Prieto González, Gonzalo

Organizational Units

Organizational Unit

Instituto Universitario Mixto de Tecnología Química

ORCID

0000-0002-0956-3040

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https://www.upv.es/ficha-personal/gprieto

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Synthetic ferripyrophyllite: preparation, characterization and catalytic application
(The Royal Society of Chemistry, 2021-01-21) Qiao, Yunxiang; Theyssen, Nils; Spliethoff, Bernd; Folke, Jan; Weidenthaler, Claudia; Schmidt, Wolfgang; Prieto González, Gonzalo; Ochoa-Hernandez, Cristina; Bill, Eckhard; Ye, Shengfa; Ruland, Holger; Schueth, Ferdi; Leitner, Walter; Instituto Universitario Mixto de Tecnología Química; Deutsche Forschungsgemeinschaft
[EN] Sheet silicates, also known as phyllosilicates, contain parallel sheets of tetrahedral silicate built up by [Si2O5](2-) entities connected through intermediate metal-oxygen octahedral layers. The well-known minerals talc and pyrophyllite are belonging to this group based on magnesium and aluminium, respectively. Surprisingly, the ferric analogue rarely occurs in nature and is found in mixtures and conglomerates with other materials only. While partial incorporation of iron into pyrophyllites has been achieved, no synthetic protocol for purely iron-based pyrophyllite has been published yet. Here we report about the first artificial synthesis of ferripyrophyllite under exceptional mild conditions. A similar ultrathin two-dimensional (2D) nanosheet morphology is obtained as in talc or pyrophyllite but with iron(iii) as a central metal. The high surface material exhibits a remarkably high thermostability. It shows some catalytic activity in ammonia synthesis and can serve as catalyst support material for noble metal nanoparticles.
Metal organic framework nanosheets in polymer composite materials for gas separation
(Nature Publishing Group, 2015) Ródenas Torralba, Tania; Luz Mínguez, Ignacio; Prieto González, Gonzalo; Seoane, Beatriz; Miro, Hozanna; Corma Canós, Avelino; Kapteijn, Freek; Llabrés I Xamena, Francesc Xavier; Gascon, Jorge; Instituto Universitario Mixto de Tecnología Química; European Commission; Delft University of Technology; Alexander von Humboldt Foundation; Ministerio de Ciencia e Innovación; Ministerio de Economía y Competitividad; Consejo Superior de Investigaciones Científicas
[EN] Composites incorporating two-dimensional nanostructures within polymeric matrices have potential as functional components for several technologies, including gas separation. Prospectively, employing metal-organic frameworks (MOFs) as versatile nanofillers would notably broaden the scope of functionalities. However, synthesizing MOFs in the form of freestanding nanosheets has proved challenging. We present a bottom-up synthesis strategy for dispersible copper 1,4-benzenedicarboxylate MOF lamellae of micrometre lateral dimensions and nanometre thickness. Incorporating MOF nanosheets into polymer matrices endows the resultant composites with outstanding CO2 separation performance from CO2/CH4 gas mixtures, together with an unusual and highly desired increase in the separation selectivity with pressure. As revealed by tomographic focused ion beam scanning electron microscopy, the unique separation behaviour stems from a superior occupation of the membrane cross-section by the MOF nanosheets as compared with isotropic crystals, which improves the efficiency of molecular discrimination and eliminates unselective permeation pathways. This approach opens the door to ultrathin MOF-polymer composites for various applications.
Design of Cobalt Fischer-Tropsch Catalysts for the Combined Production of Liquid Fuels and Olefin Chemicals from Hydrogen-Rich Syngas
(American Chemical Society, 2021-04-05) Concepción Heydorn, Patricia; Jeske, K.; Kizilkaya, Ali Can; López Luque, Iván; Pfänder, Norbert; Bartsch, Mathias; Prieto González, Gonzalo; Instituto Universitario Mixto de Tecnología Química; European Commission; European Research Council; Ministerio de Economía y Competitividad; Bundesministerium für Bildung und Forschung, Alemania
[EN] Adjusting hydrocarbon product distributions in the Fischer¿Tropsch (FT) synthesis is of notable significance in the context of so-called X-to-liquids (XTL) technologies. While cobalt catalysts are selective to long-chain paraffin precursors for synthetic jet- and diesel-fuels, lighter (C10¿) alkane condensates are less valuable for fuel production. Alternatively, iron carbide-based catalysts are suitable for the coproduction of paraffinic waxes alongside liquid (and gaseous) olefin chemicals; however, their activity for the water¿gas-shift reaction (WGSR) is notoriously detrimental when hydrogen-rich syngas feeds, for example, derived from (unconventional) natural gas, are to be converted. Herein the roles of pore architecture and oxide promoters of Lewis basic character on CoRu/Al2O3 FT catalysts are systematically addressed, targeting the development of catalysts with unusually high selectivity to liquid olefins. Both alkali and lanthanide oxides lead to a decrease in turnover frequency. The latter, particularly PrOx, prove effective to boost the selectivity to liquid (C5¿10) olefins without undesired WGSR activity. In situ CO-FTIR spectroscopy suggests a dual promotion via both electronic modification of surface Co sites and the inhibition of Lewis acidity on the support, which has direct implications for double-bond isomerization reactivity and thus the regioisomery of liquid olefin products. Density functional theory calculations ascribe oxide promotion to an enhanced competitive adsorption of molecular CO versus hydrogen and olefins on oxide-decorated cobalt surfaces, dampening (secondary) olefin hydrogenation, and suggest an exacerbated metal surface carbophilicity to underlie the undesired induction of WGSR activity by strongly electron-donating alkali oxide promoters. Enhanced pore molecular transport within a multimodal meso-macroporous architecture in combination with PrOx as promoter, at an optimal surface loading of 1 Prat nm¿2, results in an unconventional product distribution, reconciling benefits intrinsic to Co- and Fe-based FT catalysts, respectively. A chain-growth probability of 0.75, and thus >70 C% selectivity to C5+ products, is achieved alongside lighter hydrocarbon (C5¿10) condensates that are significantly enriched in added-value chemicals (67 C%), predominantly ¿-olefins but also linear alcohols, remarkably with essentially no CO2 side-production (<1%). Such unusual product distributions, integrating precursors for synthetic fuels and liquid platform chemicals, might be desired to diversify the scope and improve the economics of small-scale gas- and biomass-to-liquid processes.
Prospects of Heterogeneous Hydroformylation with Supported Single Atom Catalysts
(American Chemical Society, 2020-03-18) Amsler, Jonas; Sarma, Bidyut B.; Agostini, G.; Prieto González, Gonzalo; Plessow, P.; Studt, F.; Instituto Universitario Mixto de Tecnología Química; Max Planck Society; Deutsche Forschungsgemeinschaft; Alexander von Humboldt Foundation; Baden-Württemberg Landesregierung; Helmholtz Association of German Research Centers; Agencia Estatal de Investigación; Ministerio de Economía y Competitividad
[EN] The potential of oxide-supported rhodium single atom catalysts (SACs) for heterogeneous hydroformylation was investigated both theoretically and experimentally. Using high-level domain-based local-pair natural orbital coupled cluster singles doubles with perturbative triples contribution (DLPNO-CCSD(T)) calculations, both stability and catalytic activity were investigated for Rh single atoms on different oxide surfaces. Atomically dispersed, supported Rh catalysts were synthesized on MgO and CeO2. While the CeO2-supported rhodium catalyst is found to be highly active, this is not the case for MgO, most likely due to increased confinement, as determined by extended X-ray absorption fine structure spectroscopy (EXAFS), that diminishes the reactivity of Rh complexes on MgO. This agrees well with our computational investigation, where we find that rhodium carbonyl hydride complexes on flat oxide surfaces such as CeO2(111) have catalytic activities comparable to those of molecular complexes. For a step edge on a MgO(301) surface, however, calculations show a significantly reduced catalytic activity. At the same time, calculations predict that stronger adsorption at the higher coordinated adsorption site leads to a more stable catalyst. Keeping the balance between stability and activity appears to be the main challenge for oxide supported Rh hydroformylation catalysts. In addition to the chemical bonding between rhodium complex and support, the confinement experienced by the active site plays an important role for the catalytic activity.
Synthesis of acetonitrile from NH3/syngas mixtures on molybdenum nitride: Insights into the reaction mechanism
(Elsevier, 2024-12-01) Kizilkaya, Ali Can; Martínez Monje, María Elena; Prieto González, Gonzalo; Instituto Universitario Mixto de Tecnología Química; European Commission; Generalitat Valenciana; Agencia Estatal de Investigación; European Regional Development Fund
[EN] Owing to their metallic-like surface electronic properties and their capacity to act as reservoirs and solid transfer agents for active nitrogen, transition metal nitrides are interesting as solid catalysts for C-C and C-N coupling reactions for the bottom-up production of higher (C2+) nitrogenated chemicals from unconventional carbon resources. The catalytically active state and reaction mechanism for the direct synthesis of acetonitrile from syngas/ammonia mixtures are studied on an unsupported Mo catalyst from complementary experimental and computational approaches. Temperature resolved X-ray diffraction and X-ray photoemission spectroscopy verify that an oxidic MoO(3 )catalyst precursor undergoes in situ (near-surface) nitridation, upon exposure to reaction conditions at 723 K, rendering Mo2N the actual working catalyst. Density Functional Theory mechanistic investigations on a gamma- Mo 2 N(100) model surface point to a hydrogen-assisted CO dissociation on the nitride surface. Moreover, surface oxygen, evolved from CO dissociation, is predicted to play a central role as hydrogen acceptor, to enable the dehydrogenative NH3 dissociation. Direct condensation of CH and N adspecies