Persona: Conesa Alonso, José María
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Conesa Alonso
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José María
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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 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 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.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.