Methane Production from Microalgae via Continuous Catalytic Supercritical Water Gasification: Development of Catalysts and Sulfur Removal Techniques

This doctoral thesis aims at demonstrating the technical feasibility of methane production from microalgae via continuous catalytic supercritical water gasification (CSCWG). This work focuses on three different research approaches: (i) assessment and improvement of the catalytic performance of Ru/C catalysts, (ii) optimization of the salt separation, and (iii) continuous removal of sulfur. With all the acquired knowledge, a new process demonstration unit so called KONTI-C with a pumping capacity of 1-2 kg h-1 was built in the frame of the SunCHem project. The catalytic performance of Ru/C catalysts was assessed with isopropanol (IPA) at 450 °C and 30 MPa in a fixed-bed plug flow reactor. Ru/C was able to convert efficiently IPA to a CH4-rich gas (65 vol %) over a period of 96 h at a relatively low weight hourly space velocity (WHSVgRu). By working at a higher WHSVgRu, a deactivation of the catalyst was observed. The decomposition of IPA over the carbon surface to coke that has progressively covered the Ru nanoparticles, was responsible for the loss of the catalytic activity. The Ru loading was found to be a crucial parameter for the improvement of the coking resistance. As a result, the stability of our standard catalyst was enhanced by increasing the Ru loading from 2 wt % to 5 wt %. When assessing the effect of some synthesis factors it was found that a higher Ru dispersion, the use of acetone during the catalyst impregnation, and the choice of a chloride free salt precursor (Ru(NO)(NO3)3) were needed for the improvement of the catalytic activity. Whereas the presence of carboxylic groups on the carbon support during the catalyst preparation did not improve the performance. The catalyst prepared with Ru(NO)(NO3)3 exhibited a better catalytic activity and stability than our standard commercial catalyst. By comparing the performance of a Ru/C catalyst with other Ru catalysts supported on metal oxides (Ru/TiO2, Ru/ZrO2, and Ru/Al2O3), Ru/C was found to be the most stable and active catalyst. Hence, Ru/C is the most suitable catalyst for CSCWG. The design of the salt separator was improved by modifying the configuration of the feed entrance (feeding from the bottom of the salt separator). As a result, the salts and the inorganic sulfur (SO42-) were efficiently removed from the reactor effluent when processed with a model salt solution (Na2SO4/K2SO4 in 10 wt % IPA). A commercial ZnO adsorbent showed a high mechanical stability in supercritical water (SCW) (400 °C, 30 MPa). The adsorbent was able to adsorb sulfur (S2-) when processed with a model sulfur solution (Na2S¿9H2O) at 400 °C and 30 MPa. Characterization of the spent ZnO adsorbent confirmed that sulfur was adsorbed on ZnO to form ZnS. The improved commercial catalyst (5% Ru/CBASF), the new design of the salt separator, and the commercial ZnO adsorbent were implemented in the development of KONTI-C. As a result, microalgae (Chlorella vulgaris) were successfully gasified (400 °C, 28 MPa) to a CH4-rich gas (55-60 vol %) over a period of 55 h during the gasification campaign performed in Wädenswil (CH). The low total organic carbon in the reactor effluent recorded over that period showed the good catalytic performance of the 5% Ru/CBASF. A brine effluent rich in nutrients (N, K, S, P, and Na) was obtained with the salt separator. The promising results obtained during the gasification campaign allowed to demonstrate the technical feasibility of continuous CSCWG of microalgae

Why surface hydrophobicity promotes CO2 electroreduction: a case study of hydrophobic polymer N-heterocyclic carbenes

