Bio: Daniel Escrig is an academic researcher. The author has contributed to research in topics: Dehydrogenation & Catalysis. The author has an hindex of 1, co-authored 1 publications receiving 38 citations.
TL;DR: In this article, the catalytic activity has been evaluated in terms of cyclohexanone yields and impurities from secondary reactions of dehydration and dehydrogenation of cyclomethane.
Abstract: Catalytic dehydrogenation of cyclohexanol to cyclohexanone has been carried out on phase gas in a continuous fixed bed reactor under atmospheric pressure. Copper chromite and copper zinc oxide catalysts have been checked. Effect of temperature (in the range 250–290 °C) and spatial time in reactor have been studied. The catalytic activity has been evaluated in terms of cyclohexanone yields and impurities from secondary reactions of dehydration and dehydrogenation of cyclohexanol have also been identified and quantified by GC/MS. Catalysts have been characterized by X-ray diffraction, temperature programmed desorption of ammonia and BET surface area measurement. High activity was confirmed by copper-based catalysts under the operating conditions, concerning the size and dispersion of the copper specie. It was also found that catalysts with alumina and chromium exhibit higher dehydration capacity, being cyclohexene the main impurity obtained. For a given cyclohexanone yield the impurities from dehydrogenation reactions showed similar trends for the three catalysts tested. Phenol was the main impurity obtained by dehydrogenation.
TL;DR: Progress in catalyst development for upgrading ethanol to n-butanol, which involves homogeneous catalysts, such as iridium and ruthenium complexes, and heterogeneous catalyststs, including metal oxides, hydroxyapatite (HAP), and, in particular, supported metal catalysts is reviewed herein.
Abstract: Because n-butanol as a fuel additive has more advantageous physicochemical properties than those of ethanol, ethanol valorization to n-butanol through homo- or heterogeneous catalysis has received much attention in recent decades in both scientific and industrial fields. Recent progress in catalyst development for upgrading ethanol to n-butanol, which involves homogeneous catalysts, such as iridium and ruthenium complexes, and heterogeneous catalysts, including metal oxides, hydroxyapatite (HAP), and, in particular, supported metal catalysts, is reviewed herein. The structure-activity relationships of catalysts and underlying reaction mechanisms are critically examined, and future research directions on the design and improvement of catalysts are also proposed.
TL;DR: In this paper, the catalytic activity of Mg-Al hydrotalcite supported copper catalyst was investigated for clean C C and C N bond forming reactions using alcohols as alkylating agent via borrowing hydrogen methodology.
Abstract: The catalytic activity of Mg–Al hydrotalcite supported copper catalyst was investigated for clean C C and C N bond forming reactions using alcohols as alkylating agent via borrowing hydrogen methodology. The catalyst showed excellent conversion of ketone and amine substrates (71–99%) to alkylated products with high selectivity in alkylation reactions.
TL;DR: In this paper, a co-precipitation of Zr-promoted Zn/Al2O3 with SAPO-34 zeolite was investigated for the direct synthesis of lower olefins from syngas in a fixed-bed reactor.
Abstract: Hybrid catalysts composed of different loadings of Zr-promoted Zn/Al2O3 with SAPO-34 zeolite were investigated for the direct synthesis of lower olefins from syngas in a fixed-bed reactor. Zn/Al2O3 catalysts and Zr-promoted Zn/Al2O3 catalysts with different weight ratios were prepared by a co-precipitation method, respectively. Nano-sized SAPO-34 zeolite was synthesized by a hydrothermal method. The crystallinity, morphology, textural properties and acidic properties of the catalysts were characterized well by XRD, ICP-OES, TEM, H2-TPR, N2 adsorption–desorption isotherm analysis, XPS, and NH3-TPD, respectively. The H2-TPR results suggested that the presence of Zr on the surface of the support favors the reducibility of zinc oxide with a shift to a lower reduction temperature. The Zr promoter improved the Zn dispersion and enhanced the surface area of Zn/Al2O3 catalysts. Various factors that influenced the catalytic activity, including the reaction temperature, the different weight ratios of the methanol synthesis catalyst to SAPO-34 zeolite, the gas flow rate and stability, were investigated in detail. The hybrid catalysts composed of Zr·Zn/Al2O3 and SAPO-34 showed excellent catalytic performance in terms of activity, selectivity and stability for the conversion of syngas into lower olefins. When Zr-free Zn/Al2O3 was used for the hybrid catalyst instead of Zr·Zn/Al2O3, the conversion and stability were low. The results show that a synergistic effect existed between the Zr·Zn/Al2O3 component and SAPO-34 zeolite and it was directly related to the resulting catalytic performance. This study will contribute to the development of efficient catalysts for the production of lower olefins from syngas.
TL;DR: In this paper, the effect of support nature on physico-chemical and catalytic properties of supported copper species was studied, and the loading of copper on the supports was observed to be influencing the surface acidic, basic and reducibility properties.
Abstract: The Mg–Al hydrotalcite (HT) and Mg–Al mixed oxide supported copper catalysts containing 3–3.5 wt.% copper in finely dispersed form were synthesized and characterized. The effect of support nature on physico-chemical and catalytic properties of supported copper species were studied. The loading of copper on the supports was observed to be influencing the surface acidic, basic and reducibility properties, and catalytic behavior in dehydrogenation of benzyl alcohol. The high basicity and intercalated copper ions in Mg–Al hydrotalcite supported copper sample showed multifunctional activity in catalytic transformations of alcohols (primary, secondary and aromatic alcohols).
TL;DR: In this article, PXRD, H2-TPR, XPS, XANES and EXAFS techniques were used to characterize the catalytic activity of the supported CuNi alloy particles on CeO2 by alloy-redox support interaction and segregation of Cu.
Abstract: CuNi bimetallic alloy particles supported on CeO2 are prepared by coprecipitation of the corresponding salt precursors followed by calcination and hydrogen reduction. The supported alloy particles are characterized by PXRD, H2-TPR, XPS, XANES and EXAFS techniques. The PXRD study shows that copper rich oxide phases supported on CeO2 are reduced at 200 °C. However, complete reduction of CuO–NiO phases occurs at 450 °C forming CuNi alloy particles on CeO2. The H2-TPR results show that mixed oxides are reduced at higher temperatures than pure components indicating strong wetting between oxide components and CeO2. The Ni 2p XPS shows stronger interaction between Ni2+ and CeO2 support. XANES and EXAFS studies show the formation of CuNi alloy particles with small surface segregation of Cu. The catalytic activity of the supported CuNi alloy particles is studied by non-oxidative dehydrogenation of cyclohexanol to cyclohexanone reaction. The effect of temperature, contact time and time on stream are examined to gain insights into the catalytic activity of the CeO2 supported CuNi alloy catalysts. Among all the CuNi alloy compositions, CuNi(1:1)/CeO2 catalyst shows higher catalytic activity and selectivity to cyclohexanone. Formation of stable CuNi alloy particles on CeO2 by alloy–redox support interaction and segregation of Cu are crucial factors for catalytic activity.