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Showing 1 to 20 of 68 for “"Catalyst activity"”.
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The optimization of the ZSM-5 catalyst activity with respect to crystallinity
… morphology, and acidity can result in optimal activity. Optimal activity is vital in chemical industries due to the fact that it results in higher yields, better selectivities and lower operational costs. In this project the effect of crystallinity on activity is investigated to get a better …
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Thymol synthesis via alkylation of m-cresol with isopropanol the effect of the SiO2/AI2O3 ratio of H-MFI catalysts on catalyst activity and thymol selectivity
This study was performed in context of a series of studies conducted investigating the use of acid zeolites for the synthesis of thymol of selective isopropylation of m-cresol on the 6-position. The aim of this study was to investigate the effect of the SiO2/AI2O3 ration, i.e. the aluminium content …
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The difference in the amount of cracking obtained over silica and over a Houdry pellet catalyst at temperatures from 500 to 1200 ℉
Since careful consideration must be given to the catalyst used in catalytic cracking operation in the petroleum industry to assure economic operation, laboratory catalyst activity test units have been developed. These units approximate the conditions in large scale commercial cracking units. It was …
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Effects of flow on the activity of a WO₃-SiO₂ olefin disproportionation catalyst
… of the effects of the reactant flow rate on the activity of a tungsten oxide on silica catalyst during propylene disproportionation. A 10 percent tungsten oxide on silica catalyst (223 square meters per gram B.E.T. surface area) was used in a microcatalytic reactor. The catalyst activity was …
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Effect of ammonia co-feeding on oxygenates over K-Mo2C in the Fischer-Tropsch synthesis
… conditions employed, commercial Fe and Co based catalysts have been shown to produce between 6 and 12 C% oxygenates. Rh has been shown to have a high oxygenate selectivity, but the associated high raw material cost becomes prohibitive for use as a commercial FT catalyst. Catalysts other than the …
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An investigation of phase transfer catalysis employing quantitative structure-activity relationships
The application of quantitative structure activity relationships to phase transfer catalysis (PTC) has been explored. The primary focus was on hydroxide-initiated PTC reactions, such as enolate alkylations. The tandem [4+2]/[3+2] cycloaddition of nitroalkenes was applied as the key transformation …
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On-line economic optimization of a chemical reactor
… parameter changes include the decay of reaction catalyst activity. The optimizing controller will function in conjunction with various operating policies including control to maintain a specified production rate"--Abstract, page ii.
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Engineering gas diffusion electrodes for electrochemical carbon dioxide upgrading
… analytical cells have been used to study catalyst activity, selectivity, and stability with a goal of incorporating proven materials into larger devices. However, it has been recognized that the limited CO₂ flux through bulk volumes of liquid electrolyte limit the effective reaction rate …
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Phase transfer catalysis: catalyst screening, reaction development, and mechanism analysis
… PTC (APTC) alkylation, a small library of catalysts derived from Cinchona alkaloids was examined for selectivity and activity. An array of substituent modifications were tested, examining the role of steric and electronics on catalyst activity. Catalysts that contained large substituents …
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Improving selectivity in electrochemical CO₂-to-fuels catalysis : the role of catalyst mesostructure, surface structure, and electrolyte
… on methods to measure a basic property of electrocatalysts that enables studies on the origin of catalyst activity and that allow for systematic comparisons of catalyst activity: the electrochemical surface area. Using double layer capacitance measurements in aprotic electrolytes and atomic force …
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Bubbling to turbulent regime transition in a 2D catalytic fluidized bed reactor
… catalytic fluidized bed reactor. Commercial FCC catalyst impregnated with Fe2O3 was used at superficial gas velocities ranging between 0.006 m/s and 0.55 m/s. The onset velocity of the turbulent regime (uc) was determined as 0.4 m/s. The catalyst activity was optimized so that the effect of …
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Deactivation and regeneration of immobilized titanium dioxide photocatalysts during treatment of pharmaceutical micropollutants in groundwater
… in short-term batch experiments using fresh catalysts in laboratory solutions devoid of non-target constituents that are often abundant in natural water matrices (e.g., Ca2+, HCO3-, natural organic matter). In this contribution, we describe the results of an investigation of the long-term …
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Die metatesepolimerisasie van alkyne
… molybdenehexacarbonyl and different phenolic cocatalysts via catalytic polymerization. The reaction was monitored using a gaschromatographic method. The structural and morphological entities of polyphenylacetylene as well as the role of the different cocatalysts on the proposed metal carbene …
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Design, Synthesis and Catalytic Evaluation of Mono- and Polynuclear Organometallic Materials as Hydroformylation Catalysts
… selective and recyclable rhodium-based catalysts. The strategies of introducing hydrophilic substituents, multiple active sites and bulky dendritic ligands are currently explored to enhance catalyst performance and recyclability. This study investigated the synthesis, characterisation …
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Rational Catalyst Design for Direct Conversion of CH4 and CO2
… pathways over active centers on heterogeneous catalysts needs to be advanced. To that end this work focused on initiating the development of a bifunctional catalyst for low-temperature: 200C - 450C) direct conversion of methane and carbon dioxide by tailoring the structure of each active …
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The application of novel multinuclear catalysts derived from dendrimeric ligands in the polymerization and oligomerization of unsaturated hydrocarbons
… of the dendritic complexes were evaluated as catalyst precursors in the oligomerization of α-olefins such as ethylene and 1-pentene, using aluminium alkyls such as EtAlCl2 and modified methylaluminoxane (MMAO) as activators. All the dendrimeric catalysts evaluated are active in the …
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Mechanistic studies on palladium-catalyzed carbon-nitrogen bond forming reactions
Precatalyst species present in a solution of Pd₂(dba)₃ and Xantphos were identified as Pd(Xantphos)(dba) and Pd(Xantphos)₂ by use of ³¹p NMR and independent syntheses. Pd(Xantphos)₂ was found to form at high ligand concentrations. To determine whether the formation of this species affected reaction …
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Synthesis and application of sterically flexible and water-soluble phosphine ligands in palladium catalysis
… such as the neopentyl and benzyl groups on catalyst activity, particularly for the Suzuki coupling of sterically hindered substrates. I have also synthesized two new water-soluble phosphine ligands that utilize two sterically hindered, electron-rich alkyl groups (di-tert-butyl or …
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Friedel-crafts acylation reactions using heterogeneous catalysts stimulated by microwave radiation
… acid were prepared. Characterisation of the catalysts using pyridine adsorption revealed the catalysts contained both Brønsted and Lewis acid sites. When the catalytic activities for the acylation of toluene and anisole were studied there was found to be a correlation between the Brønsted …
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Acid-base catalysts for polycondensation of acetaldehyde in flow
… a polycondensation reaction over two acid-base catalysts, pelletized Evonik P25 TiO₂ and an activated hydrotalcite-like compound (HTlc), to produce high molecular weight molecules in the transportation fuel range. The catalytic performance of these materials is evaluated in a gas phase, …
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