Carbon Dioxide Separation Through Polymeric Membrane for Biogas Applications

                                                                Carbon Dioxide Separation through Polymeric Membrane for Biogas Applications

Sang-Kyo Oh, Jin-Seok Kang, Hwi Yoon, Hyeon-jeong Kim, In-Sik Jung, Byung-Jae Park^*

Synopex Inc., Advanced Membrane Research Center, 856, Songdo-Ri, Daesong-Myun,

Nam-gu, Pohang-City, Korea, 790-840

^{*bj@synopex.com/pbjae@yahoo.com}

The control of carbon dioxide emission is one of the most challenging environmental issues because of the implications to atmospheric carbon dioxide level and climate change resulting from industrial plant and landfill site. Especially, the biogas from landfill site has drawn much attention in respect to energy recovery using gas membrane. Biogas has become an attractive alternative energy source due to its nature as a renewable resource and environment friendly, clean, cheap and versatile fuel. Generally, biogas derived from landfill site contains CH₄ of about 60%, CO₂ of about 40%, H₂S of about 1% and some vapor.  In order to use CH₄ among biogas as fuel source, further treatments, i.e. absorption, adsorption, cryogenic distillation and membrane separation or hybrid processes are needed in separating CH₄ from unwanted gas species, namely, CO₂ , H₂S, and water vapor. 

    Carbon dioxide separation from biogas using membrane technology has many merits, like its simplicity in retrofitting, ease in modularizing and also scale-up, without changing gas to liquid phase in the process. So, the membrane technology for gas separation is focused on making gas membrane with high selectivity of CO₂/CH₄, high permeability of CO_2, good thermal and mechanical stability, and long service life.

    In this study, hollow fiber membrane for CO₂/CH₄separation was prepared and by using non-solvent induced phase separation method (NIPS).  The spinning solution was consisted of modified polysulfone, organic solvent such as NMP and DMAc, and some additives like alcohols, salts, and organic solvents and was casted into coagulant like water and organic aqueous organic solvent through spinneret with double ring. The modified polysulfone(MPS) hollow fiber membrane with an outer diameter of about 420 µ and inner diameter of about 240 µ was prepared and investigated.

   The hollow fiber membrane from the above spinning dope at different conditions showed the meaningful value that CO₂/CH₄ selectivity has been improved from 30 to 40, and CO₂ permeability given up to 103 GPU. Using simulation gas containing carbon dioxide and methane of 60 % and 40%, respectively, separation of carbon dioxide from mixture gas was done by changing pressure and flow rate. Measurement results showed up to 97% purity of the methane and CH₄ recovery ratio of 70 was observed at different feed pressure in CO₂/CH₄ mixture gas. More study will be required and performed in order to increase CO₂/CH₄ selectivity and CO₂permeation of gas membrane.

References

1. M.A. Aroon, A.F. Isamail, M.M. Montazer-Rahmati, and T. Matsuura M.Y., Separation and Purification Technology, 72, 194-202 (2010).

2. Budiyono, T.D. Kusworo, A.F. Isamil, I.V. Widiasa, Seno Johari and Sunarso, Internaal Journal of Basic & Applied Sciences IJBA-IJENS, 10, 1, 1-7 (2010).