PROCESS

PROGRAM SRI INTERNATIONAL

ABSTRACT

Menlo Park, Califomir

94025

Process Economics Program Report No. 197

SUPERCRITICAL FLUID PROCESSING

(July 1989)

Supercritical fluids offer certain advantages that are unavailable from liquids and gases operating below critical conditions. This report examines the basic technology of Supercritical fluids and evaluates the current applications and possible future uses of this technology.

We also Include the process economics analyses of two potential Supercritical fluid applications: (1) reduction of water content in an acrylamide copolymer gel by Supercritical carbon dioxide extraction, and (2) extraction of ethylene oxide from an aqueous solution with Supercritical carbon dioxide.

PEP’87 WSF

I 63 ‘0

E

0 0

I I

E 0 GB

Report No. 197

SUPERCRITICAL FLUID PROCESSING

by WING SIEN FONG

July 1989

A private report by the

PROCESS ECONOMICS PROGRAM

Menlo Park, California 94025

I 1 For detailed marketing data and information, the reader is referred to one of the SRI programs specializing in marketing research. The CHEMICAL ECONOMlCS HANDBOOK

Program covers most major chemicals and chemical products produced in the United

States and the WORLD PETROCHEMG4LS Program covers major hydrocarbons and their derivatives on a worldwide basis. In addition, the SRI D/RECTORY OF CHEMCAL

PRODUCERS services provide detailed lists of chemical producers by company, product, and plant for the United States and Western Europe

1 I

ii

1 INTRODUCTION .....................................................

2 SUMMARY .........................................................

FUNDAMENTALS OF SUPERCRlTlCAL FLUID PROCESSING ..................

FEATURES .........................................................

APPLICATIONS ......................................................

Regeneration of Adsorbent9 ......................................

Chemical Processing ............................................

Coal Processing ................................................

Food and Natural Product Processing ...............................

Alkaloids (Nicotine) ..............................................

Cholesterol .....................................................

Coffee and Tea .................................................

Citrus Juices ...................................................

Essential Oils ...................................................

Fish Oils .......................................................

Hops ..........................................................

Insecticide (Natural) .............................................

Lanolin ........................................................

Lecithin ........................................................

Oils From Plants and Seeds ......................................

Potato Chips ...................................................

Spices ........................................................

Petroleum Processing ............................................

Polymer Processing .............................................

Separation of Liquid Organic Solutes from Their Solvents ..............

Hazardous and Industrial Waste Treatment ..........................

Other Applications ................................................

l-l

2-l

2-l

2-2

2-2

2-2

2-3

2-3

2-4

2-4

2-4

2-4

2-4

2-4

2-5

2-5

2-5

2-5

2-5

2-5

2-5

2-6

2-6

2-7

2-7

2-8

2-6

PROCESS ECONOMICS . . ..*...........*............*................* 2-9

3-l

3-l

3-l

3-1

4-l

4-l

4-5

3 INDUSTRY STATUS ..................................................

HISTORICAL DEVELOPMENT ...........................................

COMMERCIAL AND POTENTIAL APPLICATIONS ...........................

RECENT ACTIVITIES .................................................

4 FUNDAMENTALS OF SUPERCRITICAL FLUID PROCESSING ..................

SUPERCRITICAL FLUID PROPERTIES ....................................

Phase Diagrams ................................................

