Pyrolysis of Solid Organic Waste Over Various Catalysts: Different Mechanisms Revealed By Gas Chromatography

Hadas Raveh-Amit, Chemistry Department, NRCN, Beer Sheva, Israel (hadas.raveh@gmail.com)
Nissim Banano, Chemistry Department, Nrcn, Beer Sheva, Israel
Ofra Klein-BenDavid, Chemistry Department, Nrcn, Beer Sheva, Israel
Gabriela Bar-Nes, Chemistry Department, Nrcn, Beer Sheva, Israel

Organic waste contaminated with radionuclides is generally characterized by high volume-to-weight ratio and may pose a hazard due to radiolysis and generation of combustible and explosive gases. Thus, minimizing waste volume as well as forming a chemically stable and conditioned matrix are of high importance in the treatment of contaminated polymers. In the present study, the pyrolytic decomposition of the commonly used polyolefin, high-density polyethylene (HDPE), was explored as a method for waste minimization by obtaining high gaseous and low char and liquid yields. The effects of two aluminosilicate catalysts, Zeolite Y and ZSM-5, and reaction temperature on decomposition efficiency were evaluated based on product conversions and gas composition. Pyrolysis of the polymers over ZSM-5 resulted in higher gas conversions than over Zeolite Y. Increasing the reaction temperature from 450°C to 525°C also resulted in increased polymer decomposition. Gas chromatography analysis of the pyrolytic products revealed differences in gas composition depending on catalysts or reaction temperatures, evidenced by differences in olefinic to paraffinic ratios and carbon number distribution. Taken together, our study provides a link between pyrolysis parameters, such as catalysts and reaction temperature, and polymer decomposition mechanisms. It highlights the ability to control the decomposition efficiency of contaminated organic solid waste by fine tuning the pyrolysis treatment conditions.