Sepiolite oxidants

The relative ease with which VpOr can be reduced to V(III) in aluminosilicates indicate the exiirence of weak metal-surface interactions and the inability of the surface to effectively passivate vanadium. Similarly, V on Kaolin (and metakaolin) exist mostly as the "free oxide and can (in part) be reduced to V(III) species. Therefore, DFCC systems containing metakaolin microspheres (or amorphous aluminosilicates (15)) should not be as effective as sepiolite in passivating metals TTke Ni and V. In fact, DCC mixtures loaded with 5000 ppm Ni-equivalents (that is 0.6% V + 0.38% Ni) are not metals resistant when metakaolin is used as a metals scavenger (1) ... 

It has been found that compounds of the alkaline earth metals as well as rare earths are suitable for vanadium trapping. Patents relating to the use of titanates of calcium (22), barium (23), and strontium (24) have been issued. Equivalent stannates of calcium and strontium have also been recommended (24,25). Rare earths as separate particles (26) and in the same catalyst particle (27) have been proposed. Naturally occurring minerals such as Sepiolite and Dolomite which are rich in magnesium oxide and calcium oxide have been suggested (28). 

Magnesium trisilicate hydrate (Mg2Si30s xH20, CAS No. 39365-87-2) is constituted of magnesium oxide and silicon dioxide with varying proportions of water. It should contain not less than 20% of magnesium oxide and not less than 45% of silicon dioxide and can be prepared from sodium silicate and magnesium sulfate. It also occurs in nature as the minerals meerschaum, parasepiolite, and sepiolite. 

These results show that zinc ferrite has been formed, but in sepiolite and USY zeolite the enstatite and hercynite networks substitute some of their ions for Fe and Zn, therefore masking the ffanklinite network. In the Zr02 case such substitution does not occur, appearing the pure oxide together with the fi-anklinite (6-8%), as theoretically expected. 

Visible light-induced cleavage of water has been reported for a mixed colloidal clay system consisting of a mixture of sepiolite clay-Ru02-Ru(bpy)3 + colloid (for O2 production) and Al,cEui (OH)3-Pt colloid (for H2 production) [165]. A turnover number of 20 with respect to the sensitizer, Ru(bpy)3 +, was observed. It was reported that the gas (H2 + O2) evolution displayed a damped oscillatory behavior. Photo-oxidation of water by tran5-diaqabis-(2,2 -bipyridine)ruthenium(2- -) adsorbed on the surface of hectorite clay has also been reported [166]. 

C U I Odenbrand, A Bahamonde, P Avila, J Blanco, Kinetic study of the selective reduction of nitnc oxide over vanadia-tungsta-titania/sepiolite catalyst, Appl. Catal., B Environ. 5 117 (1994). 

Fe-Mn oxides Mixed clays (+) Dolomite Oxalates Nontronite Palygorskite Fe-Mn oxides Amphiboles Pyroxenes Pyrite Apatite Protodolomite Protodolomite Dolomite Magnesian silicate Sodium silicate Fluorides Bromides Natron Trona Sulphides Fluorides Palygorskite Sepiolite Nontronite Bentonite Dolomite... 

Irradiation at 300 nm in CCl, CHCl, or CH2CI2 promotes am irreversible reaction and formation of what is probably [Os(IV)(TTP)Cl2l. Optimum conditions have been reported for determination of osmium by measurement of the luminescence of its 1 3-complex with 1,10-phenanthroline.A catalyst, prepared by reducing the product of grafting OsO on to the C-C bond of sepiolite, has been found to mediate the photooxidation of water but to do so less efficiently than RuOjj. This is the first exaunple of a dispersed water oxidation catalyst grafted on to a solid support. 

Platinum-titania-sepiolite monolithic catalysts for the reduction of nitric oxide with propene in lean-burn conditions... 

The results presented in this study on Pt-titania-sepiolite monolithic catalysts indicated that their activity in the reduction of nitrogen oxides with propene in the presence of 10% oxygen was strongly affected by the properties of the titania selected for the support s preparation. Thus, different industrially produced titanias had different textural properties, and these differences affected the textural properties of the titania-sepiolite monoliths (MIP total pore volume, MIP surface area, MIP pore size distribution and BET surface area) and the NOx... 

This new single-step synthesis unites the simplicity of preparation and lower production costs, with the outstanding properties of the final catalysts. By the single-step procedure proposed here, deposition of dispersed nanoparticles of noble metals on ceramic supports with customised textural properties and shape was achieved. Noble metals including platinum, palladium, rhodium, ruthenium, iridium, etc. and metal oxides including copper, iron, nickel, chromimn, cerium oxides, etc on sepiolite or its mixtures with alumina, titania, zirconia or other refractory oxides have been also studied. 

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