Effect of CaO addition on fast pyrolysis behavior of solid waste components using Py GC/MS

Abstract

Pyrolysis is a promising approach for treating and recovering solid waste. Herein, we experimentally explored the fast pyrolysis of typical solid waste components, including wood biomass, food waste, and Polyvinyl Chloride (PVC) plastic, using the analytical Pyrolysis Gas Chromatography-Mass Spectrometry (Py GC/MS) technique. The chemical compositions of the volatile organic compounds in pyrolytic tar were detected and compared. The effect of the in-situ addition of calcium oxide (CaO) on the process was also validated. Results showed that different waste components yielded varied pyrolysis products. In-situ CaO addition influenced both the types and relative contents of pyrolysis tar species. The most common products from wood biomass pyrolysis were phenols (24.24 % and 34.87 % without and with CaO addition, respectively) and benzenes (15.77 % and 14.72 % without and with CaO addition, respectively). On the other hand, the most common products from food waste pyrolysis were aldehydes (18.09 % and 3.69 % without and with CaO addition, respectively) and ketones (14.45 % and 33.09 % without and with CaO addition, respectively). The most common products from PVC plastic pyrolysis were benzenes (31.87 % and 28.11 % without and with CaO addition, respectively) and naphthalenes (20.71 % and 25.58 % without and with CaO addition, respectively). During waste pyrolysis, the presence of CaO significantly reduced the formation of acidic compounds, ethers, and aldehydes through decarboxylation and decarbonylation reactions. Regarding the generation of valuable chemicals, the addition of CaO facilitated BTXN synthesis from wood and food waste pyrolytic tar. However, it slightly reduced the relative BTX content from PVC pyrolytic tar. These findings could form the basis for developing resource recovery strategies from solid waste using pyrolysis technology.