Manganese promoted

Figure 6.2 X-ray diffraction identifies phases in a manganese-promoted iron Fischer-Tropsch catalyst after reduction (middle) and after CO hydrogenation or Fischer-Tropsch synthesis bottom). The spectra show that Mn is present as slightly distorted MnO (see the MnO reference measurement at the top), and that bcc iron (peak at 2 6 = 57.0°) converts to iron carbides (peaks around 55°) during the Fischer-Tropsch reaction (from van Dijk et al. [7]).

In catalyst characterization, diffraction patterns are mainly used to identify the crystallographic phases that are present in the catalyst. Figure 6.2 illustrates this with an example from the studies of Kunimori et al. [7] on manganese-promoted rhodium catalysts. These authors prepared their catalysts in two-steps by first impregnating the silica support with a solution of RhCl3 in water, followed by a second impregnation with Mn(NC>3)2 in water. Figure 6.2a shows XRD patterns... 

Another possibility for the formation of free radical species from hypochlorite is through its reactions with transition metal ions. Thus, Guilmet and Meunier (1980) reported a manganese-promoted epoxidation of olefins such as styrene (Equation 5.13) and cyclohexene in a two-phase dichloromethane-water solvent mixture. The epoxide oxygen was derived from HOCl, not from air, but no mechanistic details were speculated upon. Further evidence needs to be obtained on the possibility of free-radical reactions in water and wastewater chlorination. 

T. K. Cheung, J. L. d ltri, F. C. Lange, B. C. Gates, Neopentane cracking catalyzed by iron-and manganese-promoted sulfated zirconia, Catal Lett., 1995, 31, 2-3. 

Crude 2,6-naphthalene dicarboxylic acid (2,6-NDA) can be prepared by oxidizing 2,6-dialkylnaphthalenes in the liquid phase with molecular oxygen in the presence of a transition metal catalyst and an oxidation promoter. Typically, such catalysts include mixtures of cobalt and manganese promoted with bromine as an oxidation promoter. The 2,6-NDA prepared by the process, contains impurities, such as trimellitic acid (TMLA), and aldehydes. Typical amounts of impurities are shown in Table 11.1. 

Tang X-J, Eei J-H, Hou Z-Y, Lou H, Zheng X-M (2008) Copper-zinc oxide and manganese promoted copper-zinc oxide as highly active catalysts for water-gas shift reaction. React Kinet Catal Lett 94 3-9... 

S. L. Gonzalez-Cortes, S. M. A. Rodulfo-Baechler, A. Oliveros, et al., Synthesis of light alkenes on manganese promoted iron and iron-cobalt Fischer-Tropsch catalysts, Reaction Kinetics and Catalysis Letters, vol. 75, no. 1, pp. 3—12, 2002. 

CrCl2 being formed in situ by the manganese-promoted reduction of CrCl3. 

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