超臨界流體分離技術
Special Topics on Separation Using Supercritical Fluids
化學工程學系 與 環境工程學系
碩博士班 選修課程
國立中興大學 化材館
NCHU-ChE: Ch. 1-1
Content of Lectures
NCHU-ChE: Ch. 1-2
Topics I
Overview on Separation Processes with scFluids
Solubility in Supercritical Fluids/ Phase Equilibria
Extraction from Solid Substrates (I, II)
Countercurrent Multistage Extraction (I, II)
NCHU-ChE: Ch. 1-3
Topics II
Solvent Cycle, Heat/ Mass Transfer, Precipitation
Supercritical Fluid Chromatography, SFC
Membrane Separation
Enzymatic Reactions in scFluids for Separation
Crystallization in Supercritical Fluids
General Aspects of Separation Processes
Videos Visited to Supercritical Fluid Plants
NCHU-ChE: Ch. 1-4
Generalized Process Scheme
Clean Air
Separation
Contaminants
Effluent Air
Separation
Raw
Materials
Separation
Reaction
Recycle
Side Products
Recovery
Purification
Effluent Water
Separation
Contaminants
Clean Water
NCHU-ChE: Ch. 1-5
Products
Separation Technology in the Past
Focus on Chemistry and Reactor Technology
Separation Technology was Added Afterwards
for
•Recovery and Purification of Products from
Reaction Mixtures
•Minimisation of Waste Discharged into the
Environment
Chemical Engineering Education Focussed on
Large Scale Petrochemical Separations
NCHU-ChE: Ch. 1-6
Separation Technology in the Past
Consequences:
Chemistry and Reactor Technology Capabilities Limits
Maximum Yields
Minimal Time for Separation Technology Development
Most New Processes use Existing Separation Technology
Drive for Product Purity and Environmental Impact Minimization Results in Increased Production
NCHU-ChE: Ch. 1-7
Conventional Process
Distillation
Best Known
Most Used
Strengths:
Limited Equipment
Simple Staging
Economy of Scale
Energy Costs
Reliable Design and Scale Up
NCHU-ChE: Ch. 1-8
Limits to Distillation
Low Relative Volatilities
•Azeotropes
•Close Boiling Points
•Isomers
Feed Composition
•Low Concentrations with High Boiling Point
•Overlapping Boiling Points
Non-Volatile Components
Extreme Conditions (Pressure, Temperature)
Small Capacities
Product Degradation
Fouling
Uneconomical for Environmental Applications
NCHU-ChE: Ch. 1-9
Drivers for New Separation Concepts
Sustainable Processes
•Higher Molecular Efficiencies
•New Feedstock Chemistry
•Reduction Energy Consumption
•Environmentally Benign Mass Separatiing Agents
•Minimal Consumption Separating Agents
Cleaner and Purer Products
•Contamination with Mass Separating Agents
•Removal of Undesired Components
•Purer Feedstocks
Minimisation Environmental Impact
•Further Emission Reduction
•Minimal Waste Stream Production
NCHU-ChE: Ch. 1-10
Some Challenges
Clean Processes
•Environmentally Benign Solvents
•Solid Solvents
•No Solvents
Reduced Energy Consumption
•Increases Solvent / Adsorbent Capacities
•Selectivity Enhancement
•Reduction Evaporative Operations
Process Intensification
•In Situ Separations
•Hybrid Separations
NCHU-ChE: Ch. 1-11
Benign Solvents
Replacement of Chlorinated, Aromatic and Other Harmful
Solvents in Reactions and Separations by:
Water
•Aqueous Solvents
•Two Aqueous Phases
Carbon Dioxide (Supercritical or Liquid)
•Food Applications
•Neutraceuticals, Pharmaceuticals ?
Mixtures of Unsuspected Solvents (Reactive Solvents)
•Insoluble Alkane / Complexing Agent Mixtures
Solid Solvents (Adsorbents)
No Solvents
However:
Low Volatile Solvents in Reactions may Create
Problems in Separation and Purification
NCHU-ChE: Ch. 1-12
Separation Processes
Distillation
General
Use
Special
Absorption
Crystallization
Solvent Extraction
Extractive & Azeotropic
Distillation
Ion Exchange
Adsorption: liquid feed
Adsorption:
gas feed
Membranes: gas feed
Supercritical Extraction
Membranes:
liquid feed
Liquid
Membranes
Chromatography
Field-induced Separations
Affinity Separationes
NCHU-ChE: Ch. 1-13
Knowledge
Summary & Conclusions
Strong Drive to For New Separation Concepts
•Chemical instead of Physical Separation
•Solvent Free Separations
•Rate Based Separations
•Environmental and Product Acceptable Mass Separating
Agents
•Hybrid Separation Systems
•Integration of Reaction and Separation
This Requires the Application of New Often Highly
Selective Separation Systems
Application of New Separation Systems often Prohibited
by Lack of Knowledge on Design and Scale-Up
NCHU-ChE: Ch. 1-14
Definition “Supercritical”
Supercritical
Fluid
Supercritical
Fluid Extraction SFE
(Gas Extraction)
NCHU-ChE: Ch. 1-15
State of Solvent
High pressure
liquid
extraction
Adsorption
Absorption
Supercritical
Fluid Extraction SFE
(Gas Extraction)
L-L extraction
Stripping
NCHU-ChE: Ch. 1-16
Generalized Process Scheme
NCHU-ChE: Ch. 1-17
Solvents
EC directive 84/344/EEC
Extraction solvents which are acceptable for all uses when used in
compliance with GMP provided any residues or derivatives present in
the product in technically unavoidable quantities present no danger to
human health.
