Persona: Conesa Alonso, José María
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Conesa Alonso
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José María
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Publicación Selective hydrogenation reactions of 5-hydroxymethylfurfural over Cu and Ni catalysts in water: Effect of Cu and Ni combination and the reagent purity(ELSEVIER, 2023) Morales, María V.; Galvin, Antonio J.; Rodríguez Ramos, Inmaculada; Guerrero Ruiz, Antonio R; Conesa Alonso, José María; https://orcid.org/0000-0003-2834-0296; https://orcid.org/0000-0003-1848-5985; https://orcid.org/0000-0003-4622-6008This work studies the catalytic properties of Cu and Ni catalysts, as well as the effect of Cu and Ni combination on the activity and selectivity during the aqueous phase hydrogenation of 5-hydroxymethylfurfural (HMF) in a batch reactor, at 60 °C under 30 bar H2. Catalysts with different Ni/Cu ratios (10 wt%) were synthesized over a high surface area graphite (HSAG). While Ni provides the bimetallic catalyst the capacity for hydrogenation of Cdouble bondO and Cdouble bondC groups, Cu contributes to suppress the hydrogenation of the furan ring, reaching a 99% of selectivity to the partial hydrogenated product, 2,5-di-hydroxymethylfuran (DHMF), over 5Cu5Ni/HSAG. The increase of reaction temperature (180 °C) conduced to the hydrolytic ring-opening and rearrangement of HMF. Under such reaction conditions, monometallic Ni afforded the highest yield towards the hydrogenative rearrangement product, 3-hydroxymethylcyclopentanone (81%). However, Cu and CuNi bimetallic catalysts were less reactive to the ring-rearrangement reaction and showed higher tendency to deactivation, especially when the HMF supplier contain sulfur impurities.Publicación Graphite supported heteropolyacid as a regenerable catalyst in the dehydration of 1-butanol to butenes(ELSEVIER, 2023) Morales, María V.; García-Bosch, N.; Rodríguez Ramos, Inmaculada; Guerrero Ruiz, Antonio R; Conesa Alonso, José María; https://orcid.org/0000-0003-2834-0296; https://orcid.org/0000-0003-1848-59851-butanol dehydration reaction has recently emerged as a sustainable route to produce butenes which can be further oligomerized to be applied as jet fuel. However, the high catalyst deactivation rates observed during this reaction due to coke deposition is still a pending matter. As promising catalysts for this reaction, we have supported two heteropolyacids (HPA), i.e. H4SiW12O40 (STA) and H3PW12O40 (TPA), on two commercial carbon materials: an activated carbon (AC) and a high surface area graphite (HSAG). Aiming to evaluate the role of HPA-support interactions, the STA was also dispersed over metallic oxides of different acidic nature, namely SiO2, Al2O3 and ZrO2. An exhaustive physicochemical characterization revealed that after the HPA dispersion thorough the support, the Keggin structure was maintained and an increase in the amount and strength of acid sites was provoked, but in different degree according to the HPA type and support’s nature. While the TPA-based catalysts developed less quantity of total acid sites, but higher strength than their STA-carbon counterparts, the STA/AC and TPA/AC samples exhibited a slight major amount of acid sites than STA/HSAG and TPA/HSAG. The HPA-support interactions have ultimately modulated to some extent the activity, selectivity, stability and regeneration ability of the synthesized catalysts, when applied in the gas phase butanol dehydration reaction at 275 °C. The higher STA decomposition temperature prompted by the graphitic support, among other factors, allowed the total regeneration of the highly active (39 mmolBuOH∙min−1∙ga.p) and n-butenes selective (>98 %) STA/HSAG catalyst by means of combustion of carbon deposits at 400 °C.Publicación Carbon-supported non-noble metal catalysts for efficient synthesis of the biofuel 2,5-dimethylfurfural from 5‑hydroxymethylfurfural in 1-butanol under mild conditions(ELSEVIER, 2025-04-01) Morales Vargas, Mª Virtudes; Guerrero Ruiz, A.; Rodríguez Ramos, I.; Conesa Alonso, José María2,5-Dimethylfuran (DMF), which is one of the most