Thermochemical Conversion 4

Report
CONVERSION OF BIOMASS TO BIOFUELS
WSU ChE 481/581 & UI BAE 504
THERMOCHEMICAL CONVERSION SECTION
LECTURER: MANUEL GARCIA-PEREZ , Ph.D.
Department of Biological Systems Engineering
205 L.J. Smith Hall, Phone number: 509-335-7758
e-mail: [email protected]
CREDIT HOURS: 3
MEEETING PLACE: EME B46, TUESDAY AND
THURSDAY 1:25-2:40 AM
OUTLINE OF OUR PREVIOUS LECTURE
A.- GASIFICATION
B.- COMBUSTION
C.- HYDROTHERMAL CONVERSION
OVERVIEW OF THE THERMOCHEMICAL SECTION
LECTURE 1
INTRODUCTION TO BIOMASS THERMOCHEMICAL CONVERSION
TECHNOLOGIES AND THERMO-CHEMICAL REACTIONS
LECTURE 2
TORREFACTION AND PYROLYSIS (SLOW AND FAST)
LECTURE 3
GASIFICATION, COMBUSTION AND HYDROTHERMAL CONVERSION
LECTURE 4
CHARACTERIZATION AND USES OF PRODUCTS OF THERMOCHEMICAL
REACTIONS (THERMOCHEMICAL BIO-REFINERIES)
FOURTH LECTURE OUTLINE
CHARACTERIZATION AND USES OF PRODUCTS OF
THERMOCHEMICAL REACTIONS (THERMOCHEMICAL
BIO-REFINERIES):
A.- BIO-OIL
B.- BIO-CHAR
C.- SYNTHESIS GAS
A.- BIO-OIL
PYROLYSIS OIL IS A DARK-BROWN, FREE
FLOWING LIQUID FUEL DERIVED FROM
PLANT MATERIAL VIA FAST PYROLYSIS.
PYROLYSIS OIL CAN BE STORED, PUMPED
AND TRANSPORTED LIKE PETROLEUM
PRODUCTS AND CAN BE COMBUSTED
DIRECTLY IN BOILERS, GAS TURBINES, AND
SLOW TO MEDIUM SPEED DIESEL FOR
HEAT AND POWER. IT HAS A DENSITY OF
1.2 kg/L, AND HEATING VALUE 16-19 GJ/t
(APPROXIMATELY 55 % OF THE HEATING
VALUE OF DIESEL ON A VOLUMETRIC BASIS
AND 45 % ON A WEIGHT BASIS). PYROLYSIS
OIL IS NOT DANGEROUS BUT IT IS ACIDIC.
pH IS 2-3 COMPARED WITH DIESEL AT pH
5. IT IS NOT AN HOMOGENEOUS LIQUID. IF
LEFT STANDING FOR LONG PERIODS,
LIGNIN WILL EVENTUALLY PRECIPITATE.
ORENDA TURBINE
BLADES BEFORE COMBUSTION
BLADES AFTER COMBUSTION
THE ACIDIC AND CORROSIVE NATURE OF PYROLYSIS OIL MEANS THAT ENHANCEMENTS ARE
REQUIERED FOR STORAGE AND TRANSPORTATION, BUT THESE ARE NOT ONEROUS. STORAGE VESSELS
AND PIPING SHOULD BE STAINLESS 304, PVC, TEFLON OR LIKE SUBSTANCES.
Brown R, Holmgren J: Fast Pyrolysis and Bio-Oil Upgrading . http://www.ars.usda.gov/sp2UserFiles/Program/307/biomasstoDiesel/RobertBrown& JenniferHolmgren
presentationslides.pdf
Bradley D: European Market Study for Bio-oil (Pyrolysis Oil) Climate Change Solutions. National Team Leader – IEA Bioenergy Task 40-Biotrade.
A.- BIO-OIL
DIRECT USE AS A FUEL
THE CRUDE BIO-OIL CAN BE USED FOR THE GENERATION OF HEAT AND ELECTRICAL
POWER. THE COMBUSTION OF PYROLYSIS OILS IN INTERMEDIATE SIZE BOILERS (100
kW to 1 MW) SEEMS TO BE ECONOMICALLY VIABLE. SEVERAL RESEARCH PROGRAMS
HAVE BEEN UNDERTAKEN TO ADAPT MORE EFFICIENT SYSTEMS (TURBINES,
STATIONARY DIESELS, BOILERS) TO BE ABLE TO OPERATE WITH BIO-OILS AS FUEL.
THE HEATING VALUE OF BIO-OILS (ABOUT 17 MJ/kg WET WEIGHT BASIS OR 22 MJ/kg
DRY WEIGHT BASIS) IS TYPICALLY ABOUT HALF OF THAT OF No 2 FUEL OIL. IT DOES
NOT BURN EFFICIENTLY WITHOUT PRE-HEATING AND TEND TO GEL AFTER SITTING
FOR PROLONGED PERIODS OF TIME. BECAUSE OF THESE PROPERTIES BIO-OIL DOES
NOT CURRENTLY APPEAR TO BE A GOOD SUBSTITUTE FOR No 2 FUEL IN HOME
HEATING APPLICATIONS.
BIO-OILS CAN BE USED IN INDUSTRIAL BOILERS BUT REQUIRES THE BOILER BE
EQUIPPED WITH STAINLESS STEEL OR PLASTIC-LINED, FUEL INJECTION COMPONENTS
AND STORAGE TANKS TO RESIST CORROSION, A SYSTEM THAT HEATS AND/OR STIRS
THE BIO-OIL DURING STORAGE PREVENTING GELLING, AND A SYSTEM THAT PREHEATS THE INCOMING BIO-OIL TO A TEMPERATURE HIGH ENOUGH TO ENSURE A
GOOD ATOMIZATION.
Laid DA, Brown RC, Amonette JE, Lehmann J: Review of the Pyrolysis Platform for coproducing bio-oil and bio-char. Bio-fuels,
Bioproducts & Biorefining. 2009, 547-561
Meier D, Faix O: State of the art of applied fast pyrolysis of lignocellulosic materials- a review. Bioresource Technology 68 (1999) 71-77
A.- BIO-OIL
BIO-OIL COMPOSITION
HYDROXYACETALDEHYDE DIMER
METHANOL
O O
O
CH3OH
O
FORMIC ACID
O ACETOL
CH3-C-CH2OH
H-C-OH
HO
WATER
H2O
ETHYLENE GLYCOL
CELLULOSE
GLYOXAL
OH
O
CYCLOPENTANONE
HOCH2CH2OH
O
CELLOBIOSE
LEVOGLUCOSAN
5-HYDROXYMETHYL FURFURAL
O
OH
OH
H
O
FORMALDEHYDE
H-C-H
OH
HO
H-C-C-H
O
O
OH
O
OH
O
O
OH
OH
OH
OH
OH
OH
SUGARS
ARABINOSE
O
HEMICELLULOSE
HO
XYLOSE
O
OH
OH
OH
2-FURALDEHYDE
ACETIC ACID
H
H3C-C-OH
O
OH
VANILLIN
CRESOL
O
PHENOL
FURFURYL ALCOHOL
O
OH
OH
OH
FURANS
O
VANILLIN
H
O
OH
O
CH3
H
METHANOL
CH3OH
LIGNIN
EUGENOL
OH
OCH3
OH
H3CO
OCH3
OH
HO
OH
CH3
OCH3
A.- BIO-OIL
PRODUCTS OF LIGNIN
MAIN MONOMERS OBTAINED FROM THE PYROLYSIS
OF LIGNIN
BOILING POINT (100-200 oC)
(Yield: 4-5 mass %)
DIMERIC STRUCTURE IN PYROLYTIC LIGNIN
WATER INSOLUBLE-CH2Cl2 SOLUBLE COMPOUNDS
(Yield: 10-12 mass %)
Bayerbach R, Meier D: Characterization of the water-insoluble fraction from fast Pyrolysis liquids (pyrolytic lignin) Part IV: Structure
elucidation of oligomeric molecules. Journal of Analytical and Applied Pyrolysis, 85 (2009) 98-107.
