Roman Klimkiewicz

The role of Lewis acidic centers in stabilized zirconium dioxide

Abstract The physico-chemical properties of ZrO 2 , MgO and admixtured (stabilized) zirconium dioxide are presented. The synthesis of stabilized ZrO 2 was conducted in a low-temperature process. The catalysts obtained on the basis of zirconium dioxide were monophase materials of a regular structure. The lattice parameter of the materials did not differ much from the standard value. The character of the surface active centers was being changed as a result of the admixturing. Synthesized monophase materials of catalytic properties, Zr-Mg-O and Zr-Mg-Y-O, have many strong Lewis centers at surfaces. There appeared not only the stabilization of the regular polymorphous structure of ZrO 2 , but also a modification of catalytic properties of the materials when the basic admixture (MgO and Y 2 O 3 ) was being introduced to basic zirconium dioxide. The authors present a mechanism of alcohol or aldehyde condensation to ketone at the surface of the materials with the participation of Lewis acidic centers.

ZnFe2O4 as a new catalyst in theC-methylation of phenol

This paper reports the investigation ofC-alkylation of phenol with methanol over zinc ferrite as a catalyst. The reactions were carried out in gas phase at atmospheric pressure in dependence of increasing temperature. The total selectivity towardsortho-cresol and 2,6-xylenol over 300°C surpassed 90%. ZnFe2O4 was obtained by oxidative precipitation method from solution of iron (II) sulphate and zinc sulphate at 60°C. Based on the results, the best equation describing the oxidation reaction rate was found. The obtained products have been investigated using X-ray fluorescence spectrometry and X-ray diffraction analysis.

Ru/Fe2O3 catalysts in n-butanol conversion

The activity of iron oxides prepared by different methods and ruthenium catalysts supported on these iron oxides was studied in n-butanol conversion. A correlation between the susceptibility to reduction and the acid-base properties of the supports, prepared from iron oxide-hydroxides of α-, β- γ- and δ-FeOOH types, and their selectivity in the reaction of n-butanol conversion was found. Deposition of ruthenium on the selected supports led to obtaining catalysts of enhanced activity and selectivity towards aldehyde or ester.

Ketonization of long chain esters from transesterification of technical waste fats

The methyl ester mixture obtained from rape oil, and the mixture of butyl esters produced from animal fatty acids, were converted into mixtures of ketones with a total yield above 65%. The experiments were performed at atmospheric pressure in a temperature range of 300-400°C using a standard flow system, with an iron catalyst modified with silicon, chromium, and potassium oxides, in the molar ratio of 100:2:1:0.1. The described method may extend the prospects of using waste technical fats.

Catalytic reactions of oxidized n-C10 derivatives over an iron oxide

Abstract The susceptibility to ketonization of oxidized derivatives of n -decane ( n -decanol, n -decanal, their equimolar mixtures, n -decyl n -decylate, and 3-hydroxy-2-octyl-dodecanal) in the gas phase at atmospheric pressure over Fe 3 O 4 catalyst was studied. Using those reactants, 10-nonyldecanone was the main product. Condensing n -decanal, n -decyl n -decylate, and 3-hydroxy-2-octyl-dodecanal, ketone is obtained with higher yields than from n -decanol.

Vapor-Phase Conversion of Esters into Ketones in the Presence of an Sn-, Ce-, and Rh-Containing Oxide Catalyst

The catalytic conversion of acyclic and cyclic esters into ketones was studied. Based on an analysis of data on the yields of the products of ester conversion, the conclusion was drawn that ketones result from a reaction between two ester molecules with the intermediate formation of a β-ketoester. This reaction is accompanied by the partial thermal decomposition of esters to aldehydes (reverse Tishchenko reaction) with the subsequent condensation.

Formation of long chain ketones over an iron catalyst

Primary aliphatic alcohols, aldehydes, esters, carboxylic acids, and their anhydrides undergo a transformation to ketones with high yield and selectivity. The reactions proceed in a continuous way in the gas phase over an iron catalyst.

Catalytic properties of Sn-Ce-Rh-O in dehydrogenation and oxidative dehydrogenation reactions

A new, single-phase Sn0.925Ce0.07Rh0.005O2 gas sensitive material has up to now been used as a catalyst for the bimolecular condensation of aldehydes and C-alkylation of hydroxyarenes with alcohols. It was subjected to the isopropanol test, the oxidative dehydrogenation of cyclohexane test, and the cyclohexene + H2 test. A general physico-chemical analysis was done, and it included XRD, SEM, mercury porosimetry, TPD NH3, and IR (pyridine) spectroscopy. The tests results are compliant with the basic character of the catalyst; however, it reveals significant total acidity (0.274 mmol NH3/g) and the presence of Lewis strong acid centers (0.126 mmol Py/g). The presence of these centers in the dehydrogenating catalysts cause the ability to catalyze both the bimolecular condensation of aldehydes and C-alkylation of hydroxyarenes with alcohols.

Transformation of methyl laurate to tricosanone-12 over Sn-Ce-Rh-O catalyst

The catalytic conversion of methyl laurate to tricosanone-12 in the gas phase over Sn-Ce-Rh-O catalyst has been studied. The yield of ketone in excess of 62% shows that the new catalyst can be applied to the ketonization of esters. Also long-chain esters can be used as substrates.

Catalytic reactions of pentamethylene and hexamethylene glycols over an iron oxide

Pentamethylene and hexamethylene glycols over a catalyst consisting of iron, silicon, chromium and potassium oxides undergo intramolecular condensation at about 640 K, but considerably different products are obtained: 2,3-dihydropyran and cyclopentanone, respectively. Above 650 K, both glycols undergo intermolecular condensation forming corresponding 5-nonanone and 6-undecanone. Reactions were carried out in a standard flow system under atmospheric pressure in the gas phase.