COAL-LIQUEFACTION IN PRIMARY ALIPHATIC AMINE SYSTEMS

The objective of this research is to investigate the lignite and coal liquefaction characteristics in primary aliphatic amines. Selection of low molecular weight primary aliphatic amines allowed liquefaction to be performed below 300 °C and 500 psi with near complete conversion of the organics present in lignite. Dissolution of higher rank coals requires higher severity. A series of aliphatic amines up to 12 carbons was tested under various conditions, and their products were selectively characterized. Primary aliphatic amines were found to be more effective solvents than tetralin and nitrogen heterocycles in terms of product distillability and total gas yield. However, the effectiveness is at the expense of a large amount of amine chemically incorporated into the products. The addition of hydrogen and/or tetralin to the amine solvent system enhanced the liquefaction rate and conversion in the early stage of the reaction. The synergistic effects decrease and completely disappear in the later stage of the reaction. In addition to aminolysis, evidence of ether cleavage, hydrogenolysis, and hydrolysis is discussed. Solvent consumption is found to be unpractically high, but a large portion of it is due to the secondary reactions between coal-derived liquids and amine. Further, addition of water appears to reduce amine consumption at 230 °C. © 1990, American Chemical Society. All rights reserved.