From PS catalytic cracking

Likewise, Tang et al. [95] have investigated the catalytic cracking of mixtures of several polyolefins and PVC (PP/PVC, PE/PVC, PS/PVC) at 360-380°C over a novel Al-Zn composite. These authors observed that the composite accelerated the degradation of the plastic mixtures and retained the chlorine resulting from PVC degradation. 

The components of products from thermal and catalytic cracking of HDPE, LDPE, LP, PP, PS were analyzed [48], and the results are shown in Table 28.2 and Table 28.3. The products from thermal cracking of HDPE, LDPE and LP (linear polyethylene) are mainly wax-like substances at normal temperamre. The fraction under 200°C recovered from HDPE accounts for 16% of the total cracking products, while that from LP accounts for 23%. Compared with tlie products of PE, PP produces less solid residue, but more liquid components, and PS produces the highest proportion of liquid fraction, which is 99.17% by thermal cracking and 99.56% by catalytic cracking. 

Puente et al.33 have studied the conversion of PS dissolved in benzene in a fluidized bed reactor over a commercial FCC catalyst. The product distribution obtained in the catalytic degradation of PS was compared to that obtained in styrene conversion (Figure 5.15). The same relationship between the conversion and the selectivity towards the different products was observed in both PS and styrene catalytic conversion at 550 °C, suggesting that styrene is also the primary product in the catalytic PS cracking. The authors proposed a mechanism to explain the formation of the main products from styrene. 

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