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

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

“…Approximately 0.3 g of diatomite and Al-incorporated diatomite was spread on the bottom of a ceramic crucible to form a thin layer and was evacuated for 1 h. NH 3 was then slowly introduced and maintained airtight for 48 h. Then, the samples were heated at 120°C for 1 h under vacuum to remove the physically adsorbed NH 3 . The resulting NH 3 -adsorbed samples were denoted as Dt-NH 3 , Dt/Al 250 -NH 3 , Dt/Al 350 -NH 3 and Dt/Al 500 -NH 3 . Moreover, the re-adsorption of NH 3 was carried out for KBr pellets prepared by KBr and NH 3 -adsorbed diatomite or Al-incorporated diatomite followed by the above processes before FTIR analysis.…”

“…After Al 13 loading and subsequent heating from 250 to 500°C, the signal of the Si(OSi) 3 (OH) group is gradually weakened and cannot be distinguished in the Dt/Al 500 sample (Fig. 2).…”

“…Diatomite is primarily composed of amorphous hydrated silica (SiO 2 ÁnH 2 O), which is categorized as non-crystalline Opal-A, according to the mineralogical classification [3,4]. Diatomite is easily obtained at very low cost and has many unique physical and chemical characteristics, enabling their wide uses in a variety of applications for high-performance technologies; thus and widely utilized [5][6][7][8]2,[9][10][11][12].…”

Enhancement of diatomite solid acidity by Al incorporation, as evaluated by the catalytic effects on the thermal decomposition of 12-aminolauric acid

“…Diatomite is primarily composed of amorphous hydrated silica (SiO 2 ·nH 2 O), which is categorized as non-crystalline opal-A, according to the mineralogical classification [3][4][5]. Because diatomite has macroporous structures with pore sizes that range from the nanometric to the micrometric domains [2,6], it has been widely used as adsorbents [7][8][9][10][11], supports [12][13][14][15][16][17][18], and templates of macroporous materials [2,6] [19][20][21][22].…”

“…In our previous study [20][21][22][23], the inherent solid acidity of diatomite was utilized to catalyze the decomposition of furfuryl alcohol to prepare diatomite-templated carbon with a unique macroporous structure. However, the catalytic activity of diatomite is ordinary because of the small number and weak acidity of these solid acid sites and because of the lack of Lewis (L) acid sites in the structure of diatomaceous silica.…”