Modification of Recycled Industrial Solid Waste Incineration Fly Ash as a Low-cost Catalyst for NOx Removal

Abstract

Fly ash is solid waste from incinerators that contains complex compounds that have great potential to synthesize valuable materials. This study devises synthesizing a low-cost catalyst from recycled fly ash using a combination of metal oxides (ZrO2, TiO2, and MgO) to remove NOx. This study also investigated the impact of various factors on the synergetic purification of NOx as an air pollution emission. Microscopic characterization showed that increasing the composition of metal oxides can increase the specific surface area of fly ash, crystallinity, binding energy, and the dispersion of metal oxides into the fly ash, favoring the adsorption and the oxidation of NOx onto the surface-modified fly ash catalysts. The NOx removal in raw fly ash (RFA) at 25°C is 10.39%, increasing to 90.3% in the modified fly ash catalyst (FA/Zr-10%) at 250°C. The modified fly ash catalysts can reduce catalyst costs for NOx removal by one-ninth, and the operating temperature is about 10–15% lower than conventional catalysts. In summary, industrial solid waste incineration fly ash holds excellent potential when modified with metal oxides, serving as an economical and highly efficient catalyst for NOx removal.