The present disclosure relates to a method of decomposing a phenolic by-product, including: a step of feeding and thermally cracking a phenolic by-product stream to and in a decomposition apparatus, recovering an active ingredient from a top discharge stream, and discharging a high-boiling substance through a bottom discharge stream; a step of pressurizing each of a side discharge stream of the decomposition apparatus and a bottom discharge stream of the decomposition apparatus; a step of mixing the pressurized side discharge stream of the decomposition apparatus and the pressurized bottom discharge stream of the decomposition apparatus with each other to form a mixed stream; and a step of passing a part of the mixed stream through a reboiler, circulating the part of the mixed stream to the decomposition apparatus, and discharging a residual mixed stream.

Disclosed are antioxidants used in compositions and methods to stabilize synthetic feedstock derived from plastic. Some methods disclosed herein include adding an antioxidant composition to a plastic-derived synthetic feedstock composition. Some methods disclosed herein include heating plastic under substantially oxygen free conditions at a temperature of from about 400° C. to about 800° C. to produce a pyrolysis effluent, distilling the pyrolysis effluent, recovering the synthetic feedstock, and adding a stabilizer to the synthetic feedstock to reduce contamination. The disclosure also provides compositions including a synthetic feedstock derived from plastic and an antioxidant.

Disclosed are antioxidants used in compositions and methods to stabilize synthetic feedstock derived from plastic. Some methods disclosed herein include adding an antioxidant composition to a plastic-derived synthetic feedstock composition. Some methods disclosed herein include heating plastic under substantially oxygen free conditions at a temperature of from about 400° C. to about 800° C. to produce a pyrolysis effluent, distilling the pyrolysis effluent, recovering the synthetic feedstock, and adding a stabilizer to the synthetic feedstock to reduce contamination. The disclosure also provides compositions including a synthetic feedstock derived from plastic and an antioxidant.

Systems and methods for recycling waste plastics are provided, including a system for recovering styrene monomer from waste polystyrene. The system includes a mixing, heating and compacting apparatus to receive a supply of waste polystyrene and to output a densified polystyrene containing melt; a pyrolysis reactor configured to receive the densified polystyrene containing melt and a supply of recycled oligomers, pyrolyze the densified polystyrene containing melt and the recycled oligomers, and output a hydrocarbon gas stream and a solids residue stream; a quenching apparatus configured to receive the hydrocarbon gas stream output from the pyrolysis reactor and condense out oligomers for routing upstream to the pyrolysis reactor to be combined as the supply of recycled oligomers with the densified polystyrene containing melt, and to discharge an altered hydrocarbon gas stream for further processing; and a condenser configured to receive the altered hydrocarbon gas stream from the quenching apparatus and condense out styrene to form a styrene monomer oil product.

Systems and methods for recycling waste plastics are provided, including a system for recovering styrene monomer from waste polystyrene. The system includes a mixing, heating and compacting apparatus to receive a supply of waste polystyrene and to output a densified polystyrene containing melt; a pyrolysis reactor configured to receive the densified polystyrene containing melt and a supply of recycled oligomers, pyrolyze the densified polystyrene containing melt and the recycled oligomers, and output a hydrocarbon gas stream and a solids residue stream; a quenching apparatus configured to receive the hydrocarbon gas stream output from the pyrolysis reactor and condense out oligomers for routing upstream to the pyrolysis reactor to be combined as the supply of recycled oligomers with the densified polystyrene containing melt, and to discharge an altered hydrocarbon gas stream for further processing; and a condenser configured to receive the altered hydrocarbon gas stream from the quenching apparatus and condense out styrene to form a styrene monomer oil product.

Systems and methods for recycling waste plastics are provided, including a system for recovering styrene monomer from waste polystyrene. The system includes a mixing, heating and compacting apparatus to receive a supply of waste polystyrene and to output a densified polystyrene containing melt; a pyrolysis reactor configured to receive the densified polystyrene containing melt and a supply of recycled oligomers, pyrolyze the densified polystyrene containing melt and the recycled oligomers, and output a hydrocarbon gas stream and a solids residue stream; a quenching apparatus configured to receive the hydrocarbon gas stream output from the pyrolysis reactor and condense out oligomers for routing upstream to the pyrolysis reactor to be combined as the supply of recycled oligomers with the densified polystyrene containing melt, and to discharge an altered hydrocarbon gas stream for further processing; and a condenser configured to receive the altered hydrocarbon gas stream from the quenching apparatus and condense out styrene to form a styrene monomer oil product.

The invention relates to an improved process for providing purified styrenic monomers, such as styrene, from styrene-containing polymer waste. Styrene-containing waste is depolymerized in a suitable reactor, and the depolymerization products are condensed and separated in a three-step distillation process.

The invention relates to an improved process for providing purified styrenic monomers, such as styrene, from styrene-containing polymer waste. Styrene-containing waste is depolymerized in a suitable reactor, and the depolymerization products are condensed and separated in a three-step distillation process.

The invention relates to an improved process for providing purified styrenic monomers, such as styrene, from styrene-containing polymer waste. Styrene-containing waste is depolymerized in a suitable reactor, and the depolymerization products are condensed and separated in a three-step distillation process.

Methods of depolymerizing polyolefin-based material into useful petrochemical products using styrene oligomers or polymers, and heat are described. The styrene oligomers or polymers improve the depolymerization reaction by decreasing the halftime for the depolymerization, which results in a higher depolymerization rate and a shorter residence time in the depolymerization unit, allowing for a predictable depolymerization reaction, and decreasing the branching or aromatic formations in the product.