Zeolites and molecular sieves

Martens J A and Jacobs P A 1999 Phosphate-based zeolites and molecular sieves Catalysis and Zeolites, Fundamentals and Applications ed J Weitkamp and L Puppe (Berlin Springer) pp 53-80... 

Nadimi S, Oliver S, Kuperman A, Lough A, Ozin G A, Garces J M, Olken M M and Rudolf P 1994 Nonaqueous synthesis of large zeolite and molecular sieve crystals Stud. Surf. Sol. Catal. 84 93-100... 

Zeolite and Molecular Sieve-Based Process. Mobil has commercialized several xylene isomerization processes that are based on ZSM-5. Amoco has developed a process based on a medium-pore borosiUcate molecular sieve. 

Figure 2. Comparison of Calculated Diffusional barriers for 2,4,4-trimethyl-3-pentane (TMP) in Various Zeolites and Molecular Sieves... 

Synthesis of Large Pore Zeolites and Molecular Sieves... 

SYNTHESIS OF LARGE PORE ZEOLITES AND MOLECULAR SIEVES... 

The issues and challenges in molecular sieve science have dramatically changed in recent years and will continue to be redefined. As new and clever approaches to nanoporous materials are developed, the pore size and structural limitations that presently exist will no doubt be vanquished. As bolder endeavors expand the scope of this field, many new applications should also emerge. It seems the progress and innovations described in this chapter reflect a growing interdisciplinary nature in molecular sieve research. It is likely that the importance of large pore zeolites and molecular sieves will evolve in many nontraditional areas. 

Balkus, Kenneth J., Jr., Synthesis of Large Pore Zeolites and Molecular Sieves 50 217... 

Flanigen, E.M. (2001). Zeolites and molecular sieves. An historical perspective, in Introduction to Zeolite Science and Practice, 2nd edn (eds H. Van Bekkum, E.M. Flanigen, P.A. Jacobs, and J.C. Jensen), Stud. Surf. Sd. Catal., vol. 137, Elsevier, Amsterdam, pp. 11-35. Some content was reprinted from this review with permission of Elsevier. 

Zeolite and molecular sieve science is still a very active area of investigation and numerous new developments are continually appearing. This sechon is topical but not comprehensive, covering some new areas that should be of interest to the reader. 

Microwave Synthesis of Zeolites and Molecular Sieves The use of microwaves holds promise for efficiency improvements in zeolite synthesis due to the rapid heating possible when using microwave radiation [166], The first report of microwave synthesis of zeolites was by Mobil Oil in 1988, which broadly claimed the synthesis of zeolite materials in the presence of a microwave-sympathetic material, such as water or other pro tic component [167]. A number of reports have appeared since, including synthesis of zeolites Y, ZSM-5 [168] and metaUoaluminophosphate-type materials, such as MAPO-5 [169], There have also been extensive investigations in using microwaves for zeoHte membrane synthesis. Recent reviews discuss the progress in microwave zeoHte synthesis [170, 171]. 

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]. 

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