Synthesis and surface characterization of todorokite-type microporous manganese oxides: implications for shape-selective oxidation catalysts

Studies on the formation of todorokite-type manganese oxide with different crystalline birnessites by Mg2+-templating reaction

“…The XRD pattern of TodMO synthesized by the present method is similar to that of the natural TodMO, and most of peaks are in agreement with those in the literatures [21][22][23][24]. This indicates that the synthesized TodMO has a [3 × 3] tunnel structure which belongs to a monoclinic system.…”

“…Almost all synthetic routes to TodMO differ only in the initial synthesis of Na-BirMO. A series of works on the synthetic researches of Na-BirMO have been made because it is found that the initial Na-BirMO affects the thermal stability, crystallinity, particle size, and porosity of the synthesized TodMO [23][24][25]. The most common synthetic Na-BirMO is classically prepared by oxidation of aqueous Mn 2+ in concentrated NaOH or KOH.…”

Aging promotes todorokite formation from layered manganese oxide at near-surface conditions

“…Almost all synthetic routes to todorokites differ only in the initial synthesis of layered manganese oxides and the type of metal ions introduced into the interlayer of the precursor to form Me-buserite (Me stands for metal ions). Several studies have reported that the initial layered manganese oxide affects the thermal stability, crystallinity, particle size, and porosity of the synthesized todorokite (Ching et al 1999;Al-Sagheer and Zaki 2004). Suib and his coworkers found that double-aging treatment can alter the physicochemical properties of the initial layered manganese oxide (Na-buserite) and increase the amount and type of metal ions incorporated into the buserites and their conversion to todorokites under hydrothermal conditions (Luo et al 1999).…”

Synthesis of manganese oxide octahedral molecular sieves containing cobalt, nickel, or magnesium, and the catalytic properties for hydration of acrylonitrile

“…However, the todorokite catalysts with magnesium ions can result in undesired by-products for some reactions because of the base catalysis of magnesium species. On the other hands, there have been few reports of synthetic todorokite samples not containing magnesium [5,32], whose catalytic properties were not reported. For the development of todorokite catalysts, it is required the synthesis of crystalline todorokites containing the other metal ions from magnesium and the clarification of catalytic properties of the todorokites.…”