Separation of Gases with an A-Type Zeolite Membrane

Abstract

A highly hydrophilic A-type zeolite membrane was prepared by a hydrothermal synthesis on the outer surface of a porous α-alumina tube. Increasing and decreasing the permeation temperature between 308 and 473 K over 40 cycles in a period of 4 months did not damage the membrane. Permeation tests with a variety of permeates showed that the membrane possessed two types of pores: zeolitic pores of 0.4−0.43 nm diameter and nonzeolitic pores. Molecules larger than C2H6 were not able to permeate through the zeolitic pores. The separation factors of the membrane were dependent on molecular size, affinity to the pore walls, and hydrophobicity of the permeating molecules. The combination of permeants also affected the permeation rates. H2O molecules could be concentrated in the zeolitic and nonzeolitic pores, thus reducing the permeation of the hydrophobic permeants. The H2O/H2 separation factor was larger than 160 at permeation temperatures of 303−473 K.

Nanocomposite sodalite/ceramic membrane for pre-combustion CO2 capture: synthesis and morphological characterization

“…Furthermore, compared to existing technologies like absorption and adsorption, membranes possess noticeable advantages over absorption and adsorption processes, they have simple modular system, no waste streams and no regeneration energy required. Membrane technology eliminates limitations of conventional gas absorption towers and adsorption processes, thus offering high selectivity and high driving force with a simple modular design (Aoki et al 2000).…”

Emerging Applications of Environmentally Friendly Zeolites in the Selective Catalytic Reduction of Nitrogen Oxides

“…However, the improvement of the HC poisoning resistance of the Cu/ZSM-5 catalyst arising from Na + co-cations was still limited. Due to the shape selectivity, large molecules could not pass through small pore zeolites because of steric hindrance [89]. For example, because of the small pores and cages, the NH 3 -SCR activity over Cu-FER catalysts was less affected than that over Cu-ZSM-5 in the presence of decane [17].…”

Zeolite Membranes for Gas and Liquid Separations

“…Seeding can be accomplished simply by rubbing the support with the zeolite powder [40,43,44], or by especially immersing the support in a suspension of crystals [41,42].…”