Dehydration of ethyl lactate over alkaline earth phosphates: Performances, effect of water on reaction pathways and active sites

Blanco, Élodie; Lorentz, Chantal; Delichère, P.; Burel, L.; Vrinat, M.; Millet, J.M.M.; Loridant, S.

doi:10.1016/j.apcatb.2015.07.005

Cited by 21 publications

(22 citation statements)

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“…Based on the previous characterizations of the BaOP catalyst 11,12 and on the fact that Ca and Ba are expected to have similar properties being both alkaline-earth elements, we selected the Brushite, a well-known layered calcium hydrogen orthophosphate dihydrate, [26][27][28] to model the amorphous layer lying over the catalyst crystallites. In solution, Brushite forms thin hexagonal platelet.…”

Section: Dft Computational Detailsmentioning

confidence: 99%

Acidic Properties of Alkaline-Earth Phosphates Determined by an Experimental-Theoretical Approach

Blanco

Couble

et al. 2019

J. Phys. Chem. C

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Alkaline-earth phosphates efficient in the dehydration of lactic acid to acrylic acid were previously shown to contain a surface mono/dihydrogen phosphate amorphous layer composed of M 2+ cations and both PO and POH groups. In this work, acidic properties of such a layer were determined combining Fourier transform infrared (FTIR) spectra achieved at the dehydrated state and under water vapor and density functional theory (DFT) simulations of nondefective and defective MPOH structure. The FTIR spectra of adsorbed pyridine and lutidine revealed the presence of moderate Lewis acid sites (LAS) and of POH groups interacting by H-bonding without significant protonation. DFT calculations were key to interpret FTIR spectra after adsorption of NH 3 : when solely adsorbed, NH 3 interacts with the LAS on both the nondefective surface and the defective surface, whereas the POH for which H points up toward the gas phase are reoriented downward. Brønsted acid sites (BAS) were shown to form under water vapor. This phenomenon was shown by DFT to arise from a more acidic character of HPO 4 2− species for the nondefective surface and casual formation of nondefective surface leading to higher amount of H 2 PO 4 − species, which are more acidic BAS.

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Section: Dft Computational Detailsmentioning

confidence: 99%

Acidic Properties of Alkaline-Earth Phosphates Determined by an Experimental-Theoretical Approach

Blanco

Couble

et al. 2019

J. Phys. Chem. C

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“…12,14−16,19−22,24,25 Moreover, it is well known that the vapor-phase catalytic conversion of lactates to AA proceeds selectively over various heterogeneous acid catalyst systems. 6,25,42−48 To provide evident insights into the roles of LA, lactate, acrylate, and propionate salts in the catalytic pathway of dehydration of LA to AA, we monitored the chemical behavior of LA and C 3 H 5 KO 3 on SiO 2 and SiO 2 -Al 2 O 3 (36) and the reactivities of LA with C 3 H 3 KO 2 and C 3 H 5 KO 2 on KBr and SiO 2 -Al 2 O 3 (36) under flowing N 2 at different temperatures by transmission IR spectroscopy.…”

Section: Results and Discussionmentioning

confidence: 99%

In Situ-Generated Supported Potassium Lactate: Stable Catalysis for Vapor-Phase Dehydration of Lactic Acid to Acrylic Acid

et al. 2019

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We have studied unsupported, silica gel- and amorphous silica–alumina-supported catalysts derived from K salts for the vapor-phase dehydration of lactic acid (LA) to acrylic acid (AA). A catalytic study shows that the supported catalysts improve the activity and selectivity for the production of AA and decrease the selectivity for the production of propionic acid (PA). The silica–alumina-supported catalysts remain fairly stable in the catalytic performance during 90 h of reaction. The IR spectroscopic characterization combined with the catalytic study demonstrates that potassium lactate (C 3 H 5 KO 3 ) in situ generated from LA and a K salt is an important reaction intermediate for the production of AA and the catalytic stability is associated with the chemical stability of C 3 H 5 KO 3 and the activity for the regeneration of C 3 H 5 KO 3 in the catalytic cycle. On silica–alumina, C 3 H 5 KO 3 is well stabilized and smoothly regenerated during the reaction, leading to the good catalytic stability. This work suggests for the first time that lactate salt acts as the true catalytic active species for the dehydration of LA to AA. We also propose a predominant reaction pathway for the vapor-phase dehydration of LA to AA with K salt catalyst systems.

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“…After butyl acrylate and ethyl acrylate, methyl acrylate is the third most important acrylic ester with a worldwide annual production of about 200,000 tons per year [91]. The alkaline earth phosphates have been prepared and evaluated in the gas phase dehydration of ethyl lactate to acrylic acid and ethyl acrylate [92]. However, zeolites are much more promising materials for biomass conversion into lactates and acrylates.…”

Section: State-of-art Of Actual Research Of Obtaining Acrylic Acid Anmentioning

confidence: 99%

Concepts of modern technologies of obtaining valuable biomass-derived chemicals

2018

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Dehydration of ethyl lactate over alkaline earth phosphates: Performances, effect of water on reaction pathways and active sites

Cited by 21 publications

References 50 publications

Acidic Properties of Alkaline-Earth Phosphates Determined by an Experimental-Theoretical Approach

Acidic Properties of Alkaline-Earth Phosphates Determined by an Experimental-Theoretical Approach

In Situ-Generated Supported Potassium Lactate: Stable Catalysis for Vapor-Phase Dehydration of Lactic Acid to Acrylic Acid

Concepts of modern technologies of obtaining valuable biomass-derived chemicals

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