DDR-type zeolite membranes

Nakayama, K., Suzuki, K., Yoshida, M., Yajima, K., and Tomita, T. (2006) Method for preparing DDR type zeolite membrane, DDR type zeolite membrane, and composite DDR type zeolite membrane, and method for preparation thereof US Patent 7,014,680. 

Kanezashi, M., O Brien-Abraham,)., Lin, Y.S., and Stmiki, K. (2008) Gas permeation through DDR-type zeolite membranes at high temperamres. AIChE J., 54, 1478-1486. 

Some small-pore zeolite and molecular sieve membranes, such as zeolite T (0.41 nm pore diameter), DDR (0.36 x 0.44nm) and SAPO-34 (0.38nm), have been prepared recenhy [15-21]. These membranes possess pores that are similar in size to CH4 but larger than CO2 and have high CO2/CH4 selechvihes due to a molecular sieving mechanism. For example, a DDR-type zeolite membrane shows much higher CO2 permeability and CO2/CH4 selechvity compared to polymer membranes [15-17]. SAPO-34 molecular sieve membranes show improved selechvity for separation of certain gas mixtures, including mixtures of CO2 and CH4 [18-21]. 

Tomita, T., Nakayama, K., and Sakai, H. (2004) Gas separation characteristics of DDR type zeolite membrane. Micropor. Mesopor. Mater., 68, 71-75. 

Himeno S, Tomita T, Suzuki K, Nakayama K, Yajima K, Yoshida S. Synthesis and permeation properties of a DDR-type zeolite membrane for separation of CO /CH gaseous mixtures. Ind Eng Chem Res... 

When zeolites are grown as films, zeolite membranes are formed. Efforts to prepare polycrystalline zeolite membranes started in the late 1980s, but not until the early 1990s were MFI-type zeolite membranes (ZSM-5 and silicalite-1) successfully prepared with very good permeation and separation properties [3]. Since then, zeolite membranes have constantly attracted considerable attention because of their unique properties in terms of size uniformity, shape selective separation behavior, and good thermal/chemical stabilities. So far, more than 20 different types of zeolite membranes have been prepared - such as LTA, FAU, MOR, FER, MEL, CHA, DDR, and AFI - with significant separation interest [4, 5]. Table 3.1 lists a few typical zeolite membranes and their potential applications for separation of fluid mixtures. 

Membranes of various zeolites, such as deca-dodecasil 3R (DDR) type, 15 16 19... 

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