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KR-20260066062-A - Process for the chemical conversion of hydrocarbon streams

KR20260066062AKR 20260066062 AKR20260066062 AKR 20260066062AKR-20260066062-A

Abstract

The present invention relates to a process for the chemical conversion of a hydrocarbon stream. The chemical conversion process of the present invention comprises the following steps: providing a hydrocarbon stream comprising a paraffinic alkane represented by the following structural formula (I); converting at least a portion of the paraffinic alkane into a C₂ - C₆n -alkane during a conversion reaction in the presence of a catalyst and hydrogen gas to obtain a converted product, wherein the catalyst comprises a molecular sieve and a non-noble metal hydration-active metal component; and stream-cracking the converted product to obtain a decomposed product comprising ethylene. (I) In structural formula (I), R is a C2 - C6 linear or branched alkyl. According to the present invention, low-quality ethylene raw materials can be effectively converted into high-quality ethylene raw materials, and the yield of ethylene and triene from the ethylene apparatus can be significantly improved by the hydrocarbon stream after hydrogenation conversion, the process is simple and the difficulty of execution is low, and the process has excellent economic advantages.

Inventors

  • 추이 저
  • 두 옌쩌
  • 쩡 룽후이
  • 펑 사오중
  • 류 창
  • 우 쯔밍
  • 하오 원웨

Assignees

  • 차이나 페트로리움 앤드 케미컬 코포레이션
  • 시노펙 다롄 리서치 인스티튜트 오브 페트로리움 앤드 페트로케미칼스 컴퍼니 리미티드

Dates

Publication Date
20260512
Application Date
20240808
Priority Date
20230904

Claims (14)