promising liquid biofuels, has garnered significant attention due to its potential to develop the utilization of biomass energy. In this work, its synthesis through the hydrodeoxygenation reaction (HDO) of 5-hydroxymethylfurfural (HMF) has been studied on Ni catalysts supported on various metal oxides and a high surface graphite (HSAG), in a batch reactor, using 1-butanol as a solvent. At 180 °C and under 30 bar H2, the catalytic activity and the predominant reaction route were found to be strongly conditioned by the nature of the support, as well as by the presence of impurities depending on the commercial HMF feedstock employed. The HSAG support turned out to be the most suitable for the HDO of HMF leading to the formation of DMF, via rupture of the C-O bonds. Additionally, the catalytic performance of Co and Cu supported on this graphitic material was studied, being Cu the one that offers the best yields to DMF (95 %), even in the absence of external hydrogen (84 %), confirming that butanol acts as a hydrogen donor in addition of solvent.Publicación Comparative study of Cu, Ag and Ag-Cu catalysts over graphite in the ethanol dehydrogenation reaction: Catalytic activity, deactivation and regeneration(ELSEVIER, 2019) Morales, María V.; López-Olmos, Cristina; Rodríguez Ramos, Inmaculada; Guerrero Ruiz, Antonio R; Conesa Alonso, José María; https://orcid.org/0000-0003-2834-0296; https://orcid.org/0000-0003-4622-6008; https://orcid.org/0000-0003-1848-5985The physicochemical and catalytic properties of bimetallic AgCu catalysts and their monometallic counterparts supported on a high surface area graphite have been comparatively evaluated in the ethanol dehydrogenation reaction, performed in a continuous-flow reactor. While Cu was incorporated by the incipient wetness impregnation technique, for Ag catalysts two synthesis procedures were explored: incipient wetness impregnation and adsorption of Tollens’ reagent. The catalysts prepared by wetness impregnation exhibited higher metal dispersion, being improved for the bimetallic catalysts in comparison with the monometallic counterparts. The results obtained in the catalytic tests revealed that Cu catalysts is nearly two orders of magnitude more active than Ag catalyst in the dehydrogenation reaction of ethanol on either a turnover frequency or a weight basis, but at the same time both catalysts were 100% selective to acetaldehyde. Whereas selectivity was not affected by the bimetallic composition, there was a substantial decrease in the reaction rate among the bimetallic catalysts as the Cu/Ag ratio diminished, due to blockage of copper surface active sites by silver. Both silver and copper, and the bimetallic catalysts, suffered from deactivation at 523 K, caused by blocking of active sites by adsorbed hydrocarbons on the catalyst surface (fouling). Carbonaceous deposits were removed through a thermal treatment under H2 flow, which allowed the total recovery of the initial catalytic activity.Publicación Formic Acid Dehydration Using Mechanochemically Prepared TiO2-Graphite Composites(Wiley, 2024-07-27) Yruela Garrido, Marta; Martín Rodríguez, Nuria; Castillejos López, Eva; Campos Castellanos, Eduardo; Rodríguez Ramos, Inmaculada; Guerrero Ruiz, Antonio R; Conesa Alonso, José MaríaCommercial high surface area graphite (HSAG300) and commercial TiO2 were used to produce composite materials through a simple mechanochemical method involving milling and ultrasonic treatments. The acid and basic sites exposed on the surfaces of these materials were characterized by temperature-programmed desorption (TPD) of ammonia and carbon dioxide. The catalytic materials were tested in the dehydration reaction of formic acid to produce hydrogen-free CO. While HSAG300 is practically inactive under reaction conditions (continuous gas flow at temperatures in the range of 100–250 °C), all samples containing TiO2 are active, exhibiting high selectivity to CO without significant deactivation at moderate reaction temperatures. It is demonstrated that the presence of graphite in the catalysts enhances the specific catalytic activity of TiO2. Assuming that the