Method for producing tetrafluoromethane through plasma pyrolysis of waste polytetrafluoroethylene

Patent metadata

Field	Value
Publication number	US-12448290-B2
Application number	US-202418856520-A
Country	US
Kind code	B2
Filing date	Jan 25, 2024
Priority date	Aug 7, 2023
Publication date	Oct 21, 2025
Grant date	Oct 21, 2025

Abstract

Provided is a method for producing tetrafluoromethane through plasma pyrolysis of waste polytetrafluoroethylene (PTFE). The method includes: subjecting the waste PTFE to a plasma pyrolysis reaction to obtain a pyrolysis product, and subjecting the pyrolysis product to quenching and gas-solid separation in sequence to obtain a pyrolysis gas including the tetrafluoromethane, wherein the plasma pyrolysis reaction is performed at a temperature of 1,800 K to 5,000 K.

First claim

What is claimed is:

1. A method for producing tetrafluoromethane through plasma pyrolysis of waste polytetrafluoroethylene (PTFE), comprising the following steps:
subjecting the waste PTFE to a plasma pyrolysis reaction to obtain a pyrolysis product,
subjecting the pyrolysis product to quenching and gas-solid separation in sequence to obtain a pyrolysis gas comprising the tetrafluoromethane; and
subjecting the pyrolysis gas to adsorption and rectification to obtain the tetrafluoromethane;
wherein, the plasma pyrolysis reaction is performed at a temperature of 2,000 K to 4,500 K;
wherein, the plasma pyrolysis reaction is conducted in a plasma reactor;
wherein, the plasma reactor is selected from the group consisting of a radio frequency plasma reactor, a microwave plasma reactor, and an arc plasma reactor;
wherein, the waste PTFE is introduced into the plasma reactor through a carrier gas; and
wherein, the waste PTFE is in a form of a granular material.

2. The method according to claim 1 , wherein the carrier gas comprises at least one selected from the group consisting of argon and nitrogen.

3. The method according to claim 1 , wherein a feed rate of the waste PTFE is in a range of 0.5 kg/h to 3,000 kg/h.

4. The method according to claim 1 , wherein the quenching is performed by surface-type heat-exchange quenching, direct quenching, or surface-type heat-exchange quenching and direct quenching.

5. The method according to claim 4 , wherein a cooling medium adopted for the surface-type heat-exchange quenching is at least one selected from the group consisting of water and a refrigerating fluid; and
a cooling medium adopted for the direct quenching is at least one selected from the group consisting of argon and nitrogen.

6. The method according to claim 1 , wherein the pyrolysis gas further comprises hexafluoroethane and tetrafluoroethylene; and
a total volume content of the tetrafluoromethane, the hexafluoroethane, and the tetrafluoroethylene in the pyrolysis gas is higher than or equal to 90%, with tetrafluoromethane being the largest volume in the pyrolysis gas.

7. The method according to claim 6 , wherein a volume content of the hexafluoroethane is higher than that of the tetrafluoroethylene.

8. The method according to claim 1 , wherein the plasma pyrolysis reaction is a millisecond pyrolysis reaction.

Assignees

• Univ Zhejiang
• Zhejiang Juhua New Material Res Institute Co Ltd

Inventors

• Yang Qiwei
• Zhang Wenjun
• Ren Qilong
• Zhou Liyang
• Wang Shuhua
• Qin Wei
• Li Hongfeng
• Zhang Zhiguo
• Bao Zongbi
• Su Baogen

Classifications

• C08J2499/00

  Characterised by the use of natural macromolecular compounds or of derivatives thereof not provided for in groups C08J2401/00 - C08J2407/00 or C08J2489/00 - C08J2497/00 · CPC title

• C08J11/12

  by dry-heat treatment only · CPC title

• B01J19/12

  employing electromagnetic waves · CPC title

• C10B53/07

  {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) · CPC title

• C07C17/38

  Separation; Purification; Stabilisation; Use of additives · CPC title