Activity of Bi4v2-2xcu2xo11–δ in the Transformation of Isobutanol After Plasma-Chemical Treatment

Abstract

The catalytic properties of plasma-chemically and thermally treated Bi4V2-2xCu2xO11-δ with х= 0.00-0.16 (BICUVOX) in the transformation of isobutanol are studied. Plasma treatments lead to the total deactivation of the active sites of dehydration reaction, and the alcohol is converted with 100% selectivity into aldehyde. Activity of the dehydrogenation of alcohol after PCT increases in ~ 1.7 times on samples with xCu=0.04-0.06 (. phases) compared to the initial samples. Similar values which were found for the samples with xCu=0.0-0.06, including the double vanadate, suggests that PCT affects the ceramic matrix with Bi, O and V elements. Addition of small amounts of copper does not change this effect. Keywords: new materials, nano-design, perovskite, plasma-chemical treatment IntroductionLayered materials, with their structure consisting of stacked sheets, represent an interesting opportunity for developing new materials with a tailored nano-design, controlled accessibility to the sites and properties, tuneable pore size and volume, and high surface area. The use of layered materials (layered perovskite, anionic clays, pillared clays) in catalytic reactions is reviewed with emphasis on the possibilities offered from these catalysts to develop new processes for environmental protection, selective oxidation and refinery/biorefinery [1]. Of a great interest are bismuth vanadates belonging to the BIMEVOX family, for which oxygen-ionic conductivity is typical. In the crystal structure of bismuth vanadate Bi4V2O11-δ, cations Bi 3+ are in tetrahedral coordination; V 5+ cations, in octahedral coordination. Bismuth vanadates exist in several polymorphic modifications (α-, or monoclinic; β-, or orthorhombic; and γ-, or tetragonal). The tetragonal modification occupies a special place among bismuth vanadate polymorphic modifications due to its high transport characteristics. It is the γ-phase that has the highest conductivity and the lowest activation energy value [2,3], since all oxygen atoms in vanadium octahedra are involved in the diffusion processes. In polymorphic perovskites, α ↔ β and β ↔ γ phase transitions are observed as abrupt changes in the total conductivity with rising temperature. The catalytic activity of polymorphic copper-containing BICUVOX perovskites with the composition Bi4V22xCu2xO11-δ (х =0.00-0.16) in isobutanol transformations was studied in [4]. Plasma-chemical treatment (PCT) allows us to obtain completely new materials with widely varied surface properties, while preserving most properties of the original materials. This