Vanadium-containing ordered mesoporous silicas: Synthesis, characterization and catalytic activity in the hydroxylation of biphenyl

Mesoporous Silicates with Spherical Morphology Modified with Vanadium Highly Active in Oxidation of Cyclohexene with H2O2

“…This technique is generally accepted as an additionally way of establishing the element location in the silicate framework, or as extra framework species [5,10,19,29,30]. For our samples, as the content of V is increased (Table 1), the main peak corresponding to plane (100) shifted towards lower diffraction angles and a increase in the parameter a 0 , consistent with a probable incorporation of V into the siliceous structure, was observed.…”

“…Additionally, contrary to the earlier observed results [8,11,27] it should be noted that, with the increase in the percentage of vanadium loading, the peak of X-ray intensity of the V-MMS catalysts is increased. This discrepancy can be explained as follows: the simultaneous condensation between metal and silica precursors in the presence of structure directors may enhance the structural ordering, because the metal species act as a promoter for the condensation of the silica species with an increased probability for the incorporation of vanadium into the framework of silica [19,28].…”

“…It is noteworthy that a higher concentration of isolated vanadium active sites in the ordered mesoporous lattice can be obtained compared with the conventional silica support [11]. However, coordination, location, and aggregation degree of vanadium in these materials are still not well understood [11,[18][19][20][21].…”

An Overview of Zeolite, Zeotype and Mesoporous Solids Chemistry: Design, Synthesis and Catalytic Properties

“…These have often involved small metal complexes, the ligands of which were removed by calcination after being grafted onto the walls. [88] Some recent examples of MCM-41 based materials are the Sn(IV) Lewis acids by Corma et al, [94] vanadium-containing species by Singh et al, [95,96] and a luminescent europium complex by Fernandes et al [97] Rhodium and molybdenum complexes have been given attention by Pillinger et al in analogous procedures, whereby bimetallic acetonitrile complexes have been grafted onto MCM-41. [98,99] These complexes have been shown to be sensitive to air, undergoing dissociation to create a mononuclear species in the case of Rh.…”

Structural and Catalytic Properties of a Novel Vanadium Containing Solid Core Mesoporous Shell Silica Catalysts for Gas Phase Oxidation Reaction

“…In the recent past, Vanadium-substituted molecular sieves have been found to be excellent catalysts for many selective oxidation reactions [15][16][17][18]. The catalytic activity and selectivity of vanadium-substituted molecular sieves are directly related to the co-ordination structures of the vanadium species in the molecular sieves.…”