Oxygen availability and catalytic performance of NaWMn/SiO 2 mixed oxide and its components in oxidative coupling of methane

Fluctuating Storage of the Active Phase in a Mn‐Na2WO4/SiO2 Catalyst for the Oxidative Coupling of Methane

“…It is postulated that the process described in Equation (1) provides mobile lattice oxygen under steady-state operation of the catalyst. This is in agreement with O 2 -TPD experiments performed by Gordienko et al, [13] who identified two forms of lattice oxygen that may potentially contribute to catalysis upon desorption at relevant temperatures.T he source of oxygen has been attributed to manganese oxide, [6j, 7] or any unspecified lattice oxygen. [14] Potentially more decisive is the release of an active form of sodium oxide species that has been proposed to catalyse the oxidative coupling of methane by generation of OH radicals at high temperatures, [6l,m,o] presumably under involvement of homogeneous gas-phase reactions [15] due to the high volatility of sodium compounds under operation conditions.…”

Fluctuating Storage of the Active Phase in a Mn‐Na2WO4/SiO2 Catalyst for the Oxidative Coupling of Methane

“…It is postulated that the process described in Equation (1) provides mobile lattice oxygen under steady‐state operation of the catalyst. This is in agreement with O 2 ‐TPD experiments performed by Gordienko et al., who identified two forms of lattice oxygen that may potentially contribute to catalysis upon desorption at relevant temperatures. The source of oxygen has been attributed to manganese oxide, or any unspecified lattice oxygen .…”

“…Furthermore, the supported Mn 7 SiO 12 phase was observed to function as oxygen‐donor at working temperatures, which further enhances sodium oxide formation and, thus, has implications for the reactivity. However, the availability of adsorbed or lattice oxygen due to the presence of redox‐active elements alone cannot be responsible for the outstanding performance of the Mn‐Na 2 WO 4 /SiO 2 catalyst and does not explain the mechanistic role and importance of Na in this system. On the other hand, a pure silica‐supported sodium oxide would rapidly deactivate under the severe reaction conditions applied in the oxidative coupling of methane .…”

Synthesis and Characterization of A-Site Doped Lamno3 Nano Catalysts and its Application for Soot Oxidation

“…The perovskite catalyst prepared in this research study displayed a surface area 24-45 m 2 /g as shown in Table 1. These values are among the highest so far to the best of our knowledge and they are remarkably higher than those which have been attained by other methods of preparing perovskites (1-11 m 2 /g) 9,31,34,41,42 . Also there is an increase in the surface area from 27-45 m 2 /g when barium was doped, this suggest that the introduction of barium into the perovskite structure has helps in increasing the surface area of the catalyst hence improving the catalytic activity.…”

“…Nevertheless, some structural distortion were observed in the patterns of the doped perovskite catalysts as there was a shift in the pattern of the doped perovskite catalysts towards the 2θ mark on the XRD plots. This structural distortion have been reported by many researchers to depend on the nature of the cations on either the A-site or the B-site [28][29][30][31][32] . Therefore, in order to properly analyse these structural differences, the shift in the XRD observed towards the 2θ (31-34) was extended as shown in Figure 2(b).…”