We report the use of polymer N-heterocyclic carbenes (NHCs) to control the microenvironment surrounding metal nanocatalysts, thereby enhancing their catalytic performance in CO2 electroreduction. Three polymer NHC ligands were designed with different hydrophobicity: hydrophilic poly(ethylene oxide) (PEO–NHC), hydrophobic polystyrene (PS–NHC), and amphiphilic block copolymer (BCP) (PEO-b-PS–NHC). All three polymer NHCs exhibited enhanced reactivity of gold nanoparticles (AuNPs) during CO2 electroreduction by suppressing proton reduction. Notably, the incorporation of hydrophobic PS segments in both PS–NHC and PEO-b-PS–NHC led to a twofold increase in the partial current density for CO formation, as compared to the hydrophilic PEO–NHC. While polymer ligands did not hinder ion diffusion, their hydrophobicity altered the localized hydrogen bonding structures of water. This was confirmed experimentally and theoretically through attenuated total reflectance surface-enhanced infrared absorption spectroscopy and molecular dynamics simulation, demonstrating improved CO2 diffusion and subsequent reduction in the presence of hydrophobic polymers. Furthermore, NHCs exhibited reasonable stability under reductive conditions, preserving the structural integrity of AuNPs, unlike thiol-ended polymers. The combination of NHC binding motifs with hydrophobic polymers provides valuable insights into controlling the microenvironment of metal nanocatalysts, offering a bioinspired strategy for the design of artificial metalloenzymes

Electrical behaviour, characteristics and properties of anodic aluminium oxide films coloured by nickel electrodeposition

Porous anodic films on 1050 aluminium substrate were coloured by AC electrodeposition of nickel. Several experiments were performed at different deposition voltages and nickel concentrations in the electrolyte in order to correlate the applied electrical power to the electrical behaviour, as well as the characteristics and properties of the coatings. The content of nickel inside the coatings reached 1.67 g/m2, depending on the experimental conditions. According to the applied AC voltage in comparison with the threshold voltage Ut, the coating either acted only as a capacitor when U\Ut and, when U[Ut, the behaviour during the anodic and cathodic parts of the power sine wave was different. In particular, due to the semi-conducting characteristics of the barrier layer, additional oxidation of the aluminium substrate occurred during the anodic part of the electrical signal, whilst metal deposition (and solvent reduction) occurred during the cathodic part; these mechanisms correspond to the blocked and pass directions of the barrier layer/electrolyte junction, respectively

Modulation of a protein free-energy landscape by circular permutation

Circular permutations usually retain the native structure and function of a protein while inevitably perturb its folding dynamics. By using simulations with a structure-based model and a rigorous methodology to determine free-energy surfaces from trajectories we evaluate the effect of a circular permutation on the free-energy landscape of the protein T4 lysozyme. We observe changes which, while subtle, largely affect the cooperativity between the two subdomains. Such a change in cooperativity has been previously experimentally observed and recently also characterized using single molecule optical tweezers and the Crooks relation. The free-energy landscapes show that both the wild type and circular permutant have an on-pathway intermediate, previously experimentally characterized, where one of the subdomains is completely formed. The landscapes, however, differ in the position of the rate-limiting step for folding, which occurs before the intermediate in the wild-type and after in the circular permutant. This shift of transition state explains the observed change in the cooperativity. The underlying free-energy landscape thus provides a microscopic description of the folding dynamics and the connection between circular permutation and the loss of cooperativity experimentally observed

Muscle inactivation of mTOR causes metabolic and dystrophin defects leading to severe myopathy

mTor, acting mainly via mTORC1, controls dystrophin transcription in a raptor- and rictor-independent mechanism

Adaptation au changement climatique dans la gestion des ressources en eau des Pyrénées. Mémoires scientifiques du projet PIRAGUA, vol. 2.

