aiche 2011 ethanol water
TRANSCRIPT
Ethanol/Water Biomass Feedstock Separation Through Inorganic A-Type Zeolite Membrane on Thin Porous Ni
Sheet Support
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Yuxiang(Tony) Rao, Rong Xing, Wei Liu*
Pacific Northwest National Laboratory
Richland, WA, USA
Presentation at AIChE 2011 Meeting
Minneapolis, MN,USAOct 18th, 2011
Outline
Motivation
New Membrane Product Concept Robust, Large Surface Area Packing Density, Low Cost
Membrane Preparation and Characterization Porous Ni sheet support A-type Zeolite Membrane Layer
Application (Ethanol/water Separation Testing) Model feed (90% ethanol, 10% de-ion water) Real feedstock (1:1 mixture of PEI #4 and PEI #5, Pacific Ethanol Inc’s
plant)
Concluding Remarks
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Motivation
Ethanol production worldwide(Global Renewable Fuels Alliance, GRFA)
Energy consumption for a 40M gal/year dry corn mill ethanol plant:
2/3 of the overall energy (excluding co-products) is consumed in concentration and purification of ethanol from fermentation broth.
Energy consumption is even greater when ethanol level becomes lower from cellulosic biomass.
(Unit in Btu/gal) Steam Natural gas Electricity Total %
Grain Handling 0 0 352 352 2%Starch Conversion 5,544 0 133 5,677 29%
Fermentation 0 0 231 231 1%Ethanol/water separation 13,141 0 33 13,174 68%
Co-Product Drier 0 13,914 1,859 15,773
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Background and Objective
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Develop thin porous metal sheet-supported zeolite membrane for selective removal of water molecule from process streams with combination of desirable performance attributes High flux and selectivity Good chemical and thermal stability Mechanical strength and flexibility High surface area packing density Low cost
A type Zeolite:
3A-(KA), 4A- (NaA), and 5A-(CaA) type zeolite
materials have been widely used in industrial
drying processes as an adsorbent. Their
selective water adsorption and material stability
has been well demonstrated.
A very attractive class of materials used to
make membranes 4A-type zeolite
Kinetic Diameter
Ethanol: 4.46ÅWater: 2.65Å
Fabrication of porous Ni sheet support
Precursor material•Metallic powder precursor (NiO powder)•Organic pore former•Binder
Green body
Porous support sheet•Pore size, 1-10µm•Porosity,30-60%•Thickness, 25-200µm•Thermal stability up to 600ºC•Chemical stability, pH=2-13•Rupture pressure, >50bar
Tape casting Thermal treatment
•O2/N2
•H2
Thin
Flexible and robust
Uniform structure suitable for membrane deposition5
Seed Coating Secondary membrane growth on porous Ni sheet support
Seed coatingSubstrate Seed coated Ni sheet
03.um/1.4um 4A seeding crystals
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Hydrothermal membrane growth
Hydrothermal growthA-type MembraneSeeded coated Ni sheet
100C, 3.5hrs, 1C/min
Membrane-# Feb-07-2011-No.2-#3
Si:Al:Na:H2O 2:2:2:150
NaA seeding particle 0.3 µm/1.4 µm 4A seeds
Slip coating step First coating w/1.4 µm seed, followed w/ 0.3 µm seed
Membrane growth 100 C, 3.5 hr, 1C/min in 1 L Parr reactor7
CharacterizationXRD
All membranes are NaA zeolite membranes8
Application (model feed)Ethanol/Water Separation (90wt% ethanol+10wt% water)
Separation temperature100ºC
Feed: wt.% of water 10%
Feed: flow rate3sccm
Permeate: sampling
Liquid N2 cold trap
Permeate: vacuum<10 tor
Feed: PH6.6
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Scheme 1 Ethanol/water separation testing unit setup for model feed
Ethanol/Water Separation Results(model feed)
Membranes H2O/EtOH separation factor Permeation flux, kg/(m2.h)
NaA-type membrane
>10,000 7.927
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90wt% ethanol+10wt% water
Application (real feed)Ethanol/Water Separation (EtOH/H2O content=58/42,wt%)
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Element Atomic%C 2.83O 48.57Na 25.51Al 2.79Si 2.87S 13.91Ni 3.01Total 100
NaA membrane lost selectivity due to the corrosion of sulfuric acid, which was deposited on the surface of membrane during separation process (100ºC, pH=4.5)
Feed ID# wt % ethanol pH Note
PEI#4 23.0 3.6 Sampled from bottom of the stripper column
PEI#5 93.6 5.3 Sampled from overhead of the distillation column
PEI #4 & #5 58.3 4.5 1:1 mixture of PEI#4 and #5 to simulate overhead stream of the beer column
Table 1 Feedstock obtained from Ethanol Plant for membrane separation tests
Application (real feed)Ethanol/Water Separation (Titration Experiment)
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Figure 1 Color change of 1:1 mixture of PEI#4 and #5 mixture after addition of base
NaOH NH4OH
Table 2. ICP result for PEI#4 and PEI#5 feed samples
Sample ID# K(ppm) Na(ppm) Ca(ppm) S(ppm)
PEI #4 2.52 5.89 0.89 10.53
PEI #5 0.26 3.05 0.73 5.51
Baker Soda (NaHCO3) Urea
Sulfur and calcium element detected by ICP from real biomass feedstock most likely come from the fermentation and upstream chemical process.
