Coal can be converted to liquid fuels either by
removal of carbon or addition of hydrogen.
The first approach is known as carbonization,
and the second is known as liquefaction.
The major objective of coal liquefaction is to
produce synthetic oil to supplement the
natural sources of petroleum.
Coal liquefaction is the conversion of coal into a
synthetic oil in order to supplement natural
sources of petroleum.
It is an attractive technology because
1) It is well developed and thus could be
implemented fairly rapidly and
2) There are relatively large quantities of coal
3. Stable supplies of coal, however, are readily
available worldwide, and the known
resources of minable coal are four times that
Hence, technology is required to make fossil
energy consumption efficient and
A bit of something………
Coal liquefaction offers promise for nations that are
rich in coal, yet scarce in oil.
There are four plants in the United States and South
Africa currently using coal as feedstock to create
A plant using more than 6 million tons of coal
annually could produce more than 3.6 million barrels
of Diesel and Naptha annually, making diesel
liquefaction competitive at $35 to $40 per barrel oil
China has earmarked $15 billion for coal-to-
diesel-fuel conversion plants and has
targeted replacing 10 percent of its oil
imports with coal-liquified oil by 2013.
Coal liquefaction can be accomplished either directly
The difference between these two different types of
coal liquefaction lies in that
1. Indirect coal liquefaction needs to go through
2. while direct coal liquefaction involves making a
partially refined synthetic crude oil from coal.
It is widely believed that indirect liquefaction is more
efficient than direct coal liquefaction techniques
1. A single-stage direct liquefaction process
produces distillates via one primary reactor or
a train of reactors in series.
2. A two-stage direct liquefaction process is
designed to produce distillates via two
reactors or reactor trains in series.
The primary function of the first stage is coal
dissolution and is operated either without a
catalyst or with only a low-activity disposable
The heavy coal liquids produced in this way
are hydro treated in the second stage with a
high-activity catalyst to produce additional
Indirect liquefaction involves two steps.
The first step is the complete breakdown of the
coal structure by gasification.
The composition of the gasification products is a
mixture of H 2 and CO referred to as syngas.
Sulfur-containing compounds are also removed
in this step.
The resulting gasification products are
reacted in the presence of a catalyst at
relatively low pressure and temperature.
The synthetic liquid products include
paraffin's, olefin hydrocarbons or alcohols
(particularly methanol), depending on the
catalyst selected and the reaction conditions
Types of Processes
Alternatively, coal can be converted into a
gas first, and then into a liquid, by using the
1. Fischer-Tropsch process
2. Bergius process
3. Low Temperature Carbonization (LTC)
The Bergius Process is a method of
production of liquid hydrocarbons for use as
synthetic fuel by hydrogenation of high-
volatile bituminous coal at high temperature
It was first developed by Friedrich Bergius in
This process was used by Germany during
World War I and World War II and has been
explored by SASOL in South Africa.
Several other by GULF oil:-
2. and SRC-II (Solvent Refined Coal)
The coal is finely ground and dried in a stream of
The dry product is mixed with heavy oil recycled
from the process along with the catalyst like
tungsten or molybdenum sulfides, tin or nickel
The mixture is pumped into a reactor. The reaction
occurs at between 400 to 500 °C and 20 to 70 MPa
hydrogen pressure. The reaction produces heavy
oils, middle oils, gasoline, and gases.
Fischer-Tropsch Process (FTP)
It is an indirect route, coal is first gasified to make
Next, Fischer-Tropsch catalysts are used to convert
the syngas into light hydrocarbons (like ethane) which
are further processed into gasoline and diesel.
This method was used on a large technical scale in
Germany between 1934 and 1945 and is currently
being used by Sasol in South Africa.
In addition to creating gasoline, syngas can also be
converted into methanol, which can be used as a fuel,
or into a fuel additive.
Low Temperature Carbonization (LTC)
This also convert coal into a liquid fuel.
Coal is coked at temperatures between 450 and 700°C
compared to 800 to 1000°C for metallurgical coke.
These temperatures optimize the production of coal
tars richer in lighter hydrocarbons than normal coal
tar. The coal tar is then further processed into fuels.
This process was developed by Lewis C. Karrick, an oil
shale technologist at the U.S. Bureau of Mines in the
Significance of Coal Liquefaction
Coal liquefaction can significantly improve
national and economic security by lessening
dependence on foreign oil and substituting
plentiful, more affordable coal.
can be used in current engines, leading to
reduction in all regulated emissions
provides a fuel platform for development of
new generation compression ignition engines
Ideal hydrocarbon fuel for fuel cells
1. Coal liquefaction is a more secure way to
produce liquid fuels that can help the U.S.
decrease reliance on oil imports.
