The Success Story of Gold-Based Catalysts for Gas- and Liquid-Phase Reactions: A Brief Perspective and Beyond

Gold has long held the fascination of mankind. For millennia it has found use in art, cosmetic metallurgy and architecture; this element is seen as the ultimate statement of prosperity and beauty. This myriad of uses is made possible by the characteristic inertness of bulk gold; allowing it to appear long lasting and above the tarnishing experienced by other metals, in part providing its status as the most noble meta

Promoter effect of sodium in graphene-supported Ni and Ni–CeO2 catalyst for the low-temperature WGS reaction

The low temperature water–gas shift (WGS) reaction has been studied over Ni–CeO2/Graphene and Ni/Graphene. The catalysts were prepared with 5 wt.% Ni and 20 wt.% CeO2 loadings, by deposition-precipitation employing sodium hydroxide and urea as precipitating agents. The materials were characterized by TEM, powder X-ray diffraction, Raman spectroscopy, H2-temperature-programmed reduction and X-ray photoelectron spectroscopy (XPS). The characterization and the reaction results indicated that the interaction between the active species and the support is higher than with activated carbon, and this hinders the reducibility of ceria and thus the catalytic performance. On the other hand, the presence of residual sodium in samples prepared by precipitation with NaOH facilitated the reduction of ceria. The catalytic activity was highly improved in the presence of sodium, what can be explained on the basis of an associative reaction mechanism which is favored over Ni-O-Na entities.Authors thank to CONICYT (Chile, Postdoc FONDECYT 3130483) and Ministerio de Economía y Competitividad (Spain, MAT2010-21147 and MAT2013-45008-P) for financial support

Solvent- and Ligand-free Diboration of Alkynes and Alkenes Catalyzed by Platinum Nanoparticles on Titania

Platinum nanoparticles supported on titania efficiently catalyzed the diboration of alkynes and alkenes under solvent- and ligand-free conditions in air. The cis-1,2-diborylalkenes and 1,2-diborylalkanes were obtained in moderate to excellent yields following, in most cases, a simple filtration workup protocol. The versatility of the cis-1,2-diboronvinyl compounds was demonstrated in a series of organic transformations, including the Suzuki–Miyaura cross coupling and the boron–halogen exchange.This work was generously supported by the Spanish Ministerio de Economía y Competitividad (MINECO; CTQ2007-65218 and CTQ2011-24151), the Generalitat Valenciana (GV; PROMETEO/2009/002 and PROMETEO/2009/039), and FEDER

Bimetallic Cu–Ni catalysts for the WGS reaction – Cooperative or uncooperative effect?

In this work, bimetallic Cu–Ni catalysts have been studied in the water-gas shift (WGS) reaction, and they have shown different levels of synergy and anti-synergy in terms of catalytic activity and selectivity to the desired products. Cu–Ni interactions alter the physicochemical properties of the prepared materials (i.e. surface chemistry, redox behaviour, etc.) and as a result, the catalytic trends are influenced by the catalysts' composition. Our study reveals that Cu enhances Ni selectivity to CO2 and H2 by preventing CO/CO2 methanation, while Ni does not help to improve Cu catalytic performance by any means. Indeed, the monometallic Cu formulation has shown the best results in this study, yielding high levels of reactants conversion and excellent long-term stability. Interestingly, for medium-high temperatures, the bimetallic 1Cu–1Ni outperforms the stability levels reached with the monometallic formulation and becomes an interesting choice even when start-up/shutdowns operations are considered during the catalytic experiments.Financial support for this work was provided by the EPSRC grants EP/J020184/2 and EP/R512904/1 as well as the Royal Society Research Grant RSGR1180353. The Spanish team acknowledges Ministerio de Economía, Industria y Competitividad of Spain (Project MAT2013-45008-P). L. Pastor-Perez acknowledges Generalitat Valenciana for her postdoctoral grant (APOSTD/2017). Sasol is kindly acknowledged for providing the support

Multicomponent NiSnCeO2/C catalysts for the low-temperature glycerol steam reforming

In this work, the low-temperature hydrogen production via glycerol steam reforming over activated carbon-supported Ni and Ni-Sn catalysts promoted by ceria was studied. A combination of N2 adsorption, powder X-ray diffraction, temperature-programmed reduction with H2, X-ray photoelectron spectroscopy and TEM analysis were used to characterise the Ni-Sn-CeO2 interactions and the CeO2 dispersion over the activated carbon support. The catalytic activity results show that the presence of ceria enhances the water-gas shift reaction, thus promoting the selectivity towards hydrogen. The inclusion of Sn stresses the influence of ceria in the displayed performance. Moreover, the formation of a Ni-Sn alloy seems to be an efficient way to mitigate Ni sintering and therefore to improve the overall catalyst’s stability.This work has been supported by Ministerio de Economía y Competitividad (Spain, project MAT2013-45008-P). L. P-P. acknowledges her grant BES-2011-0406508

Low temperature glycerol steam reforming on bimetallic PtSn/C catalysts: On the effect of the Sn content

Steam reforming of glycerol to produce syngas or H2-enriched streams is a promising route that has caught the attention of many researchers around the world. This reaction is typically carried out over metal-based catalysts supported on stable materials. Herein we report a study on the effect of Sn on the catalytic properties of Pt/C in the aforementioned reaction. A series of Pt-Sn/C catalysts with different Pt:Sn ratios were prepared and characterized using ICP, H2-TPR, TEM and XPS techniques, and they were tested in the glycerol steam reforming reaction at 623 K and atmospheric pressure. The best performance was observed for the catalysts with low tin contents. It was found that Sn promoted oxidation reactions and inhibited methanation. Furthermore, the presence of Sn improved the stability of the catalysts when operating at harsher conditions of temperature and glycerol concentration. A promoter effect of Sn hindering platinum sintering and the formation of coke precursors is proposed as the origin of the observed behaviour.This work has been supported by Ministerio de Economía y Competitividad (Spain, Project MAT2010-21147). L.P.P. acknowledges her grant BES-2011-0406508

DE MI FOR YOU. Artistic project of international collaboration between people affected by severe mental disorder

The international and collaborative art project consisted in producing a communication and a creation channel between two groups of participants affected by acute mental disorders who are clients of mental health services placed in diferent countries: one group is located in Calatayud, Zaragoza (Spain) and the other in London (UK). The framework was based on a creative, free and flexible setting founded on a simple suggestion which was supported with the artist Hundertwasser theory of the “five skins”

Ir supported over carbon materials for the selective hydrogenation of chloronitrobenzenes

In the present work we have studied the effect of carbon supports with different graphitic character (carbon nanotubes, mesoporous graphite and activated carbon) on the catalytic performance of iridium nanoparticles on the liquid phase chemoselective hydrogenation of para-chloronitrobenzene at room temperature. The effect of the oxygen groups was also evaluated by oxidizing a portion of the carbon nanotubes. The Raman and XRD spectra showed that the mesoporous graphite displayed the strongest graphitic character. The characterization of the catalysts by HR-TEM, XPS and TPR-H2, showed that the catalysts had similar particle size and that the catalysts prepared over the previously oxidized support, Ir/CNTox, was not fully reduced. The activity and selectivity achieved with the catalyst Ir/CNT was the best among the samples and the presence of irdium oxide on Ir/CNTox diminished the yield to p-chloroaniline, being the worse catalyst. The reactivity of different isomers was also studied over Ir/CNT and it followed the order m > o > p.Authors thank to CONICYT (Chile, FONDECYT 3130483) and Generalitar Valenciana (Spain, PROMETEOII/2014/004–FEDER) for financial support