Selective Synthesis of Manganese/Silicon Complexes in Supercritical Water

Abstract

A series of manganese salts (Mn(NO 3 ) 2 , MnCl 2 , MnSO 4 , and Mn(Ac) 2 ) and silicon materials (silica sand, silica sol, and tetraethyl orthosilicate) were used to synthesize Mn/Si complexes in supercritical water using a tube reactor. X-ray diffraction (XRD), Xray photoelectron spectrometer (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were employed to characterize the structure and morphology of the solid products. It was found that MnO 2 , Mn 2 O 3 , and Mn 2 SiO 4 could be obtained in supercritical water at 673 K in 5 minutes. The roles of both anions of manganese salts and silicon species in the formation of manganese silicon complexes were discussed. The inorganic manganese salt with the oxyacid radical could be easily decomposed to produce MnO 2 /SiO 2 and Mn 2 O 3 /SiO 2 . It is interesting to found that Mn(Ac) 2 can react with various types of silicon to produce Mn 2 SiO 4 . The hydroxyl groups of the SiO 2 surface from different silicon sources enhance the reactivity of SiO 2 .

Hydrothermal synthesis and characterization of Co2.85Si0.15O4 solid solutions and its carbon composite as negative electrodes for Li-ion batteries

“…The similar type of observations has already been reported by Wang et al [24]. The reaction mechanism for the formation of Co 2.85 Si 0.15 O 4 solid solutions is as follows [22][23][24]. 26 , corresponding to the lattice planes of (111), (2 2 0), (3 11), (2 2 2), (4 0 0), (4 2 2), (5 11) and (4 4 0) respectively, which inferred the formation of the cubic spinel structure without any impurity phases.…”

“…Therefore, the excess Si(OH) 4 formed as amorphous silica. The similar type of observations has already been reported by Wang et al [24]. The reaction mechanism for the formation of Co 2.85 Si 0.15 O 4 solid solutions is as follows [22][23][24].…”

Effect of Activated Carbon Supports on Removing H2S from Coal-Based Gases using Mn-Based Sorbents

“…It could be deduced that reactions exist between the Mn precursor and the Si species in the support, as it has been reported recently that Li 2 MnSiO 4 and MnSiO 4 can be synthesized in the supercritical fluid media. 31,32 The formation of these Mn/Si compounds could impact the desulfurization activity of the sorbents in this work. Figure 8 shows the normalized Mn K-edge XANES spectra of reference compounds (MnS, MnO, M 2 O 3 , and Mn 3 O 4 ), the fresh and used MnO x /AC (M) sorbents prepared at 300, 350, and 400°C.…”

“…It could be deduced that reactions exist between the Mn precursor and the Si species in the support, as it has been reported recently that Li 2 MnSiO 4 and MnSiO 4 can be synthesized in the supercritical fluid media. 31,32 The formation of these Mn/Si compounds could impact the desulfurization activity of the sorbents in this work.…”

Plasma Generating—Chemical Looping Catalyst Synthesis by Microwave Plasma Shock for Nitrogen Fixation from Air and Hydrogen Production from Water for Agriculture and Energy Technologies in Global Warming Prevention

“…Currently, anode of these batteries is made from intercalating graphite. In order to enhance anode energy density capacity, metal silicates such as M 2 SiO 4 (M = Co, Fe, Mn) have been studied [87][88][89][90][91][92].…”