# US 12,760,166 B2 · Pyrolysis of polycarbonate-containing material in order to recover raw materials > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,760,166 B2 - Document ID: US12760166B2 - Status: Granted - Kind: B2 - Application number: 18/274,059 - Filed: 2021-12-22 - Published: 2024-12-26 - Granted: 2026-10-13 - Earliest claimed: 2021-02-17 - Assignees: Covestro Deutschland AG - Applicants: Covestro Deutschland AG - Inventors: Stefanie Eiden; Rainer Bellinghausen; Aurel Wolf; Erik Sluyts; Jonas Krause; Andreas Seidel - Web page: https://patentgrep.com/patent/US12760166B2 ## CPC - C08J 11/12: by dry-heat treatment only - B01J 6/008: {Pyrolysis reactions (of hydrocarbons C10G9/00)} - C07C 4/22: by depolymerisation to the original monomer, e.g. dicyclopentadiene to cyclopentadiene - C07C 29/48: by oxidation reactions with formation of hydroxy groups - C07C 37/84: by crystallisation - C07C 51/43: by change of the physical state, e.g. crystallisation - C10B 53/07: {of solid raw materials consisting} of synthetic polymeric materials, e.g. tyres (recovery or working-up of waste materials of organic macromolecular compounds or compositions based thereon by dry-heat treatment for obtaining partially depolymerised materials C08J11/10; production of liquid hydrocarbon mixtures from rubber or rubber waste C10G1/10) - C10B 57/14: Features of low-temperature carbonising processes - C08J 2325/06: Polystyrene - C08J 2369/00: Characterised by the use of polycarbonates; Derivatives of polycarbonates - C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29) - B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS - C10B: DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS (cracking oils C10G; underground gasification of minerals E21B43/295) ## Abstract A method for pyrolysis of polycarbonate-containing material in order to recover raw materials is provided. The method comprises at least the following steps: (a) introducing material intended for the pyrolysis, at least comprising material that contains a mixture of a polycarbonate-containing compound and a polystyrene-containing compound, into a reactor; (b) decomposing, at a temperature of 300° C. to 700° C., at least the material intended for pyrolysis introduced into the reactor in step (a) and obtaining a product that is present in the gaseous phase as the pyrolysate and of pyrolysis residues that are present in a non-gaseous phase; and (c) cooling the removed pyrolysate to a temperature of less than 300° C. while obtaining a pyrolysis product, selected from pyrolysis condensate, pyrolysis sublimate or a mixture thereof. ## Claims ### Claim 1 A pyrolysis process, comprising at least the following steps: (a) introducing of a pyrolysis feedstock that includes at least: (i) material comprising a mixture of polycarbonate-containing compound and polystyrene-containing compound into a reactor; and (ii) one catalyst from the group consisting of aluminum oxide, magnesium oxide, zirconium oxide, titanium oxide, chromium oxide, zinc oxide, tin oxide, combinations of aluminum oxide with magnesium oxide and/or calcium oxide, aluminosilicates, silicon aluminum phosphates, silicalite, spinels, and clays; (b) degrading of at least the material of the pyrolysis feedstock introduced in step (a) in the reactor at a temperature of 300° C. to 700° C. to obtain a gas-phase product as pyrolysate and a non-gas-phase pyrolysis residue, wherein (i) during breakdown, the amount of oxygen gas in the reactor is not more than 2.0% by volume based on the total volume of the gases present in the reactor; (ii) during said breakdown, the pyrolysate is discharged from the reactor; and (iii) said pyrolysis residue is discharged from the reactor; and (c) cooling of the discharged pyrolysate to a temperature of less than 300° C. to obtain pyrolysis product selected from pyrolysate condensate, pyrolysate resublimate or a mixture thereof, wherein the pyrolysis product comprises aromatic compounds having at least one hydroxyl group. ### Claim 2 (depends on 1) The process as claimed in claim 1, wherein the temperature in step (b) is from 350° C. to 650° C. ### Claim 3 (depends on 1) The process as claimed in claim 1, wherein the introduced pyrolysis feedstock is temperature-controlled at 