Hydrocracking of Plastics

Plastic hydrogenation has recently been used for the conversion of various polymers PE, PP, PS, PET and mixtures. The reactions are usually conducted in autoclaves at temperatures around 400 °C, under pressures of cold hydrogen up to 150 atm, and in some cases in the presence of solvents. Enhanced activities are obtained by means of a variety of catalysts. 

The catalytic hydrocracking of HDPE and PP over Zr02 modified by SO4-and WO2- groups and promoted by Pt and Ni as hydrogenation metals has been investigated by Venkatesh et al HDPE was almost completely converted over Ni- or Pt-containing Zr02-S04 catalysts at 375 °C and 82 atm of cold- 

The lower reactivity of PE compared with PS and PET under hydrocracking catalytic conditions (430 °C, 86 atm of cold-hydrogen pressure) has also been observed by Joo and Curtis7 over a presulfided NiMo/Al203 catalyst. Thus, after 1 h of reaction, about 94% of PS and PET were converted, whereas the reaction with LDPE yielded a conversion of only 72%. 

A1203 catalyst (240 °C). On the contrary, the incorporation of ZSM-5 zeolite into the CP sample did not cause a decrease in this temperature. 

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