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Alexis T Bell - One of the best experts on this subject based on the ideXlab platform.
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effect of alcohol structure on the kinetics of Etherification and dehydration over tungstated zirconia
Chemsuschem, 2018Co-Authors: Julie Rorrer, Suresh Pindi, Dean F Toste, Alexis T BellAbstract:Author(s): Rorrer, Julie; Pindi, Suresh; Toste, F Dean; Bell, Alexis T | Abstract: Linear and branched ether molecules have attracted recent interest as diesel additives and lubricants that can be produced from biomass-derived alcohols. In this study, tungstated zirconia was identified as a selective and green solid acid catalyst for the direct Etherification of primary alcohols in the liquid phase, achieving ether selectivities of g94 % for C6 -C12 linear alcohol coupling at 393 K. The length of linear primary alcohols (C6 -C12 ) was shown to have a negligible effect on apparent activation energies for Etherification and dehydration, demonstrating the possibility to produce both symmetrical and asymmetrical linear ethers. Reactions over a series of C6 alcohols with varying methyl branch positions indicated that substituted alcohols (2°, 3°) and alcohols with branches on the β-carbon readily undergo dehydration, but alcohols with branches at least three carbons away from the -OH group are highly selective to ether. A novel model compound, 4-hexyl-1dodecanol, was synthesized and tested to further demonstrate this structure-activity relationship. Trends in the effects of alcohol structure on selectivity were consistent with previously proposed mechanisms for Etherification and dehydration, and help to define possible pathways to selectively form ethers from biomass-derived alcohols.
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Mechanism and kinetics of 1-dodecanol Etherification over tungstated zirconia
Journal of Catalysis, 2017Co-Authors: Julie Rorrer, Ying He, F. Dean Toste, Alexis T BellAbstract:Abstract Growing interest in finding renewable alternatives to conventional fossil fuels and petroleum-derived specialty chemicals has motivated the investigation of biomass-derived alcohols to make ethers as diesel additives or lubricants. To optimize the direct Etherification of long chain alcohols in the liquid phase, it is necessary to develop an understanding of the kinetics and mechanism of Etherification and dehydration reactions. In this study, tungstated zirconia was identified as a selective solid-acid catalyst for the liquid-phase Etherification of 1-dodecanol. Investigations of the mechanism and kinetics of this reaction suggest that cooperation between Bronsted- and Lewis-acid sites on tungstated zirconia enhances the selectivity to ether by increasing the surface concentration of adsorbed alcohol, thereby promoting bi-molecular ether formation relative to unimolecular alcohol dehydration. The suggested rate limiting step for Etherification is the formation of a C O bond between two adsorbed alcohol molecules, and the suggested rate-limiting step for dehydration is the cleavage of the C H bond of the β-carbon atom in an adsorbed alcohol. Measurements of the kinetic isotope effects for Etherification and dehydration support the proposed mechanism. A microkinetic model based on the proposed mechanism for dodecanol Etherification and dehydration over tungstated zirconia accurately describes the observed effects of alcohol concentration and product inhibition.
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biomass conversion to diesel via the Etherification of furanyl alcohols catalyzed by amberlyst 15
Journal of Catalysis, 2014Co-Authors: Eric R Sacia, Madhesan Balakrishnan, Alexis T BellAbstract:Abstract The Etherification of furanyl alcohols produced from biomass-derived glucose and fructose has been a growing area of research for production of alternative diesel additives. We have determined that the Bronsted acidic resin catalyst, Amberlyst-15, is highly active and selective for the Etherification of furanyl alcohols by both ethanol and butanol. The mechanism and kinetics of this reaction were investigated using 5-methylfurfuryl alcohol (MFA) as a probe molecule. Etherification of MFA was found to be first order in both the concentrations of furanyl alcohol and the acid sites. The mechanism of MFA Etherification also holds for the Etherification of 2,5-bis(hydroxymethyl)furan (BHMF) and 5-(hydroxymethyl)furfural (HMF). In the case of HMF, we find that acetalization of HMF precedes Etherification in alcohol solutions. The apparent activation energy of furanyl alcohol Etherification in ethanol and butanol solutions ranged from 17.0 to 26.3 kcal/mol. Electron donation/withdrawal at the 2 or 5 position of the furan ring in addition to solvent polarity was found to have significant effects on the rate of furanyl alcohol Etherification.