proceeds with a low energy barrier of 33 kJ mol(-1), which makes C-N coupling preferred over full hydrogenation of CHx species, in agreement with the experimental modest selectivity to methane (ca. 10 %). Both experimental and computational results indicate that HCN is a major intermediate product along the reaction pathway to acetonitrile. No energetically feasible associative reaction pathways could be identified for C-C coupling from HCN. The dissociation of the latter intermediate product is predicted to precede the reaction of CN adspecies to CHx. Similarly to NH3 dissociation, dehydrogenative HCN activation on the Mo2N 2 N surface is predicted to be facilitated through hydrogen abstraction by surface oxygen species, yet subjected to a comparatively higher energy barrier (>120 kJ mol(-1)), therefore likely to control the overall kinetics. These findings suggest that the enhancement of HCN dissociation is a central design objective towards Mo2N-based 2 N-based catalysts with advanced performance.
Metal-Specific Reactivity in Single-Atom Catalysts: CO Oxidation on 4d and 5d Transition Metals Atomically Dispersed on MgO
(American Chemical Society, 2020-09-02) Sarma, Bidyut B.; Plessow, Philipp N.; Agostini, Giovanni; Concepción Heydorn, Patricia; Pfänder, Norbert; Kang, Liqun; Wang, Feng R.; Studt, Felix; Prieto González, Gonzalo; Instituto Universitario Mixto de Tecnología Química; Max Planck Society; Alexander von Humboldt Foundation; Baden-Württemberg Landesregierung; Fonds der Chemischen Industrie, Alemania; Helmholtz Association of German Research Centers; Agencia Estatal de Investigación; Ministerio de Economía y Competitividad
[EN] Understanding and tuning the catalytic properties of metals atomically dispersed on oxides are major stepping-stones toward a rational development of single-atom catalysts (SACs). Beyond individual showcase studies, the design and synthesis of structurally regular series of SACs opens the door to systematic experimental investigations of performance as a function of metal identity. Herein, a series of single-atom catalysts based on various 4d (Ru, Rh, Pd) and Sd (Ir, Pt) transition metals has been synthesized on a common MgO carrier. Complementary experimental (X-ray absorption spectroscopy) and theoretical (Density Functional Theory) studies reveal that, regardless of the metal identity, metal cations occupy preferably octahedral coordination MgO lattice positions under step-edges, hence highly confined by the oxide support. Upon exposure to O-2-lean CO oxidation conditions, FTIR spectroscopy indicates the partial deconfinement of the monatomic metal centers driven by CO at precatalysis temperatures, followed by the development of surface carbonate species under steady-state conditions. These findings are supported by DFT calculations, which show the driving force and final structure for the surface metal protrusion to be metal-dependent, but point to an equivalent octahedral-coordinated M4+ carbonate species as the resting state in all cases. Experimentally, apparent reaction activation energies in the range of 96 +/- 19 kJ/mol are determined, with Pt leading to the lowest energy barrier. The results indicate that, for monatomic sites in SACs, differences in CO oxidation reactivity enforceable via metal selection are of lower magnitude than those evidenced previously through the mechanistic involvement of adjacent redox centers on the oxide carrier, suggesting that tuning of the oxide surface chemistry is as relevant as the selection of the supported metal.
Multifunctional materials for catalyst-specific heating and thermometry in tandem catalysis
(The Royal Society of Chemistry, 2023-09-26) Garcia-Farpon, Marcos; Peláez-Fernández, Raquel; Recio Ballesteros, Veronica; Atakan, Burak; Zaldo, Carlos; Prieto González, Gonzalo; Instituto Universitario Mixto de Tecnología Química; European Commission; European Research Council; Agencia Estatal de Investigación; Universitat Politècnica de València; Ministerio de Ciencia, Innovación y Universidades; Conselleria de Innovación, Universidades, Ciencia y Sociedad Digital, Generalitat Valenciana
[EN] A multifunctional material design, integrating catalytic as well as auxiliary magnetic susception and contactless thermal sensing functionalities, unlocks catalyst-specific heating and thermometry for spatially proximate solid catalysts in a single reactor. The new concept alleviates temperature incompatibilities in tandem catalysis, as showcased for the direct production of propene from ethene, via sequential olefin dimerization and metathesis reactions.
FIB-SEM tomography in catalysis and electrochemistry
(Elsevier, 2022-12-01) Ródenas Torralba, Tania; Prieto González, Gonzalo; Instituto Universitario Mixto de Tecnología Química; European Research Council; Universitat Politècnica de València
