Effect of Residence Time on Volatile Products Obtained in the HDPE Pyrolysis in the Presence and Absence of HZSM-5

Products obtained in the pyrolysis of high-density polyethylene (HDPE) can be very useful in plastic waste energy recovery or as raw materials in several processes in the chemical industry. The products obtained, however, depend on many variables such as temperature, volatile residence time, type of catalyst−polymer contact, or type of pyrolysis. Because of this, it is necessary to know how these factors can modify the yield and the composition of the volatile compounds obtained during the pyrolysis of different polymers. In this work, thermal and catalytic (HZSM-5) flash pyrolysis of HDPE at different residence times is widely studied using two different types of reactors:  a pyroprobe apparatus, where the volatile residence time is in the range of few milliseconds, and a fluidized bed reactor, where the secondary reactions take place in a larger extension. Significant differences between thermal and catalytic pyrolysis were observed, and the influence of the residence time on the yield of the different ...