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KR-20260065851-A - Process to improve the quality of hydrocarbon streams

KR20260065851AKR 20260065851 AKR20260065851 AKR 20260065851AKR-20260065851-A

Abstract

The present invention relates to a process for improving the quality of a hydrocarbon stream. The process for improving the quality of a hydrocarbon stream according to the present invention comprises the following steps: providing a hydrocarbon stream containing C5 - C6 iso-alkanes, wherein the content of C5 - C6 iso-alkanes in the hydrocarbon stream is 60-90 wt% based on the total weight of the hydrocarbon stream being 100 wt%; converting at least a portion of the C5 - C6 iso-alkanes to C2 - C6 n-alkanes in the presence of a catalyst and hydrogen via a conversion reaction to obtain a conversion product, wherein the catalyst comprises a molecular sieve and a non-precious metal hydration-active metal component; and steam-cracking the conversion product to obtain a cracking product containing ethylene. According to the present invention, low-quality ethylene feedstock can be effectively converted into high-quality ethylene feedstock. The hydrocarbon stream after hydrogen conversion can significantly improve the ethylene yield and triene yield of an ethylene apparatus. Furthermore, the process procedure according to the present invention was simple and had low operational difficulty, thus providing 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
20260511
Application Date
20240808
Priority Date
20230904

Claims (15)

  1. As a process for improving the quality of hydrocarbon streams, 1) a step of providing a hydrocarbon stream containing C5 - C6 iso-alkanes, wherein the content of C5 - C6 iso-alkanes in the hydrocarbon stream is 60-90 wt% (preferably 70-80 wt%) based on the total weight of the hydrocarbon stream being 100 wt%, 2) a step of converting at least a portion of the C5 - C6 iso-alkane (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 a C2 - C6 n-alkane in the presence of a catalyst and hydrogen through a conversion reaction to obtain a conversion product, wherein the catalyst comprises a molecular sieve and a non-noble metal hydration-active metal component. 3) A step of steam-cracking the above conversion product to obtain a decomposition product containing ethylene.
  2. In paragraph 1, The hydrocarbon stream has a sulfur content of 50-5000 mg/kg (preferably 200-1000 mg/kg) based on the total weight of the hydrocarbon stream, process.
  3. In paragraph 1, The hydrocarbon stream comprises, based on a total weight of 100 wt% of the hydrocarbon stream, C7 + hydrocarbons in an amount of 0-10 wt% (preferably 0.5-5 wt%), C5 - C6 n-alkanes in an amount of 10-30 wt% (preferably 15-25 wt%), C4 hydrocarbons in an amount of 0-10 wt% (preferably 2-5 wt%), and cyclic hydrocarbons in an amount of 1-10 wt% (preferably 2-5 wt%). process.
  4. In paragraph 1, The above conversion product comprises C2 - C3 alkanes and C4 - C6 n-alkanes (preferably C5 - C6 n-alkanes), and the weight ratio of C2 - C3 alkanes to C4 - C6 n-alkanes (preferably C5 - C6 n-alkanes) is 0.5:1 to 8:1 (preferably 0.9:1 to 5:1), process.
  5. In paragraph 1, The above-mentioned conversion product comprises, based on a total weight of 100 wt% of the conversion product, an amount of 5 wt% or less (preferably 1 wt% or less) of C7 + hydrocarbons, an amount of 0-50 wt% (preferably 10-40 wt%) of C5 - C6 iso-alkane, an amount of 40-90 wt% (preferably 50-80 wt%) of C2 - C6 n-alkane, and an amount of 3 wt% or less (preferably 1 wt% or less) of cyclic hydrocarbons. process.
  6. 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 (particularly preferably, the weight ratio of mordenite to ZSM-5 molecular sieves is 0-100:100:0, preferably 10-50:50-10), process.
  7. In paragraph 1, The above non-precious metal hydration-active metal component is one or more selected from the group consisting of a non-precious metal of Group VIB of the periodic table and a non-precious metal of Group VIII of the periodic table, preferably, the non-precious metal of Group VIB is one or more selected from the group consisting of molybdenum and tungsten (particularly preferably molybdenum), and the non-precious metal of Group VIII is one or more selected from the group consisting of cobalt and nickel (particularly preferably nickel). process.
  8. In Paragraph 7, Based on the weight of the catalyst, a non-precious metal of Group VIB (calculated as an oxide) is present in an amount of 5.0-30.0 wt% (preferably 10-20 wt%), and a non-precious metal of Group VIII (calculated as an oxide) is present in an amount of 0.5-15.0 wt% (preferably 3-10 wt%). process.
  9. 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.
  10. 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-hourly volume 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).
  11. In paragraph 1, Step 3) above is, 3-A-1) A step of separating the conversion 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 steam cracking the separated stream to obtain a cracked product containing ethylene. including, process.
  12. In Paragraph 11, 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.
  13. In paragraph 1, Step 3) above is, 3-B-1) A step of separating the above conversion 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 second separation) to obtain a higher-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 lower-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 steam cracking the above low-carbon stream to obtain a cracked product containing ethylene, including, process.
  14. In Paragraph 13, 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.
  15. In paragraph 1, The performance conditions for the steam cracking described above include a reaction temperature of 750-900 ℃, a reaction pressure of 0.1-0.5 MPaG, a weight ratio of water to oil of 0.2-0.6, and a system sulfur content of 100-200 mg/kg, process.

