve two options: gas and aqueous phase furfural oxidation with oxygen (air) and hydrogen peroxide as oxidants, respectively, considered as sustainable technologies because of the use of renewable feedstock. Conventional routes, used as benchmarks, include the current production processes using benzene or butane as raw materials. The results show that the aqueous phase process is far from being viable from an energy and environmental point of view due to the high exergy destruction and the use of H2O2 as oxidant (whose production entails important environmental drawbacks). On the contrary, the gas phase oxidation of furfural shows competitive results with petrochemical technologies. Nevertheless, the major environmental drawback of the new furfural-to-maleic anhydride production processes is detected on the environmental profile of the starting raw material. The results suggest that a better environmental footprint for maleic anhydride production in gas phase can be obtained if environmentally friendly furfural production technologies are used at the commercial scale.
Life cycle assessment applied to bio-based platform molecules: Critical review of methodological practices
(Elsevier, 2023) Blanco-Cejas, Jorge; Martín, Sandra; Linares, María; Iglesias, Jose; Moreno, Jovita
Bio-based platform molecules are chemicals identified as key agents in the development of circular bioeconomy. Their penetration into the current market would sustain the shift of a chemical industry mainly based on the use of petrochemical feedstock to the use of resources of biological origin. Bio-based platform chemicals have received much attention during the last decades, and thus, there is plenty of literature focused on their production throughout a plethora of different technologies. Nevertheless, most of these procedures lack of maturity and are subject to constraints. Thus, the way to ensure improved environmental sustainability is through the application of tools such as life cycle assessment (LCA). Although the integration of LCA is increasingly common during the design phase of these processes, the diverse modeling options can lead to very unlike results. Converging practices around consensus methodologies would lead to more reliable and comparable results. The purpose of this review is to identify the critical points of divergence that hinder this comparison and try to reconcile them towards the best options within biomass-derived platform chemicals specific context. The performed meta-analysis revealed the existence of three key aspects to be considered in the comparison of LCA studies: cradle-to-gate scope (mostly intermediate chemicals), prospective analysis (technologies under development), and multifunctional processes (biorefineries with several valuable outputs). Regarding the scope, reconciling the temporal scope of the studies with the correct allocation of biogenic carbon fluxes is the aspect that requires a deeper discussion. Evaluating novel technologies (characterized by industrial data scarcity) require careful scaling of the systems, as well as rigorous calculations of the uncertainty of results. Concerning multifunctionality, modelling many flows and their interactions is the most challenging task. Within this context, the consequential perspective seems a more correct approach to capture all the elements of these novel and complex systems, although the lack of data can make it unfeasible in numerous cases. Finally, a limited comparison is performed based on the key aspects previously identified. Thus, broader conclusions are inferred for the most promising routes to produce three bio-based platforms among the selected as a case study: lactic acid (chemo-catalytic transformation of swine manure), succinic acid (fermentative pathways using lignocellulosic biomass), and ethylene (wood gasification).
Production of Methyl Lactate with Sn-USY and Sn-β: Insights into Real Hemicellulose Valorization
(American Chemical Society, 2024-02-19) Jiménez-Martin, José M.; El Tawil-Lucas, Miriam; Montaña, Maia; Linares, María; Osatiashtiani, Amin; Vila, Francisco; Martín Alonso, David; Moreno, Jovita; García, Alicia; Iglesias, José
Potassium exchanged Sn-β and Sn-USY zeolites have been tested for the transformation of various aldoses (hexoses and pentoses), exhibiting outstanding catalytic activity and selectivity toward methyl lactate. Insights into the transformation pathways using reaction intermediates─dihydroxyacetone and glycolaldehyde─as substrates revealed a very high catalytic proficiency of both zeolites in aldol and retro-aldol reactions, showcasing their ability to convert small sugars into large sugars, and vice versa. This feature makes the studied Sn-zeolites outstanding catalysts for the transformation of a wide variety of sugars into a limited range of commercially valuable alkyl lactates and derivatives. [K]Sn-β proved to be superior to [K]Sn-USY in terms of shape selectivity, exerting tight control on the distribution of produced α-hydroxy methyl esters. This shape selectivity was evident in the transformation of several complex sugar mixtures emulating different hemicelluloses─sugar cane bagasse, Scots pine, and white birch─that, despite showing very different sugar compositions, were almost exclusively converted into methyl lactate and methyl vinyl glycolate in very similar proportions. Moreover, the conversion of a real hemicellulose hydrolysate obtained from Scots pine through a simple GVL-based organosolv process confirmed the high activity and selectivity of [K]Sn-β in the studied transformation, opening new pathways for the chemical valorization of this plentiful, but underutilized, sugar feedstock.
