Catalytic and spectroscopic study of the allylic alcohol synthesis by gas-phase hydrogen transfer reduction of unsaturated ketones on acid–base catalysts

Braun, Fernando; Cosimo, J.I. Di

doi:10.1016/j.cattod.2006.01.026

Cited by 30 publications

(15 citation statements)

References 37 publications

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“…Initially, the reaction would proceed by the C C bond shift in the ␣,␤-unsaturated ketone C12UK a giving C12UK b . Although we did not detect any unsaturated ketone among the reaction products on 8.0CuMgAl, it has to be remarked that in previous works we reported that on similar bifunctional metal-base catalysts, and in the absence of molecular hydrogen, ␣,␤-unsaturated ketones are unstable reaction intermediates that rapidly convert into other products; the C C bond migration is fast and occurs on base sites before the C C bond reduction on a metallic site [9,39,40]. In other words, the base-catalyzed C C bond shift of C12UK a would take place faster than the Cu 0 -promoted C C bond hydrogenation.…”

Section: Effect Of the Reaction Atmosphere And Contact Time Reactionmentioning

confidence: 68%

Liquid transportation fuels from biomass-derived oxygenates: Gas-phase 2-hexanol upgrading on Cu-based mixed oxides

Luggren

Apesteguı́a

Cosimo

2015

Applied Catalysis A: General

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Section: Effect Of the Reaction Atmosphere And Contact Time Reactionmentioning

confidence: 68%

Liquid transportation fuels from biomass-derived oxygenates: Gas-phase 2-hexanol upgrading on Cu-based mixed oxides

Luggren

Apesteguı́a

Cosimo

2015

Applied Catalysis A: General

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“…The selectivity of the MPV reaction to either C=O or C=C hydrogenation is controlled by the catalyst electronegativity, that is, acid–base character . This explains the increasing BAL and BOH formation as the B content increased.…”

Section: Resultsmentioning

confidence: 99%

Fine‐Tuning the Acid–Base Properties of Boron‐Doped Magnesium Oxide Catalyst for the Selective Aldol Condensation

et al. 2016

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Controlled incorporation of dopants into the structure of metal oxide catalysts can be used to fine‐tune their topological, chemical, and electronic properties. Conventional preparation methods (coprecipitation and impregnation) tend to produce materials with a limited extent of chemical interaction between metal oxide and dopant, small pore volume, and disconnected pore structure. Herein, we describe a combustion method to optimize both the porous structure of metal oxides and the chemical interaction with dopants. By exploiting the differences in melting points between metal oxide (MgO) and dopant (B), it is possible to create hierarchical mixed oxides with tailored chemical structure. As a model reaction, we employed the aldol condensation of acetaldehyde to crotyl alcohol, a key intermediate step in the conversion of bioethanol to 1,3‐butadiene, to show the unique characteristics of these materials. The B–Mg mixed oxide prepared by combustion exhibits an order of magnitude higher productivity of C4 products than conventional MgO and B–MgO. We anticipate that our approach could be extended to the development of other dual oxides with open structure for unrestricted diffusion and enhanced chemical interaction of acid and basic metal oxides.

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“…Although unsaturated ketones were not detected among the reaction products, it has to be remarked that in previous works we reported that a,b-unsaturated ketones are unstable reaction intermediates that rapidly convert into other products on similar bifunctional metal-base catalysts. We have shown [9,30,31] that in the absence of molecular hydrogen in the feed, the base-catalyzed C=C bond shift is a fast reaction that competes with the Cu 0 -promoted C=C bond reduction toward C12K, thereby supporting formation of C12UK b . Consecutive base-catalyzed Michael and retro-Michael reactions convert C12UK b in C9K, after which conventional aldol condensation steps lead to C15 and C21 products.…”

Section: Product Distributionmentioning

confidence: 96%

Conversion of Biomass-Derived 2-Hexanol to Liquid Transportation Fuels: Study of the Reaction Mechanism on Cu–Mg–Al Mixed Oxides

2015

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The reaction mechanism of 2-hexanol conversion to high molecular weight compounds to be used as liquid transportation fuels was studied on MgO, Cu/SiO 2 and a bifunctional Cu-Mg-Al mixed oxide with 8 wt% Cu (catalyst 8.0CuMgAl). Catalysts were characterized by several physical and spectroscopic techniques. The evolution of 2-hexanol conversion and yields in inert (N 2 ) and reducing (H 2 ) reaction atmospheres at different contact times (W/F 0 ) was investigated, which allowed distinguishing between primary and secondary products. In H 2 , at W/F 0 = 500 g h/mol, the bifunctional 8.0CuMgAl catalyst yielded more than 90 % of branched C9-C24 oxygenates and hydrocarbons that were obtained via sequential steps comprising dehydrogenation, C-C coupling, dehydration and hydrogenation reactions. The metal-base bifunctional nature of this reaction network on 8.0CuMgAl was elucidated: nano-sized Cu 0 particles promote dehydrogenation and hydrogenation steps whereas Mg-O pairs participate mainly in C-C coupling reactions. The product distribution depended on the reaction atmosphere. In H 2 , the reaction pathways leading to formation of even carbon atom number products (C12, C18 and C24) were favored and hydrocarbons were the main products at high conversion levels. In N 2 , significant amounts of odd carbon atom number products (C9, C15 and C21) were formed with a higher contribution of oxygenates to the product pool.

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Catalytic and spectroscopic study of the allylic alcohol synthesis by gas-phase hydrogen transfer reduction of unsaturated ketones on acid–base catalysts

Cited by 30 publications

References 37 publications

Liquid transportation fuels from biomass-derived oxygenates: Gas-phase 2-hexanol upgrading on Cu-based mixed oxides

Liquid transportation fuels from biomass-derived oxygenates: Gas-phase 2-hexanol upgrading on Cu-based mixed oxides

Fine‐Tuning the Acid–Base Properties of Boron‐Doped Magnesium Oxide Catalyst for the Selective Aldol Condensation

Conversion of Biomass-Derived 2-Hexanol to Liquid Transportation Fuels: Study of the Reaction Mechanism on Cu–Mg–Al Mixed Oxides

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