recent advances in direect coal liquefaction
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RECENT ADVANCES IN DIREECT COAL LIQUEFACTION
Presented by:
Muhammad Naqi Shah
Roll No: CH-22/2010-2011
RECENT ADVANCES IN DIREECT COAL LIQUEFACTION
Presentation includesIntroductionCoal & its ClassificationInfluencing factors for DCLEffects of coal pre-treatment on DCLMulti-stage DCL processDCL catalystConclusion
INTRODUCTION
Importance of coal liquefactionRapid increase in petroleum demand
Declining reserves of petroleum oils
Processes of coal liquefactionIndirect Coal Liquefaction (ICL)
Direct Coal Liquefaction (DCL)
Direct Coal Liquefaction (DCL)
coal+solvent+catalyst+hydrogen gas
450-500 C under 15-30 MPa
Table.1 Summary of major DCL process developed around the world
CountryProcess
Reactor Catalyst
Capacity (t/d) Year
SRC-I Coal slurry dissolver — 6 1974
SRC-II Coal slurry dissolver — 50/25 1974-1981
USA
EDS Entrained bed Ni/Moc 250 1979-1983
H-Coal Fluidized bed Co-Mo/Al2O3 600 1979-1982
CTSL Fluidized bed Ni/Mo 2 1985-1992
HTI Suspended bed GelCatTM 3 1990s
IGOR Fixed bed
Red- muda,
200 1981-1987b
Germany Ni-Mo/Al2O3
PYROSOL Counter-current — 6 1977-1988
BCL Fixed bedb
Fe-baseda,
50 1986-1990b
Japan Ni-Mo/Al2O3
NEDOL Fluidized bed Nature pyrite 150 1996-1998
UK LSE
Stirred tank-typea,
— 2.5 1983-1995
fluidized bedb
USSR CT-5 — Mo 7 1986-1990
China
Shenhua I Suspended bed Fe-based 6 2002-
Shenhua II Suspended bed Fe-based 3,000 2004-
a First-stage; b Second-stage; c Recycled solvent catalytic hydrogenation
Table.2 . The operating parameters and
experiment results of some major DCL processes.
Process HTI IGOR NEDOL Shenhua
Coal Shenhua Xianfeng lignite Shenhua Shenhua
Temperature ( °C) 440~450 470 465 455
Pressure (MPa) 17 30 18 19
Space velocity (t/m3/h) 0.24 0.60 0.36 0.70
Conversion (%,daf coal) 93.5 97.5 89.7 91.7
C4+oils (%, daf coal) 67.2 58.6 52.8 61.4
Residues (%, daf coal)a 13.4 11.7 28.1 14.7
Hydrogen consumption (% daf coal) 8.7 11.2 6.1 5.5
a Including ash, spent catalyst and un-converted coal
COAL AND ITS CLASSIFICATION
Rank of the coalPeat lignite sub-bituminous anthracite bituminous
Constitutes of coalI. Fixed carbon
II. volatile carbon
III. other constitutes
COAL LIQUEFACTION CATALYSIS
Self catalysis Mineral present in coal (pyrite)
Catalyst usedHeterogeneous catalyst are used so that, separation product from catalyst is simple
Porous structure of catalyst
INFLUENCING FACTORS FOR DCL
Temperature: Cracking of coal at elevated temperature Enhance free radical formation Enhance free radical reaction Influencing temperature range is 350-
800 C
Solvent: To stabilize the free radicals by donating
hydrogen Promote the cracking of coal macromolecules
Continued…
Facilitate the heat and mass transfer for coal liquefaction reaction
Classification : specific, non-specific, degrading, reactive
Used solvent: tetra line, tetrahydrofluoranthene (4HFL)
Continued..
Pressure & atmosphere High pressure beneficial as: keep the
solvent and products in liquid phase prevent coke build up on reactor wall and catalyst surface
Range 15-30 MPa Preferred atmospheric are nitrogen (N2)
and hydrogen (H2)
EFFECTS OF COAL PRE-TREATMENT ON DCL
Swelling treatment Enhance coal priority Improve the dispersion of catalyst onto the coal
structure Pre-swollen in tetra line for 4 hr at temperature
from room temp to 160 C
Thermal & hydro-thermal treatment Thermal treatment under drying in not
beneficial Thermal treatment under vacuum and steam is
beneficial
Continued…
Treatment in hot compressed water (hydro-thermal) is also beneficial
Multistage DCL process Multigas (mostly two stages) process is
beneficial Higher conversion and higher oil yield 15 MPa, 10 wt% Fe-10 wt% Ni 380 C for 15 min in 1st stage 450 C for 105 min in 2nd stage
DCL CATALYST
Catalyst typesIron based, Co, Mo, Rn etc
Loading amount, the preparation method, dispersion state, solvents, coal-containing minerals
CONCLUSION
Overall, although many commercialized processes have been developed in the U.S, Europe, Japan and china, the optimization of the operating conditions for these DCL processes is still the focus for many studies
In addition to the common Fe based catalyst, Mo,Co and Ru as well as SO42-/MxOy, solid acids were also demonstrated effective for DCL
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