•According to a recent forecast by the EIA, liquid
fuels from coal will account for about 3% of the
total U.S. supply of petroleum products by 2030
China began developing coal-to-liquid fuel
technologies in the 1980s.
The coal liquefaction project was given strategic
significance in the mid-1990s, after China became
a net oil importer in 1993.
In 1999, China launched its first coal-to-liquid
project in Pingdingshan, Central China's Henan
In 2001, a high-tech research project, the 863
Programme, picked up the pace on coal-to-liquid
Shenhua Group took the lead in the process in August 2004.
The project is designed to have an annual capacity of 5million
The first, designed to produce 3.2 million tons of oil products,
is scheduled for production by 2007.
The second phase is scheduled for production by 2010, with a
designed annual production capacity of 2.8 million tons.
In February 2006, a coal liquefaction project with a designed
initial annual capacity of 160,000 tons was launched by Lu'an
Group in Tunliu, Shanxi Province.
Two months later, Yankuang Group initiated a huge two-
phase coal liquefaction project in Yulin. The project is expected
to reach an annual output of 10 million tons of oil products by
Syntroleum Corporation and Linc Energy are
planning to develop a coal-to-liquids (CTL) project in
Australia that integrates Fischer-Tropsch technology
with Linc Energy’s underground coal gasification
This will be the first such project to combine the two
technologies for the production of synthetic diesel
The CTL work will be part of Linc Energy’s ongoing
Chinchilla Project (350 km west of Brisbane) which
also includes early development of an integrated
Sasol currently supplies about 28% of South Africa’s fuel needs
from coal, saving the country more than R29 billion (US5,1
billion) a year in foreign exchange.
The South Africa’s petrochemicals giant is promoting its
ambitious Coal to Liquid transportation fuel technology in
India that boasts of 248 billion tonnes of coal reserves .
Observing that a CTL plant could produce 500-1000 MW of
export electricity depending on the configuration, he said five
such plants could replace 20% of India’s fuel imports by 2020.
A CTL plant having a capacity of three million tonne per
annum could offer a clean diesel production of 68%, Naphtha
production of 30% and LPG 2%
Current and Potential Future CTL Worldwide
GTL Qatar: 800,000 BPD (Shell, Sasol,
ConocoPhillips, ExxonMobil, Marathon)
Other GTL Worldwide: 480,000 BPD (includes
plants and proposed plants in Iran, Russia, Australia,
CTL Sasol South Africa 150,000 BPD
CTL Sasol Potential Plants in China 160,000 BPD
Bench & pilot facilities at Rentech, Syntroleum, and
OIL carried out in-depth studies regarding
conversion of various shales and coals from NE
India into liquid fuel and found that the high
sulfur, low ash bituminous coal of NE India is
quite amenable for liquefaction
OIL had embarked on coal liquefaction project
based on HRI’s Coal oil co-processing
technology and set up a 25 Kg/day pilot plant
in Duliajan, Assam.
OIL’s Coal liquefaction Pilot Plant
Pilot plant in collaboration with HRI, USA
Coal processing capacity of the plant - 25 kg/day
Plant is equipped with ebullated bed reactor,
high pressure pumps
Highly sophisticated - process monitoring,
control and data
acquisition with the help of PLC based control
Plant commissioned in March 1999
Total cost of the project - Rs. 15 crores
Why Coal to Liquid
– Size of coal resources
– Distribution of resources
– Utilization of clean coal technology
– Sequestration technology expected
– Advanced technology
– Co-production capability
– Competitive with alternatives
– World oil price volatility
Barriers to Coal-To-Liquids
– Integrated operations of advanced CTL technologies have never been
– Uncertainties about future world oil production
– High capital and operations costs
– Investment risks
– Energy price volatility
– CO2 and criteria pollutant emissions
– Expansion of coal production and requisite infrastructure (railroads, railcars,
– Water use
Barriers to Coal-To-Liquids
– Competition for critical process equipment, engineering,
and skilled labour
– Who would take the lead in commercial deployment? Part
power part liquid fuels
–public resistance to coal use
Many complex energy challenges face America over the
next several decades
Coal can play key role in ways that go beyond power
Technologies exist to use coal as feedstock for production of
liquid fuels, chemicals, and hydrogen
Successful demonstrations of advanced technologies could
lead to a new generation of coal plants that coproduce
power, liquid fuels, chemicals, and/or hydrogen while
capturing and sequestering carbon dioxide