Coal liquefaction
[2] The best-known CTL process is Fischer–Tropsch synthesis (FT), named after the inventors Franz Fischer and Hans Tropsch from the Kaiser Wilhelm Institute in the 1920s.
Friedrich Bergius, also a German chemist, invented direct coal liquefaction (DCL) as a way to convert lignite into synthetic oil in 1913.
[6] Although it was generally much more expensive to produce oil from coal than from natural petroleum, the political as well as economic importance of achieving as much independence as possible in this sphere was sufficient to overcome any objections.
Early attempts to attract private capital, foreign or domestic, were unsuccessful, and it was only with state support that the coal liquefaction could start.
CTL continued to play a vital part in South Africa's national economy, providing around 30% of its domestic fuel demand.
The democratization of South Africa in the 1990s made Sasol search for products that could prove more competitive in the global marketplace; as of the new millennium the company was focusing primarily on its petrochemical business, as well as on efforts to convert natural gas into crude oil (GTL) using its expertise in Fischer–Tropsch synthesis.
[7] Indirect liquefaction processes generally involve gasification of coal to a mixture of carbon monoxide and hydrogen, often known as synthesis gas or simply syngas.
[9] Since liquid hydrocarbons generally have a higher hydrogen-carbon molar ratio than coals, either hydrogenation or carbon-rejection processes must be employed in both ICL and DCL technologies.
[citation needed] At industrial scales (i.e. thousands of barrels/day) a coal liquefaction plant typically requires multibillion-dollar capital investments.
It produces condensable coal tar, oil and water vapor, non-condensable synthetic gas, and a solid residue - char.
[14] H-Coal process, developed by Hydrocarbon Research, Inc., in 1963, mixes pulverized coal with recycled liquids, hydrogen and catalyst in the ebullated bed reactor.
[11] The SRC-I and SRC-II (Solvent Refined Coal) processes were developed by Gulf Oil and implemented as pilot plants in the United States in the 1960s and 1970s.
[14] Shenhua, a Chinese coal mining company, decided in 2002 to build a direct liquefaction plant in Erdos, Inner Mongolia (Erdos CTL), with barrel capacity of 20 thousand barrels per day (3.2×10^3 m3/d) of liquid products including diesel oil, liquefied petroleum gas (LPG) and naphtha (petroleum ether).
Based on this methanol synthesis, China has also developed a strong coal-to-chemicals industry, with outputs such as olefins, MEG, DME and aromatics.
The Great Plains Gasification Plant in Beulah, North Dakota is a coal-to-SNG facility producing 160 million cubic feet per day of SNG, and has been in operation since 1984.
[22] High water consumption in the water-gas shift reaction or steam methane reforming is another adverse environmental effect.
Also, legislation in the United States has restricted the military's use of alternative liquid fuels to only those demonstrated to have life-cycle GHG emissions less than or equal to those of their conventional petroleum-based equivalent, as required by Section 526 of the Energy Independence and Security Act (EISA) of 2007.
A number of avenues of research & development will need to be pursued, including: Since 2014, the U.S. Department of Energy and the Department of Defense have been collaborating on supporting new research and development in the area of coal liquefaction to produce military-specification liquid fuels, with an emphasis on jet fuel, which would be both cost-effective and in accordance with EISA Section 526.
Every year, a researcher or developer in coal conversion is rewarded by the industry in receiving the World Carbon To X Award.
The 2016 Award recipient is Mr. Jona Pillay, executive director for Gasification & CTL, Jindal Steel & Power Ltd (India).
The 2017 Award recipient is Dr. Yao Min, Deputy General Manager of Shenhua Ningxia Coal Group (China).
