Study Of The Pyrolysis Kinetics Of Several Typical Waste Plastics

With the development of economy, the municipal solid wastes, especially waste plastics, increase in a large scale—about 10 percent the annual growth rate. The photodegradability and biodegradability of these plastics are poor, so they will take part in material circulation of ecosystem through soil,water and atmosphere if packed long-term, and will give potential and long hazard to human body. In addition, we are facing the shortage of energy present, if we can reuse the waste plastics as secondary energy resources, the energy situation will be greatly relieved.At present, we focus on the recycle of waste plastics, including materials recycling, chemical raw recycling and energy recycling. For the latter two, the typical topics are the pyrolysis for fuel oil and combustion for power generation. Although the technique for producing fuel oil from waste plastics has been successfully realized in the small-scale, but at the current level, some problems still exist if we want to make the technique industrialized, moreover, the high quantity of heat and diversity of the plastics result in the operation difficulties of combustion furnace. If we large-scale the power generation, there will be other issues such as fuel shortage. Therefore, currently, the feasible treatment for waste plastics is materials recovery, namely the Carbonization and Pyrolysis Technique of waste plastics.Plastic is a very complex organic compound. There are many complex reaction during pyrolysis with the change of temperature. In this paper, PET,PS,PE and PVC were pyrolysised to study their pyrolysis mechanism. The variation of weight with temperature Were determined and the experiment data were simulated by nth-order and ASTM E698 model.It turned out that nth-order model can simulate the pyrolysis process to a very high degree for these plastics, while the simulate results of ASTM E698 model is poor. However, the simulate data of ASTM E698 model for PET and PS is better than for PE and PVC. In this paper, the reaction rates and kinetic parameters of these plastics are also solved to predict the product distribution. And these information will be very important function for rational choosing the reactors, designing and operating the optimized reactor.In the experiment of preparation of activated carbon from polycarbonate by chemical activation, activated carbons prepared from polycarbonate at higher pyrolysis temperatures (>600℃) generally have a rapid increase of adsorption amount in P/Ps=0.45-0.7, and the maximal amount adsorbed is also increased. At high pyrolysis temperature and chemical ratio, the distribution of pores is widened, the volumes of mesopores and macropores is enhanced. The yield of activated carbons is 40% or over. Activated carbon of high surface area can be obtained.