Chemical and Biomolecular Engineering

Membrane Technologies for Energy Cost Reduction

Prof. David ShollMichael E. Tennenbaum Family Chair and GRA Eminent Scholar in Energy Sustainability

School of Chemical & Biomolecular Engineeringand Strategic Energy Institute,

Georgia Tech

Chemical and Biomolecular Engineering

Georgia Tech’s Strategic Energy Institute

• SEI Mission• Develop technologies, policies

and educational programs that have the potential for offering high impact solutions to near-term energy issues

• Engage in fundamental energy research that will have a long –term, transformative effect on our nation’s energy future

SEI was established to serve as conduit for integrating, facilitating and enabling Institute-wide programs in energy research and development. Engaging the best and brightest from industry, government and academia, SEI creates innovative solutions to current and future energy challenges

Strategic Energy Institute

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Georgia Tech’s Strategic Energy Institute

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Georgia Tech’s Energy Research Strengths

•Center for Innovative Fuel Cell & Battery Technologies

•Aerospace Engineering Combustion Laboratory

•Institute for Paper Science & Technology (IPST)

•Center for Organic Photonics and Electronics (COPE)

•Intelligent Power Infrastructure Consortium (IPIC)

•Membranes Research Group

•National Electric Energy Testing, Research and Applications Center

•Specialty Separations Center

•University Center for Excellence in Photovoltaic Research and Education

Chemical and Biomolecular Engineering

Background – A Biological Example

Nerve cells use K+ ions for signaling

K+ protein channels are optimal membranes: essentially perfect selectivity forK+ over Na+ (even though Na+ is smaller), and essentially optimal K+ fluxNobel prize to MacKinnon for solving crystal structures that explained these observations

Source: www.biologyreference.com

Chemical and Biomolecular Engineering

Background – Water Desalination

Source: Water World, Vol. 1 Issue 2(www.waterworld.com)

Tampa Bay Water Desalination Plant25 million gallons fresh water/day9400 polyamide/polysulfone membranes~400,000 m2 membrane surface area19 million gallons of salt solution/day diluted at nearby power plant

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Membrane Terminology

RO = reverse osmosis

NF = nanofiltration

UF = ultrafiltration

MF = microfiltration

Source: Adnan et al., Appita June/July 2010

Chemical and Biomolecular Engineering

Membrane Terminology

Source: Adnan et al., Appita June/July 2010

Ultrafiltration (UF) Reverse Osmosis (RO)

UF performed with ceramic membranes (tolerant of harsh conditions)RO performed with polymeric membranes

Large pressure difference required to overcome osmotic pressure

Chemical and Biomolecular Engineering

Source: Adnan et al., Appita June/July 2010

Membranes in Pulp & Paper Processes

Chemical and Biomolecular Engineering

Membranes for Treatment of Black Liquor

Multiple studies have examined UF membranes for treating black liquor

Ceramic membranes do not requireT or pH of stream to be changed

Mechanical stability of ceramics aidsin backflushing to reduce fouling

UF can remove macromolecules(e.g. lignin) but not salt

Cost estimates by Jonsson & Wallberg, Desalination 237 (2009) 254Estimates for a plant processing 200 m3/h pulping liquorLignin concentrated to 100 g/L by membrane (and 4 g/L in permeate stream)Treating black liquor yields 108,000 tonne lignin/year costing ~33 Euros/tonneMembrane area of ~4200 m2 requiredCost could be reduced by increasing membrane flux

Chemical and Biomolecular Engineering

Membranes for Reducing Evaporation Costs

Evaporation of black liquor is a major energy user 195 TBtu in pulp industry in 2002 (R. B. Kinstry, D. White, Pulp and paper industry energy

bandwidth study, 2006)

NF

Evaporatorplant

RecoveryBoiler

Steam &Electricity

Digester

DissolvingTank

SmeltNa, CO3S, SO4

Weak WashNa, CO3,SO4, OH

Slaker

CaO

DregsC, Metals

GLNa, CO3, HS

WL Clarifier

Wood

WLNa, OH,HS

RO Permeate to BSW

NF Concentrate

RO

?

WBL

NF Permeate

RO Concentrate

Membrane conceptfrom Nikolai DeMartiniand Bill Koros (GT)

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Membranes for Reducing Evaporation Costs (cont.)

NF

Evaporatorplant

RecoveryBoiler

Steam &Electricity

Digester

GL Clarifier

SmeltNa2CO3Na2S, C

Weak WashNa, CO3,SO4, OH

Slaker

CaO

DregsC, Metals

GLNa, CO3, HS

WL Clarifier

Wood

WLNa, OH,HS

Water to BSW/other42 % of H2O in WBL

Concentrate:49% of Na43% of S81% of Org C36% of WBL H2O

RO?