[EN] Tomographic imaging methods have been incorporated, mostly from other scientific disciplines, into catalysis research. They are invaluable tools for the structural diagnostics of solid catalyst and electrode materials, which uniquely provide information on notions of spatial character which remain out of reach for conventional singleprojection, i.e. 2D, microscopy methods. Focused-Ion-Beam Scanning-Electron-Microscopy (FIB-SEM) tomography is a destructive, slicing-type tomographic method which offers spatial resolutions down to few nm for inspection volumes up to several tens of mu m across. As such, it has attracted a significant deal of attention as a means to study mesoscale features and macropore networks in catalytic materials. In this review, we first provide a succinct account on the recent technical developments in dual-beam technologies and discuss their implications for tomographic imaging experiments. Next, an exemplary experimental workflow for FIB-SEM experiments is discussed, with emphasis on technical aspects which concern specifically work with highly porous, electrically insulating catalyst materials. Contributions of FIB-SEM tomography to the quantification of mass transportrelevant topological parameters in porous catalysts, and multiple-phase boundaries of significance for concomitant mass and charge transport phenomena in electrode materials are surveyed. The application of FIBSEM tomography for the analysis and rational development of materials in catalysis and electrochemistry has seen a fast surge over the last decade. It promises to continue consolidating as an important diagnostic tool for meso- and nano-spatial structural features, e.g. in multi-functional composite catalyst materials, wherein the relative spatial location of different sub-materials/functionalities are determinant for performance.
New insights into the role of the electronic properties of oxide promoters in Rh-catalyzed selective synthesis of oxygenates from synthesis gas
(Elsevier, 2011-06-13) Prieto González, Gonzalo; Concepción Heydorn, Patricia; Martinez Feliu, Agustin; Mendoza, Ernest; Instituto Universitario Mixto de Tecnología Química
[EN] A series of 2.5% Rh/M@Al2O3 model catalysts were prepared by supporting Rh on high-area gamma-Al2O3, resulting in a surface covered by a monolayer (4.5-7 atoms/nm(2)) of MO promoter oxides (M = Fe, V. Nb, Ta, Ti, Y, Pr, Nd, Sm). The catalysts were extensively characterized and evaluated for the conversion of synthesis gas to oxygenates at 553 K, 5.0 MPa, H-2/CO = 1, and space velocity adjusted to attain CO conversion around 15%. The broad range of products formed depending on the specific promoter were, for the first time, quantitatively described using the selectivity parameter (Phi) defined here, which indicates, for a given reaction product, the contribution of carbon atoms derived from dissociative (C-dis) and nondissociative (C-ins) activation of CO. Both the catalytic activity and, more interestingly, the selectivity pattern given by the Phi parameter were correlated with the electronic properties of the MOx promoters (i.e., electron-donating/electron-withdrawing capacity) for an extensive series of catalysts. Low-temperature and at-work CO-FTIR experiments suggested that the high activity and hydrocarbon selectivity displayed by catalysts promoted by more electron-withdrawing (acidic) oxide promoters (e.g., TaOx) were related to a higher proportion of bridged Rh-2(CO)(B) adsorption sites and to a higher electron density (i.e., a higher electron back-donation ability) of the Rh-0 surface sites, both factors promoting CO dissociation events. In contrast, linear CO adsorption on Rh-0 sites displaying decreased electron back-donation in catalysts promoted by electron-donating (basic) oxides (e.g., PrOx, SmOx) was likely related to nondissociative CO activation and thus to the selective formation of oxygenates. TEM. XPS, and CO-FTIR results pointed to differences in morphology, rather than size or partial electronic charge, of the nano-sized Rh-0 crystallites as the likely cause for the different proportions of CO adsorption sites. The Rh NP morphology, both as-reduced and at-work, is a function of the electronic properties of the underlying promoter oxide. (C) 2011 Elsevier Inc. All rights reserved.
Solid Single-Atom Catalysts in Tandem Catalysis: Lookout, Opportunities and Challenges
(John Wiley & Sons, 2022-12-07) Ródenas Torralba, Tania; Prieto González, Gonzalo; Instituto Universitario Mixto de Tecnología Química; European Research Council
[EN] Tandem catalysis stands out as a major instrument towards the intensification of existing and future chemical processes. Initially formulated in the field of homogeneous catalysis, the concept relies on the single-pot integration of two (or more) catalysts showing high specificity for mechanistically decoupled reactions, while being operational and compatible under a single set of operation conditions. Isolated metal atoms stabilized on solid carriers in single-atom catalysts (SACs) hold the potential to reconcile the high reaction specificities of mononuclear sites in molecular catalysts with an intrinsic catalyst compartmentalization on inorganic matrices. Understandably, SACs have started to be considered as platforms in tandem catalysis. Tandem (electro)catalytic processes based on SACs have been showcased recently. While this sets excellent prospects for the expansion of this research subarea, challenges are faced, particularly as to the verification of the tandem nature of the processes.