Examinando por Autor "Tapiador, Jesús"

Mostrando 1 - 6 de 6

A novel Zn-based-MOF for efficient CO2 adsorption and conversion under mild conditions
(Elsevier, 2021) Tapiador, Jesús; Leo, Pedro; Rodríguez-Diéguez, Antonio; Choquesillo-Lazarte, Duane; Calleja, Guillermo; Orcajo, Gisela
A novel Zn-based-MOF material, called Zn-URJC-8, containing two different organic linkers, 2-aminoterephtallic acid and 4,4-bipyridyl, has been synthetized and used for catalytic purposes for the first time. The structure of Zn-URJC-8 has been determined by single-crystal X-ray diffraction (XRD) showing -NH2 groups inward-facing of narrow pores, providing the material with excellent properties as CO2 adsorbent. The good results obtained by means of carbon dioxide adsorption isotherms have demonstrated the high interaction between CO2 and -NH2 groups with a Qst value of 54 kJ/mol at low coverage. The Zn-URJC-8 material also display promising results as catalyst for CO2 transformation in added value products. Almost complete conversion of epichlorohydrin and CO2 in cycloaddition reaction has been achieved under mild conditions, and the influence of different radical groups coordinated to the epoxides has been evaluated on the reaction yield. The recyclability has been also tested and the structural integrity of the catalyst is maintained after several consecutive reaction cycles.
Catalytical advantages of Hf-MOFs in benzaldehyde acetalization
(Elsevier, 2024-05-15) García-Rojas, Elena; Tapiador, Jesús; Leo, Pedro; Palomino, Carlos; Martos, Carmen; Orcajo, Gisela
The potential use of acetals as bioadditives based on sustainable feedstocks in the automotive industry is of great interest. If such feedstock is a residual stream, the process would represent a dual environmental challenge, such as the valorization of glycerol obtained as a by-product of biodiesel to produce acetals. There are just scarce works about this synthetic route due to the challenge in finding efficient catalytic converters for glycerol valorization in a single process. Herein four different Metal-Organic Frameworks (MOFs) are evaluated as heterogeneous catalysts for the acetalization reaction of benzaldehyde with methanol, specifically, two structures, MOF-808 and UiO-66, containing two structural metal ions, zirconium and hafnium. The aim of this work is to investigate the influence of the MOF structure, the metallic active sites and the reaction conditions on the catalytic performance of this acetal production-type reaction. Furthermore, the recyclability of the catalyst is evaluated, and a potential reaction mechanism is suggested. As relevant results, Hf-MOFs showed higher benzaldehyde conversion than Zr-based ones, and significant improvements in reaction conditions were achieved, such as a significant reduction in catalyst loading of 99.6 % using UiO-66-Hf, and an optimization of reagent ratios reducing methanol consumption by 50 % for a 92 % of benzaldehyde conversion. The Brønsted character of UiO-66-Hf seems to enhance the reaction rate more than the metal center accessibility and larger pore volumes offered by MOF-808
Copper MOFs performance in the cycloaddition reaction of CO2 and epoxides
(Elsevier, 2023) Tapiador, Jesús; García-Rojas, Elena; Leo, Pedro; Martos, Carmen; Calleja, Guillermo; Orcajo, Gisela
The research in advanced materials for effective CO2 capture and conversion is an imperative duty for the next years. In this sense MOF materials are being intensively tested for this purpose. Herein, seven different copperbased MOF materials with different functional organic groups in their linkers have been assessed to comprehend some structural features that influence the CO2 transformation via cycloaddition reaction with epoxides: CuURJC-1 (tetrazole group), Cu-URJC-8 (primary amine group), Cu-MOF-74 (hydroxyl group), JUC-62 (azo group), PCN-16 (triple bond group), HNUST-1 (amide group) and HKUST-1. When epichlorohydrin was used as a substrate, Cu-URJC-8 produced the best epoxide conversion (90%) and selectivity to cyclic carbonate (>99%), despite showing a modest surface area. This result can be explained by the higher basicity of primary amines than other basic functional organic groups of the MOFs. However, when styrene oxide was used as substrate, CuURJC-1 led to the best reaction results with a conversion and selectivity toward cyclic carbonate of 60 and 86%, respectively. This result was achieved because this material presents the synergic effect of having in its flexible structure 12 Å channels, that favors the styrene oxide diffusion, and a great number of basic nitrogen atoms, which can increase the reactivity of carbon dioxide. In summary, the presence of nitrogen atoms in the organic linker increases the CO2 conversion by promoting the reactivity of this molecule.