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Etherification and reductive Etherification of 5 hydroxymethyl furfural 5 alkoxymethyl furfurals and 2 5 bis alkoxymethyl furans as potential bio diesel candidates
Green Chemistry, 2012Co-Authors: Madhesan Balakrishnan, Eric R Sacia, Alexis T BellAbstract:A low energy intensive process for the production of diesel fuel has been delineated from both 5-(hydroxymethyl)furfural (HMF) and its sugar precursor D-(–)-fructose. Alcoholic solutions of the above produced a mixture of potential bio-diesel candidates namely, 5-(alkoxymethyl)furfural, 5-(alkoxymethyl)furfural dialkylacetal, and alkyl levulinate, in the presence of solid acid catalysts. Sulfonic acid functionalized resins, Amberlyst-15 and Dowex DR2030 showed exceptional reactivity and selectivity for these reactions. Production of another potential diesel candidate 2,5-bis(alkoxymethyl)furan has been optimized through both sequential reduction/Etherification and one-pot reductive Etherification processes. During the metal catalyzed hydrogenation of HMF, platinum showed an exclusive selectivity for the reduction of the carbonyl functionality of HMF. Both Pt and Pt/Sn supported on Al2O3 catalysts have been optimized for the production of 2,5-bis(alkoxymethyl)furan from HMF. The reaction mechanisms of Etherification and reductive Etherification have been discussed in detail on the basis of intermediates observed during these processes.
John F. Knifton - One of the best experts on this subject based on the ideXlab platform.
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Diisopropyl ether one-step generation from acetone-rich feedstocks
Catalysis Letters, 2000Co-Authors: Robert J. Taylor, John F. KniftonAbstract:A one-step integrated process for the generation of the high-octane fuel ether, diisopropyl ether (DIPE), from acetone-rich feedstocks has been demonstrated. Three continuous, downflow, reactor configurations have been considered, including a two-bed catalyst design separated by inerts, gradient multicatalyst combinations, and an integrated two-zone layout with differing catalyst compositions. The bifunctional catalysts have both hydrogenation and Etherification/dehydration capabilities and may comprise groups IB, VIB, and VIII metals incorporated into acidic, large and medium-pore zeolites, groups III or IV metal oxides, as well as heteropoly acid structures. DIPE syntheses are typically conducted at 100–165°C, under hydrogen pressure. The gradient reactor design, with careful choice of hydrogenation and Etherification catalysts, allows DIPE to be generated in high selectivity and productivity.
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Methyl tert-butyl ether synthesis from tert-butanol via inorganic solid acid catalysis
Applied Catalysis A: General, 1999Co-Authors: John F. Knifton, John C. EdwardsAbstract:Three classes of inorganic solid acid catalyst have been demonstrated to be effective for methyl tert-butyl ether (MTBE) syntheses from methanol/fert-butanol (TBA) feed mixtures using a continuous, plug-flow, reactor system. These catalysts include heteropoly acids, such as 12-tungstophosphoric acid and 12-molybdophosphoric acid, on Group III and IV oxide supports, such as titania, HF-treated montmorillonite clays, as well as mineral acid-activated clays. Changes in the structure of the 12-tungstophosphoric acid-on-titania during Etherification service have been investigated using 31P and 1H MAS NMR. An unexpected, in situ, phase separation of the desired MTBE plus isobutene products from aqueous methanol has been observed at high (>80%) tert-butanol conversion levels and operating temperatures ≥160°C. Milder Etherification conditions allow MTBE selectivites to 94 mol% and sustained Etherification activity for the HF/clay catalyst even with crude TBA feedstocks. © 1999 Elsevier Science B.V. All rights reserved.
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C4 alkene separation process using solid acid catalysis
Applied Catalysis A General, 1994Co-Authors: John F. KniftonAbstract:A two-step procedure for separating isobutene from mixed C4 hydrocarbon streams, such as Raffinate-1, has been demonstrated using solid acid catalysis. The procedure involves initial Etherification of the C4 mixture with a suitable aliphatic diol, such as ethylene glycol or 1,2-propylene glycol, to give the corresponding glycol mono-t-butyl ethers, followed by deEtherification of the said monoethers at higher temperatures to yield pure isobutene plus regenerated glycol. Suitable classes of solid acid catalysts include acidified montmorillonite clays and heteropoly acids dispersed on Group IV oxides, such as 12-tungstophosphoric acid on titania. Preliminary Etherification parameter, and catalyst characterization, studies for these two very different classes of strongly acidic catalyst are also detailed herein. © 1994.
Yoshiaki Nishibayashi - One of the best experts on this subject based on the ideXlab platform.
