Apr 22, 2015 - Propane (C3H8). 44.09 .... solvent. Reduction in dielectric constant & polarity at ... water less polar behaves like organic solvent). Water at ...
Supercritical Fluid Extraction and Conversion
Seminar By Prafulla D Patil 4/22/2015
Outline • Supercritical Fluids Fundamentals • Supercritical Carbon-dioxide (SC-CO2) for oil recovery • Subcritical Water Hydrolysis/ Extraction • Supercritical Methanol (SCM) Conversion Process for Fuel • Microwave-mediated Transesterification of Biomass to Biofuel under Supercritical Ethanol Conditions • Residual Oil Supercritical Extraction (ROSE) • Supercritical Fluid chromatography 2
Supercritical Fluids A supercritical fluid is any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist. It can effuse through solids like a gas, and dissolve materials like a liquid. Close to the critical point, small changes in P or T result in large changes in density, allowing many properties of a supercritical fluid to be "fine-tuned". Critical Temperature (Tc) : The maximum temperature at which a gas can be converted into a liquid by an increase in pressure. Above which it cannot be liquefied, no matter how much pressure is applied. Critical Pressure (Pc): The pressure required to liquefied
Triple Point a gas at its critical temperature. Above the critical Critical Point pressure, increasing the temperature will not cause a fluid Supercritical Fluid- Highly to vaporize to give a two-phase system. dense and non-compressible http://en.wikipedia.org/wiki/Triple_point Wikipedia
Critical properties of various solvents Solvent
Molecular Weight (g/mol)
Critical Temperature (C /F)
Critical Pressure (psi/atm)
Critical Density (g/cc)
Carbon dioxide (CO2)
44.01
30.95 / 87.71
1070 / 72.8
0.469
Water (H2O)
18.015
374 / 705
3200 / 218
0.322
Methane (CH4)
16.04
-82.75 / -117.31
667 / 45.4
0.162
Propane (C3H8)
44.09
96.65 / 206
616 / 41.9
0.217
Methanol (CH3OH)
32.04
239.45 / 463
1173 / 79.8
0.272
Comparison of Gases, Supercritical Fluids and Liquids Density (kg/m3)
Viscosity (µPa∙s)
Diffusivity (mm²/s)
Gases
1
10
1-10
Supercritical Fluids
100–1000
50–100
0.01–0.1
Liquids
1000
500–1000
0.001
http://en.wikipedia.org/wiki/Supercritical_fluid
Supercritical Fluid
Supercritical Fluids (SCF)- Importance SCF replacing Organic solvents Used in Industrial purification & recrystallization due to regulatory and environmental pressures on HCs and Ozone depleting emission SCF has helped to eliminate use of hexane and methylene chloride. With Increasing scrutiny of solvent residue in pharmaceutical , medical products, with stricter regulations on VOC emissions, use of SCFs increasing rapidly in all Industrial sectors. SCF plants are operating at throughputs of 100,000,000 lb/yr or more in Food Industry. Coffee and tea are decaffeinated via Supercritical fluid extraction and most brewers in US and Europe use flavors that are extracted from hops (flower) with SCF. SCF processes are being commercialized in the Polymer, Pharmaceuticals, specialty lubricants, bio-lipids and fine chemical industry etc SCF are advantageously applied to increasing product performance to levels that cannot be achieved with traditional processing technologies…and such applications for SCF offer the potential for technical and economic success. SCF & SCE presentation at Univ. of Illinois at Chicago
Green High-Pressure Solvents or Reaction Media
J. King, 2012 . OPTIMIZING THE USE OF CRITICAL FLUIDS FOR BIOMASS CONVERSION Presentation @ NMSU
Supercritical Fluid Extraction Supercritical Fluids
High dissolving power Low viscosity, no surface tension High diffusivity Easy separation No harmful solvents Selective extraction/separation CO2, H2O, CH3OH ….
