Molecular Dynamics Simulation of Waste Tire Pyrolysis at High Temperature

Pyrolysis is one of the most promising methods to treat waste tires. In this paper, a waste rubber model is established, and the pyrolysis process of rubber polymer at 1500–3000 k is investigated by molecular dynamics simulation. The whole pyrolysis process, the pyrolysis behavior of each component and the formation of S and N compounds are studied in detail. The results show that natural rubber (NR), styrene butadiene rubber (SBR) and nitrile rubber (NBR) are in the leading position in the pyrolysis process. When the carbon chain of rubber macromolecule breaks, many C and H atoms escape from it and combine with each other to form CH 3 , H radicals, CH 4 , H 2 , etc.; The pyrolysis products of waste rubber mainly include hydrocarbons CH 4 , C 2 H 2 , C 4 H 2 , C 5 H 4 , sulfur compounds H 2 S, CH 3 SH, HS, nitrogen compounds NH 3 , HCN and small molecule substances H 2 ; The increase of temperature can promote the pyrolysis of rubber, promote the carbon chain fracture, and promote the formation of more H 2 S; For H 2 S formation, HS is an important intermediate. HS compounds are mainly formed through the gradual pyrolysis of thiophene and polysulfide rubber. HS is stabilized by the transfer of H atoms. For nitrogenous pollutants, HCN is an important component in the pyrolysis. With the increase of temperature, the amount of HCN increases because of the decomposition of complex nitrogen compounds. The amount of oxygen has little effect on sulfide and nitride. At high temperature, nitrogen will also participate in the pyrolysis reaction. This paper reveals the pyrolysis behavior of waste rubber and the formation mechanism of S and N pollutants through simulation research, which provides a reference for the further development of waste tire rubber pyrolysis recovery.