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copper catalyzed enantioselective propargylic Etherification of propargylic esters with alcohols
ChemInform, 2015Co-Authors: Kazunari Nakajima, Masashi Shibata, Yoshiaki NishibayashiAbstract:A copper-catalyzed enantioselective propargylic Etherification of propargylic carbonates with simple alcohols and phenols is developed to provide propargylic ethers in good to excellent enantioselectivities.
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copper catalyzed enantioselective propargylic Etherification of propargylic esters with alcohols
Journal of the American Chemical Society, 2015Co-Authors: Kazunari Nakajima, Masashi Shibata, Yoshiaki NishibayashiAbstract:Enantioselective propargylic Etherification of propargylic esters with not only aliphatic alcohols but also phenols in the presence of a catalytic amount of copper-Pybox complex gives the corresponding propargylic ethers in good to high yields with a high to excellent enantioselectivity (up to 99% ee). The result described here provides the first successful example of enantioselective propargylic Etherification
A. O. I. Krause - One of the best experts on this subject based on the ideXlab platform.
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Etherification over a novel acid catalyst
Studies in Surface Science and Catalysis, 2020Co-Authors: Reetta S. Karinen, A. O. I. Krause, K. Ekman, M. Sundell, Robert PeltonenAbstract:A novel fibrous catalyst, Smopex-101, was tested in an Etherification reaction of C 8 and C 5 alkenes. Compared to a traditionally used Etherification catalyst, Amberlyst 35 ion exchange resin, the novel catalyst indicated better performance especially in reactions with large and branched molecules: the mass transfer limitations had a minor effect and the reaction rate was thus faster.
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New biocomponents from glycerol
Applied Catalysis A: General, 2006Co-Authors: Reetta S. Karinen, A. O. I. KrauseAbstract:Glycerol is a by-product of biodiesel production, for which new uses are being sought. Etherification of glycerol with isobutene in liquid phase with acidic ion exchange resin catalyst gave five product ethers and, as a side reaction, isobutene reacted to C8-C16 hydrocarbons. The effect of the reaction conditions on the system was studied and conditions for optimal selectivity toward ethers were discovered near with isobutene/glycerol molar ratio of 3 at 80 °C. The conditions controlling the distribution of the product ethers were studied and it was found that the extent of the Etherification reaction and thus the main ether products can be changed by varying the reaction conditions. © 2006 Elsevier B.V. All rights reserved.
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Simultaneous Isomerization and Etherification of Isoamylenes with Methanol
Chemical Engineering & Technology, 2003Co-Authors: P. Kiviranta‐pääkkönen, A. O. I. KrauseAbstract:The effect of feed MeOH/2M1B molar ratio on the initial isomerization and Etherification rates of 2-methyl-1-butene (2M1B) was studied in a batch reactor. The initial reaction rates for Etherification and isomerization increased when the MeOH/2M1B molar ratio decreased. The ratio of Etherification and isomerization rate was 2-3 until at lowest initial MeOH/2M1B molar ratio 0.2, where the isomerization rate increased significantly. At MeOH/2M1B molar ratio 0.2 the isomerization reaction rate was twice as high as the Etherification reaction rate. Several kinetic formulations were tested to explain this new data and the data obtained in earlier studies. According to the statistics, a kinetic model based on three active sites gave the best fit, but it was discussed that the basic Langmuir-Hinshelwood mechanism might be more adequate. An improved fit of the Langmuir-Hinshelwood model was obtained, when a correction factor describing the acceleration of isomerization rate with the molar fraction of 2M1B was added into the kinetic equations.
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Etherification of C5- and C8-Alkenes with C1- to C4-Alcohols
Catalysis Letters, 2001Co-Authors: Reetta S. Karinen, Juha Linnekoski, A. O. I. KrauseAbstract:Etherification of two alkenes, 2-methyl-1-butene and 2,4,4-trimethyl-1-pentene, was studied with seven different C1- to C4-alcohols. Although Etherification was of primary interest, the isomerisation of the alkenes was the main reaction to occur. For the primary alcohols the Etherification and isomerisation rates correlated well with the properties of the alcohols. Both rates increased with decreasing polarity and with increasing carbon number, acidity and Mulliken charge of the oxygen atom of the alcohol. It is difficult to distinguish the effect of each property separately, and probably the differences in the reactivities are not due to any one property alone but rather the synergy of the properties affects the reactivities. The secondary alcohols behaved in a different way than the primary ones: the Etherification was almost negligible. The effect of alcohol on the isomerisation of alkenes was notable even though alcohol does not directly react in the reaction, which was concluded to be due to the stronger adsorption of the more polar alcohols which hinders the reactions of other components.
