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CN-122029254-A - Process for decontaminating petrochemical compositions obtained from chemical recycling of polymeric materials

CN122029254ACN 122029254 ACN122029254 ACN 122029254ACN-122029254-A

Abstract

The process of the invention comprises the steps of (a) a stripping step in a stripping vessel (1), (b) a first liquid-liquid extraction step in a first extraction vessel (2) wherein an aprotic solvent is used as extraction medium, and (c) a second liquid-liquid extraction step in a second extraction vessel (3) wherein a protic solvent is used as extraction medium, wherein steps (a) - (c) may be applied in any order. The use of such a process allows the hydrocarbon composition to be purified to such an extent that the content of chlorine-containing compounds can be reduced to less than 1ppm by weight. Such low chlorine content is desirable for processing of hydrocarbon compositions in many different chemical processing operations, such as steam cracking operations. The presence of higher levels of chlorine-containing compounds may lead to corrosion of equipment in these processes, which may lead to, for example, equipment failure and/or reduced time between equipment maintenance cycles. In view of its significant impact on process economics, it is clearly desirable to avoid the presence of chlorine-containing compounds to any extent.

Inventors

  • F. Cook
  • HUANG KAIXIN
  • A. C. Aka
  • R. Aresa

Assignees

  • SABIC环球技术有限责任公司
  • 沙特阿拉伯石油公司

Dates

Publication Date
20260512
Application Date
20241011
Priority Date
20231013

Claims (16)

