C. Bezouhanova

Cyclohexanol conversion as a test of the acid-base properties of metal oxide catalysts

Cyclohexanol conversion on oxide catalysts is proposed as a test for the acid-base properties of oxide catalysts. The quantity of cyclohexene formed reflects the existence of Broensted acid sites. The dehydrogenation to cyclohexanone might be related to basic sites if at least one proton is released from the organic molecule. In some cases dehydrogenation to phenol occurred.

Synthesis of aromatic ketones in the presence of zeolite catalysts

Abstract The synthesis of aromatic ketones containing benzene ring, naphthalene ring or aromatic heterocycle in the presence of zeolite catalysts has been discussed. The replacement of the classical acid catalysts mainly AlCl 3 or HF by a zeolite diminishes the environmental problems. Different acylating agents are used acid chlorides, anhydrides or carboxylic acids. The mechanism of the acylation in the presence of zeolite catalysts is supposed to include acylium cation as electrophilic species. BEA zeolite is most studied.

Alkylation of phenol with methanol over Mn3O4

Abstract Vapour-phase alkylation of phenol with methanol was carried out in a fixed-bed flow reactor over manganese manganic oxide Mn 3 O 4 catalyst, obtained by the decomposition of hydroxycarbonate. The influence of the temperature, the contact time and the molar ratio of methanol-to-phenol on the yields of o -cresol and 2, 6-xylenol have been examined. The participation of basic sites in phenol alkylation has been suggested.

Zeolite catalysts for pinacol rearrangement

Abstract The dehydration of 2,3-dimethyl-2,3-butanediol (pinacol) on LaHY, CaHY and HZSM-5 zeolites has been investigated in the temperature range 393–438 K in solvent-free liquid phase. The formation of pinacolone (3,3-dimethyl-2-butanone) and of 2,3-dimethyl-1,3-butadiene was observed. The higher activity of Y faujasites was followed by considerable deactivation, while that of HZSM-5 remained constant.

Methylation of 2-naphthol over molecular sieves

The mesoporous molecular sieves of the type MCM-41 with different pore openings (40, 64 and 80 Å) were used as catalysts in the gas-phase methylation of 2-naphthol by methanol at 473 K. Their catalytic activity was compared with that of BEA, SAPO-5 and SAPO-11. The molar ratio of 2-naphthol : methanol was varied from 1 : 4 to 1 : 6. The alkylation of the hydroxyl group (O-alkylation) as well as of the aromatic ring (C-alkylation) proceeded. The best yield of 2-methoxynaphthalene was achieved using MCM-41 40 Å and molar ratio 2-naphthol : methanol = 1 : 6.

IR study of 1-hexene isomerization on HZSM-5 zeolites

In the IR spectra of 1-hexene adsorbed on HZSM-5 zeolites with different Si/Al ratios, a new band at 1510 cm−1 has been observed. The cis/trans-2-hexene and trans-2-hexene/1-hexene ratios were determined.AbstractВ ИК спектрах 1-гексена, адсорбированного на цеолитах типа HZSM-5 с раэными соотношениями Si/Al, наблюдалась новая полоса при 1510 cm−1. Были определены соотношения цис/транс-2-гексен и транс-2-гексен/1-гексен.

Selective cyclodehydration of diols on zeolites

Abstract1,4-Butanediol, 2,5-hexanediol and 1,5-pentanediol were selectively converted to tetrahydrofuran and tetrahydropyran in the presence of LaHY, CaHY and H-ZSM-6 zeolites. The advantage of these zeolites is in their high stability and faster regeneration.

I.r. study of the interaction of n-butanols with HZSM-5 zeolites

The interaction of 1- and 2-butanol with HZSM-5 zeolites with different Si/Al molar ratios was studied in the temperature range 298–473 K by means of i.r. spectroscopy. The dehydration of the alcohols was accompanied by isomerization of the formed olefins. The ratio between the isomers was estimated by the integral intensity of the i.r. bands. The results were explained on the basis of intermediate carbenium ion formation.

Dehydrogenation of Alcohols on H ZSM 5 Zeolites

The dehydration and dehydrogenation of alcohols on H ZSM 5 zeolites with different ratios Si/Al has been studied at 473–673 K in a flow reactor and by IR spectroscopy. The corresponding carbonyl compounds formed easily from cyclohexanol and from unsaturated allylic alcohols, while only dehydration occurred in the case of the isomeric propanols and butanols. The role of the basic sites in the dehydrogenation as well as the geometric factor is discussed.

Infrared study of cyclohexanol chemisorption in SAPO molecular sieves

The infrared spectra of cyclohexanol adsorbed on SAPO molecular sieves (four SAPO-5 samples with different SiO2 contents, SAPO-11 and SAPO-31 were studied) show bands due to cyclohexanone (1732 cm–1) at room temperature, while on heating cyclohexene is formed. The results are discussed in terms of the existence of basic sites parallel to the Bronsted acid sites.