  1. As a process for the chemical conversion of a hydrocarbon stream, 1) A step of providing a hydrocarbon stream containing a paraffinic alkane represented by the following structural formula (I): (I) In the above formula (I), R is a C2 - C6 linear or branched alkyl (preferably a C2 - C4 linear or branched alkyl, more preferably a C2 - C3 linear alkyl), 2) a step of obtaining a converted product by converting at least a portion of the paraffinic alkanes (e.g., 30 wt% or more, 40 wt% or more, 50 wt% or more, 60 wt% or more, 70 wt% or more, 80 wt% or more, or 90 wt% or more of the total amount) into C2 - C6 n-alkanes in the presence of a catalyst and hydrogen gas during the conversion reaction, wherein the catalyst comprises a molecular sieve and a non-precious metal hydration-active metal component. 3) stream-cracking the converted product to obtain a decomposed product containing ethylene, including, process.
  2. In paragraph 1, The above molecular sieve is one or more selected from the group consisting of mordenite, ZSM molecular sieve, SAPO molecular sieve, and EU-1 molecular sieve, or More preferably, one or more selected from the group consisting of mordenite and ZSM molecular sieves, or Particularly preferably one or more selected from the group consisting of mordenite, ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-12 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, ZSM-35 molecular sieve, beta molecular sieve, and ZSM-38 molecular sieve, or In particular, one or more selected from the group consisting of mordenite and ZSM-5 molecular sieves, preferably in the range of 0-100:100:0 (preferably 10-50:50-10), process.
  3. In paragraph 1, The above non-precious metal hydration active metal component is one or more selected from the group consisting of non-precious metals of Group VIB, non-precious metals of Group VIII, oxides thereof, or sulfides thereof, or more preferably one or more selected from the group consisting of molybdenum, tungsten, cobalt, nickel, sulfides thereof, or oxides thereof. process.
  4. In paragraph 3, Based on the weight of the catalyst, a Group VIB non-precious metal (calculated as an oxide) is present in an amount of 5.0-30.0 wt% (preferably 10-20 wt%), and a Group VIII non-precious metal (calculated as an oxide) is present in an amount of 0.5-15.0 wt% (preferably 3-10 wt%), process.
  5. In paragraph 1, Based on the weight of the catalyst, the molecular sieve is present in an amount of 30-80 weight% (preferably 40-70 weight%), process.
  6. In paragraph 1, The above conversion reaction is carried out under the following reaction conditions: a reaction pressure of 0.5-10.0 MPaG (preferably 2.0-8.0 MPaG or 2.0-5.0 MPaG), a reaction temperature of 300-500 °C (preferably 350-450 °C), a liquid phase hourly space velocity of 0.1-15.0 h⁻¹ (preferably 0.5-5.0 h⁻¹ ), and a hydrogen-to-oil volume ratio of 50:1-2500:1 (preferably 100:1-2000:1 or 100:1-1000:1).
  7. In paragraph 1, In the above hydrocarbon stream, based on the total weight of the hydrocarbon stream being 100 wt%, C7 + hydrocarbons are present in an amount of 0-10 wt% (preferably 0.5-5 wt%), C5-6 iso-alkanes are present in an amount of 50 wt% or more (preferably 60-90 wt%, more preferably 70-80 wt%), C5 - C6 n-alkanes are present in an amount of 10-30 wt% (preferably 15-25 wt%), C4- hydrocarbons are present in an amount of 0-10 wt% (preferably 2-5 wt%), and cyclic hydrocarbons are present in an amount of 1 to 10 wt% (preferably 2-5 wt%). process.
  8. In paragraph 1, The converted product comprises C2 - C3 alkanes and C4 - C6 n-alkanes (preferably C5 - C6 n-alkanes), and the weight ratio of the C2 - C3 alkanes to the C4 - C6 n-alkanes (preferably C5 - C6 n-alkanes) is 0.5:1-8:1 (preferably 0.9:1-5:1). process.
  9. In paragraph 1, In the above converted product, based on the total weight of the converted product being 100 wt%, C7 + hydrocarbons are present in an amount of 5 wt% or less (preferably 1 wt% or less), C5 - C6 iso-alkanes are present in an amount of 0-50 wt% (preferably 10-40 wt%), C2 - C6 n-alkanes are present in an amount of 40-90 wt% (preferably 50-80 wt%), and cyclic hydrocarbons are present in an amount of 3 wt% or less (preferably 1 wt% or less). process.
  10. In paragraph 1, Step 3) above is, 3-A-1) A step of separating the converted product (referred to as the first separation) to obtain a separated stream having C2 + hydrocarbons as the main component (e.g., at least 95 wt%, at least 98 wt%, at least 99 wt%, or substantially 100 wt% of the total amount), 3-A-2) A step of stream-cracking the separated stream to obtain a decomposed product containing ethylene, including the steps of, process.
  11. In Paragraph 10, The first separation is performed under conditions including a pressure of 0.5-10.0 MPaG (preferably 2.0-8.0 MPaG or 2.0-5.0 MPaG) and a temperature of 40-70 ℃, process.
  12. In paragraph 1, Step 3) above is, 3-B-1) A step of separating the converted product (referred to as the first separation) to obtain a separated stream having C2 + hydrocarbons as the main component (e.g., at least 95 wt%, at least 98 wt%, at least 99 wt%, or substantially 100 wt% of the total amount), 3-B-2) A step of separating the separated streams (referred to as a second separation) to obtain a high-carbon stream composed mainly of C4 + hydrocarbons (e.g., 90 wt% or more, 95 wt% or more, 98 wt% or more, 99 wt% or more, or substantially 100 wt%) and a low-carbon stream composed mainly of C2 - C3 hydrocarbons (e.g., 90 wt% or more, 95 wt% or more, 98 wt% or more, 99 wt% or more, or substantially 100 wt%), 3-B-3) Optionally, a step of recirculating the high-carbon stream as a hydrocarbon stream to step 2) for the conversion reaction, 3-B-4) A step of stream cracking the above low-carbon stream to obtain a cracked product containing ethylene, including, process.
  13. In Paragraph 12, The first separation is performed under conditions including a pressure of 0.5-10.0 MPaG (preferably 2.0-8.0 MPaG or 2.0-5.0 MPaG) and a temperature of 40-70 ℃, and the second separation is performed under conditions including a pressure of 0.5-1.5 MPaG and a temperature of 30-60 ℃. process.
  14. As a hydrocarbon mixture comprising C5 - C6 n-alkanes and C2 - C3 alkanes, Based on the total weight of the hydrocarbon mixture being 100 wt%, the C5 - C6 n-alkane is present in an amount of 5-30 wt% (preferably 10-25 wt%), and the C2 - C3 alkane is present in an amount of 20-50 wt% (preferably 25-45 wt%). Hydrocarbon mixture.

