超臨界流體分離技術 special topics on separation using supercritical fluids...

NCHU-ChE: Ch. 1-1

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. 1-2

Content of Lectures

NCHU-ChE: Ch. 1-3

Overview on Separation Processes with scFluids

Solubility in Supercritical Fluids/ Phase Equilibria

Extraction from Solid Substrates (I, II)

Countercurrent Multistage Extraction (I, II)

Topics I

NCHU-ChE: Ch. 1-4

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

Topics II

NCHU-ChE: Ch. 1-5

RawMaterials

Separation

Clean Air

Contaminants

Effluent Air

Reaction Recovery

Separation

Purification

Separation

Separation

Recycle Side Products

Products

Effluent Water

Contaminants

Clean Water

Generalized Process Scheme

NCHU-ChE: Ch. 1-6

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

Separation Technology in the Past

NCHU-ChE: Ch. 1-7

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 Minimi-zation Results in Increased Production

Separation Technology in the Past

NCHU-ChE: Ch. 1-8

Best Known

Most Used

Strengths:

Limited Equipment

Simple Staging

Economy of Scale

Energy Costs

Reliable Design and Scale Up

Distillation

Conventional Process

NCHU-ChE: Ch. 1-9

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

Limits to Distillation

NCHU-ChE: Ch. 1-10

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. 1-11

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. 1-12

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. 1-13

SpecialUse

Liquid Membranes KnowledgeAffinity Separationes

Field-induced Separations

Chromatography

Supercritical Extraction

Membranes: gas feed

Adsorption: liquid feed

Membranes:liquid feed

Adsorption:gas feed

Ion Exchange

Solvent Extraction

Crystallization

Absorption

Distillation

Extractive & Azeotropic

Distillation

Separation Processes

General

NCHU-ChE: Ch. 1-14

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 Prohibitedby Lack of Knowledge on Design and Scale-Up

NCHU-ChE: Ch. 1-15

Supercritical Fluid

Supercritical Fluid Extraction -

SFE

(Gas Extraction)

Definition “Supercritical”

NCHU-ChE: Ch. 1-16

Supercritical Fluid Extraction -

SFE

(Gas Extraction)

State of Solvent

Stripping

Adsorption

L-L extraction

Absorption

High pressure liquid extraction

NCHU-ChE: Ch. 1-17

Generalized Process Scheme

NCHU-ChE: Ch. 1-18

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

MixturesNitrogen, Water

NCHU-ChE: Ch. 1-19

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. 1-20

--- typical operating conditions

Density of Carbon Dioxide

Calculated with Bender-EOS

NCHU-ChE: Ch. 1-21

New, better products

Clean products

New, better processes

„Supercritical Fluids“, Why?

NCHU-ChE: Ch. 1-22

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. 1-23

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. 1-24

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. 1-25

CaffeineTheobromine

Example: Decaffeination

NCHU-ChE: Ch. 1-26

Decaffeination of green coffee beans

Lack and Seidlitz 1993

NCHU-ChE: Ch. 1-27

Decaffeination of green coffee beans

Lack and Seidlitz 1993

NCHU-ChE: Ch. 1-28

Flow scheme of decaffeination plant

Schoeller-Bleckmann design

Lack and Seidlitz 1993

NCHU-ChE: Ch. 1-29

Dissolution:Separation Processes

ReactionsCombinations

(e.g. Separation by Reaction)

Engineering of Properties (liquid) Dilution

Lowering of viscosityLowering of concentration

Application of Supercritical Fluids

NCHU-ChE: Ch. 1-30

Product Engineering (Materials)

Small particlesParticles with large surface areaAdsorbatesCoated particles

Engineering of Properties (solid)

PenetrationSwellingRemoval of monomersImpregnation of substances(Dyes, pharmaceuticals)

Application of Supercritical Fluids

NCHU-ChE: Ch. 1-31

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. 1-32

Product Applications I

Extraction, purification, and separation of:

Edible oils and fatsHops extract

Natural dyes: Annatto, HibiscusVitamins (Tocopherols, Vit. E, Tocotrienols)

Carotenoids Sterols

Essential fatty acids (EPA, DHA, DPA)......

........

Application of Supercritical Fluids

NCHU-ChE: Ch. 1-33

Product Applications II

Bioactive compounds, e.g. PyrethrumCaffeine, Theobromine

Cholesterol

Spices: Capsaicin, Pepper, Coriander

Mono- and DiglyceridesAroma compounds

ThiosulfinatesCitrus oils

Antioxidants: Vitamin E, Ascorbic acid, Polyphenoles, Diacin, Genicin (Steroids)

......

Application of Supercritical Fluids

NCHU-ChE: Ch. 1-34

Separation Processes:

Extraction from solidsCountercurrent multistage separationChromatographic separationsPrecipitationCrystallizationAbsorptionAdsorption/Desorption

and with the application of:

Chemical reactionsSolid and liquid surfaces....

Application of Supercritical Fluids

NCHU-ChE: Ch. 1-35

Chemical Reactions

New Syntheses

Variation of reaction equilibrium

Variation of reaction rate

Replacing liquid solvents

Application of Supercritical Fluids

Examples:

Hydrolysis: From starch to sugars

Enzymes as catalyst in CO2-atmosphere

NCHU-ChE: Ch. 1-36

Environmental Engineering

Replacement and Recycling of Solvents

Recovery of Hazardous Waste Compounds

Destruction of Hazardous Waste Compounds

Application of Supercritical Fluids

NCHU-ChE: Ch. 1-37

Biotechnology

Enzymatic Catalysis

Engineered degradation of Biopolymers (Starch)

Production of Proteins

Separation of Products from aqueous solutions

Sterilization/Deactivation

Enantiomeric selective reactions

Application of Supercritical Fluids