Gotowa bibliografia na temat „Catalyseur de surface”

This paper investigated the use of titanium dioxide sol-gel coatings to photo-catalyse red wine stains on wool fabrics. Coatings were produced by the hydrolysis and condensation of titanium butoxide (Ti(OC4H9)4) on the surface of wool fabrics after pad application. Coatings were partially converted to the anatase form of titanium dioxide by prolonged immersion in boiling water. The coating presence was confirmed using scanning electron microscopy, UVspectrophotometry and atomic force microscopy. Coated samples were measured for photo-catalytic activity by degrading red wine stains from the surface of the coated fabric. The level of photocatalysis was determined for each of the coating systems after 168 hours. Red wine stains were photo-catalysed and level of staining was reduced from the UV exposed surface of the coated wool fabric.

Microbial biofilms produce electrochemical interactions with metal surfaces by following a wide variety of different electron exchange pathways. Reviewing the mechanisms identified in the biocorrosion of steels leads us to distinguish direct and indirect mechanisms for biofilm-catalysed cathodic reactions. Indirect mechanisms are due to the production of metal oxides or hydrogen peroxide (aerobic corrosion) or metal sulphides (anaerobic corrosion), which further react with the metal surface. Direct mechanisms involve adsorbed biocompounds, generally enzymes or their active sites, which catalyse the cathodic reduction of oxygen for aerobic biocorrosion or the proton/water reduction in anaerobic processes. Recent studies dealing with the role of hydrogenases in anaerobic corrosion have shed light on the important role of phosphate species via so-called cathodic deprotonation. Advances in the development of microbial fuel cells have also resulted in new concepts, mainly for oxidation processes. Some microbial cells have been shown to be able to produce their own electron mediators. Others can transfer electrons directly to electrodes through membrane-bound electron shuttles or achieve long-range transfer through conductive pili.

The aldol condensation of indane-1,3-dione (ID) to give ‘bindone’ in water is catalysed by an M8L12 cubic coordination cage (Hw). The absolute rate of reaction is slow under weakly acidic conditions (pH 3–4), but in the absence of a catalyst it is undetectable. In water, the binding constant of ID in the cavity of Hw is ca. 2.4 (±1.2) × 103 M−1, giving a ∆G for the binding of −19.3 (±1.2) kJ mol−1. The crystal structure of the complex revealed the presence of two molecules of the guest ID stacked inside the cavity, giving a packing coefficient of 74% as well as another molecule hydrogen-bonded to the cage’s exterior surface. We suggest that the catalysis occurs due to the stabilisation of the enolate anion of ID by the 16+ surface of the cage, which also attracts molecules of neutral ID to the surface because of its hydrophobicity. The cage, therefore, brings together neutral ID and its enolate anion via two different interactions to catalyse the reaction, which—as the control experiments show—occurs at the exterior surface of the cage and not inside the cage cavity.

Abstract Although homogeneous alkali-catalysed transesterification is the typical process used in biodiesel production, it caused complications in downstream separation processes and an oversupply of glycerol as a by-product. The present work studied the synthesis of a novel sulfonated biomass-derived solid acid catalyst and its application in biodiesel production via interesterification of oleic acid. Solid acid catalysts were prepared by direct sulfonation via thermal treatment with concentrated sulfuric acid. The design of experiments was conducted via four-factors central composite design (CCD) coupled with response surface methodology (RSM) analysis. The parameters considered for optimisation included carbonisation and sulfonation temperatures, catalyst loading and reaction time, each varied at five levels. The maximum yield of fatty acid methyl ester (FAME) was obtained using optimum parameters as carbonisation temperature of 586 °C, sulfonation temperature of 110 °C, catalyst loading of 10.5 wt.% and reaction time of 7 h was 54.3 % based on the theoretical ester formation. A quadratic mathematical model in RSM was successfully established that can make effective predictions about the anticipated biodiesel yield. This study proved that the low-cost heterogeneous catalyst derived from biomass waste with a simple production route could catalyse the interesterification process under moderate process conditions.