Anna Basińska

The behaviour of Ru/Fe2O3 catalysts and Fe2O3 supports in the TPR and TPO conditions

Abstract The texture of Fe 2 O 3 support and Ru/Fe 2 O 3 catalysts supported on iron oxides obtained from β-FeOOH (B) or δ-FeOOH (D) and their catalytic activity in WGSR were studied. Also their susceptibilities to reduction and reoxidation, were studied by TPR, using H 2 or CO and TPO methods. In the case of TPR CO the composition of the reducing mixture containing traces of H 2 O enabled investigation of water gas shift reaction (WGSR). The catalysts from series D were found more readily reducible and oxidised than those from series B. The supported ruthenium enhanced the redox effects and caused the appearance of additional effects related directly to its presence. Depending on the kind of support and on ruthenium presence considerable differences in temperatures of WGSR onset were found. It is suggested that the susceptibility of the catalysts to reduction and oxidation is responsible for their activity in the WGSR.

The influence of alkali metals on the activity of supported ruthenium catalysts for the water-gas shift reaction

This paper presents the results of the studies on the influence of alkali metals on the activity of ruthenium catalysts, which were supported on the products of α- and δ-iron oxide-hydroxide calcination. Modification of these supports with alkali metals, in particular potassium, rubidium and cesium, prior to deposition of ruthenium was found to increase the activity of Ru/Fe2O3 catalysts in the water-gas shift reaction. It was also established that the activity and stability of catalysts prepared on iron oxide obtained from α-FeOOH increased when the latter was modified with sodium ions. The favourable effect of sodium on the activity of the catalysts was shown to appear at a certain proportion of the base to the active component, i.e. ruthenium.

Chlorine-free iron-ruthenium catalyst for the water-gas shift reaction

We present results of studies on the activity of chlorine-free iron-ruthenium catalysts in the water-gas shift reaction. The catalysts were prepared by impregnation of calcination products of α-, β-, γ-, δ-iron oxide-hydroxides with Ru3(CO)12. For two iron oxides (from α- and δ-FeOOH) the reaction rate constants are considerably higher than those of reactions with other catalysts based on RuCl3. Among the catalysts used, those obtained by impregnation of δ-FeOOH calcination product with Ru3(CO)12 appeared to be the most active.

Iron-ruthenium catalyst for the water-gas shift reaction

Iron-ruthenium catalysts prepared by impregnation of calcination products of α-, β, γ -and δ-iron oxide-hydroxides with either ruthenium chloride or ruthenium red were tested for the activity for the water-gas shift reaction. The effect of support, ruthenium containing impregnation agent and thermal treatment on catalyst performance was discussed.

The effect of lanthanides on the Ru/Fe2O3 catalysts for water-gas shift reaction

Abstract The paper reports results of the studies on the influence of lanthanum, cerium and samarium used as modifiers of carriers of the Ru/Fe2O3 catalysts on their activity in the water-gas shift reaction. It has been shown that modification of iron oxides with Sm or La ions significantly improves the activity of the Ru/Fe2O3 catalysts. The maximum activity of the catalysts has been achieved for the molar ratio of Ru:lanthanide=1:1. No correlation between the catalysts texture and their activity in the WGS reaction has been observed.

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.

Reduction requirements for Ru(Na)/Fe2O3 catalytic activity in water-gas shift reaction

This paper is focused upon the influence of potassium on the reduction behavior and catalytic properties of Fe2O3, Ru/Fe2O3 and Ru/(K)Fe2O3 catalysts for the water gas shift (WGS) reaction. The effect of promotion by potassium is attributed to stabilization of a highly dispersed ruthenium phase on the iron oxide surface. The hydrogen reduction behavior of Fe2O3 catalysts is strongly influenced by time-pressure dependent processes and comprises two or three heavily overlapped TPR peaks which can be ascribed to the following stages of the iron(III) oxide reduction 3Fe2O3 → 2Fe3O4 → 6FeO → 6Fe. The appearance of FeO as an intermediate phase was confirmed by XRD. The presence of ruthenium(IV) oxide substantially changes the kinetics of the reduction process. In the case of potassium-doped catalysts, the reduction of Fe2O3 is substantially different and is assigned to the reduction phase of KFeO2. Both ruthenium and potassium have a promoting effect on the catalytic activity for the WGS reaction.

INFLUENCE OF IRON OXIDE SUPPORT PREPARATION METHOD ON THE PROPERTIES OF RU/FE2O3 CATALYSTS FOR WATER-GAS SHIFT REACTION

Studies were undertaken of phase transitions of iron oxide obtained from iron oxide-hydroxides of type α-, β-, γ- and δ-FeOOH, and used as a support of ruthenium catalysts Ru/Fe2O3, employed in the water-gas shift reaction. In asprepared pure supports and ruthenium catalysts the main phase was α-Fe2O3. After use in the water-gas shift reaction, the support showed the presence of different phases of iron oxide. The most active Ru/Fe2O3 catalysts prepared on the basis of α- and δ-FeOOH, after use in the water-gas shift reaction, revealed the presence of Fe3O4 or a mixture of phases Fe3O4 and γ-Fe2O3. The least active catalysts, prepared on the basis of β- and γ-FeOOH, contained a solid solution of Fe3O4-γ-Fe2O3 with traces of α-Fe2O3.

Catalytic activity of Ru/Fe2O3, obtained by adsorption of ruthenium on iron oxide supports

The effect of the method of a support preparation on its adsorption properties for ruthenium from solution and on the catalytic properties of Ru/Fe2O3 catalysts obtained by adsorption, has been studied. Moreover, the influence of the solvent in which a given ruthenium compound was dissolved on the properties of Ru/Fe2O3 catalysts was observed.

Changes in the activity of Ru/Fe2O3 catalysts modified with alkali metal salts in the water-gas shift reaction

A study was undertaken to determine the activity of ruthenium catalysts, obtained by deposition of Ru3(CO)12 on products of iron oxide-hydroxide calcination modified with alkali metals, in the water-gas shift reaction. The activity depends on the kind of starting iron support, the ruthenium precursor and the amount of alkali metal salts. The most active were the catalysts obtained by deposition of Ru3(CO)12 on calcination products of σ-FeOOH, both modified and unmodified with alkali metal salts, and of α-FeOOH modified with alkali metal salts.