Formation of chloride products in the MSW (municipal solid wastes) pyrolysis process by Py-GC/MS method with key model components

Abstract

The formation of chloride products in the process for pyrolysis of municipal solid wastes (MSW) with key model components was investigated by Py-GC/MS method. HCl and CH₃Cl are identified as the most abundant chloride products for the individual pyrolysis of polyvinyl chloride (PVC) or corn straw (CS) in the range of 200–600 °C. For the pyrolysis of CS, a higher temperature is more favorable for the generation of HCl than that of CH₃Cl. In the PVC pyrolytic products, chlorobenzene (Ph-Cl), benzyl chloride (Ph-CH₂Cl), and 1-(chloroethyl)benzene (Ph-CHClCH₃) are also detected but in extremely low amounts. For the co-pyrolysis of PVC/CS, the formation of CH₃Cl is significantly promoted. The synergistic effect in the PVC/CS co-pyrolysis process is mainly attributed to the reaction between the HCl derived from PVC and the decomposition products of lignin. The products of Ph-Cl and Ph-CH₂Cl are mainly generated from the cyclization of Cl-containing chain species. CH₃Cl and Ph-CHClCH₃ are mainly generated from secondary reactions between HCl and other pyrolytic products. No remarkable synergistic effect is observed on the formations of chlorides in the co-pyrolysis of PVC/PP (polypropylene), while the generation of Ph-CHClCH₃ is significantly enhanced in the co-pyrolysis of PVC/PS (polystyrene).