Open Zn-URJC-13 efficient catalyst for mild CO2 transformation using bulky epoxides
(Elsevier, 2023) Tapiador, Jesús; Leo, Pedro; Calleja, Guillermo; Orcajo, Gisela
In CO2 cycloaddition reactions with epoxides that have bulky or long-chain substituents, the yield significantly decreases when using heterogeneous catalysts, including MOFs, with micropores smaller than 14 Å. In this study, a new MOF material called Zn-URJC-13 is reported. This MOF combines different features such as that it contains acid and basic Lewis sites based on Zn and -NH2 groups, exhibits permanent porosity with a bimodal porous system centered at 11 and 17 Å suitable for the diffusion of cycloaddition reaction species, and it is chemically stable in various common organic solvents. The aim of this material is to improve the textural properties of other MOFs with similar chemical compositions, making it suitable as a catalyst for CO2 cycloaddition reactions with epoxides even bulky. This novel material exhibits high affinity to CO2 molecules, with a Qst of 62 kJ/mol. The Zn-URJC-13 catalyst demonstrates efficient performance in CO2 cycloaddition reactions using a wide range of epoxides, including those with long-chain and bulky substituents such as allyl glycidyl ether and styrene oxide. It can achieve an epoxide conversion as high as 84 % and selectivity to carbonate products above 90 % for the bulkiest styrene oxide. When compared to other Zn-based MOF materials with similar or different structures but without amino groups, the new material exhibits superior catalytic performance. Furthermore, Zn-URJC-13 can be reused in five consecutive reaction cycles while maintaining its efficient catalytic behavior and crystalline structure. These findings highlight the notable potential of Zn-URJC-13 for CO2 cycloaddition transformation routes.
Reversible acidochromism and thermo-responsive luminescence properties of a novel Zn(II)/Eu(III) coordination polymer
(Elsevier, 2020-05-30) Cuerva, Cristián; Tapiador, Jesús; Sánchez-Peláez, Ana Edilia; Torralba, María del Carmen; Gutiérrez, Ángel
Robust Cu-URJC-8 with mixed ligands for mild CO2 cycloaddition reaction
(Elsevier, 2022) Tapiador, Jesús; Leo, Pedro; Gándara, Felipe; Calleja, Guillermo; Orcajo, Gisela
The synthesis of the new MOF Cu-URJC-8, containing two different organic ligands, 2-aminoterephtalic acid and 4,4-bipyridyl, is reported in this work. Cu-URJC-8 shows a pillared-layer structure consisting of [Cu2(-CO2)4(- N)2] paddlewheel secondary building units, with the 4,4’-bypiridyl linkers acting as pillars in the two-fold interpenetrated networks, which provides a robust structure to the material. Cu-URJC-8 presents Lewis acid and basic sites, constituted by Cu2+ and -NH2 groups, respectively, and it is chemically stable in different commonly used organic solvents. This new material shows a CO2 uptake of 1.59 and 1.07 mmol/g at 25 and 45 ◦C, respectively, and a Qst value of 27 kJ/mol, higher than those observed for other reported MOFs with higher textural properties, possibly due to the presence of amino groups in the MOF structure. Its catalytic activity in the cycloaddition reaction of epichlorohydrin and CO2 was evaluated under various conditions and the best performance (90 conversion and 99% selectivity) was achieved when using 1% mol of catalyst, 4% mol of co-catalyst, 12 bar of carbon dioxide pressure, and room temperature. When different epoxides with bulkier radical groups are used as substrates, the epoxide conversion decreases, evidencing steric hindrances for diffusion inside cavities of Cu-URJC-8. Finally, Cu-URJC-8 has a high stability, keeping its structural integrity and catalytic activity after successive CO2 cycloaddition reaction cycles. These results show that Cu-URJC-8 is a promising catalyst for CO2 revalorization.