Olefin-paraffin separations

Olefin—Paraffin Separation. The catalytic dehydrogenation of / -paraffins offers a route to the commercial production of linear olefins. Because of limitations imposed by equiUbrium and side reactions, conversion is incomplete. Therefore, to obtain a concentrated olefin product, the olefins must be separated from the reactor effluent (81—85), and the unreacted / -paraffins must be recycled to the catalytic reactor for further conversion. 

FacilitatedTransport Process for Eow-Cost Olefin—Paraffin Separation, ATv2iacedTec m.o ogyPi.ogt.2im.E o. 70NANB4H1528 National Institute of Science and Technology, 1994. 

Okamoto, K.,S. Kawamura, M. Yoshino, H. Kita, Y. Hirayama, N. Tanihara, and Y. Kusuki, Olefin/ paraffin separation through carbonized membranes derived from an asymmetric polyimide hollow fiber membrane, Ind. Eng. Chem. Res., 38, 4424,1999. 

Padin, J. and Yang, R.T. (2000) New sorbents for olefin/paraffin separations by adsorption via tc-complexabon Synthesis and effects of substrates. Chem. Eng. Sd., 55, 2607. 

I. Pinnau and L.G. Toy, Solid Polymer Electrolyte Composite Membranes for Olefin/ Paraffin Separation, 7. Membr. Sci. 184, 39 (2001). 

A. Morisato, Z. He, I. Pinnau and T.C. Merkel, Transport Properties of PA12-PTMO/ AgBF4 Solid Polymer Electrolyte Membranes for Olefin/Paraffin Separation, Desalination 145, 347 (2002). 

D.T. Tsou, M.W. Blachman and J.G. Davis, Silver-facilitated Olefin/Paraffin Separation in a Liquid Membrane Contactor System, Ind. Eng. Chem. Res. 33, 3209 (1994). 

Reactive absorption is probably the most widely applied type of a reactive separation process. It is used for production purposes in a number of classical bulk-chemical technologies, such as nitric or sulfuric acid. It is also often employed in gas purification processes, e.g., to remove carbon dioxide or hydrogen sulfide. Other interesting areas of application include olefin/paraffin separations, where reactive absorption with reversible chemical complexation appears to be a promising alternative to the cryogenic distillation (62). 

In general, a C3 stream is obtained that contains propane, propylene, pro-padiene, and propyne, and these are separated in a C3 distillation column, also referred to as the C3 splitter. Propane-propylene separation and, as a rule, olefin-paraffin separation, are energy-intensive, and some estimates are that 1.27 x 1017 J are used for olefin-paraffin separation on an annual basis [4] while roughly 3% is used by paraffin-olefin distillation columns [5]. This provides an incentive to examine the propane-propene separation, which is an example of paraffin-olefin separation. 

High-Performance Olefin-Paraffin Separation Membranes... 

In addition to the polymer and facilitated transport membranes, novel materials are being proposed and investigated to achieve membranes with economically attractive properties. Carbon molecular sieve (CMS) membranes prepared by pyrolysis of polyimides displayed much better performance for olefin/paraffin separation than the precursor membranes [39, 46, 47]. Results obtained with CMS membranes indicated properties well beyond the upper-bond trade-off curve, as shown in Figure 7.8. Nonetheless, this class of materials is very expensive to fabricate at the present time. An easy, reliable, and more economical way to form asymmetric CMS hollow fibers needs to be addressed from a practical viewpoint. 

The preceding discussions illustrate that membranes have shown great potential as an alternative for olefin/paraffin separation, yet the performance of current membranes is insufficient for commercial deployment of this technology. Advanced material development is highly desired to improve the membrane properties and reduce cost. Another possible approach involves hybrid membranes with zeolites or CMS incorporated in a continuous polymer phase. More discussion in this regard will be covered later in this chapter. 

Eldridge, R.B. (1993) Olefin paraffin separation technology - a review. Industrial... 

Burns, R.L. (2002). Investigation of Poly (pyrrolone-imide) Materials for the Olefin/Paraffin Separation, PhD Dissertation, The University of Texas... 

Yoshino, M., Nakamura, S., Kita, H., Okamoto, K.-i., Tanihara, N. and Kusuki, Y. (2003) Olefin/paraffin separation performance of asymmetric hollow fiber membrane of 6FDA/BPDA-DDBT copolyimide. Journal of Membrane Science, 212, 13-27. 

A. tt - Complex ation Sorbents for Olefin-Paraffin Separations... 

Olefin-paraffin separations represent a class of most important and also most costly separations in the petrochemical industry. Cryogenic distillation has been used for more than 60 years for these separations (Keller et al, 1992). They remain to be the most energy-intensive distillations because of... 

D. J. Safarik, R. B. Eldridge, Olefin/ paraffin separations by reactive absorption a review, Ind. Eng. 

Title Dithiolene Functionalized Polymer Membrane for Olefin/Paraffin Separation... 

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