Coal liquefaction moderating

Background Indirect coal liquefaction differs fundamentally from direct coal hquefaction in that the coal is first converted to a synthesis gas (a mixture of H9 and CO) which is then converted over a catalyst to the final product. Figure 27-9 presents a simplified process flow diagram for a typical indirect coal hquefaction process. The synthesis gas is produced in a gasifier (see a description of coal gasifiers earlier in this section), where the coal is partially combusted at high temperature and moderate pressure with a mixture of oxygen and steam. In addition to H9 and CO, the raw synthesis gas contains other constituents (such as CO9, H9S, NH3, N9, and CHJ, as well as particulates. 

Coal liquefaction research after the second world war focused on moderating reaction conditions in terms of temperature and pressure in order to lower construction costs of the coal liquefaction facility. At present, typical conditions are 150-200 atm and 300-480°C. Moderation was achieved primarily through improvements in catalysts and donor solvents and through... 

Since the 1970s, coal liquefaction has been extensively studied worldwide to produce petroleum substitutes (Speight, 2008). Major processes are operated under high or moderate hydrogen pressures with significant consumption of this element to depolymerize coal into a product similar to petroleum—it should be noted that the word depolymerize is used incorrectly since coal is not a... 

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