No abstract

Samples of mesoporous silica, SBA-15, were prepared under hydrothermal conditions and Cu cations were incorporated into the framework by two different impregnation techniques. The corresponding adsorption/desorption isotherms of propylene, propane, and N 2 were measured to evaluate the material's effectiveness in the separation of propane/propylene mixtures.Adsorption uptake of propylene increased and that of propane decreased in Cu containing samples as compared to the uptakes observed in undoped SBA-15 samples. It was demonstrated that the presence of Cu atoms in the adsorbent lattice led to a greater selectivity towards propylene. Furthermore, the highest level of Cu(I) were obtained in samples prepared by equilibrium impregnation, which in turn improved the olefin/paraffin uptake ratio. Under some working conditions, the amount of propylene adsorbed in selected samples is totally reversible while propane uptake was negligible. E. I. Basaldella ( ) •

No abstract

No abstract

Abstract--The level of Fe impurities in 2 well-crystallized kaolinites was modified (by addition or chemical removal treatment) to analyze the Fe influence in the aluminosilicate zeolite synthesis.The original and modified clays were heat-treated in order to change their reactivity for zeolite A synthesis, and their thermal transformations were studied by X-ray diffraction (XRD), determination of point of zero charge (PZC) and infrared (IR) techniques. It was established that many structural changes took place, regardless of the Fe clay content. Furthermore, the presence of Fe species in alkaline solution or in the solid phase did not seem to greatly influence the zeolite crystallization, because only small differences in the conversion values among samples with different Fe contents were registered. The crystallization process seemed to be related mainly to A1 coordination changes produced by the thermal and Fe removal treatments used.