Synthesis Optimization of SSZ-13 Zeolite Membranes by Dual Templates for N2/NO2 Separation

Abstract

igh-silica SSZ-13 zeolite membranes are promising in industrial separations of light gases and continuous membranes are highly demanded for better separation performances. Herein, pure-phase, continuous and thin SSZ-13 zeolite membranes were synthesized using dual templates of N,N,Ntrimethtyl-1-adamantammonium hydroxide(TMAdaOH) and tetraethylammonium hydroxide(TEAOH). Systematical investigations of TMAdaOH/TEAOH ratios and their concentrations show that TMAdaOH acts as the main structure-directing agent in the formation of the SSZ-13 zeolite. TMAdaOH cooperatively plays with TEAOH in promoting the SSZ-13 crystal intergrowth to form a continuous polycrystalline membrane. Additionally, appropriate introduction of TEAOH is able to adjust the membrane thickness to the crystal-comparable size of ca. 2.0 μm. The SSZ-13 membranes are further applied for N2/NO2 separation, which is firstly reported on zeolite membranes. The gas permeation results show that the SSZ-13 membrane synthesized by the dual-template approach exhibits selective separation of N 2 over NO 2 with N 2 /NO 2 separation factor of 7.6 and N 2 permeance of 1.66×10 -8 mol•m -2 •s -1 •Pa -1 .

An anion-promoted increase of the SiO2/Al2O3 ratio of zeolites

“…Aluminosilicate zeolites are widely used as ion exchangers, catalysts and adsorbents 1–12 because of their regular pore structure, adjustable acidity and high thermal stability. The intensity and amount of acidity as well as the thermal/hydrothermal stability of zeolites depend on their SiO 2 /Al 2 O 3 ratio.…”

Silicalite-1/PDMS Hybrid Membranes on Porous PVDF Supports: Preparation, Structure and Pervaporation Separation of Dichlorobenzene Isomers

“…Due to the low mass transfer resistance, low energy consumption, high zeolites utilization and efficiency, zeolite membranes (inorganic and polymer) have been widely used in many fields such as chemical, medicine, environmental and other industrial fields [21][22][23][24][25][26][27][28]. The uniform narrow molecular−sized pore distribution makes them attractive as new shape−selective materials for gas and liquid separation [29][30][31][32], especially for isomeric and close−boiling mixtures [33][34][35], such as DCB isomers separation. Fortunately, in our previous study, we have successfully adopted dense and continuous silicalite-1/α−Al 2 O 3 membranes for the pervaporation separation of DCB from binary−isomers solutions [3].…”