n-Hexane Extraction Microalgae
Pretreatment
Extraction
Phase Separation
Degumming
Transesterifi cation
Biodiesel
Transesterifi cation
Biodiesel
Transesterifi cation
Biodiesel
323 K
Solvent Treatment Thermochemical Liquefaction Microalgae
Pretreatment
Heating 3 MPa,623 K
Phase Separation
Degumming
Gas Treatment
Pyrolysis Microalgae
Pretreatment
Supercritical Carbon dioxide SCCO Extraction (SC-CO2)
Heating 873 K
Phase Separation
Degumming
Gas Treatment
2
Microalgae
• Tc = 31 C; Pc = 73.8 bar • Ideal extractant for non-polar • •
Pretreatment
Extraction
Phase Separation
Degumming
Transesterifi cation
30-40 Mpa,323 K
species, e. g. HCs, TAGs Gas at room temperature, allows for coupling to GC and SFC Cheap, inert, non-toxic Székely. Supercritical Fluid Extraction. Budapest University of Technology and Economics. 7 Retrieved 2007-11-20.
Biodiesel
Supercritical CO2 Properties Critical Properties Solvent
Molecular
Critical
Critical
Critical
weight
temp
pressure
density
g/mol
C/ K
psi/bar
g/cm3
44.01
31/ 304.1
1070/73.8
0.469
CO2
T (K)
ρ (g/cm3)
73
313
0.22
73
353
0.14
73
393
0.12
400
313
0.96
400
353
0.82
400
393
1.2
1.2
1
1
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0
0
At lower P, > T, < solubility
At Constant
At higher P, > T, > solubility
Density, solubility
25
> T, < solvent ρ
increases with
Tem per a
>P, > solvent ρ
8
0.70
1.4
1.4 Density (g/cm3)
P (bar)
increase in T
0
0 30
ture (
0 35
K)
0 40
0 0 45
Solvating power α density
Reid et al., 1987 .Critical properties of various solvents
100
200
300 Pr
400
es
500
(ba re u s
r)
Supercritical Extraction (SCE) Reactor
Waters (TharSFC) SFE Reactor
Operating range:
Supercritical CO2 extraction Video
Pressure : 0-600 bar Max Temp : 150 ºC Operating Vol. : 2000 mL 9
Web: https://www.youtube.com/watch?v=LQfVJ0MvqEo
http://lyophilizedproducts.com/lyophilization-process/
Subcritical Water Extraction/HTL of Oils from Algal Biomass 100 C/ 212 F < Subcritical water temp < 374 C /705 F ( critical temp of water)
Optimum conditions for C-SCW extraction: Extr. temp. 220 oC biomass load. 7.5 %, Extr. Time 25 min.
Water is environmentally benign, non-toxic, green solvent. Reduction in dielectric constant & polarity at higher temp & increases solubility of oil in water ( water less polar behaves like organic solvent) Water at subcritical condition acts as a tunable cosolvent that increases solubility and acidity.
Subcritical water extracted bio-crude and pure algal oil
In HTL, macromolecules present in biomass….subjected to hydrolysis….. degrades them into smaller molecules….substantial part of the oxygen in the biomass is removed by dehydration or decarboxylation. Water also makes the separation very easy when the process temperatures are reduced to room temperature
11 et al. 2014 . Subcritical water extraction of algal oil from algal biomass . Fuel 133, 73-81 Harvind
Residual Oil Supercritical Extraction (ROSE) The purpose of the ROSE Unit refining operation is to separate a carbonaceous resin material from cylinder stock oil to produce a lighter de-resined oil for further processing Propane, at controlled temperatures and pressures is used to selectively dissolve the lighter oil from the resins. The propane, at a controlled supercritical temperature and pressure, is then separated from the oil, recovered, and recycled to storage for re-use.
> T, < solvent ρ …. Thus decreases solubilizing power E-16 Tower : Separate cylinder stock by mixing with the Propane. The lighter phase (Waxy finished oil) goes overhead while the heavy phase goes out the bottom of the tower. Waxy finished oil separates from the Propane in E-17 tower
Propane: Tc: 206 F, Pc: 616 psi
Conversion Technologies for Biomass
DOE: National Algal Biofuel Technology Roadmap (2010)
Novel Method- One Step Process for Wet Biomass • Why Supercritical Methanol (SCM) Process? 1. One Step Process Simultaneous Extraction and Transesterification 2. Non-catalytic-Simpler purification of products 3. Lower reaction time and More environmental friendly 4. Supercritical Methanol solves the problem of two-phase nature of methanol/oil mixture. 5. Water (60%) don’t affect SCF conversionv 6. Conversion rate is faster in SCF than sub-critical 7. In water added SCM, Water-Methanol mix has both properties hydrophilic and hydrophobic properties that helps speeding up the reaction 5. Proposed cost of Supercritical Technology $0.26/gal Vs Conventional Method $ 0.51/gal * * Anitescu, G. et al., Integrated Technology for Energy & Fuels (2008), 22(2), 1391-1399.