. . . - III -

CONTENTS

4 FUNDAMENTALS OF SUPERCRlTICAL FLUID PROCESSING (Continued)

Solubility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

MODELS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12

5 FEATURES OF SUPERCRlTlCAL FLUID PROCESSING ....................... 5-l

ADVANTAGES AND DISADVANTAGES/LIMITATIONS ........................ 5-1

Advantages .................................................... 5-1

Disadvantages/Limitations ........................................ 5-2

SUPERCRITICAL FLUIDS .............................................. 5-2

Carbon Dioxide ................................................. 5-3

Soluble Compounds ............................................. 5-3

Low-Soluble Compounds ......................................... 5-4

Insoluble Compounds ............................................ 5-4

Water ......................................................... 5-4

Propane ....................................................... 5-8

Ethane ........................................................ 5-8

Ethylene ....................................................... 5-8

Nitrous Oxide ................................................... 5-8

Ammonia ...................................................... 5-8

Xenon ......................................................... 5-8

ENTRAINERS AND COSOLVENTS ....................................... 5-l 1

MIXED SOLUTES .................................................... 5-l 1

6 PATENT SUMMARY .................................................. 6-l

7 REGENERATION OF ADSORBENTS ...................................... 7-l

8 CHEMICAL (INCLUDING MONOMER) PROCESSING ......................... 8-l

CHEMICAL SEPARATlONIRECOVERY/PURlFlCATlON ........................ 8-l

Isomer Separations .............................................. 8-l

1,3-Butadienell -Butene Separation ................................ 8-l

1 . 1 0-DecanediolIBenzoic Acid Separation ........................... 8-2

Titanium Tetrachloride Recovery ................................... 8-2

Phthalic Anhydride Purification ..................................... 8-2

MONOMER PURlFlCATlON ............................................. 8-2

Diacetone Acrylamide’ ............................................ 8-2

Dixylenol Sulfide Purification ....................................... 8-3

Methacryloxy-Terminated Dimethylsiloxane .......................... 8-3

2,2-bis-(p-2i-Hydroxy-3i-Methacryloxypropoxy)-Phenylene-Propane .... 8-3

0 -

0

0

- iv -

CONTENTS

l 8 CHEMICAL (INCLUDING MONOMER) PROCESSING (Continued)

CHEMICAL REACTION . ..m...m...................,.,..,... ..*..,..,.,. 8-3

Direct Hydration of n-Butene to Secondary-Butanol ...................

In Situ Catalyst Reactivation in l-Hexene Isomerization ................

Oxidation of n-Butane ............................................

C&Cl 4 Hydrocarbon Isomerization ................................

Photoisomerization of trans-Stilbene ...............................

Ethanol Dehydration to Ethylene ...................................

1,3 Dioxolane Dehydration to Ethylene Glycol and Formaldehyde . . , . , . . ,

Benzylphenylamine Reactions .....................................

Ethyl Acetate from Ethanol and Acetic Acid .........................

Aniline Hydrolysis to Phenol .......................................

1,3-Dioxolane to 2-Methoxyethanol ................................

Cyclohexane Addition to 1 -0ctene .................................

Alkene to Alkene Addition and Intermolecular ‘ene” Reactions .........

Reactions Between Alkynes and Alkanes ............................

Oxidation of Organic Compounds in Supercritical Water ...............

8-4

8-4

8-4

8-5

8-5

8-5

8-5

8-6

8-6

8-6

8-6

8-6

6-6

6-6

8-6

9 COAL PROCESSING ................................................. 9-l

COAL ............................................................. 9-l

SOLVENT SYSTEMS ................................................. 9-4

Hydrocarbons .................................................. 9-5

Alcohols ....................................................... 9-8

Water ......................................................... 9-9

Primary Aliphatic Amines (Including Ammonia) ....................... 9-10

PROCESSING CONDITIONS ............................................ 9-10

SUPERCRITICAL EXTRACTlON PROCESSES .............................. 9-10

Donor-Solvent Supercritical Extraction Process (DSSE) ................ 9-13

Critical Solvent Deashing (CSD) or ROSE-SR Process ................. 9-13

ECONOMICS ....................................................... 9-l 3

10 FOOD AND NATURAL PRODUCT PROCESSING ............................ 10-l

ALKALOIDS ........................................................ 10-l

Nicotine ....................................................... 1 o-2

CHOLESTEROL ..................................................... 1 o-3

COFFEE AND TEA ................................................... 10-3

CITRUS JUICES ..................................................... 10-10

-v-

CONTENTS

10 FOOD AND NATURAL PRODUCT PROCESSING (Continued)

ESSENTIAL OILS ....................................................

FISH OILS ..........................................................

HERBS ............................................................

