Acid-catalyzed conversion of chlorinated plastic waste into valuable hydrocarbons over post-use commercial FCC catalysts

Abstract

Plastic waste can be regarded as potentially cheap source of chemicals and energy. A mixture of post-consumer plastic waste (HDPE/LDPE/PP/PVC) was pyrolyzed over cracking catalysts using a fluidizing reaction system similar to the FCC process operating isothermally at ambient pressure. Experiments carried out with various catalysts gave good yields of valuable hydrocarbons with differing selectivity in the final products depending on reaction conditions. A newly developed model is presented that combines kinetic and mechanistic considerations which take into account chemical reactions and catalyst deactivation in the modeling of the catalytic degradation of polymers. Though acid-catalyzed hydrocarbon cracking reactions involve a large number of compounds, reactions and catalyst deactivation and are very complex, the model gives a good representation of experimental results from the degradation of post-consumer plastic waste. This model provides the benefits of lumping product selectivity, in each reaction step, in relation to the performance of the catalyst used and particle size selected as well as the effect of operation conditions, such as rate of fluidizing gas and reaction temperature. The results of this study are useful for the utilization of post-use commercial FCC catalysts for the production of chemicals and hydrocarbons and for determining both the product yield and product distribution from PVC-containing plastic degradation, and specifically for leading to a cheaper process with more valuable products.