Laura Olivia Alemán-Vázquez

Polyisobutenylsuccinimides as detergents and dispersants in fuel: infrared spectroscopy application

Polyalkenylsuccinimides are synthesized and their detergency and dispersancy properties evaluated in an internal combustion engine. The synthesis is based on the reaction of polyisobutene with maleic anhydride as the first step. The polyisobutenylsuccinic anhydride obtained reacts with primary amines in the last step to give polyalkenylsuccinimides. The results of the evaluations showed that some polyisobutenylsuccinimides reduce the deposit formation in the intake system with good efficiency. Infrared spectra of the prepared compounds allowed their identification.

Industrial Aplication of Catalytic Systems for n-Heptane Isomerization

The ideal gasoline must have a high pump octane number, in the 86 to 94 range, and a low environmental impact. Alkanes, as a family, have much lower photochemical reactivities than aromatics or olefins, but only the highly branched alkanes have adequate octane numbers. The purpose of this work is to examine the possibilities of extending the technological alternative of paraffin isomerization to heavier feedstocks (i.e., n-heptane) using non-conventional catalytic systems which have been previously proposed in the literature: a Pt/sulfated zirconia catalyst and a molybdenum sub-oxide catalyst. Under the experimental conditions at which these catalysts have been evaluated, the molybdenum sub-oxide catalyst maintains a good activity and selectivity to isomerization after 24 h, while the Pt/sulfated zirconia catalyst shows a higher dimethylpentanes/methylhexanes ratio, probably due to a lower operating temperature, but also a high formation of cracking products, and presents signs of deactivation after 8 h. Though much remains to be done, the performance of these catalysts indicates that there are good perspectives for their industrial application in the isomerization of n-heptane and heavier alkanes.

The Effect of Sulfates Concentration in Sulfated Zirconia (SZ) Catalysts n-Heptane Isomerization

Abstract Interest in new catalysts for alkanes isomerization, such as sulfated zirconia, has been increasing in the last years. These catalysts, due to their superacid character, have a good activity for this reaction but undergo a rapid deactivation. For sulfated zirconia catalysts, the effect of sulfates concentration on the activity and stability for alkanes isomerization is not clear. In this work, Pt/sulfated zirconia catalysts with different sulfates content were prepared by the impregnation method; characterized by X-ray diffraction, high-resolution Raman spectroscopy, infrared spectroscopy, and BET surface area; and evaluated in an experimental system for n-heptane isomerization.