Iron-containing defect-rich mixed metal oxides for Friedel–Crafts alkylation

Jäger, Benjamin; Wermann, Antje; Scholz, Peter; Müller, Matthias; Reislöhner, U.; Stolle, Achim; Ondruschka, Bernd

doi:10.1016/j.apcata.2012.07.025

Cited by 8 publications

(4 citation statements)

References 34 publications

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“…In view of this, a catalytic mechanism for the F‐C alkylation reaction between indole and β ‐nitrostyrene in the presence of x %Co−Al 4 B 6 O 15 has been proposed (see Figure 11). [31,32,43] Initially, the Co 2+ sites act as the electron pair acceptor and Lewis acid sites to interact with the nitro group of β ‐nitrostyrene, improving the electrophilic reactivity of the aliphatic carbon atom and accepting the attack from indole ring. Meanwhile, the active oxygen species O ads on the catalyst surface interact with the N−H group of indoles, increasing the nucleophilicity of C3 position and promoting two substrates efficiently close to form the alkylated products [31,32] .…”

Section: Resultsmentioning

confidence: 99%

Co²⁺ to Al³⁺ Substitution Induced Dual‐Site Synergistic Catalysis to Friedel‐Crafts Alkylation Reactions

Yang

Sun

Gao

et al. 2023

Chemistry A European J

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The dual-site synergistic effect in heterogeneous catalysis is quite interesting, and also complex because at least two substrate molecules are adsorbed or activated on the catalyst surface, which apparently needs two spatially separated and functionally independent active sites. It would become more difficult when the substrate molecules are large ones. The replacement of Al 3 + in Al 4 B 6 O 15 lattice with Co 2 + leads to the formation of unsaturated Co 2 + (4-fold coordination) along with oxygen vacancies (O v ). The former one behaves as a medium-strength Lewis acid site, and can adsorb and activate molecules with a nitro group (e. g., βnitrostyrene). The latter one can adsorb and activate oxygen species, which further activates the indole derivatives. Next, the spatially separated dual sites on the catalyst surface can synergistically and efficiently catalyze their Friedel-Crafts alkylation reactions under mild conditions. The high durability can be proved by the as-maintained high yields, that is, 98, 93, 96, 92 and 90 % for 5 runs, respectively. The reaction kinetics obey the second-order characteristic. Annealing under hydrogen condition can further generate more surficial O v , leading to an improvement to the catalytic activity. A simple and probably routine aliovalent doping endows such a complex synergistic catalysis involving two large substrate molecules, providing an inspired perspective of developing dual-site catalysts.

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Section: Resultsmentioning

confidence: 99%

Co²⁺ to Al³⁺ Substitution Induced Dual‐Site Synergistic Catalysis to Friedel‐Crafts Alkylation Reactions

Yang

Sun

Gao

et al. 2023

Chemistry A European J

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“…This suggests that coke may be formed on the surface of the electrodes. The iron spinel oxide provides Lewis acidic sites that have a catalytic activity toward aromatics oxidation and oligomerization [ 32 ]. Iron oxide is more affected by aging and coke formation leading to a reduction of its catalytic activity [ 33 ].…”

Section: Resultsmentioning

confidence: 99%

Development of Potentiometric Sensors for C2H4 Detection

Toldrá‐Reig

Serra

2018

Sensors

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Gas exhaust emissions in vehicles are increasingly restrictive in EU and USA. Diesel engines are particularly affected by limitation in hydrocarbons and NOx concentrations. This work presents a screening of working electrode materials to develop a potentiometric sensor, with the most promising material to detect being C2H4 at 550 °C. The device consists of a dense 8YSZ (8 mol% Y2O3 stabilized ZrO2) disk as oxide-ion conducting electrolyte, whereas platinum is screen-printed in the back face as reference electrode. As working electrode, several materials such as Fe0.7Cr1.3O3, ZnCr2O4, Fe2NiO4, La0.8Sr0.2CrO3−δ (LSC), La0.8Sr0.2MnO3 (LSM), and NiO+5%wt Au were tested to detect C2H4. Sensor voltage was measured for several concentrations of C2H4 and CO as these are two of the major oxidizable compounds in a diesel exhaust gas. Fe0.7Cr1.3O3 was selected as the most promising material because of its response to C2H4 and CO. Not only is the response to the individual analytes important, but the C2H4 cross-sensitivity toward CO is also important. Fe0.7Cr1.3O3 showed a good performance to C2H4, with low cross-sensitivity to CO. In addition, when 0.16 ppm of phenanthrene is added, the sensor still has a slightly better response to C2H4 than to CO. Nevertheless, the sensor exposure to high concentrations (>85 ppm) of polycyclic aromatic hydrocarbons led to signal saturation. On the other hand, the operation in wet conditions induces lower sensor sensitivity to C2H4 and higher cross-sensitivity toward CO increase, i.e., the sensor response becomes similar for C2H4 and CO.

