Synthesis and properties of catalytic chemisorbents based on titanium oxide

Abstract

In this work, we studied the synthesis and properties of catalytic chemisorbents based on titanium dioxide with additions of ZnO and γ-Al2O3. The goal was to obtain chemisorbents with desired performance characteristics and evaluate their potential in destructive hydrogenation of organosulfur compounds. Their sulfur capacity and hydrogenating capacity were measured by the static method with carbon disulfide absorption. Textural and morphological characteristics were determined with the use of X-ray phase analysis, low-temperature nitrogen adsorption/desorption, and scanning electron microscopy. It was also found that addition of alumina did not give additional reflections on the X-ray pattern, in contrast to introduction of zinc oxide. It was found that addition of zinc oxide significantly increased the values of the specific surface area, many times more than expected, according to additivity principle. Conversely, addition of alumina did not give the expected increase in surface area. The one and the other were explained through active interaction of phases. The ratios of components for obtaining chemisorbents with optimal strength properties were established. It was found that a composite consisting of titanium and aluminum oxides was more resistant to sulfurization than one with additions of zinc oxide. SEM and low-temperature nitrogen adsorption/desorption methods confirmed the mesoporous structure of the studied samples, while the sample containing gamma alumina showed a more pronounced desorption branch together with the surface consisting of spherical formations arranged in a regular order. The sample with zinc oxide had slit-like pores in its volume. Hydrogenation of thiophene with gaseous hydrogen was carried out for the studied composites. Chromatographic analysis of the resulting product was performed. It was proven that composites based on titanium, zinc, and aluminum oxides not only had sorption properties with respect to organosulfur compounds, but also catalyzed their destructive hydrogenation. Thus, it was established that the studied samples were chemisorbents. The study provides insight into synthesis and properties of catalytic titania-based chemisorbents, highlighting the influence of additives and their potential for organosulfur reduction reactions.