Propane
Ethanol
Butane
Carbon Dioxide
Butylacetate
Acetone
Ethylacetate
Nitrous Oxide
Nitrogen, Water
NCHU-ChE: Ch. 1-18
Mixtures
Comparison of States
Gas
Supercritical
Liquid
Fluid
______________________________________________
0.1 MPa
Pc,Tc
4Pc,Tc
0.1 MPa
298 K
288 K
______________________________________________
 kg/m3
1
200 - 500 400 - 900
1000
 kg/(ms)
10- 5
1.3.10-5
3.9.10-5
10- 3
D m2/s
10- 5
0.7.10-7
0.2.10-7
10-9
_____________________________________________________________________
NCHU-ChE: Ch. 1-19
Density of Carbon Dioxide
--- typical operating
conditions
Calculated with Bender-EOS
NCHU-ChE: Ch. 1-20
„Supercritical Fluids“, Why?
New, better products
Clean products
New, better processes
NCHU-ChE: Ch. 1-21
Advantages of Supercritical Fluids
•Lower operating temperatures
•improved yield
•improved product properties
•favourable combination of process steps
•easier regeneration of the sc solvent
•no liquid solvent
•lower production cost
NCHU-ChE: Ch. 1-22
Advantages of Supercritical Fluids ctd.
•Solvent power comparable to liquid solvents
•Solvent power adjustable by pressure and
temperature changes
•Very hígh volatility compared to the dissolved
substances
•complete separation of solvent from extract and
raffinate
•second phase achievable in all cases
•high diffusivity, low viscosity
•CO2: nontoxic, nonflammable, inexpensive,
available
NCHU-ChE: Ch. 1-23
Disadvantages of Supercritical Fluids
•Elevated pressures required
•Relative high costs of investment (not in general !)
•Unusual operating conditions (for some
industries)
•Complicated phase behaviour (but only some
knowledge needed for application)
NCHU-ChE: Ch. 1-24
Example: Decaffeination
Theobromine
Caffeine
NCHU-ChE: Ch. 1-25
Decaffeination of green coffee beans
Lack and Seidlitz 1993
NCHU-ChE: Ch. 1-26
Decaffeination of green coffee beans
Lack and Seidlitz 1993
NCHU-ChE: Ch. 1-27
Flow scheme of decaffeination plant
Schoeller-Bleckmann design
Lack and Seidlitz 1993
NCHU-ChE: Ch. 1-28
Application of Supercritical Fluids
Dissolution:
Separation Processes
Reactions
Combinations
(e.g. Separation by Reaction)
Engineering of Properties (liquid)
Dilution
Lowering of viscosity
Lowering of concentration
NCHU-ChE: Ch. 1-29
Application of Supercritical Fluids
Product Engineering (Materials)
Small particles
Particles with large surface area
Adsorbates
Coated particles
Engineering of Properties (solid)
Penetration
Swelling
Removal of monomers
Impregnation of substances
(Dyes, pharmaceuticals)
NCHU-ChE: Ch. 1-30
Application of Supercritical Fluids
Engineering of phase transitions
Formation of solid phases
(Micronization, thin layers)
Variation of solubility (g-l)
Variation of melting point (l-s)
NCHU-ChE: Ch. 1-31
Application of Supercritical Fluids
Product Applications I
Extraction, purification, and separation of:
Edible oils and fats
Hops extract
Natural dyes: Annatto, Hibiscus
Vitamins (Tocopherols, Vit. E, Tocotrienols)
Carotenoids
Sterols
Essential fatty acids (EPA, DHA, DPA)
......
........
NCHU-ChE: Ch. 1-32
Application of Supercritical Fluids
Product Applications II
Bioactive compounds, e.g. Pyrethrum
Caffeine, Theobromine
Cholesterol
Spices: Capsaicin, Pepper, Coriander
Mono- and Diglycerides
Aroma compounds
Thiosulfinates
Citrus oils
Antioxidants: Vitamin E, Ascorbic acid, Polyphenoles,
Diacin, Genicin (Steroids)
......
NCHU-ChE: Ch. 1-33
Application of Supercritical Fluids
Separation Processes:
Extraction from solids
Countercurrent multistage separation
Chromatographic separations
Precipitation
Crystallization
Absorption
Adsorption/Desorption
and with the application of:
Chemical reactions
Solid and liquid surfaces
....
NCHU-ChE: Ch. 1-34
Application of Supercritical Fluids
Chemical Reactions
New Syntheses
Variation of reaction equilibrium
Variation of reaction rate
Replacing liquid solvents
Examples:
Hydrolysis: From starch to sugars
Enzymes as catalyst in CO2-atmosphere
NCHU-ChE: Ch. 1-35
Application of Supercritical Fluids
Environmental Engineering
Replacement and Recycling of Solvents
Recovery of Hazardous Waste Compounds
Destruction of Hazardous Waste Compounds
NCHU-ChE: Ch. 1-36
Application of Supercritical Fluids
Biotechnology
Enzymatic Catalysis
Engineered degradation of Biopolymers (Starch)
Production of Proteins
Separation of Products from aqueous solutions
Sterilization/Deactivation
Enantiomeric selective reactions
NCHU-ChE: Ch. 1-37