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“…The previous research has already illustrated that temperature was a vital factor for alkylation reaction, and different temperatures could showed different conversions [34,35]. So here the temperature was also deemed to an ingredient to explore.…”

Section: The Effect Of Reaction Temperaturementioning

confidence: 99%

Synthesis of magnetically recyclable MOF-5@SiO2@Fe3O4 catalysts and their catalytic performance of Friedel–Crafts alkylation

Jiang

et al. 2015

J Porous Mater

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Magnetic Fe 3 O 4 particles were synthesized by solvo-thermal method, and then hydrolysis method was used to encapsulate a compact layer of SiO 2 on the surface of Fe 3 O 4 particles. Finally, the magnetic MOF5@SiO 2 @Fe 3 O 4 catalysts were prepared by in situ coating different contents of MOF-5 on the surface of SiO 2 @Fe 3 O 4 particles. The as-synthesized samples were characterized by TEM, SEM, XRD, FT-IR, N 2 adsorption/desorption, VSM and NH 3 -TPD. The catalytic activities of the magnetic MOF-5@SiO 2 @Fe 3 O 4 catalysts for the FriedelCrafts alkylation of toluene with benzyl chloride were evaluated. The results showed that magnetic MOF5@SiO 2 @Fe 3 O 4 catalysts exhibited superparamagnetic property, and could be separated by a magnet from the liquid reaction system. The conversion of toluene was increased gradually with the increase of catalyst contents and reaction temperature, respectively. 97 % conversion of toluene has been achieved by using 26.8 %MOF-5@SiO 2 @Fe 3 O 4 catalyst at 120°C for 6 h. Furthermore, electron-donating group, such as -OCH 3 , and -CH 3 , exhibited positive effect on the alkylation reaction. Besides, the catalyst could be easily separated from the reaction mixture after the reaction and reused for five times without significant decrease in activity.

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Iron-containing defect-rich mixed metal oxides for Friedel–Crafts alkylation

Cited by 8 publications

References 34 publications

Co²⁺ to Al³⁺ Substitution Induced Dual‐Site Synergistic Catalysis to Friedel‐Crafts Alkylation Reactions

Co²⁺ to Al³⁺ Substitution Induced Dual‐Site Synergistic Catalysis to Friedel‐Crafts Alkylation Reactions

Development of Potentiometric Sensors for C2H4 Detection

Synthesis of magnetically recyclable MOF-5@SiO2@Fe3O4 catalysts and their catalytic performance of Friedel–Crafts alkylation

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Iron-containing defect-rich mixed metal oxides for Friedel–Crafts alkylation

Cited by 8 publications

References 34 publications

Co2+ to Al3+ Substitution Induced Dual‐Site Synergistic Catalysis to Friedel‐Crafts Alkylation Reactions

Co2+ to Al3+ Substitution Induced Dual‐Site Synergistic Catalysis to Friedel‐Crafts Alkylation Reactions

Development of Potentiometric Sensors for C2H4 Detection

Synthesis of magnetically recyclable MOF-5@SiO2@Fe3O4 catalysts and their catalytic performance of Friedel–Crafts alkylation

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Co²⁺ to Al³⁺ Substitution Induced Dual‐Site Synergistic Catalysis to Friedel‐Crafts Alkylation Reactions

Co²⁺ to Al³⁺ Substitution Induced Dual‐Site Synergistic Catalysis to Friedel‐Crafts Alkylation Reactions