Selective Oxidation of Hydrocarbons with O2 over Chromium Aluminophosphate-5 Molecular-Sieve

Periodic Mesoporous Silicas and Organosilicas: An Overview Towards Catalysis

“…Synthesis of novel solid redox catalysts, in which the active metal sites are fixed on solid supports, can reduce or eliminate difficulties due to separation and handling. For example, the better activity of chromium catalysts (CrS-1, Cr-AlPO, Cr-MCM-41, Cr-MCM-48) for a variety of reactions, including cyclohexane oxidation, is related to the variable oxidation states, coordination environment as well as its different degrees of polymerization [44][45][46]. However, many of these solid catalysts show low activity and thus extreme reaction conditions are usually needed to improve the catalytic performance.…”

Synthesis of AlPO4-5 and CrAPO-5 using aluminum dross

“…A typical synthesis procedure of AlPO 4 -5 is as follows: dried powders of either pure Al(OH) 3, sieved Al dross, or extracted Al precipitate were slowly added into phosphoric acid solution and stirred for 2 h. Then TEA was added drop wise into the mixed gel solution and further stirred for 2 h. The synthesis gel was then transferred into a Teflon-lined stainless-steel autoclave and it was kept at 453 K for 48 h. After crystallization, the product was washed with de-ionized water, filtered, dried at 323 K overnight, and finally calcined at 823 K for 5 h. The AlPO 4 -5 samples synthesized from sieved Al dross powder, extracted Al precipitate, and pure Al(OH) 3 were denoted as AlPO 4 -5(D), AlPO 4 -5(E), and AlPO 4 -5, respectively. Introducing additional 2 mol% chromium (III) to the AlPO 4 -5 synthesis gel mixtures during the substrate prepara- …”

“…Al(OH) 3 Aldrich), triethylamine (TEA), (99.5%, Fluka), chromium (III) acetate hydroxide (Aldrich), ammonium hydroxide (29%, Sigma-Aldrich), nitric acid (65%, Duksan), and sodium hydroxide (93-100%, Duksan) were purchased and used as received. Initially, a large granular mass of aluminum dross was ground to obtain a fine powder using a commercial mixing-grinder, and the coarse aluminum dross powder was sieved to particles of less than 100 m size.…”

“…AlPO 4 -n are of great interests in the field of adsorption and catalysis [3][4][5]; the considerable interest in AlPO 4 -n can be explained by their structural diversity and simplicity in inserting various elements to the phosphorous or/and aluminum atoms comprising the porous material via isomorphous substitution [6]. Insertion of tetra-or divalent metal cations for P or Al sites in AlPO 4 -n can create acidic or redox sites in the structure, which are essential for various catalytic applications [7].…”

“…The earlier work of Murayama et al [2] was further extended and both aluminum dross powder and an extracted precipitate from Al dross in an alkali medium were tested as an aluminum source. A comparison was made against a AlPO 4 -5 sample prepared using a pure chemical Al(OH) 3 . In addition, Cr (III) was structurally incorporated as a redox species to the various AlPO 4 -5 samples, and their catalytic performances in liquid phase oxidation of tetralin were compared to that of a pure reference catalyst, demonstrating a plausible application of the materials prepared.…”