Abstract

The production of raw materials such as ethylene and propylene is one of the main activities
of the petrochemical industry. These materials are essential for the production of polyethylene,
polypropylene, styrene and other important polymers. The precursor oleffins are obtained
through energetically costly separation processes, e. g. cryogenic distillation, and 
require the design and use of expensive equipment. A similar situation occurs in the process
of rectification and natural gas drying, where the separation of CO2 and H2O requires,
huge amounts of energy. Alternative separation methods involve the use of molecular sieves, 
porous membranes or ionic liquids, the latter used in reactive distillation separacion processes.
However, the most promising separation technology involves the use of molecular sieves, mainly due
to the high degree of development in synthesis techniques, which allow
materials with well defined chemical and topological features to be synthesized

The present work involves the use of computational techniques, specifically techniques based on
force-fields, to shed light on the basic mass and energy transport phenomenology in host-guest
systems. Zeolites with windows composed by eigth tetrahedral SiO4 units have been 
recognized as potential candidates to carry out kinetic separation processes. The attention
is drawn towards the diffusivity, parameter that reflects the degree of confinement imposed
by the topology of the adsorbant on the adsorbed species. Thus, the diffusivity can
be used as a reference parameter to select materials able to achieve the goals of specific 
kinetic based separations.