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A mesoporous siliceous material of MCM-41 type was characterized by nitrogen adsorption, X-ray diffraction, and Fourier transform infrared spectroscopy. Its pore diameter, external and internal surface, pore volume, wall thickness, and pore wall density were determined. Special attention was paid to sample aging and its stability toward temperature, water vapor, and mechanical compression, aiming at using this material in industrial applications such as adsorption or catalysis. Calcined MCM-41 loses an important part of its mesoporosity during aging under ambient temperature, pressure, and humidity conditions but then becomes stable after 3 months, still retaining a noticeable porosity. The aged MCM-41 can withstand temperatures up to 873 K and uniaxial compressions up to 100 MPa without too much damage. After contact with water vapor at 358 K, the porous structure was totally destroyed and an amorphous phase was obtained.

A series of binary Cu–Al mesoporous precursors have been prepared by direct synthesis using “catanionic” (mixed cationic and anionic) surfactants. The as-synthesized materials, involving a mesotructured framework composed of minor Cu hydroxynitrate domains overdispersed within the major alumina based mesophase, yielded through controlled calcination and reduction, Cu0particles of variable size, well dispersed and quite strongly attached on the alumina support. In each calcined sample, combined transmission electron microscopy and energy dispersive X-ray analyses revealed the presence of both very small, nanometer sized, CuO particles and of larger CuO domains, the size of which depends on the initial copper amount. The fact that each Cu hydroxynitrate domain in the as-synthesized sample yields, upon calcination and subsequent reduction, respectively the corresponding CuO domains and Cu0particles of about the same size and similar dispersion, reflects the regular pre-dispersion of the Cu islands during the very first synthesis stages. The (Cu,Al) mesoporous samples have been tested as catalysts for selective hydrogenation of cinnamaldehyde (CNA) and compared to classical Cu-impregnated alumina catalysts. The remarkable selectivity of the (Cu,Al) mesoporous samples towards the formation of unsaturated alcohol (hydrogenation of the carbonyl group of CNA) was attributed to the particular strong interaction of the nanometer sized Cu0“islets” with the Al mesoporous walls, while the conjugated CC bond is more readily hydrogenated on larger Cu0clusters in weaker interaction with the support.

Light-fastness properties of composites involving mesoporous calcium-modified aluminosilicate substrates (MCM-41 structure) and dye (Lithol Rubine B) were examined. High surface area Al-MCM-41 materials synthesized in the presence of Ca2+ions proved efficient hosts for Lithol Rubine B, yielding mesophase–dye composites with the highest light-fastness qualities, when compared to Ca-exchanged Al-MCM-41 aluminosilicates, to non composite pigment or to smectite–dye composites. The marked resistance of the new composites to fading was attributed to an optimized Ca–dye interaction favored by a controlled heating the Ca(OH)2-loaded mesoporous precursors, yielding tiny CaO particles, highly dispersed and retained onto the large internal surface of the substrate.

A wide series of zeolite metallosilicates was successfully synthesized using a series of short alkyl chain amines as new potential mineralizing agents. In the particular case of ZSM-5 containing various framework heteroatoms, the mobilizing-complexing role of methylamine, as compared to that of fluoride ions, can be very different and basically depends on the nature of the metallic ion. The relative strength of the various fluoro or amino complexes could be exploited to monitor and control the selective (simultaneous or successive) incorporation of various metallic species in the MFI framework. The incorporation, occurring in variable amounts, can be arbitrary considered as total (i.e. with more than 2 ionic species incorporated per MFI unit cell) for Zn2+, Al3+, Ga3+, Fe3+, B3+and Ti4+. Cd2+and Cr3+are only partly incorporated (M/u.c.<2) while Cu2+, Co2+, Mn2+and Mo5+never incorporate the MFI lattice. Besides the fact that these ions do not readily achieve a tetrahedral coordination, the other possible reason could be that their polycondensation, if any possible, does not occur when these species are involved in too strong complexes with methylamine. In some cases (Cu2+, Fe2+, Ag+), methylamine behaves as a reducing agent in the synthesis medium and the corresponding metallic species are found admixed with silicalite. At similar complexing power, the (alkali-free) “amine route” is preferred to the now more conventional “fluoride route”, that involves lower pH and less supersaturated solutions, requiring very long crystallization times. These latter can also be drastically reduced by using fluoride-amine admixtures.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.