Oxidation catalysts prepared by mechanically and thermally induced spreading of Sb2O3 and V2O5 on TiO2

Abstract

This chapter discusses the alternate method of catalyst preparation, a method based on a solventless ball-milling technique, aimed at adequately dispersing the active catalyst ingredients on a given support material to yield acceptably effective catalysts. Specifically, the spreading and the dispersion of V-oxide, Sb-oxide, and V-Subboxides on TiO2 supports were investigated by means of the ball-milling technique and the so prepared materials compared to the conventionally prepared materials. The tribo-chemieal process of the former method was followed by spectroscopic techniques, including X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES), and temperature-programmed reduction (TPR), which revealed that active phase dispersions comparable to those obtained by conventional preparation techniques can readily be achieved by the milling method. It is concluded that the solventless ball-milling technique is also an effective alternative method for the preparation of selective oxidation catalysts. For catalyst preparation, the mechanical treatment was done in a planetary mill with the dry oxidic compounds or with 10 wt. % H2O. For that purpose, the oxides were mixed carefully in a mortar and then milled (145 rpm) in an agate vessel (250 ml) with six agate balls. The time of milling was chosen to be between 1h and 20h. In case of heat treatment of the materials, 400°C for 5h was chosen for calcination.