  1. 1. A method comprising subjecting a hydrocarbon composition a to: (a) A stripping step in a stripping vessel (1); (b) A first liquid-liquid extraction step in a first extraction vessel (2), in which an aprotic solvent is used as extraction medium, and (C) A second liquid-liquid extraction step in a second extraction vessel (3), in which a protic solvent is used as the extraction medium, Wherein steps (a) - (c) may be applied in any order.
  2. 2. The method according to claim 1, comprising the steps of: (a) Subjecting the hydrocarbon composition a to a stripping step in a stripping vessel (1), wherein composition a is contacted with a stripping gas B, preferably a nitrogen-containing stream B, more preferably gaseous nitrogen, to obtain composition C; (b) Subjecting composition C to a first liquid-liquid extraction step in a first extraction vessel (2), wherein an aprotic solvent is used as extraction medium, to obtain composition E, and (C) Composition E is subjected to a second liquid-liquid extraction step in a second extraction vessel (3), wherein a protic solvent is used as extraction medium to obtain hydrocarbon composition F.
  3. 3. The process according to any one of claims 1-2, wherein the hydrocarbon composition a is a hydrocarbon-containing oil product obtained by decomposition of waste plastics.
  4. 4. A process according to any one of claims 1-3, wherein hydrocarbon composition a comprises >200ppm and <2000ppm, preferably >200ppm and <600ppm by weight of atomic chlorine determined according to ASTM UOP 779-08.
  5. 5. The process of any one of claims 1-4, wherein hydrocarbon composition a comprises: 25.0% or more and 95.0% or less, preferably 25.0% or more and 70.0% or less, more preferably 25.0% or more and 50.0% or less, by weight of normal paraffins, and/or Isoparaffin not less than 5.0 and not more than 20.0wt%, preferably not less than 5.0 and not more than 15.0wt%, more preferably not less than 7.5 and not more than 15.0wt%, and/or More than or equal to 5.0 and less than or equal to 50.0wt%, preferably more than or equal to 10.0 and less than or equal to 40.0wt%, more preferably more than or equal to 15.0 and less than or equal to 35.0wt%, more preferably more than or equal to 15.0 and less than or equal to 25.0wt% of olefins, and/or More than or equal to 5.0 and less than or equal to 20.0wt%, preferably more than or equal to 5.0 and less than or equal to 15.0wt%, more preferably more than or equal to 7.5 and less than or equal to 15.0wt% of cycloparaffin, and/or Aromatic compounds of 5.0% or more and 15.0% or less, preferably 5.0% or more and 12.5% or less, more preferably 7.5% or more and 12.5% or less, Relative to the total weight of hydrocarbon composition a.
  6. 6. The process according to any one of claims 1-5, wherein the stripping step (a) is carried out for a period of at least 100 minutes, preferably at least 150 minutes, even more preferably at least 200 minutes, or for a period of 100-300 minutes, preferably 150-300 minutes, even more preferably 200-300 minutes.
  7. 7. The process according to any one of claims 1-6, wherein the stripping step (a) is performed in a stripping column, more preferably in a stripping column equipped with a condenser and a reboiler, wherein the condenser temperature may be e.g. 50-160 ℃, preferably 70-140 ℃, more preferably 80-120 ℃, and the reboiler temperature may be e.g. 70-190 ℃, preferably 85-160 ℃, more preferably 95-140 ℃.
  8. 8. The process according to any one of claims 1-7, wherein the aprotic solvent is selected from the group consisting of dimethyl sulfoxide, dimethylformamide, sulfolane and n-methyl-2-pyrrolidone, preferably from the group consisting of dimethyl sulfoxide and dimethylformamide.
  9. 9. The process according to any one of claims 1 to 8, wherein the aprotic solvent is applied in such an amount relative to composition C that the aprotic solvent constitutes ≡40.0 and ≡70.0vol%, preferably ≡50.0 and ≡65.0vol%, more preferably ≡55.0vol% and ≡60.0vol% of the contents of the extraction vessel (2).
  10. 10. The process according to any one of claims 1-9, wherein the first extraction step (b) is carried out at a temperature of >20 ℃ and <40 ℃ at a pressure of >75 and <150kPa for a period of >5.0 and <15.0 minutes using as solvent ≡55.0vol% and ≡60.0vol% dimethyl sulfoxide or dimethylformamide of the contents of the extraction vessel (2).
  11. 11. The process according to any one of claims 1-10, wherein the protic solvent is selected from ethylene glycol and water.
  12. 12. The process according to any one of claims 1 to 11, wherein the protic solvent is applied in such an amount relative to composition E that it constitutes more than or equal to 40.0 and less than or equal to 70.0vol%, preferably more than or equal to 50.0vol% and less than or equal to 65.0vol%, more preferably more than or equal to 55.0vol% and less than or equal to 60.0vol% of the content of the second extraction vessel (3).
  13. 13. The process according to any one of claims 1-12, wherein the second extraction step (C) is performed at a temperature of >20 ℃ and <40 ℃ at a pressure of >75 and <150kPa for a period of >5.0 and <15.0 minutes using as solvent ≡55.0vol% and ≡60.0vol% of ethylene glycol of the content of the second extraction vessel (3).
  14. 14. The process according to any one of claims 1-13, wherein a stream D comprising nitrogen and compounds stripped from composition a is obtained from the stripping process (a), wherein stream D is further subjected to an adsorption step (D) in an adsorption vessel (4) to obtain a purified stream G, optionally wherein stream G is subsequently liquefied in a liquefaction step (e) by feeding it to a condenser (5) to obtain a liquid hydrocarbon stream H, which is optionally recycled back and combined with the hydrocarbon stream a fed into the stripping vessel (1).
  15. 15. The process according to any one of claims 1-14, wherein the process comprises a pyrolysis step of a waste plastic composition prior to being subjected to any of steps (a) - (c), preferably wherein the waste plastic composition comprises >40.0wt%, more preferably >50.0wt%, even more preferably >60.0wt%, or >70.0wt% of a polyolefin, wherein the hydrocarbon composition a is obtained in the form of a liquid product from the pyrolysis.
  16. 16. The process according to claim 15, wherein the pyrolysis is subjected to a low severity pyrolysis process at a temperature of > 250 ℃ and < 450 ℃, preferably > 275 ℃ and < 425 ℃, more preferably > 300 ℃ and < 400 ℃, or to a high severity pyrolysis process at a temperature of > 450 ℃ and < 750 ℃, preferably > 500 ℃ and < 700 ℃, more preferably > 550 ℃ and < 650 ℃.

