New catalysts based on Pd(0) nanoparticles (Pd NPs) on a bimodal porous silica of the UVM-7/polydopamine (PDA) support have been synthesized following two preparative strategies based on the sequential or joint incorporation of two components of the composite (Pd and PDA). We analyzed the role played by the PDA as ‘interfacial glue’ between the silica scaffold and the Pd NPs. The catalysts were tested for the hydrogenation of 4-nitrophenol using (NEt4)BH4 as the hydrogenating agent. In addition to the palladium content, the characterization of the catalysts at the micro and nanoscale has highlighted the importance of different parameters, such as the size and dispersion of the Pd NPs, as well as their accessibility to the substrate (greater or lesser depending on their entrapment level in the PDA) on the catalytic efficiency. Staged sequential synthesis has led to better catalytic results. The most active Pd(0) centers seem to be Pd NPs of less than 1 nm on the PDA surface. The efficiency of the catalysts obtained is superior to that of similar materials without PDA. A comprehensive comparison has been made with other catalysts based on Pd NPs in a wide variety of supports. The TOF values achieved are among the best described in the literature.

range of chemical transformations. Several value added chemicals can be synthetized from LA, such as succinic acid, diphenolic acid, γ-aminolevulinic acid, γ-valerolactone, as well as various esters and ketals, which are important building blocks for the synthesis of pharmaceuticals, fragrances, plasticizers, cosmetics or fuel additives [10][11][12][13][14] (Scheme 2).In this context, levulinic ketals are promising valuable biobased chemicals that have potential applications as additives for biofuels [12] as well as building blocks for producing plasticizers [13] and surfactants. [15] Reaction of LA with polyalcohols can lead to the formation of the corresponding ketals and/or esters. Ketalization and esterification reactions are both acid catalyzed reactions; therefore, the condensation of polyols with LA can result in competing ketalization and esterification reactions leading to nonselective mixtures of ketal, ester and ketal-ester products. For this reason, most of the methods described in the literature for the synthesis of levulinic ketals involve the reaction of ethyl levulinate (EL) with polyalcohols, thus avoiding the competing (trans)esterification reaction and improving the ketalization selectivity. Selifonov et al. described an efficient method for producing ketals from both LA and EL using mineral sulfuric acid as homogeneous catalyst. [16,17] Although a high selectivity of ketals was achieved, the use of sulfuric acid as catalyst causes severe corrosive, toxic and waste treatment problems, which introduce important environmental concerns. Ketalization of EL has been studied using both homogeneous and heterogeneous acid catalysts, including p-toluenesulfonic acid (p-TSA), NbP, Amberlyst-70 or H-ZSM-5 [15] (see Table S1, Supporting Information). Conversely, the direct ketalization of LA instead of levulinic esters to produce the corresponding ketals is a rather unexplored area. Recently, Amarasekara and Animashaun studied the condensation of LA with polyols in the presence of Amberlyst-15 and p-TSA as catalysts. [18] The authors explored the effect of homogeneous and heterogeneous catalysts on the competitive esterification and ketalization reactions. The highest ketal yield (88%) was achieved with 1,2-propanediol using Amberlyst-15 as a catalyst; whereas 88% of ketal-ester was obtained when p-TSA was used as catalyst. According to the authors, their results indicate that the selectivity to one of the products can be improved by controlling the structure of the catalyst as well as the nature, the accessibility and the number of active sites.Zr-containing UiO-66 materials are active and reusable heterogeneous catalysts for the selective ketalization of levulinic acid (LA) with 1,2-propanediol, affording selectivities of up to 91-93% at full LA conversion, with very low levels of ester or ketal-ester byproducts. This allows the preparation of the target ketal directly from LA and avoiding intermediate esterification steps of LA to levulinate esters to minimize the formation of unwanted side products. Th...

RESUMENLos materiales cerámicos han abierto nuevos espacios de innovación en su aplicación en las envolventes de los edificios en los últimos años. Sin embargo, ha sido escasa la investigación en su relación con la vibración de la luz, la percepción visual y su integración en el paisaje. En esta investigación se estudia la producción y aplicación de piezas de gres porcelánico en un auditorio. El uso de un recubrimiento cerámico con un acabado irisado-nacarado con reflejo metálico responde a la intención de generar una piel vibrante en constante cambio frente a la luz natural y el entorno. Se ha diseñado un proceso de vitrificado y deposición de metales, a través de tres cocciones sucesivas. Se analizan las propiedades del esmaltado y los factores de microfisuración que refuerzan el irisado. Se ha hecho un análisis colorimétrico evaluando los colores goniocromáticos o iridiscentes, midiendo el factor de radiancia espectral de la luz.Palabras clave: gres porcelánico; irisado-nacarado; deposición de metales; reflectancia; colores goniocromáticos; zirconio; titanio. ABSTRACT Recent years have witnessed the development of innovative applications for ceramic materials as building envelopes.However, little research has been conducted on the relationship between these materials and reflected light, visual perception and integration in the landscape. The aim of the present research was to study the production and application of porcelain stoneware panels in an auditorium. The idea behind using a ceramic coating with an iridescent, pearlescent finish and a metallic sheen was to create a vibrant, constantly changing surface that reflected the natural light and the environment. We designed a metal deposition and glazing process based on three successive firings, and analysed the glaze properties and microcracking factors that reinforced the iridescent lustre. We also performed a colorimetric analysis to assess the goniochromatic or iridescent colours, measuring the spectral radiance of the light.