Application (real feed)Ethanol/Water Separation
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Element Atomic%O 50.67Na 0.42Al 0.32Si 0.14S 25.22Ca 22.1Ni 0.82Total 100
NaA Membrane surface was covered with sulfur and calcium compound after three days stability test
ICP result: ppm
Sample ID# Na S
P2064 0.14 0.16
P2069 0.63 0.04
F2064 93.62 15.82
F2069 123.22 19.23
Hydrated Kinetic Diameter
Na+ 7.2 Å
SO42-: 8.6 Å
Application (real feed)Ethanol/Water Separation (EtOH/H2O content=58/42,wt%)
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Scheme 2 Ethanol/water separation testing unit setup for real feed (with guard bed)
Separation temperature100ºC
Feed: wt.% of water 42%
Feed: flow rate3sccm
Permeate: sampling
Liquid N2 cold trap
Permeate: vacuum<10 tor
Feed: PH4.5
Application (real feed)Ethanol/Water Separation
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No. Adsorbent name Supplier
1 Amberlite IRA-458 (strong basic, ion exchange resin)
Polyscience
2 Amberlite IRA-900 (strong basic, ion exchange resin) Polyscience
3 Amberlite IRA-93 (weakly basic, ion exchange resin) Polyscience
4 Amberlite IRA-958 (strong basic, ion exchange resin) Polyscience
5 MgO Aldrich
6 Type D-201 activated alumina 7x12 mesh beads UOP
7 Type A-201 activated alumina 7x12 mesh beads UOP
8 Type AW-300 molecular sieve, 1/16” pellets or beads UOP
9 Type AW-500 molecular sieve, 1/16” pellets or beads UOP
Table 3 Adsorbent materials evaluated for real ethanol/water feedstock
Different adsorbent materials (ion exchange resins, particles, molecular sieves) were tested under harsh separation conditions (100C, pH=4.5) to remove the contaminations (acid, organic compound) from the real feedstock. Only Amberlite IRA-93 shows the best stability and purification performance.
Application (real feed)Ethanol/Water Separation
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anol
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Wat
er fl
ux,
kg/m
2/h
Time on stream,h
Water flux
Ethanol in permeate
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/m2/
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Water flux
Ethanol in permeate
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Time on stream,h
Water flux
Ethanol in permeate
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r flu
x,
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2/h
Time on stream,h
Water Flux
Ethanol in Permeate
(a) MgO (b) IRA-93
(c) IRA-958 (d) IRA-458
Figure 1. Stability testing of NaA membrane samples with the actual feed by using different guard bed material.
Application (real feed)Ethanol/Water Separation
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Figure 2. 700-h stability testing of a NaA membrane sample using IRA-93 guard bed material (the model feed was used for first 96 hr, followed by the actual feed
with feed tank refilling at about 96 h and 520h)
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Time on stream,h
Water flux
Ethanol in permeate
02468101214161820
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Feed sidePermeate sidePure ethanol
Summary
NaA Zeolite membranes have been synthesized on a thin porous metal substrate sheet of 50µm thickness by secondary hydrothermal growth
For model ethanol/water separation (90wt% ethanol+ 10wt%water, pH=6.6) , it has water/ethanol separation factor >10,000 and max water flux close to 8kg/(m2.h), which is much higher than other literature reports.
For real feedstock ethanol/water separation(58wt% ethanol+42wt% water, pH=4.5), the membrane lost its selectivity quickly. However, with Amberlite IRA-93 (ion exchange resin) as guard bed material, it has max water flux close to 12kg/(m2.h) and stable performance during 700hrs stability test.
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Acknowledgment
DOE Industrial Technology Program, contract Number DE- FC36-04GO98014
Environmental Molecular Science Laboratory, PNNL
ADMA products and Pacific Ethanol Inc.
Colleagues
Nathan Canfield
Jarrod Crum
Shenyang Hu
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Thank you!
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