From coal to single-stage and two-stage products: A reactive model of coal structure

Using detailed chemical analyses of both coal and products from various liquefaction schemes, molecular models have been constructed to show the steps in the conversion process, and the nature of the products. Products from short- and long-contact time dissolution are shown in relation to structures found in the parent coal. Such molecules are highly functional, high molecular weight materials, which are difficult to process by conventional methods and tend to associate causing product stability problems. In contrast, products from two-stage liquefaction have greatly reduced molecular weight and functionality, and are consequently more amenable to downstream processing. The accurate and quantitative presentation of models reflects the analytical data on the coal and liquefaction products in terms of elemental distribution, aromaticity, functional group chemistry, and reactivity.