Luciano Carluccio

Synthesis of mesoporous SiO2–ZrO2 mixed oxides by sol–gel method

Abstract A series of SiO 2 –ZrO 2 mixed oxides were prepared by sol–gel method in the presence of directing agent, with variable amounts of ZrO 2 between pure silica and pure zirconia, with the aim to obtain catalytic materials suitable as solid acid catalysts. SiO 2 –ZrO 2 mixed oxides differ from the two pure starting oxides. While SiO 2 has a low OH density without peculiar acid character, the introduction of increasing amounts of Zr increases the density of the acid sites in the materials. Furthermore both SiO 2 /ZrO 2 molar ratio and drying procedure are able to influence the physico-chemical characteristics (textural properties, acid sites distribution, etc.) of these mixed oxides.

Multivariate approach to zeolite synthesis

The influence of seven variables on the results of zeolite synthesis performed in presence of 1-methyl-1,4-tetramethylenbis(N-methylpiperidinium)-dihydroxide as structure directing agent (SDA) was examined. The syntheses were planned according to a factorial design strategy and run by using a multiautoclave device. The produced data-set (experimental factors values and qualitative XRD responses for 72 syntheses) was explored by stepwise linear discriminant analysis (LDA): SiO2/Al2O3 molar ratio was identified as the most influent synthesis variable, discriminating between a region rich in amorphous materials and a region where the formation of MFI zeolite is favoured.

Synthesis and characterization of borosilicates with the EUO framework topology

Abstract B-EUO, a borosilicate with the EUO framework topology was successfully synthesized by using N,N,N,N′,N′,N′-hexamethyl-1,6-hexanediammonium (hexamethonium) as a structure-directing agent. The effective incorporation of B in the EUO framework was confirmed by 11 B MAS NMR, TG and XRD analyses. Up to ∼8 B atoms/unit cell were incorporated in the EUO framework, which corresponds to the number of ammonium groups accommodated in the pores. EUO was obtained also in the ternary B–Al–Si system, with the Al quantitatively incorporated into the framework. A structural model was derived for the as-synthesized EUO sample, with the position of the hexamethonium ion determined with the Quench Dynamics protocol, a procedure that combines high-temperature molecular dynamics and energy minimization techniques. The model was successfully employed for refining the experimental XRD profiles by the Rietveld method.

The synthesis of the new zeolite, ERS-7, and the determination of its structure by simulated annealing and synchrotron X-ray powder diffraction

The new zeolite ERS-7 (EniRicerche-molecular-Sieve-7), which was synthesized within a narrow temperature and compositional range using N,N-dimethylpiperidinium as a structure directing agent, has a structure consisting of 17-sided (46546582) picnic-basket-shaped cages connected by 8-membered ring windows.

Dynamic behaviour of azonia-spiro-alkanes within the MOR and MTW zeolite pore structures

The molecular packing stability and the dynamic behaviour of three azonia-spiro-alkanes involved as structure determining agents in the zeolite synthesis has been examined in the frameworks of MOR and MTW. A detailed molecular model has been set up by computer graphics methods and used to perform Monte Carlo packing and molecular dynamics simulations. The energetic stabilisation and molecular mobility have been calculated and compared to previous experimental characterisation data. The results are found useful to discuss the packing preferences of this class of molecules in the zeolite pores under investigation, with the aim of rationalising their templating ability and selectivity.