Studies of thermal and catalytic hydroliquefaction of model compounds, waste polymers and coal by high pressure TG/GC/MS

A recently developed on-line high pressure thermogravimetry (TG)/gas chromatography (GC)/mass spectrometry (MS) system provides certain advantages over other on-line analysis techniques for high pressure reactors reported previously. The high pressure TG/GC/MS system enables the simulation of solvent-free thermal and catalytic reactions for polymers and coal. During the reactions the total weight change is monitored and the volatile intermediate products are identified. It requires only very small amounts (10-100 mg) of sample and can be operated at high pressure under different atmospheres (N, He, H, etc.). Current efforts to recycle lower grade postconsumer polymers such as colored polyethylene and polystyrene or used rubber tires, are concentrated on co-processing with coal. Purely thermal degradation processes involve both decomposition and condensation (recombination) reactions and the resulting product is highly olefinic and often aromatic. In order to improve the yield and selectivity of the process, a great deal of effort has been spent on finding the proper catalysts. Catalysts selected for the present studies include ZrO{sub 2}/SO{sub 4}{sup =}, (NH{sub 4}),MoS{sub 4} and carbon black. Carbon black present in waste rubber tires has been reported to be very selective for the cleavage of specific alkylaryl bonds. (NH{sub 4}){sub 2}MoS{sub 4} has been shown tomore » improve the liquid yields in coal liquefaction. The superacid catalyst ZrO{sub 2}/SO{sub 4}{sup =} possesses markedly higher hydrogenolytic activity compared to that of conventional SiO{sub 2}-supported soluble Fe salts.« less