A.- BIO-OIL
STRUCTURAL
PROPOSAL
PYROLYSIS
LIGNIN
FOR
TETRAMETERS (B) PENTAMERS
HEXAMERS (D) HEPTAMERS
OCTAMERS
OF
(A)
(C)
(E)
A
B
B
D
WATER -CH2Cl2 INSOLUBLE COMPOUNDS
(YIELD AROUND 2 mass %)
E
Bayerbach R, Meier D: Characterization of the water-insoluble fraction from fast Pyrolysis liquids (pyrolytic lignin) Part IV: Structure
elucidation of oligomeric molecules. Journal of Analytical and Applied Pyrolysis, 85 (2009) 98-107.
A.- BIO-OIL
BIO-OIL PRODUCED BY FAST PYROLYSIS OF CELLULOSIC BIOMASS IS AN EMULSION OF
WATER (APPROXIMATELY 20 mass %) AND A WIDE RANGE OF ORGANIC COMPOUNDS
INCLUDING ORGANIC ACIDS, ALDEHYDES, ALCOHOLS, PHENOLS, CARBOHYDRATES
AND LIGNIN DERIVED OLIGOMERS.
Brown R, Rover M, Li M, Kuzhiyi N, Johnston L, Jones S: What does it mean to characterize bio-oil? TC Biomass Conference, Chicago, IL, September 16-18, 2008
Bayerbach R, Meier D: Characterization of the water-insoluble fraction from fast Pyrolysis liquids (pyrolytic lignin) Part IV: Structure elucidation of oligomeric
molecules. Journal of Analytical and Applied Pyrolysis, 85 (2009) 98-107.
Laid DA, Brown RC, Amonette JE, Lehmann J: Review of the Pyrolysis Platform for coproducing bio-oil and bio-char. Bio-fuels, Bioproducts & Biorefining. 2009, 547-561
Meier D, Faix O: State of the art of applied fast pyrolysis of lignocellulosic materials- a review. Bioresource Technology 68 (1999) 71-77
A.- BIO-OIL
GC/FID
GC/MS
9
FORMIC ACID+ HAA
8
WATER + ACETIC
ACID + ACETOL
DTG (mass %/min)
7
6
5
MONO-PHENOLS AND
FURANS
4
SUGARS
B
3
2
LIGNIN OLIGOMERS
A
1
E
C
D
0
0
100
200
300
Temperature ( o C)
OLIGOSUGARS
F
400
500
A.- BIO-OIL
APPLICATIONS USING THE WHOLE BIO-OILS
SLOW RELEASE
FERTILIZER
NOXOLENETM (NOx
Reduction)
APPLICATIONS USING
FRACTIONS
Methanol
Formic acid
Carbonyl groups
Glyoxal
NH3
-C=O
SPECIAL CHEMICALS
Methyl glyoxal
Family A,B
Ethanol
Acetic acid
BIOLIMETM
(NOx/SOx
Reduction)
Carboxyl groups
-COOH
Lime
Crude Bio-oils
Propionic acid
Acetone
Methyl formate
Phenolics
SUFACTANTS
SYNTHESIS GAS,
HYDROGEN
SOLVENTS
FUELS
Acetol
WOOD
PRESERVATIVES
RESINS
DE- ICERS
Acetaldehyde
Hydroxyacetaldehyde
Family C
All
functional
groups
Steam
Phenol
Furfuryl alcohol
Catechol
Hydroquinone
Bernzenediol
Syringaldehyde
RESINS
ANTI-OXIDANTS
CO-POLYESTERS,
CO-POLYAMIDES
SUFACTANTS
3-ethylphenol
Family D, F
HOW TO SEPARATE BIO-OIL
FRACTIONS?
Family E
Levoglucosan
Cellobiosan
1,6-anhydroglucofuranose
Fructose
Extractive derived comp.
Oligomers
HYDROLYSIS AND
FERMENTATION
(ETHANOL)
ADHESIVES, SUFACTANTS
ADVANCED CARBONS
A.- BIO-OIL
USES
THE ISOLATION OF CHEMICALS AND PRODUCING SPECIAL PRODUCTS BASED ON
PYROLYSIS OILS IS AN ACTIVE AREA OF RESEARCH. SEVERAL PRODUCTS FROM BIO-OILS
HAVE BEEN DEVELOPED: LIQUID SMOKE, PHENOL FORMALDEHYDE RESINS,
PHENOLICS, LEVOGLUCOSAN, LEVOGLUCOSANONE, OCTANE ENHANCER, SLOW
RELEASE FERTILIZER, NOX/SOX REDUCERS (BIOLIMETM). PYROLYTIC ACETIC ACID MEETS
BETTER THE NEEDS OF ELECTRONIC CHIPS PRODUCTION. CREOSOTE, A FRACTION OF
WOOD TAR, IS TRADITIONALLY USED IN THE PHARMACEUTICAL INDUSTRY, AND
WATER FREE WOOD TARS IN VETERINARY MEDICINE.
BIO-OIL CAN BE UP-GRADED INTO SYNTHETIC TRANSPORTATION FUELS. ONE
APPROACH WOULD GASIFY BIO-OIL AND CONVERT SYNGAS TO SYNTHETIC GASOLINE
AND DIESEL THROUGH FISCHER-TROPSCH (F-T) CATALYTIC SYNTHESIS. THE EUROPEAN
UNION (EU) IS CONSIDERING THE DEVELOPMENT OF A DISTRIBUTED NETWORK OF
BIOMASS PYROLYZERS THAT WOULD SUPPLY BIO-OIL TO A CENTRALIZED F-T
REFINERY. THE HIGH INITIAL INVESTMENT REQUIRED TO BUILD A F-T REFINERY IS THE
BIGGEST OBSTACLE TO THE ADOPTION OF THIS APPROACH IN THE US. FURTHERMORE
F-T REFINERIES HAVE LOW CARBON-CONVERSION EFFICIENCIES (ABOUT 50 %).
