Coal-to-liquid

During the late seventies and early eighties, when oil prices rose after the 1973 war, extensive research was done to change coal to liquid hydrocarbons. However, coal-derived hydrocarbons were more expensive than crude oils. Another way to use coal is through gasification to a fuel gas mixture of CO and H2 (medium Btu gas). This gas mixture could be used as a fuel or as a synthesis gas mixture for the production of fuels and chemicals via a Fischer Tropsch synthesis route. This process is... 

The overall conversion of coal to liquid and gaseous products was obtained from the formula ... 

For the study of catalyst concentration tin as stannous chloride was used as the catalyst and the concentration range studied was 0 - 15% by weight of the coal. Stannous chloride is one of the best, if not the best, catalyst for conversion of coal to liquid products. For the study of the effect of the reactor temperature, the temperature range studied was from 400 - 700°C. 

The conversion of coal to liquid fuels is usually carried out in the presence of an H-donor solvent (H-don) such as Tetralin. 

Coal is the main energy reserve for many countries. In order to ensure energy security, many of these countries are looking at implementing large-scale coal-to-liquid (CTL) plants. Current CTL Fischer-Tropsch (FT)-based processes at best have a carbon efficiency near 45% that is, less than half the carbon that is fed to the process ends up as hydrocarbon fuels. This has large implications for the environment, in that more than half of the carbon in the feed to the CTL ends up... 

The overall coal-to-liquid fuels process can be described as follows ... 

Conversion from coal to natural gas. Sasol 1 was designed as a coal-to-liquids facility. A natural gas pipeline was constructed and commissioned in 2004. This allowed the Sasol 1 facility to be converted to a gas-to-liquids plant. Although it implied that the associated coal tar refinery would become redundant, the decision was made by Sasol to keep the coal-to-chemicals units at Sasol 1 in operation by supplying coal pyrolysis products from its larger CTL facility in Secunda. 

COP cP CRW CSM CTL Conference of the Parties centipoise Combustibles, renewables and waste Coal-seam methane Coal-to-liquids... 

Moving to the transport sector, Fig. 15.1 quantifies the continued oil stress of the transportation sector. Even when a rather aggressive development of biofuels is included, the transportation demand for oil does not go down. This underlines that in all likelihood the energy security issue is as much a long-term issue as the climate change issue. It induces a strong motivation around the world to develop non oil-based transportation fuels, even in the absence of CO2 emission concerns. Current investments in the area of Gas-to-Liquids (GTL) and plans for Coal-to-Liquids (CTL) attest to this [7]. 

Three types of direct coal liquefaction processes have emerged to convert coals to liquid hydrocarbon fuels 8... 

The development of the liquifaction of coal has lagged and when taken together with the advantages of handling, transporting, and higher conversion efficiency, the incentive to perform additional work in converting coal to liquid products becomes apparent. 

Amestica and Wolf (12) in a study closely related to the one described herein, measured the conversion of Illinois No. 6 coal in toluene and ethanol. Their results clearly showed that conversions increased with temperature and solvent density but were not detailed enough to show the time dependence of the conversion. However, a result important to this study was that toluene converts coal to liquids without significantly reacting itself. After reaction, 98% of the toluene used was recovered versus only 73 -85% of the ethanol in runs using it. Ethanol is a hydrogen donor and reacts extensively with the coal. While toluene probably reacts with coal to a small extent, its effect was primarily physical in nature. As such, it is a good candidate for studying the effects of a supercritical solvent on coal liquefaction kinetics since the enhancement effect of supercritical conditions is physical in nature. 

The maximum conversion of coal to liquid products has been the primary objective of most work on supercritical extraction of coal reported in the literature. A 1975 article by Whitehead (1), one of the first references to supercritical coal extraction, presented data on supercritical extraction of coal by coal tar or petroleum... 

The major objective of that study was also maximum conversion of coal to liquid products reduction of sulfur in the unconverted solid was not reported. 

Early developments for producing liquid fuel from coal which can be found in many countries took place in the 1840s in Germany and England. They were the first steps of the petrochemical industry. These processes produced kerosene to fuel German airplanes during World War II and supplied up to 90% of the demand in liquid fuels at that time. Sasol s plants in the Republic of South Africa are the only industrial coal-to-liquid production capability that remains today with an annual production of 7.5 M tonnes of liquid fuels (gas oil, kerosene) and chemical products. 

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