Heterogeneous catalysis pillared clays

Most studies of water in clays are not necessarily related directly to heterogeneous catalysis, but the state of the water in the interlayer is clearly important in the pillaring process. Woessner at Mobil pioneered this area 20 years ago. It was discovered that interlayer water in clays was undergoing anisotropic motion, the result being a partially motionally averaged Pake doublet spectrum (53-551. Under typical hydration conditions, many clays appear to maintain the equivalent of one or two monolayers of water between the clay sheets, so it is not surprising that the motion is restricted. 

The introduction of micropores in clays results in a significant increase in the total specific surface area. Surface area and porosity are important characteristics of porous pillared layered solids for applications in the fields of adsorption and catalysis. They are crucial criteria in heterogeneous catalysis since they determine the accessibility of the active sites and are therefore related to the catalytic activity. The pore architecture of a porous solid controls transport phenomena and governs... 

In catalysis, oxides with well defined acidic and basic properties are used in different forms that have found application in numerous catalytic applications in the gas-solid and liquid-solid heterogeneous catalysis [3, 46, 47], Among the most used oxide materials in catalysis, we And (i) bulk oxides (one component metal oxides) (ii) doped and moditied oxides (iii) supported metal oxides (dispersed active oxide component onto a support oxide component) (iv) bulk and supported binary metal oxides to quaternary metal oxides (mixed oxide compositions) (v) complex oxides (e.g., spinels, perovskites, hexa-aluminates, bulk and supported hydrotalcites, pillared clays, bulk and supported heteropolyacids, layered silicas, etc.). 

Polymer-supported tetrabromooxomolybdate(V) was claimed to be a heterogeneous catalyst for alcohol oxidations with TBHP . However, it seems likely that molybdenum is leached from the surface and the observed catalysis may be, at least partially, homogeneous in nature. The same applies to Cr(III) and Ce(IV) catalysts supported on a perfluorinated sulfonic acid resin (Nafion K) which catalyze the oxidation of alcohols with TBHP . Similarly, vanadium-pillared montmorillonite clay (V-PILC) ° and a zeolite-encapsulated vanadium picolinate complex were shown to catalyze... 

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