Laid DA, Brown RC, Amonette JE, Lehmann J: Review of the Pyrolysis Platform for coproducing bio-oil and bio-char. Bio-fuels,
Bioproducts & Biorefining. 2009, 547-561
Meier D, Faix O: State of the art of applied fast pyrolysis of lignocellulosic materials- a review. Bioresource Technology 68 (1999) 71-77
A.- BIO-OIL
BIO-OIL REFINERIES (BIO-OIL FERMENTATION)
TO PRODUCE GASOLINE AND DIESEL
Brown R, Holmgren J: Fast Pyrolysis and Bio-Oil Upgrading . http://www.ars.usda.gov/sp2UserFiles/Program/307/biomasstoDiesel/RobertBrown& JenniferHolmgren
presentationslides.pdf
A.- BIO-OIL
BIO-OIL REFINERIES (GREEN GASOLINE FROM THE LIGNIN DERIVATIVES AND HYDROGEN
FROM THE WATER SOLUBLE PHASE )
Green Diesel
Bio-oil vapor
Hydrogen
FIBROUS
BIOMASS
PYROLYZER
Char
BIO-OIL
RECOVERY
STEAM
REFORMING
Carbohydrate derived
aqueous phase
HYDROCRACKER
CYCLONE
Lignin
ANOTHER APPROACH WOULD HYDROCRACK BIO-OIL TO TRANSPORTATION FUELS IN A MANNER
SIMILAR TO THE REFINING OF PETROLEUM TO GASOLINE. BIO-OIL VAPORS WILL BE RECOVERED AS
A CARBOHYDRATE-DERIVED AQUEOUS PHASE AND A LIGNIN RICH FRACTION. THE AQUEOUS
PHASE WOULD BE STEAM REFORMED TO HYDROGEN. THE LIGNIN FRACTION WOULD BE
HYDROCRACKED TO HYDROCARBONS. THE LARGE VOLUME OF HYDROGEN REQUIRED FOR THIS
PROCESS WOULD COME FROM THE STEAM REFORMER. THIS PROCESS IS ATTRACTIVE AND COULD
EMPLOY THE INFRASTRUCTURE AT EXISTING PETROLEUM REFINERIES.
Laid DA, Brown RC, Amonette JE, Lehmann J: Review of the Pyrolysis Platform for coproducing bio-oil and bio-char. Bio-fuels,
Bioproducts & Biorefining. 2009, 547-561
A.- BIO-OIL
REACTIVITY SCALE OF OXYGENATED GROUPS UNDER HYDROTREATMENT CONDITIONS
Elliott DC: Historical developments in Hydroprocessing Bio-oils. Energy & Fuels 2007, 21, 1792-1815
A.- BIO-OIL
HYDROTREATMENT OF WHOLE PYROLYSIS OILS
Feed
Pyrolysis Oil
H2
Mass %
100
4-5
Products
Lt ends
15
Gasoline
30
Diesel
Water, CO2
“38”
8
51-52
HYDROTREATING IS ONE OF THE KEY PROCESSES TO MEET QUALITY SPECIFICATIONS
FOR REFINERY FUEL PRODUCTS.
HIGH PRESSURE IS USED TO ADD HYDROGEN AND PRODUCE PREMIUM DISTILLATE
PRODUCTS
Brown R, Holmgren J: Fast Pyrolysis and Bio-Oil Upgrading . http://www.ars.usda.gov/sp2UserFiles/Program/307/biomasstoDiesel/RobertBrown&JenniferHolmgren
presentationslides.pdf
A.- BIO-OIL
REFINERIES
BLOCK DIAGRAM (PYROLYSIS PLANT COUPLESD WITH A BIO-OIL REFINERY) (OVER 2000 TONS/DAY)
BLOCK DIAGRAM (PYROLYSIS PLANT NOT COUPLED WITH A BIO-OIL REFINERY)
UNSTABLE OILS
STABLE OILS
Jones SB, Holladay JE, Valkenburg C, Stevens DJ, Walton C, Kinchin C, Elliott DC, Czernik S: Production of Gasoline and Diesel from Biomass via Fast Pyrolysis. Hydrotreating and Hydrocracking. A Design Case.
Pacific Northwest National Laboratory. US DOE. Contact DE-ACO5-76 RL)1830. PNNL-18284.
A.- BIO-OIL
FLOW DIAGRAM FOR PYROLYSIS OIL STABILIZATION (BIO-OIL REFINERIES)
HYDROGEN
PYROLYSIS OIL
Cost of production: 1.74 $/gal
gasoline/diesel
FUEL GAS TO
REFORMER
2000 T/DAY OF HYBRID POPLAR UNIT TO PRODUCE 76 MILLION
GALLONS/YEAR OF GASOLINE AND DIESEL (115 gal/t)
UP-GRADED
BIO-OIL TO
DEBUTANIZER
WASTE WATER
Jones SB, Holladay JE, Valkenburg C, Stevens DJ, Walton C, Kinchin C, Elliott DC, Czernik S: Production of Gasoline and Diesel from Biomass via Fast Pyrolysis,
Hydrotreating and Hydrocracking: A Design Case. US Department of Energy, February 2009, PNNL-18284 Rev. 1. DE-AC05-76RL01830
A.- BIO-OIL
REFINERIES
HYDROCRACKING AND
PRODUCT SEPARATION
UP-GRADED
BIO-OIL
FUEL GAS TO
REFORMERS
NAPHTHA
DIESEL
Jones SB, Holladay JE, Valkenburg C, Stevens DJ, Walton C, Kinchin C, Elliott DC, Czernik S: Production of Gasoline and Diesel from Biomass via Fast Pyrolysis. Hydrotreating and Hydrocracking. A Design
Case. Pacific Northwest National Laboratory. US DOE. Contact DE-ACO5-76 RL)1830. PNNL-18284.
B.- BIO-CHAR
USES
BIOCHAR IS A COMBUSTIBLE SOLID (18 MJ/kg) THAT CAN BE BURNED TO GENERATE
ENERGY IN MOST SYSTEMS THAT ARE CURRENTLY BURNING COAL. THE SUFUR
CONTENT OF BIO-CHAR IS LOW AND HENCE INDUSTRIAL COMBUSTION OF BIO-CHAR
GENERALLY DOES NOT REQUIRE TECHNOLOGY FOR REMOVING SOx FROM EMISSIONS
TO MEET EPA EMISSION LIMITS. EMISSIONS OF NOX FROM COMBUSTION OF BIOCHAR
ARE COMPARABLE TO THAT COMING FROM COAL COMBUSTION AND REQUIRE
ABATEMENT TECHNOLOGY. THE ASH CONTENT OF BIO-CHAR DEPENDS
SUBSTANTIALLY ON THE FEESTOCK. SOME BIOMASSES SUCH AS CORN STOVER AND
RICE HUSK CONTAIN HIGH LEVELS OF Si, AND AFTER PYROLYSIS IT IS CONCENTRATED
IN THE ASH. COMBUSTION OF HIGH Si BIO-CHAR WILL CAUSE SCALING IN THE WALL
OF THE COMBUSTION CHAMBER AND DECREASE THE USABLE LIFE OF THESE
CHAMBERS.
LOW-ASH BIO-CHARS CAN BE USE IN METALLURGY AND AS A FEEDTOCK FOR
PRODUCTION OF ACTIVATED CARBON, WHICH HAS MANY USES, SUCH AS AN
ADSORBENT TO REMOVE ODORANTS FROM AIR STREAMS AND BOTH ORGANIC AND
INORGANIC CONTAMINANTS FROM WASTE WATER STREAMS.