WBL

Permeate:51% of Na57% of S19% of Org C64% of WBL H2O

Assume20% d.s.

NF membrane: - Large reduction in liquid volume

to evaporator- Small change in ionic strength

(small pressure drop to drive membrane separation)

RO membrane: - Used to reduce ionic strength of

RO permeate stream- Fouling problems reduced by using

dilute stream from NF membrane

Critical challenge: membranes must operate at very high pH

Chemical and Biomolecular Engineering

Chemically Resistant Membrane Materials

www.psrc.usm.edu/MauritzSource: Simon Orr, U. Warwick

Nafion®Commercially available ionomerWidely used in PEM fuel cellsStable up to at least pH 12

Carbon Molecular SievesZeotec Adsorbents Ltd.

Extremely well developed as adsorbents, less well developed as membranes

Produced by controlled pyrolsis of hydrocarbons(e.g. furfural), giving well defined pore sizes

Very chemically stable

Chemical and Biomolecular Engineering

Chemically Resistant Membrane Materials (cont.)

Zeolite membranes

Already used in some commerical pervaporation applicationsRequire porous support layer for mechanical integrityVery chemically stable

Rich Noble & John Falconer(University of Colorado)

www.hitk.de

Chemical and Biomolecular Engineering

Membranes for Reducing Gas Emissions

Boilers are the dominant source of effluent gas from pulp & paper industry

Future regulation may place strong demands on controlling gas emissions

Low volume species (increased regulation highly likely)Hydrogen sulfide (H2S), Hydrogen Chloride (HCl), Carbon Monoxide (CO)H2S mainly released from evaporation steps

High volume species (regulation or economic opportunity likely)Carbon dioxide (CO2)

Changes in operating conditions can reduce low volume species (e.g. CO)but not high volume species.

Significant efforts associated with H2S streams for natural gas sweetening;may be synergies that can be realized from materials from this area

Chemical and Biomolecular Engineering

Membranes for CO2 Capture from Flue Gas

ARPA-E funded program at Georgia Tech by Sholl, Koros, Jones, Nair,Walton, and Meredith (Chemical & Biomolecular Engineering)

Merkel, Lin, Wei, Baker (J. Membrane Sci. 2010) process modeling

Analysis based on 600MW coal-fired power plant and sequestration-ready CO2 at 140 barDesigns based on > 95% purity in delivered CO2

• Single stage membrane processes not feasible• 2-stage processes are feasible• 2-step countercurrent sweep process gave 16% parasitic power, $23/ton capture cost• Membrane area of 1.3 million m2 for a membrane with CO2 permeance of 1000 GPU

and CO2/N2 selectivity of 50.•Increasing permeance of membranes is more critical than selectivity as long as

selectivity larger than ~30-40.

Requirements for practical membrane based solution1. Must be highly scalable base on polymeric hollow fibers2. Must be robust under real conditions (water, SOx, NOx)3. Cost per unit membrane area must be reasonable

Chemical and Biomolecular Engineering

Chemical and Biomolecular Engineering

Zeolite/Ultem composite membranes(Koros, Jones, Nair et al., JACS 2009)

Core concept: MOF-polymer composite hollow fibers

Chemical and Biomolecular Engineering

Chemical and Biomolecular Engineering

M. Eddaoudi, et al., Proc. Nat. Acad. Sci. 2002, 99, 4900.; O.M. Yaghi, et al., Nature 2003, 423, 705.; H.M. El-Kadari, et al., Science 2007, 316, 268.

Crystalline, nanoporous materials with high surface area and “designable”pore topology and functionality

4000+ distinct crystal structures are knownMuch attention has focused on “large pore” materials that will not be useful in our application.

Challenge #1: How do we rationally screen a large number of MOFs to findcandidates that are well suited for CO2/N2 membranes?

Challenge #2: How do we establish the robustness/stability of MOFs?

Metal Organic Frameworks (MOFs)

Chemical and Biomolecular Engineering

Chemical and Biomolecular Engineering

Challenge #1: How do we rationally screen a large number of MOFs to findcandidates that are well suited for CO2/N2 membranes?

Challenge #2: How do we establish the robustness/stability of MOFs?

Challenge #3: How do we synthesize MOFs in the nanoparticle formrequired for thin film membrane applications?

Challenge #4: How do we incorporate MOF particles into hollow fibersduring fiber spinning?

Challenges (cont.)

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Chemical and Biomolecular Engineering

Numerous opportunities exist in pulp & paper industry for using membranes

Reducing energy use: NF and RO membranes for treating black liquorKey challenge – implementation of chemically resistant membranes

Reducing CO2 emissions via carbon capture:Composite polymer membranes for CO2 capture from flue gasCurrent focus is on powerplants, but smaller scale applications are likely to be advantageous

Conclusion