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Titanium silicates of MWW structures with different Si/Ti ratios were prepared via hydrothermal synthesis using piperidine as the structure directing agent and boric acid as the crystallization agent. All the syntheses resulted in highly crystalline materials independent of the Si/Ti ratio. The observed morphology showed MWW-like well-defined thin hexagonal platelets. The synthesized Ti-MWW materials exhibited higher surface areas and partial meso-porosity compared to the commercial TS-1 catalyst. The coordination of the Ti-species was investigated by UV–vis- and IR-spectroscopy. The MWW titanium silicates were tested for the catalytic performance in the epoxidation of propylene in a laboratory-scale trickle bed reactor to compare their clear different physico-chemical properties with the commercial TS-1. The synthesized Ti-MWW materials showed significantly higher catalytic activities, up to 3.5 times, using acetonitrile as the solvent and enhanced epoxide selectivities partially up to 100% in methanol unlike TS-1. The effect of the Ti content in the MWW and the calcination conditions were investigated in propylene epoxidation, revealing the beneficial effect of a lower calcination temperature and an increased Ti content on the activity. The catalytic results were correlated with the physico-chemical properties of the synthesized materials. [ABSTRACT FROM AUTHOR]

Synthesis of materials with combined chemistry and textural properties of carbon and silica aerogels was studied. The synthesized support was modified with ruthenium using evaporation impregnation and deposition-precipitation methods. The ruthenium modification methods were observed to influence the particle size, dispersion, surface area, pore volume and acidity of Ru-C-SiO2 catalysts. Ruthenium particles of 1-2 nm were obtained with a simple impregnation-evaporation method, while deposition precipitations technique gave ruthenium particles ranging from 1 to 8 nm. Small Ru nanoparticles (1-2 nm) were stable even after being exposed at 700 °C or washed with ethanol for regeneration. Furthermore, the catalytic properties of Ru-C-SiO2 catalysts in sugar hydrogenation were also observed to be influenced by the synthesis methods. The catalysts were tested in hydrogenation of sugars with different molecule sizes (i.e. glucose and cellobiose). D-Glucose was more reactive than D-cellobiose when they were studied separately. For the mixture of sugars higher reactivity of both sugars was observed in comparison with neat substrates for the catalyst made by evaporation-impregnation. On the contrary no significant differences between kinetics of the separated sugars and their mixture were observed for the catalyst prepared by deposition-precipitation. The results can be attributed to acidity and a combination of meso and microporosity of the catalysts. The support composite material could also be produced as a monolith, being a promising candidate for future industrial applications.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Abstract: Synthesis of multi-component cobalt based catalysts with different metal precursors and thermal treatment was performed. A special emphasis was put on promotion with ceria. Catalysts, which were synthesized from thermally pre-activated CoCO3·mCo(OH)2·nH2O as a precursor and thereafter underwent reduction in flowing hydrogen, have a clear tendency for decomposition of mixed aluminum–cobalt containing complexes, inevitably formed during thermal treatment. The catalysts were tested in steam reforming of hydrocarbons. The size of metal particles in reduced catalysts was determined by TEM and related to catalytic activity.Graphical Abstract: [ABSTRACT FROM AUTHOR]