Eric J. Doskocil

Influence of support composition on the structure and reactivity of strontium base catalysts

Strontium was supported on a variety of carriers, including silica, alumina, titania and carbon, by impregnation and decomposition of an acetate precursor at 773 K. These supported samples were characterized by surface area measurements, stepwise temperature-programmed desorption of carbon dioxide and activity for the catalytic decomposition of 2-propanol. In some cases, infrared and X-ray absorption spectroscopy were used to identify surface species. Results from these techniques suggested that strontium supported on silica forms a weakly basic surface silicate phase that had low activity for 2-propanol dehydrogenation. On alumina and titania, strontium acetate decomposed to form supported basic carbonates that were moderately active for 2-propanol dehydrogenation. When rates are normalized by the base site density determined from CO2 desorption, strontium supported on carbon was the most active sample for dehydrogenation of 2-propanol. These results suggest that the nature of supported alkaline earth catalysts is strongly dependent on the composition of the carrier.

Improved THETA-1 for Light Olefins Oligomerization to Diesel: Influence of Textural and Acidic Properties

The increase in diesel demand, especially in Europe, and the need for high fuel quality requirements are forcing refiners to move into additional processes for production of high cetane diesel in order to meet the present market trends. Oligomerization of light olefins into middle distillate range products is a viable option. The fuel produced through this technology is environmentally friendly, free of sulfur and aromatics, and the adequate choice of the heterogeneous catalyst will direct the selectivity towards low branched oligomers, which will result in a high quality product. In this work we show the benefits of combining basic desilication treatments for generation of additional mesoporosity in mono-directional Theta-1 zeolite, with selective acid dealumination steps that restore not only the microporosity to values close to those of the parent samples, but also the total and strong Brønsted acidity. These modified Theta-1 zeolites present an outstanding catalytic behavior for oligomerization of propene, with a largely increased initial activity, a much higher resistance to deactivation with time on stream, and an improved selectivity to products in the diesel fraction, as compared to the original microporous Theta-1.Graphical Abstract