Research on pyrolysis kinetics and products analysis of waste circuit boards

Under nitrogen condition, thermo gravimetric analysis(TGA) was used to test the pyrolysis characteristics and reaction kinetics of waste printed circuit boards (WPCB) powder. Py-GC∕MS and TG∕MS were used to analyze and discuss the pyrolysis products of WPCB. The results showed that the pyrolysis process of WPCB powder was divided into three stages, including evaporation of water, decomposition of organic matter and stabilization. The decomposition stage included volatilization and decomposition of organic matter and decomposition of residue, whose apparent activation energy was 250.74 and 23.58 kJ∕mol, respectively, and the pre-exponential factors were 1.35×10 ³¹ and 3 428.92 min ^-1, respectively. The main products of the pyrolysis of the WPCB powder included aromatic compounds which mainly substituted by benzene ring-substituted aromatic compounds and bromine-containing compounds, and a small amount of low molecular weight hydrocarbons, benzofurans, etc. The benzene ring-substituted aromatic compounds mainly included benzene, toluene, ethylbenzene, xylene, phenol, isopropyl phenol, while the bromine-containing compounds mainly included methyl bromide, ethyl bromide, bromophenol, dibromophenol and hydrogen bromide.