The hydroxyl species and acid sites on diatomite surface: a combined IR and Raman study

Possible mechanism of structural incorporation of Al into diatomite during the deposition process I. Via a condensation reaction of hydroxyl groups

“…Moreover, the influence of Al incorporation on the surface properties (surface solid acidity) of diatomite is firstly investigated: the solid acidity is tuneable by heating and L acid sites appear in the diatom shell which was proposed to possess only B acid sites [43]. Rich solid acid sites of Al-incorporated diatomite are promising for applications as solid acid catalysts.…”

Facile preparation of hierarchically porous carbon using diatomite as both template and catalyst and methylene blue adsorption of carbon products

“…peak, implying multiple and partially overlapped mass-loss events, such as the dehydration of capping water and the dehydroxylation of different silanols [13,32].…”

“…fewer acid sites than Dt(JL) is due to the loss of some solid sites sourced from the tiny montmorillonite particles after purification treatment. Moreover, 650°C heating made more acid sites exposed at the surface of diatom shells and montmorillonite particles, so that the acid amount of Dt(JL)-T is higher than that of Dt(JL) [13]. And acid washing resulted in the introduction of Al species onto the surface or implant into the structure [39] of diatom shell.…”

“…It is the most abundant form of silica on earth and is easily obtained at very low cost [9]. Composed of biogenetic amorphous silica and classified as noncrystalline opal-A in mineralogy, diatom shell is characteristic of highly developed porosity and particularly macroporous structure [12][13][14] and thus has been used as the template for the preparation of macroporous materials [15,16]. The sizes of the macropores of diatomite range from nanometric to micrometric domains.…”

“…However, the addition of liquid acid is potentially harmful to the environment and makes the preparation unnecessarily complicated. In fact, our previous report has revealed that diatomite itself contains both Brønsted and Lewis acidity: the former origins from the diatomaceous silica and the very tiny clay mineral particles strongly adhered to diatom shells and the latter from the clay minerals in diatomite [13]. Therefore, it is of great practical significance to utilize these inherent acid sites of diatomite rather than any additive catalysts to catalyze the carbon precursor.…”