The influence of silver on the properties of cryptomelane type manganese oxides in N2O decomposition reaction

A solid with a hierarchical tetramodal micro-meso-macro pore size distribution

“…S2a, tetramodal α-MnO 2 demonstrates better catalytic activity compared with only micropores or bimodal α-MnO 2 ; the temperature of half CO conversion ( T 50 ) was 124 °C for tetramodal α-MnO 2 , whereas microporous and bimodal α-MnO 2 exhibited a T 50 value of 275 °C and 209 °C, respectively. In the case of N 2 O decomposition, α-MnO 2 with only micropores demonstrated no catalytic activity in the range of 200–400 °C, in accord with a previous report49. Tetramodal and bimodal α-MnO 2 showed catalytic activity and reached 32% and 20% of N 2 O conversion, respectively, at a reaction temperature of 400 °C.…”

The improved reactivity of manganese catalysts by Ag in catalytic oxidation of toluene

“…Morales et al reported that the addition of Cu into Mn catalysts prevents manganese oxide reaching crystalline structure and enhances the existence of oxygen vacancies, which gives a best performance in ethanol combustion [18]. Gac et al have found the decrease of Mn O bonds strength due to the silver effect is useful for the increase of the activity [19]. And the improvement of lattice oxygen mobility of manganese oxides sharply increases the reactivity of Mn-Ag catalysts for CO oxidation [20].…”

“…A combination of Ag and Mn seems to be an important contributing factor to the reactivity [19][20][21][22][23][24]. However the details of application in toluene catalytic oxidation are not yet available.…”

A facile one-pot hydrothermal synthesis as an efficient method to modulate the potassium content of cryptomelane and its effects on the redox and catalytic properties

“…Potassium based OMS-2 (cryptomelane) has received a great deal of attention in catalysis and it has been used not only as supports but also as catalysts [9][10][11][12]. Cryptomelane has exhibited excellent activity in different oxidation reactions of interest in environmental protection, such as CO oxidation [10,[13][14][15], decomposition of methylene blue [16], NOx removal [17], VOCs oxidation [18] or total oxidation of small alkanes [19]. Among these reactions, CO oxidation has been widely studied as a reference catalytic test in the fields of surface science and heterogeneous catalysis due to its technological importance and fundamental interest [20].…”