Study On The Degradation Of Polystyrene

Polystyrene is a thermoplastics widely used in many fields due to its excellent properties. With the increasing of amount of polystyrene consumed, more and more polystyrene waste was produced, and is becoming a major environmental concern due to its non-biodegradable nature. Recycling of waste polystyrene has received a great deal of attention in recent years.Thermal degradation and catalytic degradation are accepted as effective methods to deal with waste polystyrene for styrene monomer or other chemical recovery. In this work, the processes of thermal degradation and catalytic degradation of polystyrene were investigated by thermogravimetry-mass spectrum analysis (TG-MS); kinetics of thermal degradation and catalytic degradation of polystyrene were studied by applied Model-Free Kinetics (MFK); catalytic degradation of polystyrene in supercritical toluene was performed which combined catalytic degradation and supercritical fluid technology.The results show that the thermal degradation process of polystyrene initiates from chain end scission, and styrene dimer is the residual of degradation of polystyrene; Different catalysts have different catalytic activity on the degradation process of polystyrene, among which barium oxide is the best.The activation energy of thermal degradation and catalytic degradation process of polystyrene were 210-250kJ/mol and 200-202kJ/mol, respectively. The activation energy of polystyrene degradation decreased in the presence of BaO, especially on the initiation period of degradation .Catalytic degradation of polystyrene in supercritical toluene and n-hexane using barium oxide were carried out. The results show that toluene is better. The effect of reaction temperature and the ratio of the feed on the conversion of polystyrene, the yield of styrene and the distribution of product were also discussed in this paper. The results show that the conversion of polystyrene increases with reaction temperature. The yield of styrene keeps constant in 340-360℃, and decreases significantly at 380℃. The selectivity of diphenyl-propane increases with temperature, and the selectivity of trimer decreases with temperature. The ratio of the feed have different effects on the yield of styrene at different reaction periods.The optimization experiment conditions for catalytic degradation of polystyrene...