Alcohol Dehydration: Mechanism of Ether Formation Using an Alumina Catalyst

Shi, Bingbing; Davis, Brynmor J.

doi:10.1006/jcat.1995.1301

Cited by 125 publications

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“…As expected, an increase in reaction temperature increased ethene selectivity, Figure 2(a), and decreased DEE selectivity, Figure 2(b), ethanol dehydration to ethene is endothermic and to DEE is exothermic. [7,38] Even though the mechanism of DEE formation is still discussed in the literature, for instance, regarding whether it involves acid-base pairs, [39,40] Brønsted acid sites and/or Lewis acid sites, [40] it is understood that DEE formation should involve the reaction of the two nearest chemisorbed ethanol moieties. [41] On the other hand, ethene formation should occur through a concerted mechanism, where the methyl hydrogen of the ethoxide species, chemisorbed on a Lewis [41] or Brønsted acid site, [42] is abstracted by the adjacent Brønsted basic site.…”

Section: Reaction Temperature and Whsv Effectmentioning

confidence: 99%

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO₂ Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

et al. 2016

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Abstract:The conversion of ethanol to 1,3-butadiene (1,3-BD) has been investigated over ZrO2 and ZnO containing magnesia silica oxides prepared by co-precipitation method at different Mg-to-Si molar ratios. The effect of reaction temperature and ethanol flow rate was investigated. The catalyst acidity was modified through the addition of alkali metals (Na, K and Li) to the final materials. Catalysts were characterised by nitrogen physisorption analysis, Xray diffraction, scanning electron microscopy with energy dispersive X-ray, temperature programmed desorption of ammonia, infrared spectroscopy and 29 Si/( 7 Li) NMR spectroscopy. The catalytic results showed that the controlled reduction of catalyst acidity allows suppressing of ethanol dehydration, whilst increasing 1,3-BD selectivity. The best catalytic performance achieved 72 mol % for the combined 1,3-BD and acetaldehyde selectivity.

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Section: Reaction Temperature and Whsv Effectmentioning

confidence: 99%

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO₂ Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

et al. 2016

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“…The dominant surface species for DEE formation are common for all alumina catalysts tested in this report as noted for ethene synthesis kinetics discussed in section 3.2.1.1 above. Following the proposed S N 2-type mechanism for DEE formation 37,38,40,46,56,61 and consistent with the measured pressure dependencies of DEE formation rates on water and ethanol at 573 K on all alumina catalysts, the kinetics of DEE formation are described by the rate expression in eqn (4). (4) k DEE in eqn (4) is the rate constant of the rate determining step of DEE formation and K A1 , K A2 , and K AW represent equilibrium constants for adsorption of an alcohol monomer, alcohol dimer, and alcohol-water dimer, respectively.…”

Section: View Article Onlinementioning

confidence: 96%

Kinetics and mechanisms of alcohol dehydration pathways on alumina materials

Kang

Bhan

2016

Catal. Sci. Technol.

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The steady state rates of ethene and diethyl ether formation in parallel ethanol dehydration reactions at 573 and 623 K are mechanistically and kinetically described by the same rate expression on different alumina materials (α-, γ-, and η-Al 2 O 3 ), implying that alumina materials have similar surface sites under reaction environments. In situ chemical titration using pyridine as a titrant elucidates similar site densities (∼0.12 sites nm −2 and ∼0.07 sites nm −2 for ethene formation and ∼0.14 sites nm −2 and ∼0.09 sites nm −2 for diethyl ether formation on γ-and η-Al 2 O 3 , respectively) on γ-and η-Al 2 O 3 indicating that similar surface features exist on both γ-and η-Al 2 O 3 . Pyridine-ethanol co-feed experiments show that pyridine inhibited the formation of ethene to a greater extent than diethyl ether suggesting that the two parallel dehydration reactions are not catalyzed by a common active site.

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“…10 In addition to the dehydration steps, alumina is known to catalyse dehydrogenation. The propensity of alumina to catalyse dehydrogenation is strongly influenced by the catalyst pretreatment.…”

Section: Acid-catalysed Alcohol Conversionmentioning

confidence: 99%

Upgrading of Fischer–Tropsch Oxygenates

2010

Catalysis in the Refining of Fischer-Tropsch Syncrude

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The oxygenates in Fischer–Tropsch syncrude can be recovered and purified as chemicals, or can be converted into fuels. The main acid catalysed conversion steps of oxygenates are discussed, with particular attention on aldol condensation, dehydration, hydrolysis and carbonyl aromatisation. Oxygenate conversion in the Fischer–Tropsch aqueous and oil products are discussed. The importance of alumina as catalyst for oxygenate conversion in a Fischer–Tropsch syncrude matrix is highlighted and illustrated with examples.

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Alcohol Dehydration: Mechanism of Ether Formation Using an Alumina Catalyst

Cited by 125 publications

References 0 publications

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO₂ Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO₂ Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

Kinetics and mechanisms of alcohol dehydration pathways on alumina materials

Upgrading of Fischer–Tropsch Oxygenates

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Alcohol Dehydration: Mechanism of Ether Formation Using an Alumina Catalyst

Cited by 125 publications

References 0 publications

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO2 Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO2 Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

Kinetics and mechanisms of alcohol dehydration pathways on alumina materials

Upgrading of Fischer–Tropsch Oxygenates

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Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO₂ Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO₂ Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification