Transcript MSO/CMSO/MHSO

Natural Oil Polythiols and Polyols–
A Life Cycle Comparison
Thomas A. Upshaw, William J. Fisher, Eric J. Netemeyer
Chevron Phillips Chemical Co., LP
ACS Green Chemistry & Engineering Conference
June 25, 2008
6/25/2008
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Outline
• Study objectives
• Modeling tools and information sources
• Modeled systems and assumptions
–
–
–
–
Mercaptanized soybean oil (MSO)
Petrochemical (flexible polyether) polyol
Castor oil
Soy-based polyol
• LCA Methodology
• Impact category results
• Conclusions
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Soy Polythiol – MSO (Polymercaptan 358)
CH2O
CHO
CH2O
CH2O
n-C17H35
O
O
C7H14
H2S
n-C8H17
C7H14
n-C5H11
CHO
CH2O
n-C17H35
O
O
O
O
C7H14
n-C8H17
C7H14 HS
HS
n-C5H11
HS
Soybean Oil
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Mercaptanized Soybean Oil (MSO)
Polymercaptan 358
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Objectives
• Develop a soy polythiol life cycle inventory (LCI)
platform for product life cycle assessment through the
product manufacturing stage (cradle-to-customer)
• Compare life cycle environmental impacts using
updated LCI data for vegetable oil and petrochemical
(polyether) polyols to quantify the benefit of using a
renewable oil as raw material
• Future: assess process changes and new process
technology for reduced environmental impact
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Life Cycle Modeling Tools
• SimaPro 7.0 software, using SimaPro 7.0 database
and U.S. LCI database
• BEES (Building for Environmental and Economic
Sustainability) impact model
– NIST sponsored & EPA supported
– Methodology used by USDA BioPreferred program
– Conducted in accordance with ISO 14040:1997(E) standard
• TRACI (Tool for the Reduction and Assessment of
Chemical and other Environmental Impacts) – EPA life
cycle impact assessment method
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Data Sources
•
Soybean data
– Agriculture data from U.S. LCI database (NREL)
– Processing data from NREL LCA report on biodiesel 1998
•
Soy Polythiol – Chevron Phillips Chemical Co.
– Process inputs estimated from commercial production facility, assuming
conventional H2S process technology
•
Soy-based Polyol
– 2004 manufacturer-specific BEES input streams
•
Petroleum (flexible polyether) polyol
– U.S. LCI database
•
Castor oil
– Purdue University article and various internet sources
– Incomplete process data supplemented by analogous data on other seed oils in
U.S. LCI database
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LCA System Boundaries
LCI INPUTS
Process
energy
Materials
production,
transport
Process
energy
Materials
production,
transport
Energy,
materials
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Crop oil Feedstocks
Petroleum Feedstocks
Agricultural
production
Upstream Production
Raw materials
production
of Raw
Materials
Vegetable
oil
production
& refining
Product Polyol or Polythiol
Manufacturing
Stage
Transportation to
the customer
ACS Green Chemistry and Engineering Conference 2008
LCI OUTPUTS
Air emissions
Water effluents
Waste
Air emissions
Water effluents
Waste
Air emissions
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MSO Polythiol Assumptions
• Commercial process design based on known reaction conditions
from trial runs at Philtex plant (Borger TX):
– UV reactor
– Estimated stoichiometric excess of H2S
– Stripping and recycle of H2S
– Known reaction conditions from lab/pilot work
• Conventional energy sources (nat. gas)
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Petrochemical Polyol Assumptions
• Consolidated proprietary information for 5 North American
plants, 2003-5 data
• Polyether polyol, glycerin-initiated, 3500 mol wt (on average)
• KOH-catalyzed, solvent, water-washed
• 7.6 to 1 wt ratio PO/EO
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Castor Oil Assumptions
• Complete data were not available
– Significant uncertainty, need better data
– Analogous LCI data for other seed oils were used for some LCI
inputs (fertilizer usage, energy)
• Since growth and modernization of castor agriculture has been
occurring, mechanized production and irrigation were assumed
for 75% of production
• 8200 mile transport from India to U.S. market assumed before
distribution in the U.S.
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Soybean Oil Polyol Assumptions
•
•
•
•
•
•
2004 manufacturer-specific BEES data
Produced by simple air oxidation of soybean oil
No further refinement, purification or derivatization
Soy agricultural model
Not sure if waste/off-grade is taken into account
1000 mile transport to customer
This probably represents the most environmentally
benign vegetable oil polyol process possible; a
benchmark for comparison of other renewable
products
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LCA Methodology
• Life Cycle Inventory – quantified listing of inflows and outflows
per 1000 lbs of product (built in SimaPro 7.0)
• Converted to equivalent units per 1000 lbs and combined into
LCIA impact categories (BEES impact model)
• Normalized to unitless dimensions corresponding to fraction of
total U.S. impact per year per capita
• Overall BEES environmental score: sum of normalized impacts
weighted by importance
– 2006 BEES Stakeholder Panel
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LCA Methodology
• Life Cycle Inventory – quantified listing of inflows and outflows
per 1000 lbs of product (built in SimaPro 7.0)
• Converted to equivalent units per 1000 lbs and combined into
LCIA impact categories (BEES)
• Normalized to unitless dimensions corresponding to fraction of
total U.S. impact per year per capita
• Overall BEES environmental score: sum of normalized impacts
weighted by importance
– 2006 BEES Stakeholder Panel
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Impact Comparison
(Cradle-to-customer)
Total - per 1000 lb
Global warming potential
Acidification Potential
Eutrophication Potential
Fossil Fuel Depletion
Water Intake
Criteria Air Pollutants
Ozone Depletion Potential
Smog Formation Potential
Total Fuel Energy
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kg CO2 eq
mole H+eq
kg N eq
MJ Surplus
liters
microDALYs
kg CFC-11 eq
g NOx eq
MJ
MSO Soy
Polythiol
1104
1871
2
3565
24002
505
5.6 E-07
4242
24887
Petroleumbased Polyol
1855
684
5
4923
34322
190
1.8 E-06
6859
24759
Castor Oil
-84
390
8
809
151655
53
1.6 E-08
5942
5153
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Soy-based
Polyol
-45
149
1
464
20088
38
3.7 E-07
2335
4482
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Global Warming Potential
2000
1855
1707
1500
CO2 equivalents
1248
1104
MSO Soy Polythiol
Petroleum-based Polyol
Castor Oil
Soy-based Polyol
1000
500
229
97 101 94
68 51
68
0
Total
-84 -45
Upstream Prod'n
-212
-500
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Manuf.
Transport
-207
-414
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Fossil Fuel Depletion
6000
MJ Surplus
5000
4000
MSO Soy Polythiol
Petroleum-based Polyol
Castor Oil
Soy-based Polyol
4923
4640
3565
3143
3000
2000
1000
809
464
303
206289
195202
57
401
118 88
118
0
Total
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Upstream Prod'n
Manuf.
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Transport
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Smog Formation Potential
8000
g NOx equivalents
7000
MSO Soy Polythiol
Petroleum-based Polyol
Castor Oil
Soy-based Polyol
6859
5942
6000
6158
4932
5000
4242
4000
3000
2335
2000
2156
1465
1000
1405
667
238343309
621463
621
0
Total
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Upstream Prod'n
Manuf.
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Transport
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Impact Results Normalized to MSO
Global warming potential
Acidification Potential
Eutrophication Potential
Fossil Fuel Depletion
Water Intake
Criteria Air Pollutants
Ozone Depletion Potential
Soy-based Polyol
Castor Oil
Petroleum-based Polyol
Smog Formation Potential
MSO Soy Polythiol
Total Fuel Energy
-10%
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40%
90%
140%
190%
240%
290%
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340%
390%
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Conclusions
• LCA is a valuable tool to help assess environmental impact of
products and processes at a more detailed level.
– more standards and complete, up-to-date publicly available data are
needed to improve general utility and consistency.
• Global warming potential and fossil fuel use of MSO and vegetable
oil polyols are significantly lower than for the petroleum-based
polyether polyol due to the crop oil raw material source.
• Agricultural practices, oil extraction methods and shipping also have
a significant impact.
• Future use of renewable energy for MSO production would result in
a significant reduction in global warming potential (GWP) and fossil
fuel consumption.
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Conclusions
• Next generation process technology currently under development may
significantly reduce energy consumption, GWP and SOx generation
(i.e., criteria air pollutant and acidification impacts).
• Castor oil was comparable to MSO overall (BEES), but better life cycle
input data for castor oil is needed
– Castor suffered from the use of the solvent extraction process and
(probably high) estimated water and fertilizer use (vs MSO) and
eutrophication and smog potential were high vs soybean oil polyol.
• A best case soy oil based polyol showed less than 16% the overall
impact relative to a petroleum-based polyol
– But: best case (simple) process does not necessarily give a product with
acceptable end-use properties
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Acknowledgements
•
•
•
•
American Chemical Society
Jim Pollack, OmniTech International Ltd.
Anne Landfield Greig, Four Elements Consulting, LLC
Chevron Phillips Chemical Company, LP
6/25/2008
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