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Simultaneous Isomerization and Etherification of Isoamylenes
Industrial & Engineering Chemistry Research, 1999Co-Authors: Juha Linnekoski, A. O. I. Krause, P.k. Kiviranta-pääkkönen, Liisa Rihko-struckmannAbstract:The Etherification of isoamylenes (2-methyl-1-butene, 2M1B, and 2-methyl-2-butene, 2M2B) with methanol, ethanol, and n-propanol was studied using a commercial ion-exchange resin as a catalyst. The steady-state reaction rates for the formation of tert-amyl ethyl ether from isoamylenes and ethanol were measured in a continuous stirred tank reactor. At 333 K the reaction rate of the ether formation was measured to be zero order with respect to the ethanol (ETOH) and positive with respect to the olefin. Initial reaction rates for the simultaneous Etherification and isomerization of 2M1B were measured in a batch reactor. Initial reaction rates measured at temperatures of 333 and 353 K showed that the different alcohols (methanol, ethanol, and 1-propanol) affected the isomerization rate but not the Etherification rate. Measurements were also made with different initial ETOH/2M1B mole ratios. According to the results, Etherification and isomerization rates are equal until the lowest mole ratio (0.2) is reached. It was also found that the reaction rates have a constant value at stoichiometric or higher ETOH/2M1B mole ratios. A new model was developed to explain the obtained results.
Julie Rorrer - One of the best experts on this subject based on the ideXlab platform.
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effect of alcohol structure on the kinetics of Etherification and dehydration over tungstated zirconia
Chemsuschem, 2018Co-Authors: Julie Rorrer, Suresh Pindi, Dean F Toste, Alexis T BellAbstract:Author(s): Rorrer, Julie; Pindi, Suresh; Toste, F Dean; Bell, Alexis T | Abstract: Linear and branched ether molecules have attracted recent interest as diesel additives and lubricants that can be produced from biomass-derived alcohols. In this study, tungstated zirconia was identified as a selective and green solid acid catalyst for the direct Etherification of primary alcohols in the liquid phase, achieving ether selectivities of g94 % for C6 -C12 linear alcohol coupling at 393 K. The length of linear primary alcohols (C6 -C12 ) was shown to have a negligible effect on apparent activation energies for Etherification and dehydration, demonstrating the possibility to produce both symmetrical and asymmetrical linear ethers. Reactions over a series of C6 alcohols with varying methyl branch positions indicated that substituted alcohols (2°, 3°) and alcohols with branches on the β-carbon readily undergo dehydration, but alcohols with branches at least three carbons away from the -OH group are highly selective to ether. A novel model compound, 4-hexyl-1dodecanol, was synthesized and tested to further demonstrate this structure-activity relationship. Trends in the effects of alcohol structure on selectivity were consistent with previously proposed mechanisms for Etherification and dehydration, and help to define possible pathways to selectively form ethers from biomass-derived alcohols.
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Mechanism and kinetics of 1-dodecanol Etherification over tungstated zirconia
Journal of Catalysis, 2017Co-Authors: Julie Rorrer, Ying He, F. Dean Toste, Alexis T BellAbstract:Abstract Growing interest in finding renewable alternatives to conventional fossil fuels and petroleum-derived specialty chemicals has motivated the investigation of biomass-derived alcohols to make ethers as diesel additives or lubricants. To optimize the direct Etherification of long chain alcohols in the liquid phase, it is necessary to develop an understanding of the kinetics and mechanism of Etherification and dehydration reactions. In this study, tungstated zirconia was identified as a selective solid-acid catalyst for the liquid-phase Etherification of 1-dodecanol. Investigations of the mechanism and kinetics of this reaction suggest that cooperation between Bronsted- and Lewis-acid sites on tungstated zirconia enhances the selectivity to ether by increasing the surface concentration of adsorbed alcohol, thereby promoting bi-molecular ether formation relative to unimolecular alcohol dehydration. The suggested rate limiting step for Etherification is the formation of a C O bond between two adsorbed alcohol molecules, and the suggested rate-limiting step for dehydration is the cleavage of the C H bond of the β-carbon atom in an adsorbed alcohol. Measurements of the kinetic isotope effects for Etherification and dehydration support the proposed mechanism. A microkinetic model based on the proposed mechanism for dodecanol Etherification and dehydration over tungstated zirconia accurately describes the observed effects of alcohol concentration and product inhibition.