Provided is a continuous process for converting waste plastic into recycle for polyethylene polymerization. In one embodiment, the process comprises selecting waste plastics containing polyethylene and/or polypropylene and passing the waste plastics through a pyrolysis reactor to thermally crack at least a portion of the polyolefin waste and produce a pyrolyzed effluent. The pyrolyzed effluent is separated into offgas, a naphtha/diesel fraction, a heavy fraction, and char. The naphtha/diesel fraction is passed to a crude unit distillation column in a refinery where a straight run naphtha (C.sub.5-C.sub.8) fraction or a propane/butane (C.sub.3-C.sub.4) fraction is recovered. The straight run naphtha fraction (C.sub.5-C.sub.8) or the propane/butane (C.sub.3-C.sub.4) fraction is passed to a steam cracker for ethylene production. The heavy fraction from the pyrolysis unit can also be passed to an isomerization dewaxing unit to produce a base oil.

Provided is a continuous process for converting waste plastic into recycle for polyethylene polymerization. In one embodiment, the process comprises selecting waste plastics containing polyethylene and/or polypropylene and passing the waste plastics through a pyrolysis reactor to thermally crack at least a portion of the polyolefin waste and produce a pyrolyzed effluent. The pyrolyzed effluent is separated into offgas, a naphtha/diesel fraction, a heavy fraction, and char. The naphtha/diesel fraction is passed to a crude unit distillation column in a refinery where a straight run naphtha (C.sub.5-C.sub.8) fraction or a propane/butane (C.sub.3-C.sub.4) fraction is recovered. The straight run naphtha fraction (C.sub.5-C.sub.8) or the propane/butane (C.sub.3-C.sub.4) fraction is passed to a steam cracker for ethylene production. The heavy fraction from the pyrolysis unit can also be passed to an isomerization dewaxing unit to produce a base oil.

The invention relates to a process for the preparation of styrene monomers by depolymerising polystyrene, to a device for carrying out the process and to the use of a fluidised bed reactor for the depolymerisation of polystyrene. Said process comprising the following steps: a) feeding a polymer composition (A) containing 60 to 99.9 wt. polystyrene, based on the total weight of the polymer composition (A), into the reaction zone (R) of a pyrolysis reactor (P); b) thermally cracking the polystyrene contained in the polymer composition (A) in the reaction zone (R) of the pyrolysis reactor (P) at a temperature of between 400° C. to 1000° C. to obtain a product mixture (G) containing styrene monomers and other components; c) removing the product mixture (G) obtained in step b) from the reaction zone (R) of the pyrolysis reactor (P); d) cooling the product mixture (G) removed in step c) to obtain a condensed product mixture (K) containing styrene monomers and further components; and e) separating the styrene monomers from the further components of the condensed product mixture (K) obtained in step d), wherein the average residence time (Z) of the polymer composition (A) in the reaction zone (R) of the pyrolysis reactor (P) is from 0.01 sec to 10 sec.

The invention relates to a process for the preparation of styrene monomers by depolymerising polystyrene, to a device for carrying out the process and to the use of a fluidised bed reactor for the depolymerisation of polystyrene. Said process comprising the following steps: a) feeding a polymer composition (A) containing 60 to 99.9 wt. polystyrene, based on the total weight of the polymer composition (A), into the reaction zone (R) of a pyrolysis reactor (P); b) thermally cracking the polystyrene contained in the polymer composition (A) in the reaction zone (R) of the pyrolysis reactor (P) at a temperature of between 400° C. to 1000° C. to obtain a product mixture (G) containing styrene monomers and other components; c) removing the product mixture (G) obtained in step b) from the reaction zone (R) of the pyrolysis reactor (P); d) cooling the product mixture (G) removed in step c) to obtain a condensed product mixture (K) containing styrene monomers and further components; and e) separating the styrene monomers from the further components of the condensed product mixture (K) obtained in step d), wherein the average residence time (Z) of the polymer composition (A) in the reaction zone (R) of the pyrolysis reactor (P) is from 0.01 sec to 10 sec.