300° C. to 700° C. and that a residence time of the temperature-controlled pyrolysis feedstock is from 1 second to 2 hours. ### Claim 4 (depends on 1) The process as claimed in claim 1, wherein the discharge of the pyrolysate from the reactor is ensured by a gas stream passed through the reactor or by suction. ### Claim 5 (depends on 1) The process as claimed in claim 1, wherein the discharge of the pyrolysate from the reactor is ensured by a gas stream passed through the reactor, the flow rate of which in the reactor, as the superficial velocity, being in the range from 0.01 m/s to 20 m/s. ### Claim 6 (depends on 1) The process as claimed in claim 1, wherein at least steps (a) and (b) run concomitantly in the context of continuous process control. ### Claim 7 (depends on 1) The process as claimed in claim 1, wherein the amount of oxygen gas in the reactor in step (b) is not more than 0.5% by volume based on the total volume of the gases present in the reactor. ### Claim 8 (depends on 1) The process as claimed in claim 1, wherein the reactor packed with said material is filled with inert gas. ### Claim 9 (depends on 1) The process as claimed in claim 1, wherein the polycarbonate-containing compound is at least one compound that contains at least ten structural units, where * denotes a valence of the polymer backbone. ### Claim 10 (depends on 1) The process as claimed in claim 1, wherein the polystyrene-containing compound is at least one polymer that contains at least ten repeat units of the formula where * denotes a valence of the repeat unit of the polymer backbone, R1 is a hydrogen atom or a methyl group, and Ph is a phenyl group. ### Claim 11 (depends on 1) The process as claimed in claim 1, wherein the polycarbonate-containing compound is at least one compound obtained by reacting (i) at least one aromatic compound having at least two hydroxyl groups and (ii) phosgene or diphenyl carbonate. ### Claim 12 (depends on 1) The process as claimed in claim 1, wherein the pyrolysis feedstock includes a defined total amount of phosphorus-containing organic compound such that, based on the total weight of the pyrolysis feedstock, the proportion introduced into the pyrolysis feedstock by this total amount of phosphorus-containing organic compound is from 0% by weight to not more than 0.5% by weight of phosphorus. ### Claim 13 (depends on 12) The process as claimed in claim 12, wherein the phosphorus present in said phosphorus-containing organic compound has a formal oxidation state of +5. ### Claim 14 (depends on 12) The process as claimed in claim 12, wherein said phosphorus-containing organic compound is selected from at least one compound of the group consisting of organic phosphoric esters, organic phosphonic esters, organic phosphazenes, and phosphonate amines. ### Claim 15 (depends on 12) The process as claimed in claim 12, wherein the phosphorus-containing organic compound is selected from at least one compound of the general formula (IV) where R1, R2, R3, and R4 are each independently optionally halogenated C1 to C8 alkyl, C5 to C6 cycloalkyl optionally substituted by alkyl and/or halogen, C6 to C20 cycloalkyl optionally substituted by alkyl and/or halogen, or C7 to C12 aralkyl optionally substituted by alkyl- and/or halogen, n is each independently 0 or 1; q is a number from 0 to 30; and X is a single- or multiring aromatic radical having 6 to 30 carbon atoms, or a linear or branched aliphatic radical having 2 to 30 carbon atoms, which may be OH-substituted and may contain up to 8 ether bonds. ### Claim 16 (depends on 1) The process as claimed in claim 1, wherein said material is introduced into the reactor in the form of solid particles. ### Claim 17 (depends on 1) The process as claimed in claim 1, wherein said pyrolysis feedstock in step (a) also comprises in addition to said material at least one filler. ### Claim 18 (depends on 1) The process as claimed in claim 1, wherein said pyrolysis feedstock contains said material in a total amount based on the total weight thereof of 10.0% to 80.0% by weight. ### Claim 19 (depends on 1) The process as claimed in claim 1, wherein the catalyst is a heterogeneous catalyst comprising solid particles having an average diameter in a range of 0.01 mm to 5 cm.