Laid DA, Brown RC, Amonette JE, Lehmann J: Review of the Pyrolysis Platform for coproducing bio-oil and bio-char. Bio-fuels,
Bioproducts & Biorefining. 2009, 547-561
B.- BIO-CHAR
USES
AN EMERGIN NEW USE OF BIO-CHAR IS AS A SOIL AMENDMENT. THE HARVESTING
OF CROP RESIDUES FOR THE PRODUCTION OF BIOENERGY COULD HAVE ADVERSE
IMPACTS ON SOIL AND ENVRIONMENTAL QUALITY. THE HARVESTING OF RESIDUES
REMOVES SUBSTANTIAL AMOUNT OF PLANT NUTRIENTS FROM SOIL AGROECOSYSTEMS. UNLESS THESE NUTRIENTS ARE REPLACED BY ADDITION OF SYNTHETIC
FERTILIZERS, MANURE OR OTHER SOIL AMENDMENTS, THE PRODUCTIVITY OF THE
SOIL WILL DECLINE. EVEN IF SYNTHETIC FERTILIZERS ARE ADDED TO MAINTAIN SOIL
FERTILITY, THE SUSTAINED REMOVAL OF CROP RESIDUES WITHOUT COMPENSATING
ORGANIC AMENDMENTS WILL CAUSE A DECLINE IN LEVELS OF SOIL ORGANIC
MATTER, A DECLINE IN THE CATION EXCHANGE CAPACITY, A DECLINE IN WATER
HOLDING CAPACITY AND ACCELERATED ACIDIFICATION OF SOILS. THE RETURN OF
THE BIO-CHAR CO-PRODUCT OF PYROLYSIS TO THE SOIL FROM WHICH THE
BIOMASS WAS HARVESTED HAS ALSO BEEN PROPOSED AS A MEANS TO ENHANCE
SOIL QUALITY AND THEREBY THE SUSTAINABILITY OF BIOENERGY PRODUCTION
SYSTEMS. FURTHERMORE, MANY OF THE NUTRIENTS IN BIOMASS ARE RECOVERED
WITH THE CHAR PRODUCT OFFERING OPPORTUNITIES FOR NUTRIENT RECYCLING.
Laid DA, Brown RC, Amonette JE, Lehmann J: Review of the Pyrolysis Platform for coproducing bio-oil and bio-char. Bio-fuels,
Bioproducts & Biorefining. 2009, 547-561
B.- BIO-CHAR
THE HISTORY OF TERRA PRETA (DARK EARTH)
FRANCISCO DE ORELLANA WAS THE FIRST
EUROPEAN TO EXPLORE THE CENTRAL AMAZON
IN THE YEAR 1542. HE REPORTED BACK TO THE
SPANISH COURT THAT A LARGE AGRICULTURAL
CIVILIZATION EXISTED ALONG THE BANKS OF
THE AMAZON. FOR CENTURIES, MOST PEOPLE
ASSUMED THAT DE ORELLANA HAS INVENTED
THE STORIES OF A CIVILIZATION IN AMAZONIA.
BUT DURING THE TWENTIETH CENTURY,
ANTHROPOLOGISTS FOUND EVIDENCE OF
EXTENSIVE REGIONS OF TERRA PRETA SOILS
WITH POT SHARDS AND OTHER ARTIFACTS
ASSOCIATED WITH A LARGE CIVILIZATION. THESE
SOILS HAVE HIGH CONTENTS OF BIO-CHAR
EXHIBIT VERY HIGH FERTILITY COMPARED WITH
THE INFERTILE OXISOLS OF THE REGION.
REPRESENTATIVE TERRA PRETA AND OXISOLS
PROFILES.
TERRA PRETA SOILS TYPICALLY HAVE
HIGHER LEVELS OF ORGANIC MATTER,
HIGHER
MOISTURE-HOLDING
CAPACITY, AND HIGHER LEVELS OF
BIOAVAILABLE N, P, Ca AND K THAN
THE OXISOLS FROM WHICH THEY ARE
DERIVED.
Laid DA, Brown RC, Amonette JE, Lehmann J: Review of the Pyrolysis Platform for coproducing bio-oil and bio-char. Bio-fuels,
Bioproducts & Biorefining. 2009, 547-561
B.- BIO-CHAR
THE APPLICATION OF BIO-CHAR TO SOIL IS
PROPOSED AS A NOVEL APPROACH TO ESTABLISH
A SIGNIFICANT, LONG-TERM SINK FOR
ATMOSPHERIC CARBON DIOXIDE IN TERRESTRIAL
ECOSYSTEMS. APART FROM POSITIVE EFFECTS IN
BOTH REDUCING EMISSIONS AND INCREASING THE
SEQUESTRATION OF GREENHOUSE GASES.
CONVERSION OF BIOMASS C TO BIO-CHAR C
(SLOW PYROLYSIS) LEADS TO SEQUESTRATION OF
ABOUT 50 % OF THE INITIAL C COMPARED TO THE
LOW AMOUNTS RETAINED AFTER BURNING (3%)
AND BIOLOGICAL DECOMPOSITION (<10 - 20 %
AFTER 5 - 10 YEARS), THEREFORE YIELDING MORE
STABLE SOIL C THAN BURNING OR DIRECT LAND
APPLICATION OF BIOMASS. SOME ANALYSES
REVELEAD THAT UP TO 12 % OF THE TOTAL
ANTHROPOGENIC C EMISSIONS BY LAND USE
CHANGE CAN BE OFF SET ANNUALLY IN SOIL, IF
SLASH-AND CHAR IS REPLACED BY SLASH AND
CHAR SYSTEMS.
RANGE OF BIOMASS CARBON REMAINING AFTER DECOMPOSITION OF
CROP RESIDUES.
BIOCHAR CAN RESULT IN A NET REMOVAL OF CARBON FROM THE
ATMOSPHERE, ESPECIALLY WITH ENHANCED NET PRIMARY PRODUCTIVITY
Lehmann J, Gaunt J, Rondon M: Bio-char sequestration in terrestrial ecosystems – a review. Mitigation and Adaptation Strategies for Global Change (2006) 11: 403427.
B.- BIO-CHAR
PRODUCTION OF ACTIVATED CARBON
PHYSICAL ACTIVATION: IT IS A TWO CONSECUTIVE STEP PROCESS. IT INVOLVES CARBONIZATION OF
A CARBONACEOUS MATERIAL FOLLOWED BY THE ACTIVATION OF THE RESULTING CHAR AT
ELEVATED TEMPERATURES IN THE PRESENCE OF A SUITABLE OXIDIZING AGENT SUCH AS CARBON
DIOXIDE, STEAM, AIR OR THEIR MIXTURES. THE ACTIVATION GAS IS USUALLY CO2, SINCE IT IS
CLEAN, EASY TO HANDLE AND IT FACILITATES CONTROL OF THE ACTIVATION PROCESS DUE TO THE
SLOW REACTION RATE AT TEMPERATURES AROUND 800 oC. CARBONIZATION TEMPERATURE
RANGE BETWEEN 400 AND 850 oC, THE ACTIVATION TEMPERATURE RANGE BETWEEN 600 AND
900 oC.
