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Featured researches published by Mario Gabriele Clerici.
Journal of Catalysis | 1991
Mario Gabriele Clerici; Giuseppe Bellussi; Ugo Romano
Abstract The epoxidation of propylene with hydrogen peroxide in the liquid phase, in the presence of titanium silicalite catalyst (TS-1), is described. The best solvents are methanol and methanol/ water mixtures. The temperature is normally between room temperature and 60°C. Under these conditions, reaction rates are fast, yields on H2O2 are quantitative, and selectivity to propylene oxide is very high. Propylene glycol and its monomethyl ethers and trace amounts of formaldehyde are the only by-products formed. Selectivity is further improved and the hydrolysis of the epoxide is almost suppressed when the residual acidity of the catalyst is completely neutralized. The activity of spent catalyst is recovered by calcining at 550°C or, more simply, by washing with solvents. Complete activity recovery shows that Ti is not removed from the crystalline framework during the epoxidation reactions.
Journal of Catalysis | 1992
Giuseppe Bellussi; Angela Carati; Mario Gabriele Clerici; Giuseppe Maddinelli; Roberto Millini
The properties of titanium silicalite (TS-1) in reactions with water, hydrogen peroxide, and alcohol molecules have been studied by means of IR and NMR spectroscopy, and acid activity tests. An IR absorption is shown by TS-1 in the region 900–975 cm−1. Its exact position depends on the amount of adsorbed water, on exchange reactions with 17O- and 18O-labeled water, and on the average size of the crystallites. In 17O MAS NMR spectra a peak is shown at σ 360 ppm from H2 17O (σ = 0). IR and NMR spectra are discussed and interpreted in terms of Ti sites as constituted by tetrahedral [TiO4] units. TiOSi bonds react with water at near room temperature, producing TiOH and SiOH species. Reactions with hydrogen peroxide produce acidic derivatives, which catalyze the hydrolysis of cis and trans 2,3-epoxybutane in methanol, ethanol, and aqueous media. A five-membered ring hydrogen bonded structure, in which a titanium hydroperoxo moiety, TiOOH, and a protic molecule, ROH (R = H, CH3, C2H5), are involved, is proposed for these species. Their possible role in selective oxidations of hydrocarbons is discussed.
Archive | 1988
Giuseppe Bellussi; Giovanni Perego; Mario Gabriele Clerici; Aldo Giusti
Archive | 1986
Giuseppe Belussi; Mario Gabriele Clerici; Franco Buonomo; Ugo Romano; Antonio Esposito; Bruno Notari
Archive | 1989
Mario Gabriele Clerici; Ugo Romano
Archive | 1987
Mario Gabriele Clerici; Ugo Romano
Archive | 1986
Giuseppe Bellussi; Franco Buonomo; Antonio Esposito; Mario Gabriele Clerici; Ugo Romano; Bruno Notari
Archive | 1989
Giuseppe Bellussi; Mario Gabriele Clerici; Angela Carati; Fabrizio Cavani
Archive | 1989
Giuseppe Bellussi; Angela Carati; Mario Gabriele Clerici; Antonio Esposito; Roberto Millini; Franco Buonomo
Archive | 1998
Giuseppe Bellussi; Mario Gabriele Clerici; Angela Carati; Antonio Esposito