Desulphurization of liquid hydrocarbon fuel is necessary due to the increasingly stringent environmental regulations on the sulphur content of liquid hydrocarbon fuel. Also, oil products produced from waste tyre pyrolysis have sulphur content of about 1.0 wt% which is far higher than the regulations. Therefore, desulphurization is important for commercialization of tyre pyrolysis oil....[ Read more ]

Desulphurization of liquid hydrocarbon fuel is necessary due to the increasingly stringent environmental regulations on the sulphur content of liquid hydrocarbon fuel. Also, oil products produced from waste tyre pyrolysis have sulphur content of about 1.0 wt% which is far higher than the regulations. Therefore, desulphurization is important for commercialization of tyre pyrolysis oil.

In this project, different chemical desulphurization methods were applied to tyre pyrolysis oil. It was found that the best desulphurization system consists of three processes. Oil is first extracted by acetonitrile, followed by the oxidative desulphurization by hydrogen peroxide and acetic acid. The last step is a further extraction by acetonitrile. This desulphurization gives high desulphurization efficiency with reasonable oil recovery. After determining the best chemical desulphurization system, three reaction parameters (reaction temperature, amount of acetic acid and amount of hydrogen peroxide) were investigated. For each parameter, four conditions were examined. The results showed that the best desulphurization conditions are 50°C with 5 vol% of acetic acid and 10 vol% of 30% hydrogen peroxide solution. The desulphurization efficiency of this system is around 30%.

Biological desulphurization of tyre pyrolysis oil by Rhodococcus erythropolis IGTS8 was conducted both in flask cultures and in a controlled fermenter. It was found that the optimum oil/water ratio was 1:1. The desulphurization of this system was around 28%. Emulsification and demulsification of oil and water during biodesulphurization was also investigated. The optimum emulsification is achieved by aeration while demulsification can be achieved by either ultrasound or centrifugation depending on requirements on oil quality and reaction time requirements.

A novel scheme for combining chemical, physical and biological desulphurization was developed based on the experimental findings. In this system, biodesulphurization is conducted before chemical desulphurization. The reactor used for biodesulphurization is a plug flow reactor (PFR) while that used for chemical desulphurization is a continuous-stirred tank reactor (CSTR).