CHEMICAL ACTIVATION: THE TWO STEPS ARE CARRIED OUT SIMULTANEOUSLY, WITH THE
PRECURSOR BEING MIXED WITH CHEMICAL ACTIVATING AGENTS, AS DEHYDRATING AGENTS AND
OXIDANTS. CHEMICAL ACTIVATION OFFERS SEVERAL ADVANTAGES SINCE IT IS CARRIED OUT IN A
SINGLE STEP, COMBINING CARBONIZATION AND ACTIVATION, PERFORMED AT LOWER
TEMPERATURES AND THEREFORE RESULTING IN THE DEVELOPMENT OF A BETTER POROUS
STRUCTURE, ALTHOUGH THE ENVIRONMENTAL CONCERNS OF USING CHEMICAL AGENTS FOR
ACTIVATION COULD BE DEVELOPED. BESIDE PART OF THE ADDITIVES USED (ZINC SALTS,
PHOSPHORIC ACID) CAN BE EASILY RECOVERED. THE MOST COMMON CHEMICAL AGENTS USED
ARE: ZnCl2, KOH, H3PO4 AND K2CO3. TEMPERATURES (BETWEEN 300 AND 850 oC)
STEAM-PYROLYSIS: THE RAW BIOMASS IS EITHER HEATED AT MODERATE TEMPERATURE (500-700
oC) UNDER A FLOW OF PURE STEAM, OR HEATED AT 700-800 oC UNDER A FLOW OF JUST STEAM.
Ioannidou O, Zabaniotou A: Agricultural residues as precursors for activated carbon production – A review. Renewable and Sustainable
Energy Reviews 11 (2007) 1966-2005
B.- BIO-CHAR
ACTIVATED CARBON CAN ALSO BE USED TO REMOVE POLLUTANTS FROM LIQUID PHASE. MOST OF THE RELEVANT
BEEN THE WASTE WATER TREATMENT, THE DRINKING WATER, THE INDUSTRIAL EFFLUENTS PURIFICATION AND
GROUND WATER TREATMENT. ACTIVATED CARBONS ARE USED FOR THE REMOVAL OF PHENOLS, PHENOLIC
COMPOUNDS, HEAVY METALS AND DYES, METAL IONS AND MERCURY (II). PHENOLIC COMPOUNDS EVEN IN LOW
CONCENTRATIONS CAN BE AN OBSTACULE TO USE AND RE-USE WATER. PHENOLS CAUSE UNPLEASANT TASTE AND
ODOUR OF DRINKING WATER AND EXERT NEGATICE EFFECTS ON DIFFERENT BIOLOGICAL SYSTEMS. THEY ALSO
ADSORB ARSENIC OR CAN BE USED AS A SUPPORT CATALYST FOR LIQUID PHASE REACTIONS.
PROPERTIES OF ACTIVATED CARBON
SURFACE AREA: THE BET SURFACE AREA OF CHAR IS IMPORTANT, BECAUSE, LIKE OTHER PHYSICO-CHEMICAL
CHARACTERISTICS, IT MAY STRONGLY AFFECT THE REACTIVITY AND COMBUSTION BEHAVIOUR OF THE CHAR. THE
INCREASE IN THE SURFACE AREA IS DUE TO THE OPENING OF THE RESTRICTED PORES.
SIZE OF PORES: BOTH SIZE AND DISTRIBUTION OF MICROPORES, MESOPORES AND MACROPORES DETERMINE
THE ADSORPTIVE PROPERTIES OF ACTIVATED CARBONS. FOR EXAMPLE SMALL PORE SIZE WILL NOT TRAP LARGE
ADSORBATE MOLECULES, AND LARGE PORES MAY NOT BE ABLE TO RETAIN SMALL ADSORBATES. MATERIALS
WITH HIGH CONTENT OF LIGNIN DEVELOP ACTIVATED CARBONS WITH MACROPOROUS STRUCTURE, WHILE RAW
MATERIALS WITH HIGHER CONTENT OF CELLULOSE YIELD ACTIVATED CARBON WITH A PREDOMINANTLY
MICROPOROUS STRUCTURE.
ACIDIC SURFACES ARE IN GENERAL FAVOURABLE FOR BASIC GAS ADSORPTION SUCH AS AMMONIA WHILE
ACTIVATED CARBONES WITH BASIC SURFACE CHEMICAL PROPERTIES ARE SUITABLE FOR ACID GAS ADSORPTION
SUCH AS SULPHUR DIOXIDE.
Ioannidou O, Zabaniotou A: Agricultural residues as precursors for activated carbon production – A review. Renewable and Sustainable
Energy Reviews 11 (2007) 1966-2005
C.- SYNTHESIS GAS: Introduction
PRODUCTION AND COMPOSITION
IN PRINCIPLE SYNGAS (PRIMARILY CONSISTING OF CO AND H2) CAN BE PRODUCED
FROM ANY HYDROCARBON FEEDSTOCK INCLUDING: NATURAL GAS, NAPHTHA,
RESIDUAL OIL, PETROLEUM COKE, COAL AND BIOMASS. THE CONVERSION OF
SYNGAS INTO LIQUID FUELS AMOUNT FOR MORE THAN HALF THE CAPITAL COST OF
THESE PLANTS. THE CHOICE OF TECHNOLOGY FOR SYNGAS PRODUCTION ALSO
DEPENDS ON THE SCALE OF THE SYNTHESIS GAS OPERATION. SYNGAS PRODUCTION
FROM SOLID FUELS IS MORE EXPENSIVE THAN FROM NATURAL GAS BECAUSE IT
REQUIRES HIGHER CAPITAL INVESTMENTS WITH THE ADDITION OF FEEDSTOCK
HANDLING AND MORE COMPLEX SYNGAS PURIFIATION OPERATIONS.
IN ITS SIMPLEST FORM, SYNGAS IS COMPOSED OF TWO DIATIOMIC MOLECULES CO
BUILDING BLOCKS UPON WHICH AN
ENTIRE FIELD OF FUEL SCIENCE AND TECHNOLOGY IS BASED.
AND H2 THAT PROVIDE THE
THIS MIXTURE HAD MANY NAMES DEPENDING ON HOW IT WAS FORMED AND USED:
PRODUCER GAS, TOWN GAS, BLUE WATER GAS, SYNTHESIS GAS AND SYNGAS. THE
BEGINNING OF THE 20th CENTURY SAW THE DAWN OF FUELS AND CHEMICALS
SYNTHESIS FROM SYNGAS.
Spath PL, Dayton DC: Preliminary Screening-Technical and Economic Assessment of Synthesis Gas to Fuels and Chemicals with
Emphasis on the Potential for Biomass-Derived Syngas. NREL/tp-510-34929
C.- SYNTHESIS GAS: Introduction
Ammonia
Synthesis
Natural Gas Naphtha
CO2 + H2
Steam Reforming
Or
Partial Oxidation
Hydrotreating
Hydrogenation
Fuel Cell Power
CO + H2
(Syngas)
FT Synthesis of
Liquid Fuels
Methanol
Synthesis
Coal
Biomass
Catalytic processes based on H2 or syngas are among
the most basic and critically important processes in
providing food, fuel, and chemical resources
C.- SYNTHESIS GAS: Introduction
SYNTHESIS GAS CONVERSION PROCESSES
Spath PL, Dayton DC: Preliminary Screening-Technical and Economic Assessment of Synthesis Gas to Fuels and Chemicals with
Emphasis on the Potential for Biomass-Derived Syngas. NREL/tp-510-34929
C.- SYNTHESIS GAS: Introduction
Ammonia Synthesis
The first ammonia synthesis plant was started-up in 1913 by BASF with a total
production capacity of 30 tons per day. Synthetic ammonia production grew
from 10,000 tons per year in 1913 to about 120 million tons per year in 2000.