HOPS ............................................................. INSECTlClDE (NATURAL) .............................................

LANOLIN ...........................................................

LECITHIN ..........................................................

OILS FROM PLANTS AND SEEDS ......................................

Fluids .........................................................

Castor Beans ...................................................

Cottonseed ....................................................

Corn Germ .....................................................

Rice ..........................................................

Boy Beans .....................................................

Sunflower Seeds ................................................

Wheat Germ ...................................................

Processes .....................................................

Energy Requirement .............................................

SNACK FOODS .....................................................

SPtCES ............................................................

11 PETROLEUM PROCESSING ............................................

UPGRADING REFINERY RESIDUA .......................................

The ROSE (Residuum Oil Supercritical Extraction) Process .............

Process .......................................................

Products ......................................................

Solvent .......................................................

Utilities Requirements ...........................................

Manpower .....................................................

Conversion from Conventional Deasphalting Process .................

The HSC-ROSE Process ..........................................

The Demex Process .............................................

The SOLVAHL-ASVAHL Process ...................................

EXTRACTING FROM TAR SANDS .......................................

EXTRACTING FROM OIL SHALES .......................................

10-10

10-12

10-15

10-15

lo-16

lo-16

lo-16

10-17

10-17

10-19

10-19

10-19

lo-19

1 O-20 1 O-20

10-21

10-21

10-21

1 O-24

1 O-24

1 l-l

11-l

11-l

11-2

11-2

11-8

11-9

11-10

11-10

11-10

11-10

11-12

11-12

11-15

TERTIARY OIL RECOVERY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-16

- vi -

0 CONTENTS

11 PETROLEUM PROCESSING (Continued)

HYDROTREATING SHALE OIL AND OTHER HEAVY OILS .................... DEWAXING LUBRICATING OILS ........................................

REMOVINGIRE-REFINING USED (LUBRICATING) OIL .......................

12 POLYMER PROCESSING ..............................................

ADVANTAGES ......................................................

SOLUBILITY PARAMETERS ............................................

SOLVENTS .........................................................

POLYMER PURIFICATION ..............................................

POLYMER FRACTlONATlON ............................................

POLYMER-ORGANIC SOLVENT PHASE SEPARATION .......................

FIBER PRODUCTION .................................................

PRODUCTION OF FINE POLYMER POWDER ...............................

13 SEPARATION OF LIQUID ORGANIC SOLUTES FROM THEIR SOLVENTS ........

EXTRACTANTS .....................................................

PROCESS ..........................................................

ALCOHOLS .........................................................

Ethanol ........................................................

Economics of Ethanol Extraction ...................................

Propanol .......................................................

CARBOXYLIC ACIDS .................................................

OTHER ORGANIC SOLVENTS AND CHEMICALS ........................... SEPARATING LIQUIDS ................................................

14 HAZARDOUS AND INDUSTRIAL WASTE TREATMENT .......................

OXIDATION OF WASTES BY THE MODAR PROCESS .......................

EXTRACTION OF ORGANICS FROM AQUEOUS STREAMS ...................

EXTRACTION OF CONTAMINATED SOILS ................................

OTHERS ...........................................................

15 OTHER APPLICATIONS ...............................................

BIOPROCESSING .................................................... CHROMATOGRAPHY .................................................

FINE POWDER PRODUCTION .......................................... PROCESSING FOREST PRODUCTS ......................................

Wood .........................................................

Peat ..........................................................

PROCESSING PHARMACEUTICALS ..................................

Solvents .......................................................

Pharmaceuticals ................................................

Purification .....................................................

