Influence of phosphorus on the NH3-SCR performance of CeO2-TiO2 catalyst for NOx removal from co-incineration flue gas of domestic waste and municipal sludge

Domestic waste and municipal sludge are two major solid hazardous substances generated from human daily life. Co-incineration technology is regarded as an effective method for the treatment of them. However, the emitted NOx-containing exhaust with high content of phosphorus should purified strictly. CeO2-TiO2 is a promising catalyst for removal of NOx by NH3-SCR technology, but the effect of phosphorous in the exhaust is ambiguous. Therefore, the effect of phosphorus on NH3-SCR performance and physicochemical properties of CeO2-TiO2 catalyst was investigated in our present work. It was found that phosphorus decreased the NH3-SCR activity below 300 degrees C. Interestingly, it suppressed the formation of NOx and N2O caused by NH3 over-oxidation above 300 degrees C. The reason might be that phosphorus induced Ti-4. to migrate from CeO2-TiO2 solid solution and form crystalline TiO2, which led to the destruction of TiO-Ce structure in the catalyst. So, the transfer of electrons between Ti and Ce ions, the relative contents of Ce3+, and surface adsorbed oxygen, as well as the redox performance were limited, which further inhibited the over-oxidation of NH3. In addition, phosphorus weakened the NH3 adsorption on Lewis acid sites and the adsorption performance of NO + O-2, while increased the Bronsted acid sites. Finally, the reaction mechanism over CeO2-TiO2 catalyst did not change after introducing phosphorus, L-H and E-R mechanisms co-existed on the surface of the catalysts. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

This study investigates the effect of phosphorus on the NH3-SCR performance and physicochemical properties of CeO2-TiO2 catalyst. The results show that phosphorus decreases the NH3-SCR activity and suppresses the formation of NOx and N2O caused by NH3 over-oxidation. The introduction of phosphorus disrupts the catalyst's structure, limiting the transfer of electrons, the relative contents of Ce3+, and the surface adsorbed oxygen, leading to the inhibition of NH3 over-oxidation.