Study On The Debromination And Lightweight Of The Pyrolysis Oil From Waste Printed Circuit Board Powder

Waste Printed Circuit Boards（WPCBs）is a typical e-waste,characterized by a great variety,huge quantity and rapid growth.WPCB is the most rapidly growing hazardous solid waste,and which become an urgent and difficult research problem to find a clean,effective and safe disposal methods or resource utilization of electronic waste.The main components of WPCBs include organic polymer resin,glass fiber,copper and other precious metals.Besides,WPCBs contains a variety of valuable metals（such as gold,silver,etc.）,which are known as"urban mines",which have higher recycling value.After the recovery of precious metals,the remaining components mainly contains bromine resin and glass fiber.However,due to the existence of brominated flame retardant,bromine migration will occur during the pyrolysis process,reducing the quality of pyrolysis liquid and pyrolysis gas,and increasing its resource utilization and the difficulty in extracting chemical raw materials.In this paper,based on the single-component additive pyrolysis catalytic WPCBs powder,focuses on the effect of the combination additives on the debromination and lightweight of pyrolysis oil,so as to achieve the purpose of improving the value of the pyrolysis oil resource utilization,and provide theory basis for pyrolysis oil recycling use.Firstly,in this paper,the pyrolysis oil is subjected to atmospheric boiling point distillation and analyzed by elemental analyzer and GC/MS.The experimental results show that the fractions of the pyrolysis oil are mainly aromatic compounds,the hydrocarbon ratio（C/H）is about 0.8,and contain a small amount of N and S;the main substance of pyrolysis oil is phenol,followed by 2-methylphenol,3-methylphenol,Isopropyl phenol and other phenolic substances;the bromine content in pyrolysis oil is mainly bromophenols.In addition,the bromine distribution in pyrolysis oil is in the range of 0³00℃,which is widely distributed.Secondly,this paper studied the effect of typical single additives on the pyrolysis oil of WPCBs,mainly divided into two parts:debromination and lightweight.The results show that CaCO₃ and Fe₃O₄ have obvious effects on the debromination of WPCBs power pyrolysis oil.The 4A and Al₂O₃ zeolite can significantly improve the degree of lightweight of WPCBs powder pyrolysis oil.After adding Fe₃O₄,the inorganic bromine content was reduced from 283.04 mg/g to 37.65 mg/g,the removal rate was 86.70%;the organic bromine content was reduced from 151.13 mg/g to 18.16 mg/g,the removal rate was 87.98%.Using Al₂O₃ zeolite,the content of 0²00℃（gasoline component）fraction in the pyrolysis oil is the highest,up to 42%,and the diesel component（200³50℃）is 45%,while the heavy oil component（≥350℃）content is 13%;the C6^C9 peak of pyrolysis oil is highest,72%,while the C15 peak is reduced to 12%.The pyrolysis oil GC/MS analysis results showed that the use of different debromination agent/zeolite catalytic pyrolysis of WPCBs can increase the content of phenol and reduce the content of Isopropyl phenol and bisphenol A.The content of phenol was increased from 30.43%to 38.81%（Fe₃O₄）without addition,and bisphenol A decreased to 8.25%from 24.52%when it was not added.With regard to the debromination of pyrolysis oil,the total bromine content in the pyrolysis oil can be greatly reduced when Fe₃O₄ is used,and the content is about 2.94%.Finally,this article also studied the effect of different composite additives（CaCO₃+4A/Al₂O₃,Fe₃O₄+4A/Al₂O₃）on the debromination and lightweight of WPCBs pyrolysis oil.Among them,the yield of pyrolysis oil recovered by Fe₃O₄:4A=1:1 catalytic pyrolysis of WPCBs was 12.23%,the organic bromine content was reduced from 18.16 mg/g（Fe₃O₄）to 10.87 mg/g,and the pyrolysis oil heating value was increased to 33.27 MJ/kg.The content of C6^C9 was increased from 72%（Al₂O₃ zeolite）to 75.09%,the content of the fraction from 0 to 200℃ was increased from 42%（Al₂O₃ zeolite）to52.02%,and the content of phenol was increased to 41.53%.