LOW SEVERITY COAL CONVERSION BY AN ELECTROREDUCTION ROUTE

The feasibility of electrochemical conversion of coal to low molecular weight hydrocarbons through an electroreduction route was demonstrated for the first time by Energy Research Corporation. This electroreduction process involves reaction of hydrogen ions with the coal surface leading to hydrogenation of coal molecules at low severity operating conditions. This process produced lower molecular weight hydrocarbons, similar to those obtained in conventional liquefaction by chemical reaction. In this proof-of-concept study, at low severity conditions (101 kPa and 250-degrees-C), the electroreduction behaviour of five coals as well as a charcoal and a devolatilized coal was investigated. The liquid product compositions (at room temperature) were dependent upon the parent coal and comprised a variety of aliphatic and aromatic compounds with phenolic aromatic compounds predominating. These compounds were found to fall in a low (100-400) molecular weight range which corresponds to oils (< 400). The effects of the process variables were also investigated. Coal type was found to be the most important parameter affecting the product spectrum. The volatile components in the coal appeared to play an important role in controlling electroreduction products. No clear-cut relationship was established between temperature, volatile contents, structural origin (maceral composition), or applied potential and product quantity or composition.