Advances in molecular sieves and their applications in adsorptive gas separation processes

• Main Author: Lin, Christopher C. H.
• Other Authors: Kuznicki, Steven (Chemical and Materials Engineering)
• Format: Others
• Language: en_US
• Published: 2009
• Subjects: Adsorption; Molecular Sieves; Separation; Zeolites
• Online Access: http://hdl.handle.net/10048/522

The objective of this research was to develop new molecular sieve materials and to examine their applications in adsorptive gas separation processes. Several techniques to modify zeolite molecular sieve materials were developed, including a new pore size control mechanism and novel surface modification procedures. The new materials derived from these modification techniques were found to be potentially useful in many adsorptive gas separation processes. A novel mechanism was developed to systematically control the pore size of titanium silicate molecular sieves through halogen substitution of terminal hydroxyl groups. These halogen containing zorites represent a new class of size-selective adsorbents with readily tailored and highly specific pore sizes. Anion-controlled titanium silicates were demonstrated to have promise in multiple areas of size-based separation, particularly light hydrocarbon purification and permanent gas separation. By controlling the type and quantity of the extra-framework cations, titanium silicate molecular sieve adsorbents were modified to separate ethylene and ethane by either the kinetic phenomenon or an equilibrium process. All of these modification techniques were synergistically integrated to illustrate that multi-functional adsorbents can be designed and prepared for many target separations. This approach was demonstrated through the separations of CO2/C2H6 and CO2/CH4. Anion-controlled adsorbents were modified to selectively exclude ethane and methane by the steric effect, while the equilibrium and kinetic properties of the adsorbents were concomitantly adjusted by surface modification. The concept of gas adsorption and separation through nanometals interaction was introduced. Surface-supported nanometals, such as nanosilver, formed on titanium silicate ETS-10 were applied as unique adsorbents to separate gas mixtures, such as Ar/O2 and N2/O2. Continual research and development in new molecular sieve materials will be crucial to the future of the chemical processing industry, and should be viewed as an avenue for the discovery of next-generation adsorptive gas separation technologies. === Chemical Engineering