Efficient low-loaded ternary Pd-In2O3-Al2O3 catalysts for methanol production

Pd-In2O3 catalysts are among the most promising alternatives to Cu-ZnO-Al2O3 for synthesis of CH3OH from CO2. However, the intrinsic activity and stability of In2O3 per unit mass should be increased to reduce the content of this scarcely available element and to enhance the catalyst lifetime. Herein, we propose and demonstrate a strategy for obtaining highly dispersed Pd and In2O3 nanoparticles onto an Al2O3 matrix by a one-step coprecipitation followed by calcination and activation. The activity of this catalyst is comparable with that of a Pd-In2O3 catalyst (0.52 vs 0.55 gMeOH h−1 gcat-1 at 300 \ub0C, 30 bar, 40,800 mL h−1 gcat-1) but the In2O3 loading decreases from 98 to 12 wt% while improving the long-term stability by threefold at 30 bar. In the new Pd-In2O3-Al2O3 system, the intrinsic activity of In2O3 is highly increased both in terms of STY normalized to In specific surface area and In2O3 mass (4.32 vs 0.56 g gMeOH h−1 gIn2O3-1 of a Pd- In2O3 catalyst operating at 300 \ub0C, 30 bar, 40,800 mL h−1 gcat-1).The combination of ex situ and in situ catalyst characterizations during reduction provides insights into the interaction between Pd and In and with the support. The enhanced activity is likely related to the close proximity of Pd and In2O3, wherein the H2 splitting activity of Pd promotes, in combination with CO2 activation over highly dispersed In2O3 particles, facile formation of CH3OH

Diclofenac Salts. V. Examples of Polymorphism among Diclofenac Salts with Alkyl-hydroxy Amines Studied by DSC and HSM

pharmaceutic

“Green-earths”: vibrational and elemental characterisation of glauconites, celadonites and historical pigments

“Green-earths” have been employed since antiquity and are still used as pigments in the creation of artworks. The minerals responsible for the colour belong to four groups: (i) the clayey micas celadonite and glauconite, undoubtedly the most common; (ii) smectites; (iii) chlorites; (iv) serpentines1. Mineralogical analyses in the field of cultural heritage are rare, and often limited to the identification of the generic class “green-earth”. A multi-disciplinal study of minerals coming from the historical mining localities, besides to clarify the mineralogy of traditional green-earths, could support the correct identification of the mineralogical species employed in the artworks, and could provide a valid tool for the study of the pigments’ origin. This work presents a preliminary study on some raw minerals (glauconite, celadonite, Fe-celadonite) characterized by multi-technical approach. In particular, the attention has been focused on the possible distinction between celadonite and glauconite by μ-Raman, μ-IR and SEM-EDS techniques. Concerning μ-Raman spectroscopy, we identified the characteristic bands of minerals, considering the internal variations in the single species, and distinguishing them from spurious structures, heating effects, dependence on wavenumber of exciting source. A similar procedure has been followed with μ-IR spectroscopy. Vibrational analyses have been correlated with elemental analyses, thanks to the coupled instrument SEM-EDS-SCA that lets to collect EDS and Raman spectra on the same microscopic area. Besides pure minerals, archaeological samples and commercial “green earths” have been analyzed. 1. C.A. Grissom, “Green Earth”, in Artists’ Pigments, Vol. 1, (1986), Ed. R.L. Feller, Cambridge University Press, U

Insights into the reaction mechanism for 5-hydroxymethylfurfural oxidation to FDCA on bimetallic Pd-Au nanoparticles

This work deals with the oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) in water using supported Pd-Au nanoparticles. The active phase composition was shown to be crucial for FDCA formation. Indeed, both Au and Pd monometallic nanoparticles formed 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) under the studied conditions; however, with Pd nanoparticles HMFCA was not further transformed, while Au and bimetallic Pd-Au systems both catalysed its oxidation to FDCA. The thermal treatment of Pd-Au catalysts considerably modified their catalytic activity, because Pd atoms migrated and concentrated onto the outer part of bimetallic nanoparticles. The resulting active phase morphology showed a different reaction path for FDCA formation compared to the untreated catalyst, with an important contribution of the Cannizzaro reaction. PVP-protected Pd-Au nanoparticles with different structures (either alloy or core-shell morphology) were synthesized and their reactivity tested in order to confirm the presence of different mechanisms for HMF oxidation, depending on whether the active phase preferentially exposes either Pd or Au atom

Open-cell foams coated by Ni/X/Al hydrotalcite-type derived catalysts (X = Ce, La, Y) for CO2 methanation

NiAl hydrotalcite-type materials containing rare-earth elements (La, Ce, Y) are coated on thermal conductive NiCrAl open-cell foams by the electrodeposition method. After calcination and reduction at 600 \ub0C, the obtained structured materials have a stable coating wherein Ni nanoparticles are well-dispersed. Consequently, the catalysts with rare-earth elements show a remarkable activity enhancement in the CO2 methanation in comparison to a NiAl catalyst. At 325 \ub0C (oven temperature) CH4 productivity rates of 6.75\u20138.35 mole gNi 121 h 121 (38,200 h 121, CO2/H2/N2 = 1/4/1 v/v) are achieved. Ce has the largest effect on the improvement of the CO2 conversion and stability (also feeding a N2 free feedstock) followed by Y and La, due to the balance between the amount and activity of the catalytic coating. The Ce structured catalyst is also more active and selective than its pelletized counterpart at similar outlet temperature. Temperature profiles recorded along the centerline of the catalytic bed provide an overview of hotspot formation that plays an important role in the control of activity/selectivity and catalyst deactivation