Description

Process for the chemical conversion of hydrocarbon streams The present invention relates to the technical field of the petrochemical industry, in particular to a process for the chemical conversion of a hydrocarbon stream. Both naphtha obtained from the distillation of crude oil and light naphtha obtained from cracking reactions using molecular sieve-containing catalysts (including hydrocracking, catalytic cracking, etc.) contain large amounts of 2-methylalkanes (including isopentane, 2-methylpentane, pentane, 2-methylhexane, etc.) as part of low molecular weight iso-alkanes. Although 2-methylalkanes can be used as blending components for gasoline, their blending capacity is limited due to the influence of saturated vapor pressure. Meanwhile, with the continuous development of the chemical industry, the productivity of ethylene is also increasing year by year, which causes difficulties in supplying raw materials for ethylene. While 2-methylalkanes can be used as raw materials for ethylene, they are not ideal raw materials for ethylene production because, due to the influence of their molecular structure, the yields of ethylene and triene are low in free radical reaction processes such as stream cracking. In the prior art, established processes and suitable catalysts for the conversion of isobutane are provided, allowing the isomerization reaction of isobutane to be realized. However, no research has been disclosed on these 2-methylalkanes having a relatively high number of carbon atoms. If these low-molecular-weight 2-methylalkanes can be converted into n-alkanes and used as ethylene feedstocks, the yield of ethylene acid can be significantly increased, which can lead to significant economic benefits. The inventors of the present invention discover that low-molecular-weight iso-alkanes undergo two reaction processes, decomposition and isomerization, in the hydrogenation process; wherein conversion by decomposition produces more low-carbon alkanes, whereas conversion of iso-alkanes by isomerization produces iso-alkanes with the same number of carbon atoms. By controlling the catalyst and process conditions, the molecular composition of the hydrogenation product can be flexibly controlled, and production flexibility is also improved. The inventor of the present invention also, In the case of paraffinic alkanes having a specific structure that are present in large quantities during petroleum processing, when R=1, the energy consumed for their conversion is much higher compared to when R > 1, the reaction conditions are also harsher, and it is difficult to convert them together with the feedstock; whereas when R > 6, the molecules are relatively large, making it very easy to convert them in a conventional hydrocracking process and the process difficulty is low. When R is 2-6, the molecules are relatively small, making the reaction for the dehydrogenation or cracking of the alkanes very difficult, making it difficult to convert them by conventional process methods. Aiming at the defects of the prior art, the present invention provides a method for converting iso-alkanes having a specific molecular structure, which can effectively convert iso-alkanes into C2 - C6 n-alkanes, and furthermore, can significantly improve the target product yield of an ethylene device when iso-alkanes are used as ethylene feedstocks. The present invention aims to produce C2 - C6 n-alkanes in the maximum possible amount. In the prior art, C5 - C6 iso-alkanes are generally converted to n-alkanes only when only isomerization occurs and decomposition is suppressed, where the overall isomerization process requires reduced reaction temperature and reduced hydrogen-to-oil volume ratio. However, since the isomerization reaction is affected by chemical equilibrium, the isomerization reaction is suppressed when the concentration of n-alkanes in the product reaches a certain ratio (about 30%), making it difficult to improve the yield of straight-chain hydrocarbons in the product by adjusting the reaction process. Therefore, the reaction pathway needs to be combined with the separation of straight-chain hydrocarbons and isomerized hydrocarbons for the further conversion of unconverted iso-alkanes after the n-alkanes have been separated. However, all C2 - C6 n-alkanes are ideal feedstocks for producing ethylene through stream cracking, and to this end, the present invention uses a special catalyst and controls reaction conditions to simultaneously enhance both the occurrence of isomerization and the cracking reaction, which blocks the influence of chemical equilibrium on the isomerization reaction, and the yield of n-alkanes in the converted product is further enhanced through the cracking reaction, which is particularly suitable for direct use as feedstock for stream cracking to produce ethylene. The present invention was developed based on this purpose. Specifically, the present invention relates to the following aspects. 1. A process for the che