The invention relates to a process for the preparation of styrene monomers by depolymerising polystyrene, to a device for carrying out the process and to the use of a fluidised bed reactor for the depolymerisation of polystyrene. Said process comprising the following steps: a) feeding a polymer composition (A) containing 60 to 99.9 wt. polystyrene, based on the total weight of the polymer composition (A), into the reaction zone (R) of a pyrolysis reactor (P); b) thermally cracking the polystyrene contained in the polymer composition (A) in the reaction zone (R) of the pyrolysis reactor (P) at a temperature of between 400° C. to 1000° C. to obtain a product mixture (G) containing styrene monomers and other components; c) removing the product mixture (G) obtained in step b) from the reaction zone (R) of the pyrolysis reactor (P); d) cooling the product mixture (G) removed in step c) to obtain a condensed product mixture (K) containing styrene monomers and further components; and e) separating the styrene monomers from the further components of the condensed product mixture (K) obtained in step d), wherein the average residence time (Z) of the polymer composition (A) in the reaction zone (R) of the pyrolysis reactor (P) is from 0.01 sec to 10 sec.

To provide a method for producing olefins having the carbon atom number of 2 to 3 with a high yield. A method for producing olefins including following steps (1) and (2): step (1): heating a polyolefin plastic to obtain a decomposed product (pyrolysis step); and step (2): causing the decomposed product obtained at the step (1) to contact with an MFI zeolite containing sodium atoms in the range of 0.10% by mass to 0.30% by mass to obtain catalytically cracked products containing olefins (catalytic cracking step).

To provide a method for producing olefins having the carbon atom number of 2 to 3 with a high yield. A method for producing olefins including following steps (1) and (2): step (1): heating a polyolefin plastic to obtain a decomposed product (pyrolysis step); and step (2): causing the decomposed product obtained at the step (1) to contact with an MFI zeolite containing sodium atoms in the range of 0.10% by mass to 0.30% by mass to obtain catalytically cracked products containing olefins (catalytic cracking step).

A process for producing one or more of benzene, toluene, or mixed xylenes may include combining one or more aromatic feed chemicals, one or more aromatic-based polymers, hydrodearylation catalyst, and hydrogen in a hydrodearylation unit to form a chemical product. The process may also include passing the chemical product out of the hydrodearylation unit, where the chemical product comprises one or more of benzene, toluene, and mixed xylenes. Additionally, a system for producing one or more of benzene, toluene, or mixed xylenes may include a mixing unit and a hydrodearylation unit. An aromatic feed stream and an aromatic-based polymer stream may be in fluid communication with a mixing unit. A mixing unit effluent stream may be in fluid communication between the mixing unit and the hydrodearylation unit. A chemical product stream may be in fluid communication with the hydrodearylation unit.

A process for producing one or more of benzene, toluene, or mixed xylenes may include combining one or more aromatic feed chemicals, one or more aromatic-based polymers, hydrodearylation catalyst, and hydrogen in a hydrodearylation unit to form a chemical product. The process may also include passing the chemical product out of the hydrodearylation unit, where the chemical product comprises one or more of benzene, toluene, and mixed xylenes. Additionally, a system for producing one or more of benzene, toluene, or mixed xylenes may include a mixing unit and a hydrodearylation unit. An aromatic feed stream and an aromatic-based polymer stream may be in fluid communication with a mixing unit. A mixing unit effluent stream may be in fluid communication between the mixing unit and the hydrodearylation unit. A chemical product stream may be in fluid communication with the hydrodearylation unit.

A plastic catalytic pyrolysis process that can produce high yields of ethylene, propylene and other light olefins from waste plastics is disclosed. The plastic feed is catalytically pyrolyzed at high silica-to-alumina ratios and elevated temperature to produce high ratios of gas to liquid which results in high light olefin monomer selectivity. The catalytic pyrolysis process can be operated in a single stage or a two-stage process.