The dehydration of alcohols on alumina: XII. Kinetic isotope effects in the olefin formation from butanols
TL;DR: In this article, the primary kinetic isotope effects of the dehydration from the gas phase of tertiary, secondary and iso-butanol on alumina have been measured in a temperature range between 120 and 230 °C.
About: This article is published in Journal of Catalysis.The article was published on 1970-05-01. It has received 84 citations till now. The article focuses on the topics: Kinetic isotope effect & Chemical reaction.
Citations
More filters
TL;DR: In situ measurements of Bronsted acid sites (by titration with 2,6-di-tert-butyl-pyridine) and reduced centers (by UV-vis spectroscopy) were carried out on WOx-ZrO2 with catalysts at 2.9-32.3 W/nm2 in order to probe how these species form and act as active sites during 2-butanol dehydration as mentioned in this paper.
243 citations
TL;DR: In this article, the acid/base properties of a series of oxide supports (alumina, magnesia and silica) modified by increasing loadings of additive ions (Li+, Ni2+, and SO4 2 ) from 1 to 50% of the support surface coverage is reported using the catalytic test of isopropanol decomposition, studied as a function of the reaction temperature.
Abstract: The evolution of the acid/base properties of a series of oxide supports (alumina, magnesia and silica) modified by increasing loadings of additive ions (Li+, Ni2+, and SO4
2-) from 1 to 50% of the support surface coverage is reported using the catalytic test of isopropanol decomposition, studied as a function of the reaction temperature. The calculated kinetic parameters Ea, A, and ΔS≠ permit interpretation of the reaction mechanism with relation to the acidity/basicity of the modified surfaces. The series of alumina oxides, due to the amphoteric properties of the surfaces, decomposed isopropanol through an E2 mechanism leading to propene and di-isopropyl ether formation. The selectivity to the two products was dependent on the strength of the basicity (addition of lithium and nickel) or on the acidity (addition of sulfate) of the surfaces. Magnesia series oxides dehydrated isopropanol through an E1b mechanism due to the presence of very strong basic surfaces possessing some weak acid sites. The very weak amphoteric character of silica was strengthened by the loading of the three additives; the modified silica surfaces displayed enhanced decomposition activity with respect to pure silica.
178 citations
TL;DR: In this paper, the product distributions and Arrhenius parameters for the zero-order range have been determined for the dehydration on alumina of a series of primary, secondary, and tertiary aliphatic alcohols and for some alicyclic alcohols.
165 citations
TL;DR: In this article, the deoxygenation of methyl octanoate and methyl stearate over alumina-supported Pt was studied in both the vapor phase in a flow reactor and in the liquid phase in the semibatch reactor.
Abstract: The deoxygenation of methyl octanoate and methyl stearate over alumina-supported Pt was studied in both the vapor phase in a flow reactor and in the liquid phase in a semibatch reactor. The conversion of both methyl esters resulted in hydrocarbons with one carbon less than the fatty acid of the corresponding ester as the dominant products. In the vapor phase, acid and other oxygenates were observed in low concentrations, but they were not detected when the reaction was conducted in the liquid phase. Under He, condensation products (from esterification and ketonization) were observed. By contrast, under H2, mostly paraffins were obtained. These results show promise to directly produce standard diesel components from biodiesel.
165 citations
TL;DR: In this article, steady state, isotopic, and chemical transient studies of ethanol dehydration on γ-alumina were conducted and it was shown unimolecular and bimolecular dehydration reactions of ethanol are reversibly inhibited by the formation of ethanol-water dimers at 488 K.
Abstract: Steady state, isotopic, and chemical transient studies of ethanol dehydration on γ-alumina show unimolecular and bimolecular dehydration reactions of ethanol are reversibly inhibited by the formation of ethanol–water dimers at 488 K. Measured rates of ethylene synthesis are independent of ethanol pressure (1.9–7.0 kPa) but decrease with increasing water pressure (0.4–2.2 kPa), reflecting the competitive adsorption of ethanol–water dimers with ethanol monomers; while diethyl ether formation rates have a positive, less than first order dependence on ethanol pressure (0.9–4.7 kPa) and also decrease with water pressure (0.6–2.2 kPa), signifying a competition for active sites between ethanol–water dimers and ethanol dimers. Pyridine inhibits the rate of ethylene and diethyl ether formation to different extents verifying the existence of acidic and nonequivalent active sites for the dehydration reactions. A primary kinetic isotope effect does not occur for diethyl ether synthesis from deuterated ethanol and onl...
156 citations
References
More filters
TL;DR: In this article, a review is given of small deuterium isotope effects, the first approximation for the calculation of the ratio kH/k/sub D/, experimental data, some general and special cases, and the qualitative and quantitative aspects of the theory.
Abstract: A review is given of small deuterium isotope effects, the first approximation for the calculation of the ratio kH/k/sub D/, experimental data, some general and special cases, and the qualitative and quantitative aspects of the theory The theory is discussed in terms of carbon-hydrogen and carbon- deuterium bonds, but will also apply to bonds with other elements and, by a simple extension, to compounds of tritium (PCH)
665 citations