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CN-122029255-A - Method for purifying petrochemical compositions obtained from chemical recovery of polymeric materials

CN122029255ACN 122029255 ACN122029255 ACN 122029255ACN-122029255-A

Abstract

The process of the invention comprises the steps of (a) a stripping step in a stripping vessel (1) and (b) a liquid-liquid extraction step in an extraction vessel (2), wherein steps (a) - (b) may be carried out in any order. The liquid-liquid extraction step (b) may be carried out using a protic solvent as the extraction medium or using an aprotic solvent as the extraction medium. The use of such a process allows for the purification of hydrocarbon compositions, particularly with respect to the content of chlorine-containing compounds. Reducing chlorine content is desirable for treating hydrocarbon compositions in a variety of different chemical treatment operations, such as steam cracking. The presence of chlorine-containing compounds at higher levels may lead to corrosion of equipment in such a process, which may lead to equipment failure and/or shortened equipment maintenance intervals, for example. In view of its significant impact on process economics, it is clearly desirable to reduce the amount of chlorine-containing compounds present as much as possible.

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 (17)

  1. 1. A method comprising subjecting a hydrocarbon composition a to: (a) A stripping step in a stripping vessel (1), and (B) Liquid-liquid extraction step in extraction vessel (2) Wherein steps (a) - (b) may be performed in any order.
  2. 2. The process of claim 1, wherein the liquid-liquid extraction step (b) is carried out using a protic solvent as the extraction medium or using an aprotic solvent as the extraction medium.
  3. 3. The method of claims 1-2, 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 nitrogen-containing stream B to obtain composition C; (b) Composition C is subjected to a liquid-liquid extraction step in extraction vessel (2), wherein an aprotic or protic solvent is used as extraction medium to obtain composition E.
  4. 4. A process according to any one of claims 1 to 3, wherein the hydrocarbon composition a is a hydrocarbon-containing oil product obtained by decomposing waste plastics.
  5. 5. The process of any of claims 1-4, wherein hydrocarbon composition a comprises an atomic chlorine of > 200 ppmw and < 2000 ppmw, preferably > 200 ppmw and < 600 ppmw, as determined by ASTM UOP 779-08.
  6. 6. The process of any one of claims 1-5, wherein the hydrocarbon composition a comprises, relative to the total weight of hydrocarbon composition a: 25.0 wt% and 95.0 wt% or less, preferably 25.0 wt% or less and 70.0 wt% or less, more preferably 25.0 wt% or less and 50.0 wt% or less, of normal paraffins, and/or Isoparaffin of 5.0 wt% or more and 20.0 wt% or less, preferably 5.0 wt% or less and 15.0 wt% or less, more preferably 7.5 wt% or less and 15.0 wt% or less, and/or More preferably more than or equal to 5.0 wt% and less than or equal to 50.0 wt%, preferably more than or equal to 10.0 wt% and less than or equal to 40.0 wt%, more preferably more than or equal to 15.0 wt% and less than or equal to 35.0 wt%, more preferably more than or equal to 15.0 wt% and less than or equal to 25.0 wt%, and/or More than or equal to 5.0 wt% and less than or equal to 20.0 wt%, preferably more than or equal to 5.0 wt% and less than or equal to 15.0 wt%, more preferably more than or equal to 7.5 wt% and less than or equal to 15.0 wt%, and/or Aromatic hydrocarbons of 5.0 wt% or more and 15.0 wt% or less, preferably 5.0 wt% or more and 12.5 wt% or less, more preferably 7.5 wt% or more and 12.5 wt% or less.
  7. 7. The process of any one of claims 1-6, wherein the stripping step (a) is carried out for at least 100 minutes, preferably at least 150 minutes, even more preferably at least 200 minutes, or for 100-300 minutes, preferably 150-300 minutes, even more preferably 200-300 minutes.
  8. 8. The process of any of claims 1-7, wherein the stripping step (a) is carried out in a stripping column, more preferably in a stripping column equipped with a condenser and a reboiler, wherein the condenser temperature may for example be 50-160 ℃, preferably 70-140 ℃, more preferably 80-120 ℃, and the reboiler temperature may for example be 70-190 ℃, preferably 85-160 ℃, more preferably 95-140 ℃.
  9. 9. The process according to any one of claims 2 to 8, 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.
  10. 10. The process of any of claims 2 to 9, wherein the aprotic solvent is used in an amount such that the aprotic solvent comprises ≡40.0 vol% and ≡70.0 vol%, preferably ≡50.0 vol% and ≡65.0 vol%, more preferably ≡55.0 vol% and ≡60.0 vol% of the contents of the extraction vessel (2) relative to composition C.
  11. 11. The process of any one of claims 1-10, wherein the extraction step (b) is conducted for a period of > 5.0 minutes and < 15.0 minutes using dimethyl sulfoxide or dimethylformamide as solvent for > 55.0 vol% and < 60.0 vol% of the contents of the extraction vessel (2) at a temperature > 20 ℃ and < 40 ℃ and a pressure > 75kPa and < 150 kPa.
  12. 12. The method of any one of claims 2-7, wherein the protic solvent is selected from ethylene glycol and water.
  13. 13. The process of any of claims 2 to 7, wherein the protic solvent is used in an amount such that it comprises, relative to composition E, greater than or equal to 40.0 vol% and less than or equal to 70.0 vol%, preferably greater than or equal to 50.0 vol% and less than or equal to 65.0 vol%, more preferably greater than or equal to 55.0 vol% and less than or equal to 60.0 vol% of the contents of the second extraction vessel (3).
  14. 14. The process of any of claims 2-7, wherein ethylene glycol of > 55.0 vol% and < 60.0 vol% of the contents of the second extraction vessel (3) is used as solvent at a temperature > 20 ℃ and < 40 ℃ and a pressure > 75kPa and < 150 kPa, the second extraction step (C) being conducted for a period of > 5.0 minutes and < 15.0 minutes.
  15. 15. The process according to any one of claims 1 to 14, wherein a stream D containing nitrogen and compounds stripped by composition a is obtained from the stripping process (a), wherein said stream D is further subjected to an adsorption step (D) in an adsorption vessel (4) to obtain a purified stream G, wherein optionally said 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 and combined with the hydrocarbon stream a in the feed to the stripping vessel (1).
  16. 16. The method of any one of claims 1-15, wherein prior to performing any one of steps (a) - (b), the method comprises a pyrolysis step of a waste plastic composition, wherein the waste plastic composition preferably comprises > 40.0 wt%, more preferably > 50.0 wt%, even more preferably > 60.0 wt% or > 70.0 wt% of polyolefin, wherein the hydrocarbon composition a is obtained as a liquid product of pyrolysis.
  17. 17. The process of claim 16, wherein the pyrolysis is a low severity pyrolysis process conducted at temperatures of ∈250 ℃ and ∈450 ℃, preferably ∈275 ℃ and ∈425 ℃, more preferably ∈300 ℃ and ∈400 ℃, or a high severity pyrolysis process conducted at temperatures of ∈450 ℃ and ∈750 ℃, preferably ∈500 ℃ and ∈700 ℃, more preferably ∈550 ℃ and ∈650 ℃.