Description

Process for decontaminating petrochemical compositions obtained from chemical recycling of polymeric materials Technical Field The present invention relates to a method for decontamination of petrochemical compositions. Background In the chemical and refinery industries, a wide variety of chemical conversion processes are operated. These processes are highly optimized in terms of productivity, efficiency and sustainability to achieve economical and profitable operation and high quality of the product. One particular aspect associated with such optimized production is the use of high quality feedstock (also referred to as feed) as an input material. A large number of such chemical and refinery processes utilize petrochemical compositions as feeds. A particularly desirable type of feed that is currently sought to be used in the chemical and refinery industries is one whose source can be found in the waste stream. The use of such a feed will greatly facilitate the recycling of the material and it is highly desirable to be able to use waste as a valuable feed for the new process. There is especially great interest in using materials derived from waste plastics as feed materials. This can be highly desirable in the petrochemical and refinery industries because waste plastics are primarily material streams containing a large proportion of molecules in which carbon and hydrogen constitute the majority of atoms. Thus, such materials have atomic compositions very similar to typical hydrocarbon materials conventionally used in the petrochemical and refinery industries. Thus, materials produced from waste plastics may be well suited for use in this industry. In recent years, in the field of converting waste plastic materials into feed streams that can be suitably used in petrochemical and refinery industries, technological development and industrial activities are increasing. For example, via techniques such as pyrolysis of plastic materials, waste plastic materials that are solid at room temperature may be converted into a hydrocarbon-containing stream that is liquid at such temperatures and thus may be processed in chemical and refinery processes equipped for converting liquid hydrocarbons. Such products obtained from pyrolysis of waste plastic materials may be referred to as plastic derived oils. Typical examples of such processes include light olefin and aromatic production processes. Light olefins (e.g., ethylene and propylene) and aromatics (e.g., benzene) are well known as valuable building blocks commonly used in chemical product synthesis, especially in the synthesis of polymer products, the most abundant of which are polyethylene and polypropylene. The most widely used process for the production of light olefins and aromatics is the so-called cracking operation, typically a thermal or catalytic cracking operation. In such cracking operations, hydrocarbon molecules (which typically have fossil hydrocarbon properties) present in the feed stream are subjected to conditions that cause the atomic bonds to break and form smaller molecules. Such processes typically result in product compositions containing desirably high yields of light olefins and aromatics due to chemical reaction kinetics. After exiting the cracking unit, the product composition is typically subjected to one or more separation operations to obtain a high quality, high purity chemical stream that can be processed into the desired final product (e.g., polymeric material). Thus, when a feed stream derived from waste plastics is used in such cracking operations, it is possible to produce polymeric material from the waste polymeric material and thereby establish recycling of the polymer. It will be appreciated that this provides an attractive route for the synthesis of materials. In order for waste plastic materials to be suitable for processing in chemical operations such as thermal or catalytic cracking operations, the product must meet very stringent material specifications. Cracking operations are commercially performed in global scale operations and when process interruptions occur, large process efficiency losses can occur in terms of equipment downtime and off-grade products. Furthermore, cracking processes are very sensitive processes. The conditions must be maintained within strict specifications. This also has an effect on the feed materials that can be processed in such equipment. On the other hand, the waste plastic streams available for processing are typically not very consistent in their composition, and when they come from waste collection operations (whether consumer or industrial grade), the composition of such streams can be expected to vary considerably from batch to batch. This can conflict with the requirements of chemical processing operations for which they are useful as feed materials, which dictate a high level of consistency. Thus, there is a need to ensure that the products derived from waste plastics and which can be used