- vii -

11-16

11-17 11-17

12-1

12-1

12-1

12-2 12-3

12-3

12-5 12-5 12-5

13-l

13-1 13-3 13-3 13-3 13-7 13-11 13-11 13-13 13-13

14-1

14-1 14-4 14-5 14-6

15-1

15-1 15-2

15-3 15-3 15-3 15-4 15-5 15-5 15-6 15-7

CONTENTS

18 REDUCTION OF WATER CONTENT IN AN ACRYLAMIDE COPOLYMER GEL BY SUPERCRITICAL CARBON DIOXIDE EXTRACTION ....................... 16-l

PROCESS DESCRlPTlON .............................................. 16-l

PROCESS DISCUSSION ............................................... 16-5

COST ESTIMATES ................................................... 16-5

17 EXTRACTION OF ETHYLENE OXlDE FROM AN AQUEOUS SOLUTION WlTH SUPERCRlTlCAL CARBON DIOXIDE ................................ 17-l

PROCESS DESCRIPTlON .............................................. 17-l

PROCESS DISCUSSION ............................................... 17-6

COST ESTlMATES ................................................... 17-7

APPENDIX A PHASE BEHAVIOR REFERENCES FOR BINARY AND TERNARY SYSTEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-l

APPENDIX B ClTED REFERENCES ....................................... B-l

APPENDIX C PATENT REFERENCES BY COMPANY. ......................... C-l

APPENDIX D PROCESS FLOW DIAGRAM .................................. D-l

. . . - VIII -

4.1

4.2

4.3

4.4

4.5

4.6

5.1

5.2

5.3

7.1

7.2

9.1

9.2

9.3

9.4

9.5

9.6

10.1

10.2

10.3

10.4

10.5

10.6

10.7

11.1

11.2

ILLUSTRATIONS

Temperature-Pressure-Density Diagram of Carbon Dioxide ...........

Viscosity of Supercritical Carbon Dioxide ..........................

Effect of Pressure on the Diffusion Coefficients in Some Supercritical Fluid Systems ................................

Phase Diagram of Carbon Dioxide ...............................

Phase Diagrams for the 5 Classses of Binary Systems ..............

Phase Diagrams of Ternary Systems .............................

Effect of Carbon Dioxide Density on the Solubility of Some Compounds

Temperature-Pressure-Density Diagram of Propane ................

Densities of Supercritical Carbon Dioxide and Nitrous Oxide ..........

Diazinont and Alachlort Adsorption Breakthrough Curves on Regenerated Activated Carbon ..................................

Solubilities of Pesticides and Phenol in Supercritical Carbon Dioxide ...

Effect of Hydrogen-Carbon Atomic Ratio in the Coal on Supercritical Toluene Extraction ..................................

Effect of Temperature and Coal Particle Size on Supercritical Toluene Extraction ..................................

Effect of Temperature and Pressure on the Supercritical Extraction of Coal with Hydrocarbon (Toluene) ..............................

Supercritical Extraction Process for Coal Liquefaction ...............

DSSE Extraction Process for Coal Liquefaction .....................

Three-Stage Critical Solvent Deashing Unit ........................

Multistage Extraction of Nicotine from Tobacco with Supercritical Carbon Dioxide ....................................

Decaffeination of Coffee Beans by Supercritical Carbon Dioxide Extraction ....................................................

Equilibrium Isotherm for the Caffeine-Coffee-Carbon Dioxide System . .

Adsorption Isotherm for the Caffeine-Carbon Dioxide-Activated Carbon System ...............................................

Continuous Extraction Process to Remove Terpenes from Essential Oils

Continuous Supercritical Extraction Process for Ground Plant Seeds ...

Continuous Supercritical Extraction Process for Plant Seeds ..........

Rose Process Flow ............................................

Solvent Enthalpy Diagram for the Rose Process ....................

- ix -

4-2

4-3

4-4

4-6

4-8

4-9

5-6

5-9

5-10

7-4

7-5

9-2

9-3

9-11

9-12

9-14

9-15

1 o-4

1 O-6

1 O-8

1 o-9

10-13

1 o-22

1 O-23

11-3

11-4

ILLUSTRATIONS

11.3 Yield and Impurities Content of DA0 ............................. 11-7

11.4 Yield, Conradson Carbon Residue, and Viscosity of DA0 ............ 11-8

11.5 Demex Process for Producing DMO from Vacuum Residuum ......... 11-11

11.6 Solvahl-Asvahl Solvent Deasphalting Process ...................... 11-13

13.1 Supercritical Carbon Dioxide/Water Distribution Coefficients for Liquid Organic Esters and Normal Aliphatic Alcohols ................ 13-2

