Development of a Strengthened Al2O3 Based Material for Use in Waste Combustion Plants

Abstract

Fluidized bed catalytic combustion is the most environmentally friendly and energy-efficient method for converting various fuels, in particular, low-grade fuels. The technology involves the oxidation of volatile substances on the surface of catalyst particles diluted with an inert material in a fluidized bed. The conventional use of quartz sand as an inert material leads to the accelerated degradation of the catalyst during on-stream use due to abrasion. This study is focused on the effect of the magnesium modification of active spherical Al₂O₃ and the development of a strengthened material (with crushing and abrasion strengths comparable to the values for a deep oxidation catalyst (DOC)) capable of minimizing DOC losses. The modified support is synthesized by impregnating spherical Al₂O₃ pellets with a precursor solution (nitrate and acetate) and subsequently calcining the pellets at 80°C. The resulting pellets are studied by X-ray fluorescence analysis (XRF), inductively coupled plasma optical emission spectroscopy (ICP-OES), low-temperature nitrogen adsorption (BET), and scanning electron microscopy (SEM). In addition, the mechanical strength of the pellets and their catalytic activity in CO oxidation are determined. It is found that the strength characteristics of Al₂O₃ linearly increase upon the introduction of magnesium in an amount of 2–9 wt %. The use of the selected material under laboratory conditions provides a threefold decrease in catalyst losses during 4.5-h abrasion compared with losses in the case of using quartz sand.