G. Perot

Acylation of phenol with acetic acid over a HZSM5 zeolite, reaction scheme

Abstract The scheme of the gas phase phenol acylation with acetic acid on a HZSM5 zeolite was established from the effect of contact time (hence of conversion) on the product distribution. Phenyl acetate and o -hydroxyacetophenone are primary products, O-acylation being much faster than C-acylation. At high conversion, part of the o -hydroxyacetophenone results from the acylation of phenol with phenyl acetate. The formation of p -hydroxyacetophenone which does not occur through phenol acylation involves the hydrolysis of p -acetoxyacetophenone selectively formed through the autoacylation of phenyl acetate. The ortho -selectivity of phenol acylation can be related to a pronounced stabilization of the transition state while the para -selectivity of phenyl acetate autoacylation could be due to a steric hindrance to the approach of the acetyl group in the ortho -position of phenyl acetate.

Transformation of an alcohol in the presence of a ketone as a model reaction to characterize the acidity and the basicity of oxide catalysts

The reaction of cyclopentanol in the presence of cyclohexanone at 350°C over amorphous solids or zeolites led to alkenes and hydrogen transfer products. It was shown that these products were formed respectively on the acid sites and on the basic sites of the catalysts. Consequently, this reaction made it possible to estimate at the same time the acid and basic properties of the catalysts.

Zeolite catalyzed acylation of heterocyclic aromatic compounds. I—Acylation of benzofuran

Abstract The acylation of benzofuran by acetic anhydride was carried out in the presence of Y zeolites in the liquid phase (60°C, atmospheric pressure). It is shown that the reaction procedure has a significant influence on the activity of the catalyst. Deactivation takes place but the zeolite can be completely regenerated by reactivation in air. A reaction mechanism is proposed in which the acylium ion adsorbed on the zeolite reacts with non activated benzofuran.

Phenol acylation: unexpected improvement of the selectivity to o-hydroxyacetophenone by passivation of the external acid sites of HZSM5

The acylation of phenol by acetic acid on zeolite ZSM5 is unexpectedly oriented towards o-hydroxyacetophenone by dealumination of the outer surface of the crystallites, which can be ascribed to the existence of two different pathways for the formation of o- and p-hydroxyacetophenones.

Effect of hydrogen sulfide on the catalytic hydrodenitrogenation of 1,2,3,4-tetrahydroquinoline. Comparison of NiMo/Al2O3 and CoMo/Al2O3

The hydrodenitrogenation of 1,2,3,4-tetrahydroquinoline was carried out in a flow reactor (350 °C, 35 atm) over CoMo/Al2O3 and NiMo/Al2O3. It is shown that in both cases the addition of hydrogen sulfide to the feed promotes denitrogenation and inhibits hydrogenation.AbstractГидродеазотирование 1,2,3,4-тетрагидрохинолина проводили в проточном реакторе (350°C, 35 атм) на катализаторах CoMo/Al2O3 и NiMo/Al2O3. Показано, что в обоих случаях добавление сероводорода ускоряет деазотирование и ингибирует гидрирование.

Hydrocracking Of N-Heptane On Pt-Hzsm-5. Effect Of Calcination And Reduction Conditions

The temperature of calcination under high air-flow of a Pt-tetrammine-ZSM-5 prepared by competitive ion exchange of HZSM-5 with NH 4 + /Pt(NH 3 ) 4 2+ has a significant influence on the platinum dispersion whereas the temperature of reduction under H 2 has practically no effect. The best metal dispersion was obtained, as was the case with Pt-Y or Pt-X catalysts, for a calcination temperature of about 300°C. This shows that the nature of the support does not modify significantly the decomposition process of the Pt-tetrammine complex. In agreement with the step-by-step process of n-alkane transformation on bifunctional catalysts, the catalyst which is the best dispersed is the most active for n-heptane transformation and the most selective in isomerization.

Zeolite catalyzed acylation of heterocyclic compounds. Part II. Acylation of benzofuran over Y zeolites. Effect of reaction conditions on the activity and stability

Abstract The acylation of benzofuran by acetic anhydride was carried out in the liquid phase (333 K) in the presence of Y-zeolites ( Si Al = 4.8−86 ). The most active zeolites were those with a Si Al ratio ≈ 15 . Adsorption experiments at room temperature were carried out and the product distribution in the material (‘coke’) deposited in the course of the reaction was determined in order to understand the deactivation of the catalyst. Various parameters were found to affect the composition of the deposit especially the reaction procedure which has a drastic influence on the ageing of the catalyst.

Zeolite catalyzed acylation of heterocyclic compounds. Part III. Comparison between benzofuran and 2-methylbenzofuran

Benzofuran and 2-methylbenzofuran were acylated by acetic anhydride in the presence of Y-zeolite as catalyst (60°C, atmospheric pressure) with a 43% and 95% yield respectively.

Effect of the zeolite content on the hydrodenitrogenation of 1,2,3,4-tetrahydroquinoline over sulphided NiMo on alumina catalysts

Abstract The catalytic hydrodenitrogenation of 1,2,3,4-tetrahydroquinoline was studied on nickel and molybdenum sulphides supported on alumina-zeolite mixtures. Different ratios (number of acid sites)/(number of hydrogenating sites) were obtained by varying the weight of the zeolite in the support. The results obtained indicate the existence of an optimal ratio (number of acid sites)/(number of hydrogenating sites), hence of an optimal distance between both types of sites, for which the decahydroquinoline formed on the hydrogenating sites shifts rapidly on the neighbouring acid sites and cracks into the desired reaction product (propylcyclohexane). The corresponding catalyst exhibits a selectivity for hydrodenitrogenation much higher than classical NiMo on alumina catalysts.

On the inhibition of the HDN of anilines due to quinolines

The decomposition of 2,6-diethylaniline pure or mixed with 1,2,3,4-tetrahydroquinoline was studied at 623 K, 7 MPa in a flow reactor with dimethyldisulfide added to the feed. It is shown that 1,2,3,4-tetrahydroquinoline inhibits the decomposition of 2,6-diethylaniline, which inhibition depends on the concentration of the former.