First row transition metals on the ethanol Guerbet reaction: Products distribution and structural behavior of mixed metal oxides as catalysts

Metzker, Gustavo; Vargas, Jorge Andrés Mora; Lima, Livia Padilha de; Perrone, Olavo Micali; Siqueira, Marcos Rechi; Varanda, Laudemir Carlos; Boscolo, Maurício

doi:10.1016/j.apcata.2021.118272

Cited by 12 publications

(16 citation statements)

References 67 publications

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Section: Resultsmentioning

confidence: 99%

“…SS-NMR measurements involving 29 Si CP/MAS and 27 Al DP/MAS were employed to scrutinize the geometric/chemical changes in specific atoms in close proximity. First, 29 Si CP/ MAS NMR measurement was used to assess the distribution of silanol functionality on silica. Figure 2b shows that chemical shifts centered at −90, −100, and −111 ppm, representing geminal silanol (denoted as Q 2 ), single silanol (Q 3 ), and tetrahedral siloxane (Q 4 ), respectively, are observed in the spectra of pristine SiO 2 .…”

Section: Resultsmentioning

confidence: 99%

“…The binding energy shift was corrected by using the C 1s peak at 284.6 eV, and the XPS spectra were fitted by a Lorentzian function. 29 Si cross-polarized/magic angle spinning nuclear magnetic resonance ( 29 Si CP/MAS NMR) spectra were recorded on a Bruker AV400 spectrometer equipped with a 4 mm double resonance probe in the magnetic field of 9.4 T. In this field, the Larmor frequency of the 29 Si nuclei is 79.46 MHz. The catalyst was packed into a 4 mm zirconium MAS rotor, and the spectra were acquired at a spinning speed of 12 kHz.…”

Section: Methodsmentioning

confidence: 99%

“…For the spectra, we used the Hartmann−Hahn transfer technique with proton decoupling during acquisition to enhance the spectral sensitivity. The contact time for 29 Si CP/MAS was 2 ms with 4 s of recycle delay time, and the 90°pulse width for 1 H excitation was 2.7 ms. All 29 Si spectra chemical shifts were externally referenced to tetramethylsilane (TMS) at 0 ppm. 43 27 Al direct-polarization/magic angle spinning nuclear magnetic resonance ( 27 Al DP/MAS NMR) spectra were obtained on a Bruker AV300 spectrometer equipped with a 4 mm o.d.…”

Section: Methodsmentioning

confidence: 99%

“…Figure 2. Spectra of pristine SiO 2 and HTO/SiO 2 -X nanocomposite materials: (a) FTIR; (b)29 Si CP/MAS NMR and27 Al DP/MAS NMR spectra of (c) as-synthesized HT and HT/SiO 2 -X; (d) calcined HTO and HTO/SiO 2 -X.…”

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confidence: 99%

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Silica-Supported Nanoscale Hydrotalcite-Derived Oxides for C4 Chemicals from Ethanol Condensation

Kumar

et al. 2022

ACS Appl. Nano Mater.

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We demonstrated that the surface nature of nanoscale hydrotalcite-derived oxide (HTO) can be simply tailored through the addition of amorphous silica during the coprecipitation process of material preparation. The change in physical/chemical properties of the modified surface has been carefully scrutinized by a series of surface characterization techniques. The results showed that the HTO nanocomposite has molecular interactions with amorphous silica to form ternary Mg, Al, and Si interfaces, in accordance with enhancing chemically accessible aluminum (Al 3+ tetra ) as acidic sites. Moreover, the silica-supported HTO (HTO/SiO 2 -X) could catalyze ethanol condensation to foster C4 chemicals at 250 °C through the flow reactor. HTO with a strong basic nature promoted 1-butanol production (66% selectivity), while HTO/SiO 2 -5 with more well-distributed acidic sites favored 1,3-butadiene production (43% selectivity). This difference in catalytic performance could be attributed to the redistribution of acidic and basic sites upon the newly formed ternary interfaces, which could facilitate the surface-mediated Meerwein−Ponndorf−Verley (MPV) reduction reaction due to the relatively high ethanol affinity.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Silica-Supported Nanoscale Hydrotalcite-Derived Oxides for C4 Chemicals from Ethanol Condensation

Kumar

et al. 2022

ACS Appl. Nano Mater.

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The Mechanism of Guerbet Reaction by Metal Ligand Cooperation Catalyst Mn‐PCP

Chen,

Zhou,

Yang

et al. 2024

Chemistry A European J

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The Guerbet reaction is important for the synthesis of longer‐chain monoalcohols like isobutanol through catalytic transfer hydrogenation from short‐chain methanol and ethanol. However, the mechanism becomes complicated, especially considering the variations in the different metal‐ligand cooperation (MLC) catalysts used. In order to further understand the Guerbet reaction, DFT studies were performed to figure out the detailed mechanism initiated by the unique Mn‐PCP MLC Catalyst. Our results suggest that even with the assistance of the carbanion site of the PCP ligand, the direct substitution mechanism is less favored than the condensation‐reduction mechanism. The key step of the reaction is the final reduction of the carbonyl, in which the 1,4‐reduction of the unsaturated aldehyde is prior to the 3,4‐reduction or 1,2‐reduction due to the stronger interaction between the catalyst and the substrate. It is found that the production of isobutanol is preferred over n‐butanol because of the lower total free energy barrier and lower relative free energy of the product. Finally, by changing the electronic effect of the carbanion site of the catalyst, we found that the relation between the electronic effect and the highest free energy span was not monotonous and a point with optimal electronic effect exists numerically.

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Recent Advancement of 3d Metal-Catalyzed Ethanol Upgradation via the Guerbet Reaction

Mandal,

Pal,

Choudhury

2023

Dehydrogenation Reactions With 3d Metals

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First row transition metals on the ethanol Guerbet reaction: Products distribution and structural behavior of mixed metal oxides as catalysts

Cited by 12 publications

References 67 publications

Silica-Supported Nanoscale Hydrotalcite-Derived Oxides for C4 Chemicals from Ethanol Condensation

Silica-Supported Nanoscale Hydrotalcite-Derived Oxides for C4 Chemicals from Ethanol Condensation

The Mechanism of Guerbet Reaction by Metal Ligand Cooperation Catalyst Mn‐PCP

Recent Advancement of 3d Metal-Catalyzed Ethanol Upgradation via the Guerbet Reaction

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