Synthesis process and efficient NH3-SCR performance of alkali/alkaline earth metal-rich Chlorella@Mn catalyst

Low-temperature NH3-SCR denitrification catalyst was prepared by biological method using Chlorella cells. In this process, Chlorella cells adsorbed Mn2+ in manganous solution were centrifuged, dried and calcined to obtain the Chlorella@Mn catalyst, the adsorption process involved electrostatic interaction, complexation/chelation and ion exchange mechanisms. Compared with the pure MnOx catalyst, Chlorella@Mn catalyst contains 2.77% alkali/alkaline earth metals (K, Na, Ca, Mg), but still has higher NOx conversion, N2 selectivity and anti-H2O poisoning, with NOx conversion close to 100% at 100–225 ℃. Chlorella@Mn catalyst surface possesses more acidic species, K, Na, Mg on the surface mainly exist in the form of K2SO4, NaPO3 and MgSiO3, respectively, Ca mainly exists as amorphous CaxMnyOz, and the presence of Ca can inhibit the over-oxidation of NO. Biological methods have more advantages such as simple process and low cost, this study will provide some reference for the preparation of novel denitrification catalysts by biological methods.