Desarrollo de materiales de membrana robustos, selectivos y de alta permeabilidad para la separación de CO2
Development of highly permeable, selective and robust membrane materials for CO2 separation
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AuthorFernández Barquín, Ana
ABSTRACT: The ability of membranes to separate efficiently CO2 from other light gases has received a great deal of attention due to its importance as alternative energy-efficient process reducing greenhouse gas emissions. The aim of research is to develop membrane materials that exhibit good performance and that are robust enough for long-term operations at the process temperatures. The permeability and selectivity values of membranes should be as high as possible for their efficient use in industrial gas separation applications. Poly (1-trimethylsilyl-1-propyne) (PTMSP) has the highest known permeability of any polymer to gases. However, the high permeability is coupled with low ideal selectivity and its gas permeability decreases rather dramatically with time because of physical aging. Many attempts have been made to overcome this problem: crosslinking, substitution of functional groups, mixed matrix membranes.
Mixed-matrix membranes (MMMs) exhibit the molecular sieving effect and catalytic properties of inorganic fillers and combine desirable mechanical properties with the economical processing capacity of polymers. The main challenge of MMMs is the adhesion between the zeolites and the polymer to obtain a good interaction. Numerous attempts have been reported to incorporate zeolite particles into polymer matrices for gas separation because of their crystalline character with well-defined pore structures and shape selectivity properties.
In this work, mixed matrix membranes have been prepared from PTMSP and small pore zeolites, such as NaA (Si/Al =1) and ITQ-29 (Si/Al = ∞), at different loadings, and the CO2 and N2 permeation has been measured at temperatures from 25 to 100ºC. The physical aging of the PTMSP is delayed. The permeability and selectivity increase with increasing zeolite A loading, up to an optimum zeolite loading of 10 wt.%. Maxwell model has been used to predict MMMs performance but the predicted values underestimate the experimental results. TGA and XRD reveal that the MMMs are thermally stable up to 300ºC and there is good interaction between zeolites and polymer.