Surface Species Formed during Aniline Methylation on Zeolite H–Y Investigated by in Situ MAS NMR Spectroscopy

Ivanova, I. I.; Pomakhina, E. B.; Ребров, А. В.; Hunger, Michael; Kolyagin, Yu. G.; Weitkamp, Jens

doi:10.1006/jcat.2001.3300

Cited by 58 publications

(51 citation statements)

References 22 publications

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“…The catalyst is produced by H.C. Starck and applied e.g., by Bayer for the studied reaction. The 5 · 5 mm cylindrical pellets, containing graphite as inert additive, were crushed and sieved to a defined particle size (20)(21)(22)(23)(24)(25) in order to reduce inner particle diffusion limitation. The BET surface area, the pore volume and the average pore diameter were determined by nitrogen adsorption using a Micromeritics Gemini 2375 apparatus after evacuating the sample at 200°C for 2 h. The water content was determined by weight loss after high temperature treatment of the catalyst powder.…”

Section: Catalyst and Materialsmentioning

confidence: 99%

“…Water vapor slows down the reaction not because of a possible backward reaction but due to an inhibiting effect as a strong adsorbent on the niobic acid surface. Based on these kinetic data and considering previous reports on the mechanism [4,24], the following reaction mechanism for aniline ethylation is suggested ( figure 8). …”

Section: Kinetic Modelmentioning

confidence: 99%

“…Lewis acid sites were suggested to catalyze only C-alkylation of aniline. An investigation on aniline methylation over zeolite resulted in the proposal of a similar reaction mechanism [24]. The influence of the acid strength on the regioselectivity of aniline methylation has been investigated by several authors [2,25,26].…”

Section: Introductionmentioning

confidence: 98%

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N-alkylation of aniline with ethanol over an industrial niobic acid catalyst ? influence of water formation on kinetics and selectivity

2005

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The reaction of aniline with ethanol was carried out over an industrial niobic acid catalyst in a fixed bed reactor at atmospheric pressure and 220-260°C. The main products, N-ethylaniline and N,N-diethylaniline were formed consecutively. A kinetic study including a model discrimination between several Hougen/Watson type rate equations led to an Eley/Rideal mechanism, where the reaction of gas phase aniline with adsorbed ethanol is the rate determining step. As second adsorbing agent, water inhibits the reaction in higher partial pressures. N-alkylation was the main reaction observed but the addition of water decreased the selectivity and up to 15% C-alkylated products were found. The apparent activation energies for the first and second N-ethylation are 85.6 and 70.7 kJ/mol, respectively. The high equilibrium constants indicate a nearly irreversible reaction.

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Section: Catalyst and Materialsmentioning

confidence: 99%

Section: Kinetic Modelmentioning

confidence: 99%

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N-alkylation of aniline with ethanol over an industrial niobic acid catalyst ? influence of water formation on kinetics and selectivity

2005

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“…The reaction performed on zeolites with redox properties. Vapour phase alkylation of aniline over zeolites and aluminophosphate depends on acid-base properties and shape selectivity [20]. Selective N, N methylation over zeolites was reported.…”

Section: Introductionmentioning

confidence: 99%

Activity of Aniline Methylation over Fe-Cu-Cr Ternary Spinel Systems

George

Sugunan

2013

Bull. Chem. React. Eng. Catal.

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A series of spinels having the general formula CuCr2-xFexO4 with x = 0.25, 0.75, 1.25, 1.75 were prepared by co-precipitation method. The catalysts were characterized by various physico-chemical methods like XRD, BET, SEM, EDX and TPD. The reaction of aniline with methanol was studied in a fixedbed reactor system as a potential source for the production of various methyl anilines. It was observed that systems possessing low 'x' values are highly selective and active for N-monoalkylation of aniline leading to N-methylaniline. Reaction parameters were properly varied to optimize the reaction conditions for obtaining N-methylaniline selectively and in better yield. Among the systems CuCr1.75Fe0.25O4 is remarkable due to its very high activity and excellent stability. Under the optimized conditions Nmethylaniline selectivity exceeded 91%. CuCr1.25Fe0.75O4 gives better conversion than CuCr1.75Fe0.25O4 in CuCr2-xFexO4 series. The Lewis acid sites of the catalysts are mainly responsible for the good catalytic performance.

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“…As the zeolites exhibited effective catalytic activity to the methylation reaction of some aromatic amines [16,17,[22][23][24], several different zeolites such as H , H-ZSM-5, NaX, NaY, and MCM-41 were chosen to catalyze the reaction of MDA with DMC in order to obtain MBDMA, as shown in Table 1. Disparate catalytic performances were observed.…”

Section: Catalyst Functionmentioning

confidence: 99%

Full N,N-Methylation of 4,4′-Methylenedianiline with Dimethyl Carbonate: A Feasible Access to 4,4′-Methylene bis(N,N-Dimethylaniline)

Qiu

Wang²,

et al. 2018

Journal of Chemistry

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The full N,N-methylation of 4,4 -methylenedianiline (MDA) with dimethyl carbonate (DMC) was investigated. The yield of the major product 4,4 -methylene bis(N,N-dimethylaniline) (MBDMA) reached as high as 97% over NaY catalyst at 190 ∘ C for 6 h. The catalyst could be used for two more times with acceptable MBDMA yields higher than 90%. The main by-products were identified as three N-methylated derivatives. Surprisingly, the formation of the N-methoxycarbonylation product was extremely restrained, which could be produced in high yields of 98% on zinc acetate catalyst. Furthermore, the reaction pathway to the major product MBDMA was proposed. Finally, a feasible synthetic route of 4,4 -methylene bis(N,N-dimethylaniline) (MBDMA) was established, featuring a high yield, mild reaction conditions, and simple operations.

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Surface Species Formed during Aniline Methylation on Zeolite H–Y Investigated by in Situ MAS NMR Spectroscopy

Cited by 58 publications

References 22 publications

N-alkylation of aniline with ethanol over an industrial niobic acid catalyst ? influence of water formation on kinetics and selectivity

N-alkylation of aniline with ethanol over an industrial niobic acid catalyst ? influence of water formation on kinetics and selectivity

Activity of Aniline Methylation over Fe-Cu-Cr Ternary Spinel Systems

Full N,N-Methylation of 4,4′-Methylenedianiline with Dimethyl Carbonate: A Feasible Access to 4,4′-Methylene bis(N,N-Dimethylaniline)

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