Pd/Au based catalyst immobilization in polymeric nanofibrous membranes via electrospinning for the selective oxidation of 5-hydroxymethylfurfural

Innovative nanofibrous membranes based on Pd/Au catalysts immobilized via electrospinning onto different polymers were engineered and tested in the selective oxidation of 5- (hydroxymethyl)furfural in an aqueous phase. The type of polymer and the method used to insert the active phases in the membrane were demonstrated to have a significant effect on catalytic performance. The hydrophilicity and the glass transition temperature of the polymeric component are key factors for producing active and selective materials. Nylon-based membranes loaded with unsupported metal nanoparticles were demonstrated to be more efficient than polyacrylonitrilebased membranes, displaying good stability and leading to high yield in 2,5-furandicarboxylic acid. These results underline the promising potential of large-scale applications of electrospinning for the preparation of catalytic nanofibrous membranes to be used in processes for the conversion of renewable molecules

Effects of isopropanol on collagen fibrils in new parchment

Background: Isopropanol is widely used by conservators to relax the creases and folds of parchment artefacts. At present, little is known of the possible side effects of the chemical on parchments main structural component- collagen. This study uses X-ray Diffraction to investigate the effects of a range of isopropanol concentrations on the dimensions of the nanostructure of the collagen component of new parchment. Results: It is found in this study that the packing features of the collagen molecules within the collagen fibril are altered by exposure to isopropanol. The results suggest that this chemical treatment can induce a loss of structural water from the collagen within parchment and thus a rearrangement of intermolecular bonding. This study also finds that the effects of isopropanol treatment are permanent to parchment artefacts and cannot be reversed with rehydration using deionised water. Conclusions: This study has shown that isopropanol induces permanent changes to the packing features of collagen within parchment artefacts and has provided scientific evidence that its use to remove creases and folds on parchment artefacts will cause structural change that may contribute to long-term deterioration of parchment artefacts. This work provides valuable information that informs conservation practitioners regarding the use of isopropanol on parchment artefacts

H2 production by methane steam reforming over Rh/Al2O3 catalyst packed in Cu foams: A strategy for the kinetic investigation in concentrated conditions

The concept of Rh/Al2O3 catalyst pellets packed in highly conductive copper foams has been successfully tested in methane steam reforming showing the beneficial effects of thermal conductivity on the obtainment of gradient-less radial temperature profiles. In this work, the same concept is proposed as a strategy for the lab-scale kinetic investigation under concentrated conditions at ambient pressure; thanks to the homogeneous heating of the catalyst mass across the reactor section and the measurement of axial temperature profiles, well-controlled temperature conditions are obtained, and the experimental investigation can be extended to usually unfeasible conditions of high reactant concentrations, overcoming the typical challenges for the kinetic study. Here, steam reforming experiments were performed with CH4 and H2O feed molar fractions in the ranges of 10−20 % and 40–90 %, respectively. The co-feed of CO and H2 was also investigated. A kinetic scheme was developed that substantially confirmed the main results of previous kinetic investigations in annular micro-reactor, performed under diluted conditions; in particular, the first order dependence of the rate of steam reforming on methane partial pressure, the independence from H2O partial pressure, and the important inhibiting effect of CO were confirmed. The independence of the reaction rate from the H2 co-feed was here demonstrated for the first time. The new experimental campaign allowed to identify more clearly the kinetic dependencies of the water gas shift reaction, positively influenced by H2O partial pressure but scarcely affected by CO partial pressure, which could be also explained based on the inhibiting effect of surface CO coverage. Parameter estimates were obtained by model fit over a wide temperature range (400−850 °C), conveying robustness to the proposed kinetic scheme for future reactor design applications

Lysozyme binding onto catanionic vesicles

Mixing aq. SDS with cetyltrimethylammonium bromide solns. in mole ratios close to (1.7/1.0) allows the formation of cat-anionic vesicles with an excess of neg. charges on the outer surface. The vesicular dispersions are mixed with lysozyme, and interact electrostatically with the pos. charges on the protein, forming lipoplexes. Dielec. relaxation, zeta-potential, and light scattering indicate the occurrence of interactions between vesicles and the protein. According to CD, the vesicle-adsorbed protein retains its native conformation. Binding and surface satn., inferred by dielec. relaxation and zeta-potential, fulfil a charge neutralization stoichiometry. Adsorbed lysozyme promotes the vesicle clustering and is concomitant with the lipo-plexes flocculation. Above the charge neutralization threshold, lysozyme in excess remains dispersed in mol. form. Attempts were made to det. in what conditions protein release from the vesicles occurs. Accordingly, the full neutralization of SDS in excess by cetyltrimethylammonium bromide ensures the lipo-plexes break-up, the pptn. of the mixed surfactants and the protein release in native form

Gas-Phase Catalytic Transfer Hydrogenation of Methyl Levulinate with Ethanol over ZrO2

This paper reports about the gas-phase reduction of methyl levulinate to valerolactone (GVL) via catalytic transfer hydrogenation using ethanol as the H-donor. In particular, high-surface-area, tetragonal zirconia has proven to be a suitable catalyst for the reaction. Under optimized conditions, the reaction is selective toward the formation of GVL (yield 70%). However, both the deposition of heavy oligomeric compounds over the catalytic surface and the progressive conversion from Lewis to Brønsted acidity, due to the reaction with the water formed in situ, led to a progressive change in the chemo-selectivity, promoting side reactions, e.g. the alcoholysis of angelica lactones to ethyl levulinate. However, the in situ regeneration of the catalyst performed by feeding air at 400 °C for 2 h permitted an almost total recovery of the initial catalytic behavior, proving that the deactivation is reversible. The reaction has been tested also using a true bioethanol, derived from agricultural waste