Coal conversion chemical

Coal Conversion Chemical Reaction Steam Conversion... 

Coal is used ia industry both as a fuel and ia much lower volume as a source of chemicals. In this respect it is like petroleum and natural gas whose consumption also is heavily dominated by fuel use. Coal was once the principal feedstock for chemical production, but ia the 1950s it became more economical to obtain most industrial chemicals from petroleum and gas. Nevertheless, certain chemicals continue to be obtained from coal by traditional routes, and an interest in coal-based chemicals has been maintained in academic and industrial research laboratories. Much of the recent activity in coal conversion has been focused on production of synthetic fuels, but significant progress also has been made on use of coal as a chemical feedstock (see Coal CONVERSION processes). 

The term feedstock in this article refers not only to coal, but also to products and coproducts of coal conversion processes used to meet the raw material needs of the chemical industry. This definition distinguishes between use of coal-derived products for fuels and for chemicals, but this distinction is somewhat arbitrary because the products involved in fuel and chemical appHcations are often identical or related by simple transformations. For example, methanol has been widely promoted and used as a component of motor fuel, but it is also used heavily in the chemical industry. Frequendy, some or all of the chemical products of a coal conversion process are not isolated but used as process fuel. This practice is common in the many coke plants that are now burning coal tar and naphtha in the ovens. 

Imperial Chemical Industries (ICI) operated a coal hydrogenation plant at a pressure of 20 MPa (2900 psi) and a temperature of 400—500°C to produce Hquid hydrocarbon fuel from 1935 to the outbreak of World War II. As many as 12 such plants operated in Germany during World War II to make the country less dependent on petroleum from natural sources but the process was discontinued when hostihties ceased (see Coal conversion PROCESSES,liquefaction). Currentiy the Fisher-Tropsch process is being used at the Sasol plants in South Africa to convert synthesis gas into largely ahphatic hydrocarbons at 10—20 MPa and about 400°C to supply 70% of the fuel needed for transportation. 

Gasification. Gasification converts soHd fuel, tars, and oils to gaseous products such as CO, H2, and CH that can be burned direcdy or used in synthesis gas (syngas) mixtures, ie, CO and mixtures for production of Hquid fuels and other chemicals (47,48) (see Coal conversion processes, gasification Euels, synthetic-gaseous fuel Hydrogen). 

C -Chemisty. A great deal of research has been undertaken on the development of PGM catalysts for the manufacture of chemicals and fuels from syngas, a mixture of CO and H2 obtained from coal gasification (see Coal conversion processes). 

Gasification. Gasification of coal is used to provide gaseous fuels by surface and underground appHcations, Hquid fuels by indirect Hquefaction, ie, catalytic conversion of synthesis gas, and chemicals from conversion of synthesis gas. There are also appHcations in steelmaking (see Coal conversion PROCESSES, gasification). 

Source Adapted from Hailong, X., The Shell Coal Gasification Process (SCGP), International Hi-Tech Symposium on Coal Chemical Industry Coal Conversion, Oct. 30-31, Shanghai, China, 2004. 

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. 

Chemical Week 1980, 128, pp 25-27. Rogers and Hill, Coal Conversion Comparisons, pp 69-71 Assessment of Technology for the Liquefaction of Coal, pp 111-15 Gulf Oil Corporation Information Brochure, "Solvent Refined Coal-II Environmental Issues and Protection Measures,"... 

Direct use of coal as a primary fuel is often the most efficient and economic method of utilizing this important energy resource. In many cases, however, certain undesirable properties of coal make direct utilization difficult. Coal is a solid and requires more effort to handle, measure and control than gases or liquids. Coal is usually contaminated with ash and other undesirable components and has widely variable chemical and physical properties. As a result, there is often a need to convert coal into more convenient and cleaner forms of energy and products. Before considering the basic principles of coal conversion, some important characteristics of fossil fuels will be reviewed. 

Heat recovery efficiency is a consideration of major importance in the conversion of coal to secondary fuels. This parameter is defined as the percent of the heating value of the coal used which is recovered as heating value in the desired secondary fuel. Heat recovery efficiency which can be attained in a coal conversion process depends firstly on the theoretical chemical and thermodynamic requirements of the process, and secondly on the practical realization of the process. The first factor determines the theoretical maximum heat recovery efficiency that can be obtained under ideal circumstances. The second factor determines the extent to which the practical process approaches the theoretical ideal. 

Phenol has been detected in the effluent discharges of a variety of industries. It was found in petroleum refinery waste water at concentrations of 33.5 ppm (Pfeffer 1979) and 100 ppb (Paterson et al. 1996), in the treated and untreated effluent from a coal conversion plant at 4 and 4,780 ppm, respectively (Parkhurst et al. 1979), and in shale oil waste water at a maximum of 4.5 ppm (Hawthorne and Sievers 1984). It has also been detected in the effluent from a chemical specialties manufacturing plant at 0.01-0.30 ppm (Jungclaus et al. 1978), in effluent from paper mills at 5-8 ppb (Keith 1976 Paterson et al. 1996), and at 0.3 ppm in a 24-hour composite sample from a plant on the Delaware River, 2 and 4 miles downriver from a sewage treatment plant (Sheldon and Hites 1979). 

The sulfur distribution from the coal conversion plant is shown in Figure 4. The wt% of sulfur remaining in the ash depends on several factors among which are the relative distribution of organic and inorganic sulfur in the coal and the chemical composition of the ash. High alkaline ashes will capture sulfur as sulphide or sulfate. 

Catechol occurs naturally in fruits and vegetables such as onions, apples and crude beet sugar, and in trees such as pine, oak and willow. Catechol may be released to the environment during its manufacture and use. It has been detected at low levels in ambient and urban air, groundwater, drinking-water and soil samples. It has been foimd in wastewaters from coal conversion, coal-tar chemical production and bituminous shale (United States National Library of Medicine, 1997). It is present in cigarette smoke at 100-360 gg per cigarette (lARC, 1986). 

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