Large-scale ammonia synthesis has made it feasible for the world’s industrialagriculture complex to feed a population of several billion people
Methanol Synthesis
The first large-scale synthesis of methanol in 1923 from syngas marked the
beginning of the modern chemical industry. Conversion to formaldehyde is
currently one of the largest chemical applications of methanol and accounts
for usage of about 60% of the methanol produce.
Fischer-Tropsch Synthesis
Fischer-Tropsch Synthesis (FTS), the production of liquid hydrocarbons from
syngas, was developed by Fischer and Tropsch in the mid-1920s. It played an
important role in supplying the fuel needs of Germany during World War II
when its petroleum supplies were cut off and has been the main source of
fuels and chemical for South Africa since the 1950s. It is a developing option
for environmentally-sound production of chemicals and liquid fuels from
biomass, coal, and natural gas.
C.- SYNTHESIS GAS: Production
Steam Reforming (SR):
CnHm + nH2O = nCO + (n + 1/2m)H2
CH4 + H2O = CO + 3H2
CO2 Reforming (Dry Reforming):
CH4 + CO2 = 2CO + 2H2
Partial Oxidation (POX):
CH4 + ½ O2 = CO + 2H2
Ho=200 kJ/mol
Ho=247 kJ/mol
Ho=-40 kJ/mol
Autothermal Reforming (ATR)
CH4 + H2O = CO + 3H2
n* (CH4 + ½ O2 = CO + 2H2)
Thermally Neutral Process
Is Possible
* Gasification is a process where one oxidizes the solid with either O2 or
H2O (ex. Coal Gasification)
C.- SYNTHESIS GAS: Production
SR
POX
ATR
0.0
1.0
Natural Gas
Naphtha
2.0
3.0
4.0
5.0
H2/CO Ratio
THE SYNGAS COMPOSITION, MOST IMPORTANTLY THE H2/CO RATIO, VARIES AS A
FUNCTION OF PRODUCTION AND FEEDSTOCK. STEAM METHANE REFORMING YIELDS
H2/CO RATIOS OF 3/1 WHILE COAL GASIFICATION YIELDS RATIOS CLOSER TO UNITY
OR LOWER.
C.- SYNTHESIS GAS: Production
THE DOMINANT TECHNOLOGY FOR HYDROGEN PRODUCTION IS STEAM METHANE REFORMING. IF THE
FEEDSTOCK IS METHANE THEN 50 % OF THE HYDROGEN COME FROM THE STEAM. THE REFORMIG REACTION IS
HIGHLY ENDOTHERMIC AND IS FAVORED BY HIGH TEMPERATURES AND LOW PRESSURES. THE SHIFT REACTION IS
EXOTHERMIC AND IS FAVORED AT LOW TEMPERATURES. IN INDUSTRIAL REFORMERS, THE REFORMING AND
SHIFT REACTUONS RESULT IN A PRODUCT COMPOSITION THAT CLOSELY APPROACHES EQUILIBRIUM. THE
REFORMER STEAM TO CARBON RATIO IS USUALLY BETWEEN 2-6 DEPENDING ON THE PROCESS CONDITIONS.
EXCESS STEAM IS USED TO PREVENT COKING IN THE REFORMER TUBES. CONVENTIONAL STEAM REFORMING
CATALYSTS ARE 10-33 mass % NiO ON A SUPPORT (ALIMINA, CEMENT OR MAGNESIA).
H2S + ZnO  ZnS + H2O
CO + H2O  CO2 + H2
Spath PL, Dayton DC: Preliminary Screening-Technical and Economic Assessment of Synthesis Gas to Fuels and Chemicals with Emphasis
on the Potential for Biomass-Derived Syngas. NREL/tp-510-34929
C.- SYNTHESIS GAS: Production
THE DOMINANT TECHNOLOGY FOR HYDROGEN PRODUCTION IS STEAM METHANE REFORMING. IF THE
FEEDSTOCK IS METHANE THEN 50 % OF THE HYDROGEN COME FROM THE STEAM. THE REFORMIG REACTION IS
HIGHLY ENDOTHERMIC AND IS FAVORED BY HIGH TEMPERATURES AND LOW PRESSURES. THE SHIFT REACTION IS
EXOTHERMIC AND IS FAVORED AT LOW TEMPERATURES. IN INDUSTRIAL REFORMERS, THE REFORMING AND
SHIFT REACTUONS RESULT IN A PRODUCT COMPOSITION THAT CLOSELY APPROACHES EQUILIBRIUM. THE
REFORMER STEAM TO CARBON RATIO IS USUALLY BETWEEN 2-6 DEPENDING ON THE PROCESS CONDITIONS.
EXCESS STEAM IS USED TO PREVENT COKING IN THE REFORMER TUBES. CONVENTIONAL STEAM REFORMING
CATALYSTS ARE 10-33 mass % NiO ON A SUPPORT (ALIMINA, CEMENT OR MAGNESIA).
LIGHT
OXYGENATED
COMPOUNDS
Spath PL, Dayton DC: Preliminary Screening-Technical and Economic Assessment of Synthesis Gas to Fuels and Chemicals with Emphasis
on the Potential for Biomass-Derived Syngas. NREL/tp-510-34929
C.- SYNTHESIS GAS: Production
3C2H6 + 4H2O  2CH4 + 4CO + 9H2
Ethane Steam Reforming
Reaction Mechanism
H
H
H
C
C
H
H
H
The first step involves a rapid dehydrogenation of ethane to C2H5
C.- SYNTHESIS GAS: Production
C2H5OH + 3H2O  2CO2 +6H2
H
H
H
C
C
H
H
Ethanol Steam Reforming (ESR)
H
H
H
dehydration
-H2O
OH
dehydrogenation
-H2
H
C
coke
C
H
5H2 + 2CO2
H
O
C
C
H
steam reforming
+3H2O
H
CH4 + CO
decomposition
acetaldehyde
??? Surface intermediates
C.- SYNTHESIS GAS: Production
ALTHOUGH STEAM REFORMING HAS BEEN AROUND FOR MANY YEARS, MORE STUDIES
ON THE REFORMING OF OXIGENATED HYDROCARBONS IS NEEDED.
C.- SYNTHESIS GAS: Production of Ammonia
3H2 + N2  2NH3
H (500oC) = -109 kJ/mol N2
Catalyst: K promoted Fe
AMMONIA IS MANUFACTURED FROM NITROGEN FIXED FROM THE ATMOSPHERE AND
HYDROGEN. THE PROCESS WAS DEVELOPED IN THE EARLY 1900s BY FRITZ HABER AND CARL
BOSCH USING A PROMOTDED IRON CATALYST.