13.2 Supercritical Extraction Process for Organic Liquid Solutes ........... 13-4

13.3 Near Critical Fluid Extraction Cycle with Vapor Recompression ........ 13-8

13.4 Energy Consumption for Recovering a 99.5 Wt% Ethanol by Propane Extraction Using Vapor Recompression Cycle .............. 13-9

13.5 Near-Critical Fluid Extraction Process for Recovering a 99.5 Wt% Ethanol ...................................................... 13-10

13.8 Phase Diagrams of Isopropanol-Water-Carbon Dioxide System ....... 13-12

13.7 Equilibrium and Operating Lines for the Acetic Acid-Water-Carbon Dioxide System ............................................... 13-14

14.1 Modar Process for Treatment of Hazardous Wastes ................. 14-2

15.1 Supercritical Carbon Dioxide Extraction of Solvents from Penicillin G ... 15-9

16.1 Reduction of Water Content in an Acrylamide Copolymer Gel by Supercritical Carbon Dioxide Extraction ........................... 16-4

16.2 Reduction of Water in an Acrylamide Gel by Supercritical CO2 Effect of Capital-Related and Utilities Costs On Processing Cost Plus ROI Before Taxes ......................................... 16-10

17.1 Extraction of Ethylene Oxide from an Aqueous Solution with Supercritical Carbon Dioxide .................................... D-3

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TABLES

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0

0

3.1

4.1

4.2

5.1

5.2

5.3

5.4

6.1

8.1

8.2

8.3

8.4

9.1

9.2

9.3

9.4

10.1

10.2

10.3

10.4

10.5

Commercial and Potential Applications of Supercritical Fluid Processing ....................................................

Density, Viscosity, and Diffusion Coefficients of Gases, Supercritical Fluids, and Liquids ..............................................

The Solubilities of Polypropylene, Nylon-6 and Polybutene-1 in Supercritical Carbon Dioxide and n-Butane .........................

Critical Conditions of Some Supercritical Fluids ......................

Solubility Data in Supercritical Carbon Dioxide, Ethane, and Ethylene ..................................................

Solute-solvent Group Interaction ..................................

Classification of Molecules Based On Potential for Forming Hydrogen Bonds ........................................

Supercritical Fluid Processing Patent Summary ...............................................

The Solubilities of Dihydroxybenzene Isomers in Supercritical Carbon Dioxide .................................................

Ethanol Dehydration in Supercritical Water ..........................

Intermolecular ” Ene” Reactions ...................................

Reactions Between Alkynes and Alkanes in Presence of an Excess of Alkanes ..............................................

Composition of Raw Coal and Coal Samples Extracted with Various Supercritical Solvents ....................................

Compositions of Feed, Extract, and Residue (Char) in a Supercritical Extraction of Coal with Toluene ........................

Compositions of Raw and Extracted Coal Samples ...................

Supercritical Extraction of Coal with n-Alcohols and Their Corresponding n-Paraffins ..................................

Supercritical Extraction of Alkaloids with Carbon Dioxide or Nitrous Oxide ................................................

Parameters and Mass Transfer Coefficients for the Extraction of Caffeine with Nitrous Oxide ...........................

Sensory Properties of Essential Oils Recovered by Steam Distillation and Carbon Dioxide Extraction .....................

Fractionation of Fatty Acid Esters in Codfish Oil by Two-Stage Supercritical Extraction with Carbon Dioxide ...............

Supercritical Carbon Dioxide Extraction of Hops Pellets ...............

