[2F04-06] Oxidation(2)

[2F04] Insight into the effect of oxygen species and Mn chemical valence over MnO_x on the catalytic oxidation of toluene

○Heng Zhao¹, Guohui Yang¹, Noritatsu Tsubaki¹ (1. University of Toyama)

A series of MnOx were prepared with four different precipitants and employed to catalyze the combustion of toluene with the aim to clarify the role of Mn³⁺, Mn⁴⁺, surface adsorbed oxygen and lattice oxygen. Lower crystallinities and better microstructures were observed on the catalysts prepared by carbonates, due to the lower nucleation rates. The co-existence of Mn³⁺ and Mn⁴⁺ was beneficial to the transfer and transformation of electrons, which promoted the redox performance of the catalyst. But various contents of Mn³⁺ and surface adsorbed oxygen species were found on the catalysts synthesized with different precipitants. By the improving of Mn³⁺, the binding capacity of the catalyst using (NH₄)₂CO₃ as precipitant (Mn-AC) to oxygen was weakened, thus increasing its oxygen mobility. Furthermore, more oxygen vacancies were produced, resulting in the generation of more active oxygen species on the surface of Mn-AC. Abundant adsorbed oxygen of Mn-AC enhanced the oxidation ability of lattice oxygen by the rapid supplement of consumed lattice oxygen species. Therefore, Mn-AC with excellent catalytic activity and durability is a promising industrial catalyst for efficient removal of toluene.

Keywords:catalytic oxidation, toluene, surface oxygen species