Supercritical Biodiesel Production and Power Cogeneration.
Supercritical Transesterification Reaction & Mechanism Dielectric constant Methanol: 33 Soybean oil: 3.1 Dielectric constant α Polarity
δ −
δ
δ
+
δ
−
δ
+
−
δ
+
S Saka etc 2006. Non-catalytic production of biodiesel fuel with SCM technologies, J of Sci & Ind research, 65, 420-425
Microwave-Mediated Supercritical Transesterification
Microwave-Mediated Transesterification of Algal Biomass Under SCE Conditions 250
1600
Operating parameters: 0–80 bar, 25–300 °C, 0–1400 W
200
Pressure Temperature Power
1200
1000
150
800
100
600
400 50 200
0
0 0
500
1000
1500
2000
Reaction Time [s]
Patil, P.D., et al. Microwave-mediated non-catalytic transesterification of algal biomass under supercritical ethanol conditions. Jour of Supercritical Fluids, 2012.
2500
P ow er [W ]
Anton Paar Synthos 3000
T em p erature [°C ] / P ressu re [bar]
1400
Supercritical Methyl Acetate Process for Biodiesel All Supercritical process produces large quantity of glycerin -----Over Produced ???? ( Big Problems to Commercial biodiesel processes) Reaction Parameters: Total lipid : 7 ml, Methyl Acetate: 25 ml (1:42 molar ratio) , Time: 120 min, Temperature: 280 C, Pressure: 1178 psi (~ 81 bar) Critical Properties of Methyl acetate : 233.7 C, 45.9 bar, Sp.G- 0.927, Mol wt: 74, Boiling pt at 1 atm- 57 C, Triacetin BP: 258-260 C
A mixture of fatty acid methyl esters and triacetin found to be used as biodiesel and can enhance its oxidation stability and fuel properties since the obtained triacetin is miscible with fatty acid methyl esters, both products can readily be used as biodiesel.
Lee, K.T. etc, 2010. A glycerol-free process to produce biodiesel by supercritical methyl acetate technology: An optimization study via Response Surface Methodology. Bioresour. Technol. 101, 965-969.
Supercritical Fluid Chromatography • The mobile phase is a supercritical fluid (a fluid above its critical T and critical pressure) , CO2 (nontoxic, nonflammable, noncorrosive, inert , low Tc, operating T as low as 40oC , Moderate Pc and ρc of 0.448g/cm3 , reach high ρ with P < 40 MPa …others alkanes (ethane, pentane) • Advantages of supercritical fluids over carrier gasses and liquid mobile phases are in its solubility properties, physical properties, and detector compatibility. Moves mobile phase in the liquid state under pressure through the injector & into the column. mobile phase flow (1 to 10 µL/min SCF: solvating properties similar to liquids - viscosity closer to gases , Solvating power α density -> density, > solubility, < retention Combined T & P programming to control ρ and thereby solubility and diffusion
Solvent delivery system , Injector , Column Oven , Restrictor , Detector ,Data System
http://en.wikipedia.org/wiki/Supercritical_fluid_chromatography
SFC Advantages vs GC Can analyze non-volatile, polar, or adsorptive solutes without derivatization. Can analyze thermally sensitive compounds. Can analyze solutes of much higher molecular weight.
SFC Advantages vs HPLC Supercritical fluids have low viscosities - faster analysis (5 to 10 X faster) - less pressure drop across the column - the use of open tubular columns is feasible Column lengths from 10 to 20 m are used Can be used with a wide range of sensitive detectors (FID, TCD, ECD etc) Resolving power is ~5X that of HPLC
Limitation of SFC High-pressure vessels are expensive and bulky, special materials needed to avoid dissolving gaskets & Orings in SCF Difficulty in maintaining pressure (backpressure regulation) Difficulty in gas/liquid separation during collection of product.. Upon depressurization, co2 rapidly turns in gas
http://en.wikipedia.org/wiki/Supercritical_fluid_chromatography