P = 125 bar
C.- SYNTHESIS GAS: Production of Ammonia
3H2 + N2  2NH3
H (500oC) = -109 kJ/mol N2
Ammonia Synthesis Loop For a
Large Capacity (1000 ton per day)
(H2:N2 = 2.2-3.1:1)
C.- SYNTHESIS GAS: Production of Ammonia
3H2 + N2  2NH3
H (500oC) = -109 kJ/mol N2
C.- SYNTHESIS GAS: Production of Ammonia
3H2 + N2  2NH3
At 400oC
H (500oC) = -109 kJ/mol N2
At 400oC
C.- SYNTHESIS GAS: Production of Methanol
METHANOL SYNTHESIS BEGAN IN THE 1800s WITH THE ISOLATION OF “WOOD”
ALCOHOL FROM THE DRY DISTILLATION (PYROLYSIS) OF WOOD. RESEARCH AND
DEVELOPMENT EFFORTS AT THE BIGINNING OF THE 20tH CENTURY INVOLVING THE
CONVERSION OF SYNGAS TO LIQUID FUELS AND CHEMICALS LED TO THE DISCOVERY OF
A METHANOL SYNTHESIS PROCESS CURRENTLY WITH DEVELOPMENT OF THE FISCHERTROPSCH SYNTHESIS. IN FACT METHANOL IS A BYPRODUCT OF FISCHER-TROPSCH
SYNTHESIS WHEN ALKALI METAL PROMOTED CATALYSTS ARE USED. METHANOL
SYNTHSIS IS NOW WELL-DEVELOPED WITH HIGH ACTIVITY AND VERY HIGH SELECTIVITY.
FOR ECONOMIX REASONS, METHANOL IS ALMOST EXCLUSIVELY PRODUCED VIA
REFORMING OF NATURAL GAS (90 % OF THE WORLDWIDE METHANOL). HOWEVER A
VARIETY OF FEEDSTOCKS OTHER THAN NATURAL GAS CAN BE USED TO PRODUCE
ETHANOL.
CURRENT INTEREST IN METHANOL IS DUE TO ITS POTENTIAL AS FUEL AND ITS USED AS
CHEMICAL. IN PARTICULAR, METHANOL CAN BE USED DIRECTLY OR BLENDED WITH
OTHER PETROLEUM PRODUCTS AS A CLEAN BURNING TRANSPORTATION FUEL.
METHANOL IS ALSO AN IMPORTANT CHEMICAL INTERMEDIATE USED TO PRODUCE:
FORMALDEHYDE, DIMETHYL ETHER (DME), METHYL TER-BUTYL ETHER (MTBE), ACETIC
ACID, OLEFINS, METHYL AMINES, AND METHYL HALIDES.
Spath PL, Dayton DC: Preliminary Screening-Technical and Economic Assessment of Synthesis Gas to Fuels and Chemicals with Emphasis
on the Potential for Biomass-Derived Syngas. NREL/tp-510-34929
C.- SYNTHESIS GAS
PRODUCTION OF METHANOL
CHEMISTRY
CATALYTIC METHANOL SYNTHESIS FROM SYNGAS IS A CLASSICAL HIGH-TEMPERATURE, HIGHPRESSURE EXOTHERMIC EQUILIBRIUM LIMITED SYNTHESIS REACTION. THE CHEMISTRY OF THIS
REACTION IS AS FOLLOWS:
CO + H2O  H2 + CO2
H (25oC) = -41.2 kJ/mol CO
CO2 + 3H2  CH3OH + H2O
H (25oC) = -49.5 kJ/mol CO2
CO + 2H2  CH3OH
H (25oC) = -90.6 kJ/mol CO
H (327OC) = -105.5 kJ/mol CO
FOR METHANOL SYNTHESIS, A STOICHIOMETRIC RATIO, DEFINED AS (H2-CO2)/(CO+CO2) OF
SLIGHTLY ABOUT 2 IS PREFERRED. THIS MEANS THAT THERE WILL BE JUST THE STOICHIOMETRIC
AMOUNT OF HYDROGEN NEEDED FOR METHANOL SYNTHESIS. THE FEED GAS COMPOSITION FOR
METANOL SYNTHESIS IS TYPICALLY ADJUSTED TO CONTAIN 4-8 % CO2 FOR MAXIMUM ACTIVITY
AND SELECTIVITY.
CATALYSTS
THE FIRST HIGH-TEMPERATURE, HIGH PRESSURE METHANOL SYNTHESIS CATALYSTS WERE
ZnO/Cr2O3 AND WERE OPERATED AT 350 oC and 250-350 bar. IN 1966 ICI INTRODUCED A NEW,
MORE ACTIVE Cu/ZnO/Al2O3 CATALYST THAT BEGAN A NEW GENERATION OF METHANOL
PRODUCTION BY USING LOW TEMPERATURES (220-275 oC), LOW PRESSURE (50-100 bar) .
Spath PL, Dayton DC: Preliminary Screening-Technical and Economic Assessment of Synthesis Gas to Fuels and Chemicals with Emphasis
on the Potential for Biomass-Derived Syngas. NREL/tp-510-34929
C.- SYNTHESIS GAS: Production of Methanol
CO + H2O  H2 + CO2
H (25oC) = -41.2 kJ/mol CO
CO2 + 3H2  CH3OH + H2O
H (25oC) = -49.5 kJ/mol CO2
CO + 2H2  CH3OH
H (25oC) = -90.6 kJ/mol CO
H (327OC) = -105.5 kJ/mol CO
Operated with Cu/ZnO/Al2O3 at 220~327oC and 50~100atm
C.- SYNTHESIS GAS: Production of Methanol
CO + H2O  H2 + CO2
H (25oC) = -41.2 kJ/mol CO
CO2 + 3H2  CH3OH + H2O
H (25oC) = -49.5 kJ/mol CO2
CO + 2H2  CH3OH
H (25oC) = -90.6 kJ/mol CO
H (327OC) = -105.5 kJ/mol CO
Operated with Cu/ZnO/Al2O3 at 220~327oC and 50~100atm
Increasing in
Equilibrium Conversion
C.- SYNTHESIS GAS: Production of Methanol
CO + H2O  H2 + CO2
H (25oC) = -41.2 kJ/mol CO
CO2 + 3H2  CH3OH + H2O
H (25oC) = -49.5 kJ/mol CO2
CO + 2H2  CH3OH
H (25oC) = -90.6 kJ/mol CO
H (327OC) = -105.5 kJ/mol CO
Operated with Cu/ZnO/Al2O3 at 220~327oC and 50~100atm
Increasing in
Equilibrium Conversion
C.- SYNTHESIS GAS: Production of Methanol
ONCE THE NATURAL GAS IS REFORMED THE RESULTING SYNTHESIS GAS IS FED TO A
REACTOR VESSEL IN THE PRESENCE OF CATALYST TO PRODUCE METHANOL AND
WATER VAPOR. THIS CRUDE METHANOL WHICH USUALLY CONTAINS UP TO 18 %
WATER, PLUS ETHANOL, HIGHER ALCOHOLS, KETONES AND ETHERS IS FED TO A
DISTILLATION PLANT THAT CONSISTS OF A UNIT THAT REMOVES THE VOLATILES AND
A UNIT THAT REMOVES THE WATER AND HIGHER ALCOHOLS. THE UNREACTED
SYNGAS IS RECIRCULATED BACK TO THE METHANOL CONVERTED RESULTING IN AN
OVERALL CONVERSION EFFICIENCY OF 99 %.
