INVESTIGATION OF FIRST-STAGE LIQUEFACTION OF COAL WITH MODEL PLASTIC WASTE MIXTURES

A series of liquefaction tests have been conducted using coal, polyeth ylene (PE), polypropylene (PP), polystyrene (PS), and polyethylene ter ephthalate (PET), in various combinations and proportions. These tests were done in batch microautoclaves, 1-L semibatch reactors, and a sma ll-scale continuous unit. Results on individual plastics showed that P E and PP were converted primarily into aliphatic hydrocarbons, PS into alkyl benzenes, and PET into benzenes, ethane, and carbon dioxide. PE was by far the most difficult of the model plastics to convert. In tw o-component and multicomponent tests, tetrahydrofuran (THF) conversion s could be estimated from the behavior of the individual components un der similar conditions. Results were highly sensitive to conditions, e specially those of atmosphere and temperature. Higher conversions coul d be obtained with higher temperatures, provided that retrograde react ions that re-polymerize the products were minimized. Retrograde reacti ons could be suppressed via the use of a synthesis gas atmosphere and/ or the absence of added solvent. Acidic catalysts, such as molecular s ieves, also led to higher conversions, but only in systems where coal was absent.