Description

Process to improve the quality of hydrocarbon streams The present invention relates to the technical field of petrochemicals, more specifically, to a process for improving the quality of a hydrocarbon stream. In petroleum processing, C5 and C6 iso-alkanes are generally obtained through processes such as crude oil separation or hydrocracking, which exhibit cracking performance. Due to their small molecular weight, the bonding energy between atoms of C5 and C6 iso-alkanes is relatively high, and their molecular polarity is weak, making it difficult for them to undergo additional chemical reactions in conventional cracking processes such as hydrocracking or catalytic cracking. Currently, there are two main ways to utilize C5 and C6 iso-alkanes: one is to use them directly as gasoline blending components, but the blending amount is small due to the influence of saturated vapor pressure; and the other is to use them as feedstocks for steam cracking to produce ethylene. However, the inventors of the present invention have discovered that when iso-alkanes are used in a thermal cracking process, the yields of ethylene and triene are relatively low, and thus they are not high-quality ethylene feedstocks. During the production process within the ethylene unit, a series of complex chemical reactions occur after the feedstock undergoes high-temperature decomposition, causing varying degrees of coking on the inner walls of the radiative tubes of the decomposition furnace and the inner walls of the quenching boiler jacket. As the coking layer continuously thickens, the heat transfer resistance of the tubes increases, and heat from the outside of the tubes is not transferred in a timely manner to the decomposing feedstock inside the tubes, severely affecting the depth of feedstock decomposition. Furthermore, the external surface temperature of the tubes continuously rises, causing localized overheating which can shorten the lifespan of the tubes. When the temperature exceeds the maximum design temperature of the tube material, the furnace must be shut down for decoking. Therefore, if the ethylene feedstock contains little to no sulfides, sulfur must be injected during the reaction process to prevent tube coking; if the ethylene feedstock contains a certain amount of sulfides, injecting sulfur during the reaction process can reduce the operating costs of the plant. When iso-alkanes are used as ethylene feedstocks, both ethylene yield and triene yield are relatively low. Therefore, effectively converting iso-alkanes into n-alkanes can significantly increase the yield of high-value products in ethylene plants. Among n-alkanes, low-carbon alkanes (including ethane and propane) are better cracking feedstocks because they are easy to separate and provide high ethylene product yields. However, the process of obtaining ethane and propane through hydrogenation consumes more hydrogen. On the other hand, C4 and C4 + n-alkanes, which have isomers, can also achieve relatively high ethylene yields while consuming less hydrogen during hydrogenation; however, it is difficult to separate isomers with the same number of carbon atoms, and the hydrogenation products usually contain iso-alkanes, resulting in lower ethylene yields compared to using low-carbon alkanes as feedstocks. If the ratio of low-carbon alkanes and n-alkanes in the hydrogenation product can be flexibly controlled through the hydrogenation process, performance flexibility can be significantly enhanced. With the rapid development of the chemical industry, ethylene production capacity has increased year after year. Consequently, the demand for ethylene raw materials has also been continuously increasing. Expanding the range of ethylene raw material choices and obtaining high-quality ethylene raw materials have become urgent issues that must be resolved for the development of the ethylene industry. To address the defects of the prior art, the present invention provides a hydrogenation process for C5andC6 iso-alkanes that can effectively convert iso-alkanes with poor decomposition performance into C2- C6 n-alkanes with better decomposition performance, thereby significantly improving the ethylene and triene yields of an ethylene apparatus, wherein the triene yield refers to the weight yield of ethylene, propylene, and butadiene. The inventors of the present invention have also discovered that the ethylene feedstock obtained through the hydrogenation process allows for the desulfurization of organic sulfur within the feedstock during the hydrogenation reaction, converting it into hydrogen sulfide, which is then removed during product separation. Consequently, the sulfur content in the ethylene feedstock is generally low, and sulfur injection is required before it is fed into the ethylene cracker to prevent pipe coking. If some of the hydrogen sulfide remains in the hydrogenation product during the separation process, the need for sulfur injection before the hydrogenation produc