dehydration reaction is catalyzed by acid sites on the TiO2 surfaces, a comparative evaluation of the surface sites reveals that the graphite-TiO2 interactions not only change the density of surface sites but also modify the strength of the acid centers of TiO2. In summary, the interaction of HSAG300 with TiO2 modulates the surface properties of the prepared composite catalysts, decreasing the total number of basic surface sites and increasing the strength of acidic sites compared to bare TiO2.Publicación Critical Factors Affecting the Selective Transformation of 5-Hydroxymethylfurfural to 3-Hydroxymethylcyclopentanone Over Ni Catalysts(Chemistry Europe, 2024-06-11) Campos Castellanos, Eduardo; Guerrero Ruiz, Antonio R; Rodríguez Ramos, Inmaculada; Morales Vargas, Mª Virtudes; Conesa Alonso, José María; https://orcid.org/0000-0003-2834-0296; https://orcid.org/0000-0001-5470-7958; https://orcid.org/0000-0003-4622-6008The ring-rearrangement of 5-hydroxymethylfurfural (HMF) to 3-hydroxymethylcyclopentanone (HCPN) was investigated over Ni catalysts supported on different carbon supports and metallic oxides with different structure and acid-base properties. Their catalytic performance was tested in a batch stirred reactor in aqueous solution at 180 °C and 30 bar of H2. Under these conditions, the HMF hydrogenation proceeds through three possible competitive routes: (i) a non-water path leading to the total hydrogenation product, 2,5-di-hydroxymethyl-tetrahydrofuran (DHMTHF), and two parallel acid-catalyzed water-mediated routes responsible for (ii) ring-opening and (iii) ring-rearrangement reaction products. All catalyst systems primarily produced HCPN, but reaction rates and product distribution were influenced by several variables, some of them intensely analyzed in this work. The most proper conditions resulted to be the presence of the medium/strong Lewis's acidity of a Ni/ZrO2 catalyst (initial TOF=5.99 min−1 and 73 % HCPN selectivity) or the Brønsted acidity originated by an oxidized high surface area graphite, Ni/HSAG-ox (initial TOF=5.92 min−1 and 87 % HCPN selectivity). However, too high density of acidic sites on the catalyst support (Ni/Al2O3) and sulfur impurities from the HMF feedstock led to catalyst deactivation by coke deposition and Ni poisoning, respectively.Publicación Tunable selectivity of Ni catalysts in the hydrogenation reaction of 5-hydroxymethylfurfural in aqueous media: Role of the carbon supports(ELSEVIER, 2021) Morales, María V.; Rodríguez Ramos, Inmaculada; Guerrero Ruiz, Antonio R; Conesa Alonso, José María; https://orcid.org/0000-0003-2834-0296; https://orcid.org/0000-0001-5470-7958; https://orcid.org/0000-0003-1848-5985; https://orcid.org/0000-0003-4622-6008In addition to the nature of the solvent, the intrinsic metal properties and degree of dispersion, the selective hydrogenation of 5-hydroxymethylfurfural (HMF) has been reported to be greatly affected by the nature of the support. In this work, four Ni catalysts were prepared starting from different carbonaceous supports ─with diverse graphitic and porous structure─ and comparatively evaluated in the hydrogenation reaction of HMF. The reaction was conducted in a batch stirred reactor under 30 bar H2 pressure at 60 °C in aqueous media. Ni supported on a commercial silica and Raney Ni were also tested for reference purposes. We found that carbon supports limit in some extent the reactivity of Ni towards Cdouble bondC hydrogenation, offering higher selectivity to the carbonyl hydrogenated compound, 2,5-di-hydroxymethylfuran (DHMF), in detrimental to the total hydrogenated derivative, 2,5-di-hydroxymethyl-tetrahydrofuran (DHMTHF). However, the latter was the major product over Raney Ni and Ni/SiO2. The unusual catalytic performance of our Ni/carbon catalysts was related to the composition, structural and surface properties. Among all tested Ni/carbon catalysts, Ni over the commercial high surface area graphite (HSAG) exhibited the best catalytic behaviour in terms of DHMF selectivity (90%) and intrinsic catalytic activity. Furthermore, Ni/HSAG displayed satisfactory stability after three consecutive runs.