Preparation of fly ash based titanium dioxide composite photocatalysts using spent SCR catalyst carriers

Abstract

Selective catalytic reduction of NOx with NH3 (NH3-SCR) is a commonly used method to remove NOx from flue gas. However, spent SCR catalysts that have been landfilled bring potential environmental hazards and an enormous waste of resources. To resolve the problem, this paper explores a method for recycling spent SCR catalysts by compositing it with fly ash to prepare a high value-added photocatalyst. Ti in the spent catalysts was extracted into TiOSO4 via the acid leaching method. Then the surface of FA was loaded via hydrolysis precipitation to form nano-TiO2-coated composite particles (Ti-FA). Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) spectra confirmed the formation of heterogeneous structures including Si-O-Ti, Fe-O-Ti. The UV degradation of 10 ppm rhodamine B was found to be consistent with that of P25 at 60 min (97.12%), confirming the reliable activity of the prepared photocatalyst. A heterostructures photocatalyst with excellent catalytic performance was successfully constructed by using spent SCR catalysts and loaded on the surface of another solid waste FA via its dispersion and the abundance of active components. The catalytic ability for rhodamine B exceeds that of P25, and the technology has broad application prospects in light of its cost advantage.