J. Kijeński

Ketones from monocarboxylic acids: Catalytic ketonization over oxide systems

The ketonization of acetic acid was studied in the presence of a series of 20 oxide catalysts supported on SiO2, TiO2 and Al2O3. The reactions were performed in the continuous flow reactor. Ceria-and mangania-containing catalysts exhibited the highest activity. The influence of the oxide phase concentration, liquid hourly space velocity and of the type of the catalyst carrier on the acetone yield was determined. Alumina support showed the most pronounced effect on the activity of deposited oxides. High yields of 3-pentanone, 6-undecanone, and 7-tridecanone were achieved in the ketonization of appropriate acids in the presence of mangania and ceria catalysts in large-scale laboratory experiments.

Reduction of alkyl alkyl, aryl alkyl and cyclic ketones by catalytic hydrogen transfer over magnesium oxide

The reduction of a series of alkyl alkyl, aryl alkyl and cyclic ketones by catalytic hydrogen transfer (CTR) from isopropyl alcohol over magnesium oxide has been investigated. CTR over MgO was found to be an effective and selective route to the corresponding methanols. At temperatures above 523 K para-substituted phenylmethanols underwent consecutive dehydration leading to the formation of the corresponding styrene derivatives with satisfying yields. These processes were studied in a flow system working continuously. A long-time stability of the catalyst activity has been demonstrated.

Influence of sodium on the physico-chemical and catalytic properties of magnesium oxide

Physico-chemical and catalytic properties of two series of catalysts comprising magnesia and sodium were determined. The first (I) series of catalysts was prepared by doping magnesia with varying amounts of NaOH. The second (II) series of catalysts was obtained by evaporating metallic sodium onto MgO preparations precalcined at different temperatures.The concentration and strengths of basic and acid sites, as well as the amounts of one-electron donor and one-electron acceptor sites, were measured, and the specific surface areas of the catalysts determined. Catalytic activity in isomerization of pent-1-ene, trans-pent-2-ene and the conversion of cumene was studied. It was concluded that the (II) series of catalysts displayed remarkably strong basic and one-electron donor properties. Also, it was proved that basic sites coexist on the surfaces of catalysts with the one-electron donor sites. Catalytic activity in alkene isomerization and cumene dehydrogenation was unambiguously associated with the presence of well-defined surface active sites.

Selective hydrogenation of α,β-unsaturated aldehydes over Pt catalysts deposited on monolayer supports

Abstract New Pt catalysts deposited on monolayer supports containing TiO 2 have been tested in the hydrogenation of α,β-unsaturated aldehydes. Enhancement of selectivity towards unsaturated alcohols has been observed in comparison to the commonly used Pt/SiO 2 or Pt/TiO 2 catalysts.

Hydrogen Transfer Over MgO. An Alternative Method for Hydrogenation-Dehydro-Genation Reactions

Abstract The possibility of using aliphatic alcohols as hydrogen sources for processes of selective hydrogenation over Mg0 was shown. An attempt to take advantage of hydrogen transfer phenomenon over Mg0 in the selective dehydrogenation of long chain aliphatic alcohols and alkylaromatic hydrocarbons was undertaken. In the reactions examined, magnesia preparations exhibiting dominating two- or one-electron donor properties were used as catalysts. The object of hydrogenation reaction were acrylic, propionic, benzoic, phenylacetic, and cinnamic aldehydes, and also acrylic nitrile, epoxides and aromatic nitrocompounds. Model compounds for dehydrogenation were nonyl, decyl, and dodecyl alcohols, and cumene, p-cymene and 4-t-butyl-ethylbenzene. The hydrogen exchange examined was found to be an effective method for hydrogenation-dehydrogenation of series of industrially significant compounds.

Influence of sodium on the physico-chemical properties of oxides. Part I. Insulators — MgO, Al2O3 and SiO2

The effect of sodium on the surface properties of Al2O3, SiO2 and MgO was studied. Evaporation of sodium onto alumina and magnesia results in the formation of superbasic sites (H−≥35).AbstractБыло исследовано влияние натрия на поверхностные свойства Al2O3, SiO2 и MgO. Испарение натрия на поверхность окиси алюминия и окиси магния приводит к об-разованию суперосновных мест (H−≥35).

On the catalytic system MgO−Na

Acid-base and radical properties of two sets of MgO−Na catalysts have been studied. The catalysts were prepared (I) by impregnation of MgO with NaOH in aqueous solution, and (II) by evaporation of metallic sodium onto a MgO surface. The catalyst prepared by the second method was much more basic than pure MgO (Ho=35) and showed a high activity in olefin isomerization.AbstractБыли исследованы основно-кислотные и радикальные свойства двух серий катализаторов MgO−Na. Катализаторы были приготовлены 1) пропиткой MgO щелогью (NaOH) в водном растворе и 2) за счет испарения металлического натрия на поверхность MgO. Катализаторы, приготовленные вторым методом, были намного более основными, чем чистый MgO(H0=35), и обнаруживали высокую активность к олефиновой изомеризации.

Monolayer vanadia on titania systems from alkoxide precursors. Part I. Physicochemical properties

The physicochemical properties of V5+ ion monolayers supported on anatase, rutile, and anatase-rutile mixed carrier, using vanadyl triisobutoxide as the precursor have been investigated. The coordination and reducibility of surface vanadyl species were found to depend strongly on carrier material and its calcination temperature. The supported monolayers exhibited completely different reduction behavior than bulk V2O5. The rutile supported catalyst was the most resistant for reduction.AbstractИсследовали физико-химические свойства монослоев ионов V5+, нанесенных на анатазу, рутил и смешанных анатазу-рутил, используя ванадил-триизобутоксид в качестве прекурсора. Координация и восстанавливаемость поверхностных ванадильных частиц сильно зависят от материала носителя и температуры кальцинирования. Нанесенные монослои восстанавливаются совсем иначе, чем блочные V2O5. Наиболее устойчивым к восстановлению оказался катализатор, нанесенный на рутил.

Hydrogenation of unsaturated hydrocarbons over alkali-metal-modified zinc oxide

Superbasic catalytic systems have been obtained by evaporation of alkali metals onto a ZnO surface. The catalysts were characterized by IR and EPR spectroscopy. Similar to the case of alkali-metal-doped oxide insulators, surface colour centres Fs+, formed by the trapping of an alkali-atom electron in an oxide anionic vacancy, were identified as the source of the extremely strong one-electron donor properties. The studied catalysts exhibited a much higher activity in the hydrogenation of alkenes than the starting ZnO. A mechanism for propene hydrogenation over the superbasic alkali metal/ZnO system was proposed.

The direct synthesis of alkenylaromatics during catalytic transfer reduction (CTR) of aralkyl ketones with isopropyl alcohol over MgO of enhanced acidity

Abstract The direct synthesis of alkenylaromatics during catalytic transfer reduction (CTR) of aralkyl ketones with isopropyl alcohol over MgO of enhanced acidity has been investigated. Magnesia was successfully modified with H 2 SO 4 and H 3 PO 4 . The studied ketones, acetophenone, 4-isopropylacetophenone, propiophenone, and 5-nonanone, were quantitatively transformed to alkenes under the adopted conditions. A long-time stability of the catalysts activity and reaction selectivity has been demonstrated.