Synthesis and characterization of mesoporous ferrisilicate (FeMCM-41) molecular sieves

A systematic investigation of iron substituted mesoporous silicate (FeMCM-41) was carried out. The incorporation of the trivalent iron into the framework as well as the nature of such ions in the mesoporous matrix is presented. The results are discussed in terms of the information obtained using various analytical techniques, viz., XRD, TG, DRUV-VIS, FTIR and ESR, as well as chemical analysis and surface area measurements

Influence of aluminium sources on the synthesis and catalytic activity of mesoporous AlMCM-41 molecular sieves

Mesoporous AIMCM-41 molecular sieves were synthesized using various aluminium sources, viz., sodium aluminate, aluminium sulphate, aluminium isopropoxide and pseudoboehmite. The influence of different aluminium sources on the framework substitution of aluminium as well as on the catalytic properties of t-butylation of phenol was studied. Among the aluminium sources, the use of sodium aluminate for the AIMCM-41 synthesis showed maximum incorporation of aluminium in the framework. Further, the catalyst also showed good catalytic activity for the chosen reaction. (C) 2000 Elsevier Science B.V. All rights reserved

para-Selective t-butylation of phenol over mesoporous H-AlMCM-41

Vapour phase alkylation of phenol with t-butyl alcohol (2-methyl-2-propanol) was carried out over mesoporous H-AlMCM-41 in the temperature range 448-498 K. In this reaction, p-t-butyl phenol was obtained as a major product with high selectivity. While the phenol conversion increases with a decrease in phenol-to-t-butyl. alcohol ratio, the catalytic activity decreases with time-on-stream due to deactivation of the catalyst. At higher temperatures, both the ortho- and para-isomers, viz., o-t-butyl phenol and p-t-butyl phenol, undergoes isomerization leading to m-t-butyl phenol. (C) 2000

Nanosized metal oxides in the mesopores of MCM-41 and MCM-48 silicates

The present work describes the preparation and characterization of nanosized metal oxide particles (Fe2O3, ZnO and PbO) inside the mesopore channels of MCM-41 and MCM-48 silicate molecular sieves. The encapsulation of the metal oxides was carried out at room temperature by the incipient wetness method. Diffuse reflectance ultraviolet-visible spectroscopic studies showed a significant shift in the absorption band for the entrapped metal oxides as compared to the corresponding bulk oxides. Thus, confirming the quantum confinement of the incorporated nanoparticles in MCM-41 and MCM-48. (C) 2001 Elsevier Science B.V. All rights reserved

Tertiary butylation of phenol over mesoporous H-FeMCM-41

Trivalent-iron-substituted mesoporous molecular sieve catalysts (FeMCM-41) were synthesized hydrothermally and characterized systematically by various analytical and spectroscopic techniques. Temperature-programmed desorption studies of ammonia of the protonated catalyst (H-FeMCM-41) indicate a broad distribution of the acid sites. Vapour-phase alkylation of phenol with t-butyl alcohol (2-methyl-2-propanol) was carried out over this solid acid catalyst and p-t-butyl phenol was obtained as the major product with high selectivity

Catalytic oxidation of alkylaromatics over mesoporous (Cr)MCM-41

Liquid-phase catalytic oxidation of certain alkylaromatics over mesoporous (Cr)MCM-41 molecular sieves in the presence of chlorobenzene and tertiary butylhydroperoxide showed high substrate conversion and excellent product selectivity. The high catalytic activity of the materials is attributed to the complete oxidation of chromium ions to hexavalent chromium and the absence of pentavalent chromium in the mesoporous matrix

Oxidation of phenols over mesoporous (Cr)MCM-41 molecular sieves

The catalytic performance of mesoporous chromium containing MCM-41 molecular sieves was investigated for the oxidation of phenols. The substrate conversion and the product selectivity are remarkably enhanced by ammonium acetate, acetylacetonate treatments of this unique catalyst. In particular, phenol shows excellent results compare to the TS-1 catalyst