Carbon Hollow Fiber Membranes

The VDP method was used to coat hollow fiber carbon membranes by Linkov et al. [36]. Then the coated membranes were heated in a nitrogen atmosphere to produce composite catbon-PI membranes. The composite membranes had small wall and active skin thickness with good mechanical properties. They have resistance agairrst high pressitres and have high flexibihty. 

Polyimide derived from a reaction of 2,4,6-trimethyl-l,3-phenylene diamine, 5,5-[2,2,2-trifluoro-l-(trifluoromethyl)ethylidene]-l,3-isobertzofitrandione and 3,3, 4,4 -biphenyl tetra carboxylic acid dianhydride was used by Jorres and Ko-ros to prepare carbon molecular sieve asymmetric hollow fiber membranes [37]. These membranes were developed and optimized for air separation apphcations. However, they were also effective for the separation of other gas mixtirres such as CO2/N2, CO2/CH4 and H2/CH4. The selectivities obtained were much higher than those foimd for corrverrtional polymeric materials without sacrificing productivity. 

Kusuki et al. [42] made the asymmetric carbon membranes by carbonization of asymmetric PI hollow fiber membranes. The effects of different experimental conditions on the membrane performance were investigated. They reported that those carbon membranes showed high permselectivities. 

Asymmetric carbon membranes were made by carbonization of asymmetric PI hollow fiber membranes by Tanihara et al. [43], In their study, it was found that the permeation properties of caibon membranes were hardly affected by feed pressure and exposure to toluene vapor. Furthermore, there was only little change in the permeation properties of the caibon membrane with the passage of time. 

The researchers also investigate the difference in permeation behaviors of CO2 and CH4 between the single component and the multi-component system from the view point of the microporous stracture, which was created through the formation process of the carbonized membrane [45]. 

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N. Tanihara, H. Shimazaki, Y. Hirayama, N. Nakanishi, T. Yoshinaga and Y. Kusuki, Gas Permeation Properties of Asymmetric Carbon Hollow Fiber Membranes Prepared from Asymmetric Polymer Hollow Fibers, 7. Membr. Sci. 160, 179 (1999). 

Saufi S.M., and Ismail A.F. (2003) Development and characterization of polyacrylonitrile (PAN) based carbon hollow fiber membrane. Songklanakarin J. Sci. Technol. 24, 843-854. 

Tanihara, N.H., Shimazaki, Y., Hirayama, S., et al. (1999). Gas permeation properties of asymmetric carbon hollow fiber membranes prepared from asymmetric polyamide hollow fiber. J. Membrane Sci., 160(2), 179—86. 

Fig. 2.2 Comparison of (a) carbon hollow fiber membrane with (b) polymeric hollow fibrer membrane...

Table 3.1 summarizes the configurations of carbon membranes found in the ht-erature. It is noticed that most of the carbon membranes produced from the 1980s to early the 1990s are flat disk or flat sheet membranes. Only in the middle of the 1990s, carbon membranes supported on tubes were fabricated, followed by carbon capillary membranes and carbon hollow fiber membranes. Flat sheet carbon membranes are more suitable for laboratory or research applications while carbon membranes supported on tube, carbon capillary membranes and carbon hollow fiber membranes are more practical and suitable to apply in industry. 

Ogawa M, Nakano Y (1999) Gas permeation through carbonized hollow fiber membranes prepared by gel modification of polyanuc acid. J Membr Sci 162 (1-2) 189-198 Ogawa M, Nakano Y (2000) Separation of COJC l mixture through carbonized membrane prepared by gel modification. J Membr Sci 173 (1) 123-132... 

Furthermore, PAN hollow fiber carbon membranes were coated with zeohtes [28], PI [29] and perfluoro-srrlfonated ionomer (PSI) [30] to produce composite membranes. After this period, there was not much research involving the rrse of PAN as a precursor for carbon membranes until late 2003, when Davis and Ismail [31] prepared their carbon hollow fiber membrane from PAN precursor. 

Another type of chemical pretreatment involves the use of catalysts including mineral acids and acidic salts, such as phosphoric acid and diammonium hydrogen phosphates, before carbonization. However, the preparation of carbon hollow fiber membranes with carbonization catalyst causes problems. In carbon hollow fibers. 

Donnet JB, Bansal RC (1984) Carbon Fiber. Marcel Dekker, New York, NY, USA Saufi SM, Ismail AF (2002) Development and characterization of polyacrylonitrile (PAN) based carbon hollow fiber membrane. Songkianakarin J Sci Technol 24 (SuppI) 843-854 Schindler E, Maier F (1990) Manufacture of porous carbon membranes. US Patent 4,919,860 Yoneyama H, Nishihara Y (1990) Porous hollow carbon fiber film and method of manufacturing the same. EP Patent 0,394,449... 

Barbosa-Coutinho E, Salim VMM, Borges CP (2003) Preparation of carbon hollow fiber membranes by pyrolysis of polyetherimide. Carbon 41 (9) 1707-1714... 

David LIB (2001) Development of asymmetric polyacrylonitrile carbon hollow fiber membrane for oxygen/nifrogen gas separation. MSc Thesis, Universiti Teknologi Malaysia,... 

Nitrogen gas pyrolysis system was designed and set up to transform the PAN hollow fiber membrane into PAN-based carbon hollow fiber membrane. The instrument involved in this system is illustrated in Fig. 5.3. Caibolite (Model CTF 12/65/550) wire wound tube furnace with the Eurotherm 2416CC temperature control system is used for the pyrolysis of the PAN hollow fiber membrane. The furnace can be operated at a maximum temperature of 1200°C and has the abihty to control the heating rate and the thermal soak time during the pyrolysis process. 

Table 5.2 Nitrogen pyrolysis system for producing PAN carbon hollow fiber membrane...

Syed Mohd STC (2004) Foramtion and characterization of polyacrylonitrile (PAN) carbon hollow fiber membranes for gas separation. Master of Engineering Thesis, University Technology Malaysia, Skudai, Johor, Malaysia... 

It is the inspiration and the incentive whieh lies behind the development of carbon hollow fiber membranes, particularly designed for gas separatiom It is believed that fundamental knowledge will lead eventually to the development of tailor-made carbon membranes. 

Soffer A, Koiesh J, Sagee S (1987) Separation device. US patent 4919860 Ismail AF, Saufi SM (2003) Development and characterization of PAN-based carbon hollow fiber membrane foroxygen/nitrogen separation, Regional Symposium and Workshop Membrane Science and Technology , 13-17 January 2003, Songkhla, Thailand Dalton S, Heatley F, Budd PM (1999) Thermal stabilization of polyacrylonitrile fibers. Polymer 40 (20) 5531-5543... 

Soffer A, Azariah A, Amar A, Cohen H, Golub D, Saguee S (1997) Method of improving the selectivity of carbon membranes by chemical vapor deposition. US patent 5695618 Vu DQ, Koros WJ, Miller SJ (2002) High pressure CO /CH separation using carbon molecular sieve hollow fiber membranes. Ind Eng Chem Res 41 (3) 367-380 Ogawa M, Nakano Y (1999) Gas permeation through carbonized hollow fiber membranes prepared by gel modification of polyamic acid. J Membr Sci 162 (1-2) 189-198 Yamamoto M, Kusakabe K, Hayashi J, Morooka S (1997) Carbon molecular sieve membrane formed by oxidative carbonization of a copolyimide film coated on a porous support tube. J Membr Sci 133 (2) 195-205... 

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