Description

Method for purifying petrochemical compositions obtained from chemical recovery of polymeric materials The present invention relates to a process for purifying petrochemical compositions. In the chemical and refinery industries, there are a variety of chemical conversion processes in operation. These processes are highly optimized in terms of productivity, efficiency and sustainability to achieve economical, profitable operation and to obtain high quality products. One particular aspect associated with such optimized production is the use of high quality raw materials (also referred to as feedstock) as input materials. A large number of such chemical and refinery processes employ petrochemical compositions as feedstock. One particularly desirable type of feedstock currently being sought for use in the chemical and refinery industries is a feedstock derived from a waste stream. The use of such materials would greatly facilitate material recycling and it would be highly desirable to be able to utilize waste materials as valuable materials for new processes. There is a particular interest in the use of materials derived from waste plastics as raw materials. This may be highly desirable in the petrochemical and refinery industries because waste plastics are mainly material streams containing large amounts of molecules in which carbon and hydrogen constitute the majority of atoms. Thus, the atomic composition of these materials is very similar to typical hydrocarbon materials commonly used in the petrochemical and refinery industries. Thus, materials produced from waste plastics are likely to be suitable for use in the industry. In recent years, there has been an increasing trend in both technical development and industrial activities in the field of converting waste plastic materials into raw material streams useful in the petrochemical and refinery industries. For example, waste plastic material, which is solid at room temperature, can be converted to a hydrocarbon-containing stream, which is liquid at that temperature, by techniques such as pyrolysis of plastic material, and thus can be processed in chemical and refinery processes for converting liquid hydrocarbons. Such products resulting from pyrolysis of waste plastic materials may be referred to as plastic derived oils. Typical examples of such processes include light olefin and aromatic hydrocarbon production processes. Light olefins such as ethylene and propylene and aromatics such as benzene are well known valuable base chemicals and are widely used in the synthesis of chemical products, particularly polymer products, the most abundant examples 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 these cracking operations, hydrocarbon molecules (typically fossil hydrocarbons) present in the feed stream are subjected to specific conditions to break the atomic bonds and form smaller molecules. Due to the kinetics of chemical reactions, these processes typically produce product compositions containing desirably high levels of light olefins and aromatics. After leaving the pyrolysis 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 end product (e.g., polymeric material). Thus, when a feed stream derived from waste plastics is used in such a pyrolysis operation, one can produce polymeric material from the waste polymeric material, thereby establishing a recycling of the polymer. It will be appreciated that this provides an attractive route for material synthesis. In order for waste plastics materials to be suitable for processing in chemical operations such as thermal cracking or catalytic cracking operations, the products produced must meet very stringent material specifications. The cracking operation is industrially carried out in a world-scale operation, and when a process interruption occurs, plant downtime and product failure are caused, resulting in a significant decrease in process efficiency. In addition, the cleavage process is a very sensitive process and the operating conditions must be kept within strict regulatory limits. This also places demands on the feedstock materials that can be handled in such devices. On the other hand, the waste plastic streams available for disposal are often not very uniform in composition, and when they are produced by waste collection operations, whether at the consumer level or at the industrial level, the composition of these streams is expected to vary greatly from batch to batch. This can conflict with the requirements of the chemical treatment operations they may be used as raw materials, as these processes require a high degree of consistency. Thus, there is a need to ensure that the composition of products derived f