THERMOCATALYTIC DESTRUCTION OF POLYSTYRENE IN THE PRESENCE OF POTASSIUM POLYTITANATE

Abstract

The thermocatalytic destruction of polystyrene under the action of quasi-amorphous potassium polytitanate (PPT), used as a new catalyst of the organic polymers destruction, has been studied. Thermal and thermocatalytic destruction of polystyrene was carried out at 450 °C in a reactor of an original design, which provides cracking of polymers under isothermal conditions and purging with an inert gas (nitrogen), as well as separation and accumulation of liquid and gaseous products. It has been established that the introduction of PPT powder into the polystyrene melt in an amount of 10 wt.% provides an increase in the yield of useful cracking products (gaseous and liquid hydrocarbons) by 15.5 wt.%. The yield of liquid hydrocarbons increases by 13.6 wt.%, and gaseous hydrocarbons by 1.9 wt.%. It is shown that, in comparison with the thermal cracking, an introduction of the PPT powder (10 wt.%} in the molten polymer increases the amount of liquid product (from 56.4 to 70.0 wt.%) and gaseous product (from 17.2 to 19.1 wt.%), whereas, the amount of undecomposed residue is reduced from 26.4 to 10.9 wt.%. It is found that a chemical composition of the products of the thermal and thermo-catalytic destruction of polystyrene differ significantly. Although aromatic hydrocarbons predominate in the composition of the distillate of the thermal destruction (about 80% of which are benzene and toluene), liquid products of the thermo-catalytic destruction contain 6.9% less aromatic compounds as well as a yield of olefins increases by 16.1%. The gaseous product of the thermal cracking is enriched with ethylene and isobutylene, and does not contain alkanes, while iso-butane appeares in the gaseous product of the thermocatalytic destruction and a yield of ethylene increases by 5.4 wt.%, propylene - by 10.5 wt.% and isobutylene - by 8.2 wt.%. A mechanism of the catalytic action of PPT is discussed. For citation: Zherdetsky N.A., Gorokhovsky A.V. Thermocatalytic destruction of polystyrene in the presence of potassium polytitanate. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 3. P. 77-84. DOI: 10.6060/ivkkt.20236603.6759.