Insights into the Sintering Resistance of Sphere-like Mn₂O₃ in Catalytic Toluene Oxidation: Effect of Manganese Salt Precursor and Crucial Role of Residual Trace Sulfur

Abstract

Manganese oxides, as a highly active oxidation catalyst, are expected to have great potential for replacing platinum group material (PGM) in volatile organic compound (VOC) degradation. Manganese sulfate and manganese chloride are usually adopted as raw materials for catalyst preparation, and Cl − and SO 4 2− adsorbed on the catalyst might affect the catalytic activities. In this study, sphere-like Mn 2 O 3 was prepared from different manganese sources with a simple carbonate precipitation method, which was further used to systematically study the potential poisoning effect of residual trace species on the catalytic activity of toluene oxidation. The fully washed samples all show excellent toluene oxidation activity at the beginning; however, both chlorideand sulfate-derived samples exhibited unexpected severe inactivation after the thermal aging treatment, and the light-off temperature (T 90 ) of toluene oxidation increased by more than 116 and 252 °C, while this value is only 65 and 40 °C over nitrate-and acetatederived Mn 2 O 3 , respectively. The characterization results of ICP-OES and XPS demonstrated that the incorporated traced sulfur and chloride species existing in fresh samples were difficult to wash away completely, which has little influence on the catalytic performance of fresh samples but will greatly affect their anti-sintering behavior. During the thermal aging process, doped sulfur gradually forms uniformly dispersed sulfate that will cover on the catalyst surface, where the transports of reactants and the supplementary lattice oxygen would be restrained significantly.

In Situ Reconstruction of Active Heterointerface for Hydrocarbon Combustion through Thermal Aging over Strontium-Modified Co3O4 Nanocatalyst with Good Sintering Resistance

“…The results of these experiments are presented in Figure c,d. Figure c demonstrates the desorption of oxygen species, which can be broadly classified into three categories: , surface-adsorbed oxygen (O ads ), including physically and chemically adsorbed oxygen, in the temperature range of 50–300 °C; surface lattice oxygen (O latt ), encompassing the surface and subsurface lattice oxygen, in the temperature range of 300–600 °C; and bulk phase lattice oxygen (O latt ) above 600 °C. Based on Figure d, the peak areas of surface-adsorbed oxygen and surface lattice oxygen are ranked as follows: Co 1 Sr 0.3 -F > Co 1 Sr 0.3 -A > Co-F > Co-A.…”

Flexible Ti Mesh-Supported MnOx–CuOx/TiO2 Nanosheet Monolithic Catalysts for Low-Temperature Selective Catalytic Reduction of NOx with NH3

“…A solution containing 30 mmol of Mn(NO 3 ) 2 and Cu(NO 3 ) 2 in 50 mL of ultrapure H 2 O was prepared, followed by the addition of 50 mL of a 30 mmol/L NaHCO 3 solution as the precipitating agent. Subsequently, the H 2 Ti 2 O 5 /Ti supports were dipped into the solution, and the resulting samples were then extracted and rinsed repeatedly with ultrapure water. , The precursors underwent a final drying step at 80 °C for 30 min, followed by subsequent calcination at 350 °C for 3 h in ambient air at a temperature increase of 5 °C/min, resulting in fresh MnO x –CuO x /TiO 2 nanosheet catalysts on Ti mesh, which were marked as Cu x Mn5– x /TiO 2 /Ti ( x = 0, 1, 2, 3, 4, 5) in different Mn/Cu molar ratios.…”