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CACHET WORKSHOP
One-Step-Decarbonization A new direct route
to hydrogen
Franco Mizia
ENI R M division
San Donato Milanese (Italy)
Co-authors
S. Rossini, U. Cornaro, A. Malandrino
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CACHET WORKSHOP
Henry Cavendish. 1731-1810. British chemist and
physicist who discovered the properties of
hydrogen and established that water is a compound
of hydrogen and oxygen.
Cavendish called hydrogen flammable air.
Henry Cavendish
Antoine Lavoisier
The name Hydrogen was given by
Antoine Laurent Lavoisier (1743-1794), French
chemist, who disproved the phlogiston theory by
determining the role of oxygen in combustion, and
organized the classification of compounds.
Excerpted from American Heritage Dictionary
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CACHET WORKSHOP
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"Energy" Economy
The enormous amount of energy available in the
last centuries has been a key factor for the
mankind evolution and its technological progress.
World Energy Consumption vs GrossDomesticProduct
1971-1997, WEO 2000
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Fossil fuels as Energy sources
Fossil fuels have powered the societal
development and the improvement of standard of
living
This central role of fossil fuels is foreseen to
be kept for the next decades.
World Energy Consumption by Fuel Type
World Energy Consumption
Source International Energy Outlook, May 2004,
EIA - DOE
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Damages on the Environment
However, in the last decades, large use of fossil
fuels has been associated with health damages and
ecosystem modification and there is a growing
consciousness that the uncontrolled use of energy
is mining a sustainable development approach to
mankinds future.

• Regional impact (direct effects on population and
  surroundings)
• Air pollution in big cities
• Health damages
• Acid rains

Cleaner fuels - cleaner combustion

• Global impact (long range effects)
• Greenhouse gas accumulation
• Climate perturbations
• CO2 is unavoidable!

CO2 mitigation policy
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Tie-beam of CO2 emissions
CO2 Emissions people x GDP/person x
energy/GDP x CO2/ unit energy
population
standard of living
energy intensity
carbon intensity
(Kaya Identity)
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mitigation options to reduce CO2 emissions

• The more realistic Solutions are Based on
• market opportunities and economic driving force

Some examples

• Creating new products (hybrid engines)

• New construction standards to improve energy
  efficiency of new buildings

• Carbon Capture and Sequestration (CCS)
  technologies

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CCS technologies
commercially available technologies for CO2
capturing are very expensive.
Several international programs, sponsored by
private companies and public administrations, are
underway for identifying new and more economical
technologies for capturing CO2. Two examples
are CCP - CO2 Capture Project CCPC - Canadian
Clean Power Coalition
CO2 permanent confinement still requires
international large efforts for a safe and
worldwide accepted solution
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Trends in CO2 emissions and mitigation options
CCS technologies
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Trends in CO2 emissions and mitigation options
CCS technology
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Trends in CO2 emissions and mitigation options
CCS technology
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mitigation options to reduce CO2 emissions

• The more realistic are Solution Based on
• market opportunities and economic diving force

Some examples

• Creating new products (hybrid engines)

• New construction standards to improve energy
  efficiency of new buildings

• Carbon Capture and Storage technologies

• Rapid development and deployment of new pre or
  post combustion fuels decarbonization
  technologies (PCDC) cost effective vs conventional

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Trends in CO2 emissions and mitigation options
CO2 (CCS)
NOx (SCR)
Hg (AC)
SOx (FGD)
PM2.5 (EPS)
Conventional technologies are competitive ( 1,3
per Kw capital cost) but excluding CCS - Hg
treatment - EPS
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Trends in CO2 emissions and mitigation options
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Trends in CO2 emissions and mitigation options
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Trends in CO2 emissions and mitigation options
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Trends in CO2 emissions and mitigation options
POST-COMBUSTION DECARBONIZATION technology
direct combustion of fuels with CO2 capture
without H2 extraction
15 CO2
Coal fired traditional and supercritical
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Trends in CO2 emissions and mitigation options
POST-COMBUSTION DECARBONIZATION To enahnce CO2
concentration in the flue gas
CLC
OXYFUELLING
ASU 100Mw on 500mw total
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Trends in CO2 emissions and mitigation options
POST-COMBUSTION DECARBONIZATION To enhance CO2
concentration in the flue gas
CLC
OXYFUELLING
ASU 100Mw on 500mw total
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Trends in CO2 emissions and mitigation options
PRE-COMBUSTION DECARBONIZATION via syn-gas
(need precess integration to enhance CO2
concentration and capture)
ATR/CPO (O2TM)
IMR (H2TM)
SER (adsorbants)
SEWG (adsorbants)
IMWGS
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Trends in CO2 emissions and mitigation options
PRE-COMBUSTION DECARBONIZATION redox
approach (no need precess integration to enhance
concentration and CO2 capture )
One-Step-Decarbonization A new direct route to
Hydrogen without producing intermediate syn-gas
and down stream treatments
Steam HC air
CO2
One Step H2
H2
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The RedOx general concept Hydrogen production
via Water Splitting
The oxygen carrier captures O2 from water, and H2
becomes the product
The oxygen carrier is restored releasing the
captured lattice oxygen, to an hydrocarbon
The overall reaction is
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Energy Balance
Independently from the RedOx oxygen carrier the
overall reaction remains endothermic.
Heat has to be supplied to the system by burning
part of the available fuels CH4 or H2
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The RedOx Route
In order to design a continuous RedOx process and
establish a cycle on the solid we have initially
chosen a two vessel Circulating Fluidized Bed
reactor configuration.
This choice allows to separate physically the
vessels where the H2 and where CO2 are generated.
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The constrains

