Mesostructured vanadium-phosphorus-oxide phases

• Published in: Microporous and mesoporous materials Vol. 55; no. 3; pp. 297 - 304
• Main Authors: Carreon, Moises A, Guliants, Vadim V
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 30.09.2002; Elsevier
• Subjects: Catalysis; Catalysts: preparations and properties; Chemistry; Exact sciences and technology; General and physical chemistry; Mesostructured; Packing parameter; Self-assembly; Surfactant; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Vanadium-phosphorus-oxide; Packing parameter; Self-assembly; Mesostructured; Surfactant; Vanadium-phosphorus-oxide; Ternary compound; Crystalline phase; Catalytic reaction; Hydrocarbon; Stacking sequence; Pore structure; Transition metal Compounds; Experimental study; Partial oxidation; Thermal stability; Butane; Heterogeneous catalysis; Valence; Phosphorus Oxides; 2,5-Furandione(2,5-dihydro); Preparation; Alkane; Vanadium oxide
• ISSN: 1387-1811; 1873-3093
• DOI: 10.1016/S1387-1811(02)00432-8

Ordered mesostructured hexagonal, cubic and lamellar vanadium-phosphorus-oxide phases displaying improved thermal stability, desirable bulk compositions, and vanadium oxidation states (3.8–4.3) for the partial oxidation of lower alkanes were synthesized using cationic (alkyl trimethyl ammonium salts), anionic (alkyl sulfonates and phosphates) and primary alkylamines as structure-directing agents. It was found that hexagonal mesophases were favored at short carbon chain lengths (C 12–C 16), while cubic phases were favored for longer chains (C 18). Structure-directing agents were removed by calcination or Soxhlet extraction in ethanol. When structure-directing agents were removed by extraction, phase transformations from hexagonal to cubic to lamellar structures were observed. The improved thermal stability of these mesophases was attributed to the acidic self-assembly conditions in the vicinity of the isoelectric point of V(V) oxocations.