Molecular Separation by Nano -porous Membanes

1. Group U2: Kyle Demel Keaton Hamm Bryan Holekamp Rachael Houk Molecular Separation by Nano-porous Membanes http://www.nanowerk.com/spotlight/id4407.jpg Based on the article A theoretical analysis of non-chemical separation of hydrogen sulfide from methane by nano-porous membranes using capillary condensations

2. Outline • Need for molecular separation • Conventional separation • Membrane separation • Membrane synthesis • Conclusion • Future research http://www.nanowerk.com/spotlight/id4407.jpg

3. Introduction • Natural Gas comes out of theground with H2S, which must beremoved before further processing • H2S is very toxic • Starting levels can be high (>5%) • For U.S. pipelines, limit is 4 ppm • Currently, most separation processes employ chemical means • One alternative is to use a nano-porous membrane to achieve a physical separation http://www3.humboldt.edu/engineering/sites/www3.humboldt.edu.engineering/marsh/images/hswarn.gif

4. Conventional H2S Separation • Traditional methods • Wash with MEA, DEA, or other amines • Use an oxide adsorbent • Disadvantages • Consumes these chemicals • Added hazards due to additional chemicals http://www.istockphoto.com/file_thumbview_approve/4452175/2/istockphoto_4452175-chemical-hazard-label.jpg http://www.ripi.ir/gas%20processing.jpg

5. Amine Wash Separation • Removes H2S, CO2, and mercaptans • Need a lot of equipment • Need both heating and cooling utilities Image from http://en.wikipedia.org/wiki/Amine_gas_treating

6. Oxide Adsorbent • Excellent separation achieved • Can have significant pressure drop • Need high temperatures • Use iron oxide or zinc oxide Image from http://www.cwaller.de/sorbents.htm http://imghost.indiamart.com/data/I/0/MY-267906/Chromatography-2_250x250.jpg

7. Criteria for a Good Membrane • Good selectivity in allowing H2S through and not CH4, only a small amount of CH4 dissolved in liquid H2S phase • Minimal pressure drop in bulk phase http://upload.wikimedia.org/wikipedia/commons/5/58/Methane-3D-balls.png http://www.zyvex.com/nanotech/nano4/tuzun/paper1/fig1p1.gif

8. Mechanism Nano-porous membrane Bulk Phase Permeate H2S CH4 H2S CH4 H2S CH4 CH4 CH4 CH4 H2S H2S H2S CH4 CH4 H2S A good membrane will have a high ratio of H2S to CH4 permeate through. CH4 CH4

9. Nano-porouosMembranes sites.google.com/.../home/MAIN_NANO_2.jpg www.mdpi.com/1996-1944/3/1/165/ag csites.google.com/.../home/MAIN_NANO_2.jpg

10. Temperature vs. Permeability

11. Separation Factor Where • x = mole fraction in the pore • y= mole fraction in the bulk http://tanakalab.iis.u-tokyo.ac.jp/research/image/ViscoelasticPS_Sim.png

12. Temperature vs. Separation

13. Synthesis of Membranes How are nano-porous membranes created? • Self-ordering electrochemical process • Cyclic anodization • Anodization that creates holes in anode http://www3.interscience.wiley.com/tmp/graphtoc/107640323/122443547/122267098/ncontent http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch20/graphics/20_1.gif

14. Self-Ordering Electrochemical Process • A schematic diagram showing pore formation by electrochemical self-ordering • Scheme of electrochemical cell for anodization and corresponding electrochemical reactions. • Scheme of pore formation, which includes several steps: • the formation of oxide layer on metal surface; • local field distributions caused by surface fluctuations; • the initiation of pore growth by field-enhanced dissolution; and • the pore growth in steady-state condition • Typical current density curve obtained with anodization showing these stages

15. Cyclic Anodization • New development by Dr. DucasLosic of the University of South Australia • A series of fabrication protocols to precisely control their most critical parameters, including pore diameters, pore geometry and surface chemistry

16. Conclusion • H2S separation is necessary: traditional methods are acceptable, but nano-porous membranes perform better • The H2S condenses and flows through the membrane to separate; therefore, membrane transport depends upon temperature and pressure • Membranes can be made through self-ordering electrochemical process and cyclic anodazition http://www.outotec.com/34718.epibrw

17. Further Research • Gas mixtures of more than just methane and hydrogen sulfide, like actual natural gas • Optimized temperature and pressure • Better manufacturing techniques, particularly for large scale production • Try a pilot-plant scale testing http://www.sciencecodex.com/graphics/Nanofilter.jpg

18. References • http://en.wikipedia.org/wiki/Amine_gas_treating • http://www.chem.tamu.edu/class/majors/chem470/Synthesis_Gas.html • http://www.thefuelman.com/Documents/H2S_removal.pdf • http://en.wikipedia.org/wiki/Hydrogen_sulfide • “Engineering of Nanomembranes for Emerging Applications” by Dr. DucasLosichttp://www.azonano.com/details.asp?ArticleId=2445 • “Simple and reliable technology for manufacturing metal-composite nanomembranes with giant aspect ratio” by Jovan Matovića and ZoranJakšićhttp://www.sciencedirect.com • “Self-ordered nanopore and nanotube platforms for drug delivery applications” by DusanLosic & SpomenkaSimovichttp://informahealthcare.com/doi/pdf/10.1517/17425240903300857?cookieSet=1