1,721,056 research outputs found
A COMBINED MASS-SPECTROMETRIC GAS-CHROMATOGRAPHIC APPROACH FOR THE THERMOANALYTICAL CHARACTERIZATION OF SUPPORTED HETEROGENEOUS CATALYSTS
No full textMolecular metal carbonyl clusters and volatile organometallic compounds for tailored mono and bimetallic heterogeneous catalysts
No full textHeterogeneous catalytic epoxidation of fatty acid methyl esters on titanium-grafted silicas
No full textCu-ZSM-5 (Si/Al=66), Cu-Fe-S-1 (Si/Fe=66) and Cu-S-1 catalysts for NO decomposition: preparation, analytical characterization and catalytic activity
No full textWe prepared H-ZSM-5 (Si/Al = 66), Fe-S-1 (Si/Fe = 66), and Silicalite-1 (S-1) according to the methods described by Bellussi and coworkers, and compared their ion-exchange capacity for copper ions. The Cu-ZSM-5, Cu-Fe-S and Cu-S-1 samples thus obtained have been investigated as catalysts for the NO decomposition reaction at 773 K. We found that using copper acetate solutions with concentrations in the range 0.004 M less than or equal to[Cu2+]less than or equal to 0.1 M, at room temperature and at 323 K, it is very easy to prepare overexchanged Cu-ZSM-5, Cu-Fe-S-1, and Cu-S-1 catalysts. XRD and Vis-UV DRS techniques show that after thermal treatments of the fresh samples in air at 823 K for 4 h no segregation of bulk CuO phase occurs, suggesting the presence of low nuclearity [CunOx(OH)(y)](q+) species [q=2(n-x)-y greater than or equal to 0]. These results were confirmed by TPR studies. At 773 K, only Cu-ZSM-5 and Cu-Fe-S-1 catalysts showed NO decomposition activity (NO 1% in He, W/F = 0.2 g s cm(-3)). Instead, the activities of Cu-S-1 and of the copper-free matrices (S-1, H-ZSM-5 and Fe-S-1) were not measurable under our experimental conditions. The negative results obtained with Cu-S-1 catalysts clearly demonstrate that the active sites for NO decomposition in Cu-MFI catalysts consist of polynuclear ionic copper species strongly anchored to framework [MO4](-) species (M=Al, Fe)
A molecular approach to heterogeneous catalysis. Ethylene hydroformylation catalysed by silica-supported [Rh-12(CO)(30)](2-) cluster anion: Influence of the countercations Li+, Na+, K-+, Zn2+
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One-pot conversion of citronellal to isopulegol epoxide on ordered (Ti-MCM-41, [Ti]-MCM-41) and amorphous (MST) mesoporous silica-titania
No full textTHE STORY OF SILICA-SUPPORTED OS3(CO)12 - A MOLECULAR APPROACH TO HETEROGENEOUS CATALYSIS
No full textNiobium metallocenes deposited onto mesoporous silica via dry impregnation as catalysts for selective epoxidation of alkenes
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