Production of Sorbitol via Catalytic Transfer Hydrogenation of Glucose
(MDPI, 2020-03-07) García, Beatriz; Moreno, Jovita; Morales, Gabriel; Melero, Juan Antonio; Iglesias, Jose
Sorbitol production from glucose was studied through catalytic transfer hydrogenation (CTH) over Raney nickel catalysts in alcohol media, used as solvents and hydrogen donors. It was found that alcohol sugars, sorbitol and mannitol, can be derived from two hydrogen transfer pathways, one produced involving the sacrificing alcohol as a hydrogen donor, and a second one involving glucose disproportionation. Comparison between short-chain alcohols evidenced that ethanol was able to reduce glucose in the presence of Raney nickel under neutral conditions. Side reactions include fructose and mannose production via glucose isomerization, which occur even in the absence of the catalyst. Blank reaction tests allowed evaluating the extension of the isomerization pathway. The influence of several operation parameters, like the temperature or the catalyst loading, as well as the use of metal promoters (Mo and Fe-Cr) over Raney nickel, was examined. This strategy opens new possibilities for the sustainable production of sugar alcohols.
Ru-ZrO2-SBA-15 as efficient and robust catalyst for the aqueous phase hydrogenation of glucose to sorbitol
(2020-02-05) Melero, Juan Antonio; Moreno, Jovita; Iglesias, Jose; Morales, Gabriel; Fierro, Jose Luis García; Sánchez Vázquez, Rebeca; Cubo, A.; García, Beatriz
The hydrogenation of aqueous solutions of glucose into sorbitol has been tackled in the presence of rutheniumfunctionalized catalysts using mesostructured pure-silica SBA-15 and ZrO2-coated SBA-15 materials as supports. The influence of the metal loading and the presence of ZrO2 in the supports on the catalytic activity of these materials have been evaluated. Metal loading is a major factor affecting the dispersion of the ruthenium active phase, but the presence of a zirconia layer onto the catalyst support revealed to be a key parameter to control not only the dispersion of Ru particles, but also their stability. Catalysts characterization and reaction tests to evaluate the catalytic performance of Ru-containing materials evidenced the beneficial influence of ZrO2-containing supports to prevent the agglomeration of Ru nanoparticles during hydrogenation tests, thus leading to more robust catalysts. This work proposes an approach to the preparation of active and stable catalysts for aqueous phase hydrogenation of biomass-derived carbohydrates.
Techno-economic comparison of optimized natural gas combined cycle power plants with CO2 capture
(Elsevier, 2022) Kazemi, Abolghasem; Moreno, Jovita; Iribarren, Diego
Natural gas combined cycle (NGCC) power plants account for a large share of the global energy market. Although many alternative layouts of NGCC plants have already been addressed in the scientific literature, there are still relevant gaps of knowledge in comparative techno-economic performances of the previously proposed alternatives. This article presents a comprehensive comparative study of 19 alternative NGCC power plants with pre-combustion, post-combustion or oxy-fuel combustion CO2 capture processes involving different choices of CO2 absorbents and organic Rankine cycles for energy savings. The purpose of this study is to shed light on comparative techno-economic performances of power plants with different CO2 capture strategies and various organic Rankine cycle configurations. First, performance of each alternative was optimized from a technical (equivalent work) standpoint. Then, the economic performance of each optimized alternative was evaluated. Based on the results within the sample of NGCC plants, using activated methyldiethanolamine could lead to better technical and economic performances than monoethanolamine in pre- and post-combustion capture systems. Moreover, the efficacy of organic Rankine cycles for enhancing the technical and economic performance of NGCC plants with CO2 capture was shown, with a reduction of up to 1.39 years in the payback period for various process configurations.
Transformation of Glucose into Sorbitol on Raney Nickel Catalysts in the Absence of Molecular Hydrogen: Sugar Disproportionation vs Catalytic Hydrogen Transfer
(2019-03-01) García, Beatriz; Moreno, Jovita; Iglesias, Jose; Melero, Juan Antonio; Morales, Gabriel
Raney nickel catalysts have been tested in the transformation of glucose into sorbitol through a hydrogen transfer pathway in the presence of short chain alcohols. Comparison between different sacrificing alcohols evidenced that catalytic hydrogen transfer (CHT) was only possible from ethanol under the tested neutral conditions. Catalytic tests showed that together with CHT route, sorbitol was also produced by means of sugar disproportionation, with the simultaneous production of gluconolactone, which takes place easily in the presence of the Raney Ni catalysts. Studies on the influence of the catalyst loading on the production of sorbitol revealed the existence of a catalyst activation step, attributed to the generation of metal-hydride species, the truly catalytic sites for hydrogenation. However, a catalyst deactivation phenomenon was detected as well. In this case, TGA and FTIR analysis allowed ascribing the adsorption of organic species, coming from the oxidation of glucose (such as gluconic acid), onto the catalyst surface, to the most plausible cause for the deactivation of the catalyst. Catalyst recycling tests evidenced the deactivation occurred mainly during the first use of the Raney Ni catalyst.