Spath PL, Dayton DC: Preliminary Screening-Technical and Economic Assessment of Synthesis Gas to Fuels and Chemicals with Emphasis
on the Potential for Biomass-Derived Syngas. NREL/tp-510-34929
C.- SYNTHESIS GAS: Production of Methanol
ONE OF THE CHALLENGES ASSOCIATED WITH COMMERCIAL METHANOL IS REMOVING
THE LARGE EXCESS HEAT OF REACTION. METHANOL SYNTHESIS CATALYST ACTIVITY
INCREASES AT HIGH TEMPERATURES BUT SO DOES THE CHANGE FOR COMPETING SIDE
REACTIONS. CATALYTIC LIFETIMES ARE ALSO REDUCED BY CONTINUOUS HIGH
TEMPERATURE OPERATION AND TYPICALLY PROCESS TEMPERATURES ARE MAINTAINED
BELOW 300 oC TO MINIMIZE CATALYST SINTERING.
OVERCOMING THE THERMODYNAMIC CONSTRAINS IS ANOTHER CHALLENGE IN
COMMERCIAL METHANOL SYNTHESIS. THE MAXIMUM PER-PASS CONVERSION
EFFICIENCY OF SYNGAS TO METHANOL IS LIMITED TO ABOUT 25 %. HIGHER
EFFICIENCIES PER-PASS CAN BE REALIZED AT LOW TEMPERATURE WHERE THE
METHANOL EQUILIBRIUM IS SHIFTED TOWARDS PRODUCTS, HOWEVER, CATALYST
ACTIVITIES GENERALLY DECREASE AS THE TEMPERATURE IS LOWERED.
Spath PL, Dayton DC: Preliminary Screening-Technical and Economic Assessment of Synthesis Gas to Fuels and Chemicals with Emphasis
on the Potential for Biomass-Derived Syngas. NREL/tp-510-34929
C.- SYNTHESIS GAS: Production of Methanol
C.- SYNTHESIS GAS: Fischer-Tropsch Synthesis
History
Period 1: Discovery (1902-1928). FTS had its genesis
in the early 1900s with the discovery by Sabatier and
Senderens in 1902 that CO could be hydrogenated
over Co, Fe, and Ni to methane. In 1925, Fischer and
Tropsch first reported synthesis of hydrocarbon
liquids and solid paraffins on Co-Fe catalysts under
mild conditions of 250-300oC and 1 atm.
Period 2: Commercial Development of the Fischer Cobalt-Based Process
(1928-1945). Fischer and Koch developed the precipitated Co/ThO2/kieselguhr
catalyst between 1928 and 1934 which was to be the industrial standard for
the next 12 years. They also found that the yields of different boiling point
fractions were significantly affected by the operating temperature and
pressure. In 1944, FTS provided 10-15% of Germany’s synthetic fuel
production with a total capacity of 5.4 Mbbl/yr.
Period 3: The Age of Iron and Sasol (1946-1974). Following WWII, American
and British Allies followed up their intense interest in the German synfuels
industry by sending teams of scientists to Germany. The U.S. team was
referred to as the Technical Oil Mission (TOM). Due to a perceived shortage of
C.- SYNTHESIS GAS: Fischer-Tropsch Synthesis
History (Continues)
petroleum, the U.S., Great Britain, and Germany continued to support the
FTS R&D. This R&D led to the development of inexpensive Fe catalysts. The
first commercial GTL-FT plant (7,000 bbl/day) was operated in Brownsville,
Texas, in 1951 by a Texaco-led consortium using fluidized bed reactor with Fe
catalysts. However, this plant was shut down in 1957 after high gas prices
and low cost petroleum from the Middle East made operation uneconomical.
This fluidized bed reactor concept with Fe catalysts were used to build the
Sasol Plant in South Africa in 1955 for the large-scale commercial FTS. It
continues to operate and to produce 140,000 bbl/yr of synthetic fuels.
Period 4: Rediscovery of FTS and Cobalt (1975-1990). The 1973 oil embargo
stimulated considerable support in the U.S. and Europe for R&D of synfuels
technologies. During its “heyday” (1980) of FT research, significant progress
was realized in relating catalyst properties to activity and selectivity. These
new insights and innovations led to the development at Sasol, Gulf, Shell, and
Exxon of substantially more economical FTS of diesel processes.
Period 5: Birth/Growth of the GTL Industry Based on Biomass (1990-Present).
C.- SYNTHESIS GAS: Fischer-Tropsch Synthesis
CHEMISTRY
FTS HAS LONG BEEN RECOGNIZED AS A POLYMERIZATION REACTION WITH THE BASIC
STEPS OF:
H
H
1.- REACTANT (CO) ADSORPTION ON
THE CATALYST SURFACE
H
2.- CHAIN INITIATION BY CO DISSOCIATION
FOLLOWED BY HYDROGENATION
3.- CHAIN GROWTH BY INSERTION OF
ADDITIONAL CO MOLECULES
FOLLOWED BY HYDROGENATION
CH3
CH2
CH3
CH2
CH3
n (CH2)n
+ H
CH3-(CH2)n-CH3
CH3
4.- CHAIN TERMINATION
(CH2)n
- H
5.- PRODUCT DESORPTION FROM THE CATALYST SURFACE
CH3-(CH2)(n-1)-HC=CH2
C.- SYNTHESIS GAS: Fischer-Tropsch Synthesis
FTS produces a broad spectrum of mainly alkanes and alkenes having carbon
number from C1 to C50, the distribution of which is qualitatively governed by
the Anderson-Schulz-Flory (ASF) kinetics:
Wn/n = (n-1) (1- )2
 = rp / (rp +rt)
Wn is the weight of product containing n carbon atoms and  is the chain growth
propagation probability
The value of  increases with decreasing
H2/CO ratio, decreasing reaction
temperature, and increasing pressure
The maximum obtainable weight
percentage of light LPG hydrocarbons
(C2-C4) is 56%, of gasoline (C5-C11) 47%
and of diesel fuel (C12-C17) 40%
C.- SYNTHESIS GAS: Fischer-Tropsch Synthesis
C.- SYNTHESIS GAS: Fischer-Tropsch Synthesis
REACTORS
ONE OF THE CHALLENGES WITH FTS, IS THE REMOVAL OF THE LARGE AMOUNT OF EXCESS HEAT GENERATED BY
THE EXOTHERMIC SYNTHESIS REACTIONS. INSUFFICIENT HEAT REMOVAL LEADS TO LOCALIZED OVERHEATING
WHICH RESULTS IN HIGH CARBON DEPOSITION LEADING TO CATALYST DEACTIVATION. METHANE FORMATION ALSO
DOMINATES AT HIGHER TEMPERATURES AT THE EXPENSE OF DESIRED FTS PRODUCTS. FOR LARGE-SCALE
COMMERCIAL FTS REACTORS HEAT REMOVAL AND TEMPERATURE CONTROL ARE THE MOST IMPORTANT DESIGN
FEATURES TO OBTAIN OPTIMUM PRODUCT SELECTIVITY AND LONG CATALYST LIFETIMES. OVER THE YIELDS
BASICALLY FOUR FTS REACTOR DESIGNS HAVE BEEN USED COMMERCIALLY.
TYPES OF FISCHER-TROPSCH SYNTHESIS REACTOR
Spath PL, Dayton DC: Preliminary Screening-Technical and Economic Assessment of Synthesis Gas to Fuels and Chemicals with
Emphasis on the Potential for Biomass-Derived Syngas. NREL/tp-510-34929

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