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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 16 of 16 for “"surface acidity"”.
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Influence of Molecular Orientation and Surface Coverage of w-Functionalized Mercaptans on Surface Acidity
… the orientation of the functional group has on surface acidity. 3-dodeycloxymercaptophenol and 4-dodecyloxymercaptophenol differ in that the hydroxyl group is substituted on different carbons of the benzene ring. The difference in substitution patterns should present the hydroxyl group in …
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The inertisation of the zeolites ZSM-5, mordenite and beta by chemical vapour deposition using tetraethoxysilane
… within the channel system. However, the external surface of zeolites is accessible to all molecules and behaves in a non-shape selective manner. Coke formation on the external surface of zeolites may prevent access to the channel system of the zeolite due to pore blocking. It would thus be of …
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A multi-technique approach to characterise acidic surface properties of microporous catalysts
… to arrive at petrochemical products. Thus, surface acidity in zeolites is crucial to understand to tune parameters such as activity and selectivity of zeolite catalysts to optimize product distributions. The objective of this dissertation was to validate the use of non-invasive nuclear …
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ΡΥΘΜΙΣΗ ΤΩΝ ΕΠΙΦΑΝΕΙΑΚΩΝ ΦΟΡΤΙΩΝ ΚΑΤΑΛΥΤΙΚΩΝ ΦΟΡΕΩΝ ΜΕ ΤΗ ΧΡΗΣΗ ΤΡΟΠΟΠΟΙΗΤΩΝ
… FORREGULATING THE ZERO POINT OF CHARGE (ZPC), SURFACE ACIDITY CONSTANTS AND THE CONCENTRATION OF THE CHARGED SURFACE GROUPS, DETERMINED POTENTIOMETRICALLY, OVERA WIDE PH RANGE. THE ADSORPTION OF IONIC SPECIES CONTAINING THE CATALYTICALLY ACTIVE IONS MO(VI), CO(II) AND NI(II), ON THE SURFACE OF …
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Development of zeolite based acid catalysts for the synthesis of methyl tertiary butyl ether
… such disadvantages. However, they did not show a surface acidity which is as high as that of the organic resin. In gas phase synthesis of MTBE, the incorporation of an organic superacid trifluoromethanesulfonic acid onto the zeolite surface have shown an important enhancement in catalytic activity …
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The oligomerization of propene over nickel synthetic mica-montmorillonite
… of NiSMM is attributed to an increase in the surface acidity of the catalyst. The maximum activity over the nickel exchanged catalyst occurs at a nickel loading of 0.057 wt %. It is proposed that the bond strength of the acidic hydroxyl groups are perturbed by the polarizing effect of the …
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Supramolecular templating of mesoporous zirconia-based nanocomposite catalysts
… interest in acid catalysis because its surface acidic properties can be flexibly tailored. However, the zirconia-based materials typically have low surface areas and poorly controlled textural properties. This thesis reports on the design and synthesis of nanostructured zirconia-based …
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Fading of carbonless copying paper
… displaced readily by water vapour. When a high surface acidity was kept, the zwitterion was more resistant to displacement, the humidity and any exchanged cations being important factors. Prolonged exposure to light causes fading of the zwitterion, the products from which are mainly demethylated …
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Catalytic and adsorbent properties of solid acid catalysts studied by ammonia adsorption microcalorimetry
… within the chemical industry and their acidity is of great interest, as this determines their application, plus many of their catalytic properties can also be directly related with their acidity. There has been a drive towards heterogeneous solid acid catalysts because of the …
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Environmental impact of heavy metal pollution in natural aquatic systems
… from different adsorption systems, and type of surface sites present. The experimental data of metal adsorption is described by Langmuir adsorption model. The adsorption data are also expressed in terms of surface loading, surface acidity, adsorption density, and affinity of soils for heavy …
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Toxic Gas Sensing on Nanoporous Carbons
… graphene-based sensors. The applied specific surface chemical modifications were an effective means to control the type of the charge carriers (electrons or holes), and thus the electronic and transport properties. The mechanism of the reversible sensing was governed by several processes …
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Catalytic Reforming of Biogas for Syngas Production
… alumina catalyst support, which increases the surface acidity, poisons the water-gas shift reactions by replacing basic hydroxyl groups, and poisons the dry reforming reaction by reducing hydrogen mobility and the affinity of CO₂ for the alumina support. CH3Cl also likely competes and reacts …
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A study of aromatic cyclodehydration, I. Ortho effects II. The catalytic effect of metal oxides
… the hydroxy group. A study of the use of solid surfaces in aromatic cyclodehydration was made using 4'-chloro-2-benzylbenzophenone as a model compound. Experiments with a large number of solids brought to light two factors which seem to contribute to the ability of a surface to catalyze the …
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Spectroscopy as a tool for the management of soil acidification
Globally, soil acidity is a significant problem for crop production. It affects both surface and subsurface soils, reduces availability of essential nutrients, increases aluminium toxicity generating yield losses and reduces productivity in agricultural crops. While lime (CaCO3) application is an …
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Fast microwave-assisted thermochemical conversion of biomass for biofuel production
… to determine the structure, reducibility, and surface acidity of the catalysts. Experimental results show that the zeolite type had great influence on the activity, selectivity and stability of the bifunctional catalyst during the syngas-to-DME process. Zeolite properties including density of …
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Mechanistic and spectroscopic methods for identifying reactive intermediate structures and active site properties over metals, metal oxides, and metal phosphides
… correlate different catalyst properties (e.g., surface acidity, hydrophobicity, cluster size) under reaction conditions with changes in rates and selectivity. Here, we describe how the combination of kinetic measurements, density functional theory (DFT) calculations, and in situ spectroscopic …