• If the process is run in effective conditions
  (high oxygen conversion in the fuel reactor)
• are possible
• The partial oxydation of the fuel so the
  presence of H2/CO in the combustion gas products
• coke deposition on the solid

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The key issue of the PCDC OSD technology is the
solid oxygen carrier
It is able to convert quantitatively the NG with
negligible syn gas coke formation running the
fuel reactor at high oxygen conversion with
practical residence time
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Selection of the oxygen carrier some exclusions
EXP TD
The experimental route
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OneStep DeCO2 Reaction Network 3 oxidation
states 3 vessel loop
Conceptual reactor design based on circulating
fluidized beds
Global reaction becomes thermo-neutral
R H2/CH4 2,66 h 72
wuestite
Chemical cycle
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Iron oxides system reactivity three oxidation
states

• Fe2O3 1/12 CH4 2/3 Fe3O4 1/12 CO2 1/6 H2O
• Fe3O4 CH4 ? 3 FeO CO 2H2
• FeO CH4 ? Fe CO 2H2
• Fe2O3 1/3 CO 2/3 Fe3O4 1/3 CO2
• Fe3O4 CO ? 3 FeO CO2
• FeO CO ? Fe CO2
• Fe2O3 1/3 H2 2/3 Fe3O4 1/3 H2O
• Fe3O4 H2 ? 3 FeO H2O
• FeO H2 ? Fe H2O
• CH4 (Fe) ? (Fe)CX 2H2
• Fe H2O ? FeO H2
• 3 FeO H2O ? Fe3O4 H2
• Fe 1/2 O2 ? FeO
• 3 FeO 0.5 O2 ? Fe3O4
• 2 Fe3O4 0.5 O2 ? 3 Fe2O3

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Highlights on experimental results
Thermodynamic model R2 fuel reactor
thermodynamic involved from the reduction couple
Fe3O4? FeO and its reduction gaseus products
gas phase equilibrium composition
among 800 and 850C the CO2 selectivity approach
the maxim value (80 on ? Cox) The presence of
Fe2O3 allow to obtain the 100 selectivity to CO2
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Highlights on experimental results
Thermodynamic model R1 steam reactor
thermodynamic involved from the water splitting
couple FeO ? Fe3O4 and its gaseus oxidation
product
Log K
Log K
DG
DG
FeO
Target Conv. H2O gt 50
Fe0,947O
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Highlights on experimental results
Thermodynamic model R1 steam reactor
Water Splitting thermodynamic conversion
profile of R1
?
?
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Highlights on experimental resultsKinetic model-
R2 fuel reactor
NG
CO CO2 H2 H2O

• Macroscopic model
• Shrinking core model

Microscopic level oxides reduction Kinetic Fe2O3
? Fe3O4 very fast CO2 H2O Fe3O4 ? FeO
slow CO/CO2/H2/H2O

• NG/steam Absorption

• NG/steam Diffusion

• Oxides reduction/oxidation kinetics

• Products Desorption

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Iron oxide The reaction network
CH4 full combustion to CO2
oxid. to CO/CO2
Thermobalance
H2 prevailing
The reactivity profile can vary upon solid
composition
H2O-Ox
FeO
Fe3O4
Fe2O3
carbides
Fe
hematite
wuestite
magnetite
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Some considerations on the chemistry

• R1 - Oxydation of Fe/FeO with steam to Fe3O4 with
  H2 formation is under thermodynamic control.
• R1- Oxidation beyond Fe3O4 cannot be made with
  steam, requires molecular O2 (air)
• R2 - Quantitative Reduction with NG is critical
  because consecutive/competitive equilibrium
  reactions on Fe3O4 and FeO lead to the syn-gas
  formation
• R2 - the an excessive reduction can lead to
  metallic iron favouring FeCx and Coke which than
  arriving in R1 and could affect H2 purity
• R2 - Reduction rate of Fe3O4 is the process rate
  determing process step.
• R3 - Partial Super-oxidation to Fe2O3 is a very
  fast reaction and is controlled by the amount of
  oxygen available

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Material Preparation
Batchwise sprinkle impregnations
Spray drying
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Technology Comparison with the B.A.T.
OS_DE-CO2 fields of potential applications
Medium-Large scale plants The fluidized bed
system is expected to take advantage from the
economy of scale. Preliminar evaluations have
been performed for large scale plants (100,000
Nm3H2/h).
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Preliminary comparison with SMR

• Steam Reforming (without CO2 removal), ?
  73-76
• Energy penalty with 90 CO2 removal gt13 (? ?
  63)
• One-Step-Decarbonization, ? 72 with current
  process data, with 100 CO2 removal

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Conclusions

• A new process for H2 production is under
  development
• Centralized production
• CO2 ready to be confined
• Integration with out-of-fence NGCC options
• Use of pure hydrogen in FC applications
• Technical difficulties are really challenging
• One-Step-Decarbonization technology to be placed
  in a "Hydrogen Economy" and CO2 management era

Nevertheless
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a prudent general consideration is advisable pay
attention with your innovation !!
Do not sell unattainable dreams !
Lavoisier, the hydrogen father, was executed
during the Reign of Terror.
Thanks for your attention