分子筛与硅胶的区别.pdfVIP

Date: 2009-04-06/MLN Technical Information Sheet Adsorption materials, comparison between Silica Gel and Molecular Sieves For Rotary Heat Exchangers with a high moisture transfer capability different adsorption materials are used. The two main types of adsorption materials used for moisture transfer in normal comfort ventilation applications are Silica gel and Molecular Sieve. Silica gel: Silica gel is a partially dehydrated form of polymeric colloidal silicic acid. Silica gel has an amorphous micro-porous structure with a distribution of pore opening sizes of roughly 3-60 angstroms. These interconnected pores form a vast surface area that will attract and hold water by adsorption and capillary condensation, allowing silica gel to adsorb up to 40% of its weight in water. Silica gel is extremely efficient at temperatures below 25°C (77°F) (see Figures 1 and 2), but will lose some of its adsorbing capacity as temperatures begin to rise (Figure 3). Much of silica gels popularity is due to its non-corrosive, nontoxic nature and its having received US government approval for use in food and drug packaging. Molecular sieves: Molecular sieves (also known as Synthetic Zeolite) adsorb moisture more strongly than silica gel. This can be seen by the high initial slope of the adsorption isotherm for molecular sieve as compared to the other desiccants (Figure 2). Where a very low relative humidity is required, molecular sieves are often the most economic desiccant because of their high adsorption capacity at low relative humidity. Also, molecular sieves will not give up moisture as readily as silica gel as temperatures rise (Figure 3). Molecular sieve co