Use of plastic waste as a fuel in the co-pyrolysis of biomass: Part III: Optimisation of the co-pyrolysis process

•Properties of products obtained by pyrolysis were studied with polypropylene addition.•Were determined the optimal parameters of pyrolysis process by design of experiments.•Describe differences in properties of products get by pyrolysis with polypropylene.•Describe relationship among PP addition and differences in the high heats of products.

In this research, the synergistic relationship between the addition of polypropylene and the biomass in the thermal conversion process was studied. Additions of polypropylene in co-pyrolysis process can effect to the degassing of bio-char and may also affect the performance of the yields of liquid and gaseous products that were obtained in the thermal conversion process.The main goal of this research was the determination of the optimal quantity of polypropylene that would cover the full energy demands of the pyrolysis process, depending on the physicochemical properties of the biomass used. In this paper was calculated the degree of energy self-sufficiency of biomass pyrolysis process depending of biomass humidity content and with application of gaseous products from PP thermal depolymerisation as an additional fuel.The design of experiments (DOE) method – central composite rotatable design – was used to investigate the influence of temperature and polypropylene addition on the co-pyrolysis process. Using this method allowed the coverage of energy demand to be determined, as well as the optimal quantity of polypropylene to be added to the pyrolysis process, depending on the physicochemical properties of the biomass used. This method (DOE) was also used to optimise the composition of the solid, liquid and gaseous products obtained during the co-pyrolysis of biomass.