[EN] One PDF files with the pre-print version of the document; [ES] Un archivo PDF con la versión de pie-impresión del documento; [FR] Un fichier PDF avec la version pré-imprimée du document.[EN] Recent climate change is one of the main threats to the sustainability of human societies. The reports of the IPCC, the Paris Agreement or the United Nations Conferences on climate change attest to the global political interest in urgently taking action to mitigate climate change. Mitigation efforts, however, are not enough to minimize the negative consequences of climate change. It is necessary, in parallel to the mitigation measures, to develop adaptation strategies that make it possible to minimize the risks that climate change poses to societies. With a necessarily local focus, the development of adaptation strategies must be based on an assessment of the vulnerability of society as a whole or of sectors of it to the expected consequences of climate change. This volume explores options for adaptation to climate change in relation to the management of water resources in an important transboundary region such as the Pyrenees mountain range. After a general assessment of the region's water resources and their governance, seven local and regional case studies are presented where, in collaboration with the relevant stakeholders, different adaptation options are explored.[ES] El cambio climático reciente es una de las principales amenazas para la sostenibilidad de las sociedades humanas. Los informes del IPCC, el Acuerdo de París o las Conferencias de las Naciones Unidas sobre cambio climático atestiguan el interés político global por emprender con urgencia acciones para la mitigación del cambio climático. Los esfuerzos en mitigación, sin embargo, no son suficientes para minimizar las consecuencias negativas del cambio climático. Es necesario, en paralelo a las medidas de mitigación, desarrollar estrategias de adaptación que permitan minimizar los riesgos que supone el cambio climático para las sociedades. Con un enfoque necesariamente local, el desarrollo de estrategias de adaptación debe partir de una evaluación de la vulnerabilidad del conjunto de la sociedad o de sectores de ésta a las consecuencias esperables del cambio climático. En este volumen se exploran opciones de adaptación al cambio climático en relación con la gestión de los recursos hídricos de una importante región transfronteriza como es la cordillera de los Pirineos. Tras una evaluación general sobre los recursos hídricos de la región y su gobernanza, se presentan siete casos de estudio locales y regionales donde, en colaboración con los actores locales, se exploran diferentes opciones de adaptación.[FR] Le changement climatique récent est l'une des principales menaces à la durabilité des sociétés humaines. Les rapports du GIEC, l'Accord de Paris ou les Conférences des Nations Unies sur le changement climatique attestent de l'intérêt politique mondial à agir de toute urgence pour atténuer le changement climatique. Cependant, les efforts d'atténuation ne suffisent pas à minimiser les conséquences négatives du changement climatique. Il est nécessaire, parallèlement aux mesures d'atténuation, de développer des stratégies d'adaptation qui permettent de minimiser les risques que le changement climatique fait peser sur les sociétés. Dans une optique nécessairement locale, l'élaboration de stratégies d'adaptation doit reposer sur une évaluation de la vulnérabilité de la société dans son ensemble ou de secteurs de celle-ci aux conséquences attendues du changement climatique. Ce volume explore les options d'adaptation au changement climatique en relation avec la gestion des ressources en eau dans une région transfrontalière importante telle que la chaîne de montagnes des Pyrénées. Après une évaluation générale des ressources en eau de la région et de leur gouvernance, sept études de cas locales et régionales sont présentées où, en collaboration avec les acteurs locaux, différentes options d'adaptation sont explorées.This book has been supported by the European Regional Development Fund (ERDF) through the Interreg V-A Spain France Andorra program (POCTEFA 2014-2020), by Fundación Biodiversidad of the Spanish Ministry for the Ecologic Transition and Demographic Challenge, and the autor's institutions: CSIC, UPV/EHU, UB, OE, IGME, CNRS, BRGM, INRAE and OBSA.Peer reviewe

Adaptación al cambio climático en la gestión de los recursos hídricos de los Pirineos [Informe]. Memorias científicas del proyecto PIRAGUA, vol. 2.

[EN] One PDF files with the pre-print version of the document; [ES] Un archivo PDF con la versión de pie-impresión del documento; [FR] Un fichier PDF avec la version pré-imprimée du document.[EN] To do[ES] Pendiente[FR] Pour faireThis report was developed within the project EFA210/16 PIRAGUA (“Evaluación y prospectiva de los recursos hídricos de los Pirineos en un contexto de cambio climático, y medidas de adaptación con impacto en el territorio / Evaluation et prospective des ressources en eau des Pyrénées dans un contexte de changement climatique, et mesures d’adaptation avec un impact sur le territoire”), co-funded by the European Regional Development Fund (ERDF) through the Interreg V-A Spain France Andorra program (POCTEFA 2014-2020) (65%) and the project’s partners: CSIC, UPV/EHU, UB, OE, IGME, CNRS, BRGM, INRAE and OBSA (35%).N

Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.

Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

Peer reviewe

An embedding technique to determine ττ backgrounds in proton-proton collision data

An embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Peer reviewe