3-4

4-5

4-l 1

5-5

5-7

5-12

5-13

6-2

8-7

8-7

6-8

8-8

9-5

9-7

9-7

9-9

1 o-2

10-10

10-11

10-14

lo-18

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TABLES

10.6

10.7

10.8

11.1

11.2

Comparison of n-Hexane- and Supercritical Carbon Dioxide-extracted Soy Bean Oils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 O-20

Energy Requirements for the Extraction of Plant Seeds with n-Hexane and Supercritical Carbon Dioxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-21

Supercritical Extraction of Pepper, Nutmeg, and Chilies with Carbon Dioxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 O-25

Installations of the Rose Process and Capacities and Products . . . . . . . . . 11-2

Analyses of the Charges To and the Products From 2 Commercial Rose Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-5

11.3

11.4

11.5

11.6

12.1

13.1

13.2

13.3

14.1

Effect of Solvent-to-charge Ratio On Dao Quality for the Rose Process . 1 l-8

Utilities Requirements for the Rose, Conventional Deasphalting, and Delayed Coker Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-9

Battery Limits Cost, Utilities Requirements, and DMO Analyses for a Demex Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-12

Battery Limits Cost, Utilities Requirements, and Feed and Product Analyses of a Solvahl-Asvahl Solvent Deasphalting Unit . . . . . . . . 11-14

Fractionation of a Poly(n-Butylacrylate) by Supercritical Nitrous Oxide Extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-6

Molar Volume and Composition of the Phases Of an Ethanol-Water- Carbon Dioxide System at Various Temperatures and Pressures . . . . . . . 13-5

Effect of Temperature and Pressure On the Ethanol Loading and Selectivity in Supercritical Carbon Dioxide . . . . ..*........*.......... 13-6

lsopropanol and Ethanol Loadings in Supercritical Carbon Dioxide . . . . . . 13-l 1

Treatment of Organic Waste Containing Pcb with the Modar Process . . . . 14-4

14.2

15.1

15.2

15.3

15.4

16.1

18.2

Supercritical Carbon Dioxide Extraction of 22 Compounds Typically Found in Environmental Systems ,................................. 14-5

Effect of Supercritical Carbon Dioxide On Enzyme Activities . . . . . . . . . . . 15-2

Peat Extraction with Supercritical Water, Methanol-water, and Acetone-Water . . . . . . . . . . . . . . . . ..*............................. 15-5

Minimum Pressure Required for Extracting Tetracyclic Steroids Containing Various Structural Groups with Supercritical Carbon Dioxide . . 15-7

Removal of Pesticides in Senna Leaves by Supercritical Carbon Dioxide Extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-8

Reduction of Water Content (70-24%) in an Acrylamide Copolymer Gel by Supercritical Carbon Dioxide Extraction . . . . . . . . . . . . . . . . . . . . . . . 16-2

Reduction of Water Content (70-24%) in an Acrylamide Copolymer Gel by Supercritical Carbon Dioxide Extraction Major Equipment .,..........m........ . . . . . . . . . . . . . . . . . . . . . . . . . . 16-3

- xii -

TABLES

16.3

18.4

16.5

17.1

17.2

17.3

17.4

17.5

Reduction of Water Content (70-24%) in an Acrylamide Copolymer Gel by Supercritical Carbon Dioxide Extraction Utilities Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..a.. 16-3

Reduction of Water Content (70-24%) in an Acrylamide Copolymer Gel by Supercritical Carbon Dioxide Extraction Total Capital investment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-7

Reduction of Water Content (70-24%) in an Acrylamide Copolymer Gel by Supercritical Carbon Dioxide Extraction Processing Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-6

Extraction of Ethylene Oxide from an Aqueous Solution with Supercritical Carbon Dioxide Design Bases and Assumptions ,......,......,.................... 17-3

Extraction of Ethylene Oxide from an Aqueous Solution with Supercritical Carbon Oxide Major Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-4

Extraction of Ethylene Oxide from an Aqueous Solution with Supercritical Crabon Dioxide Utilities Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..*......*....*.... 17-5

Extraction of Ethylene Oxide from an Aqueous Solution with Supercritical Carbon Dioxide (Stand-Alone Facility) Total Capital Investment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..*......... 17-9

Ethylene Oxide by the Oxygen Process Production Costs . . . . . . . . . . . . . . . . . . . . . . ..*..............*.....*. 17-10

. . . - XIII -