Search

KR-102962796-B1 - Washing process of a vinyl aromatic compound distillation unit and a process including such washing process

KR102962796B1KR 102962796 B1KR102962796 B1KR 102962796B1KR-102962796-B1

Abstract

The present disclosure relates to a washing process for a vinyl aromatic compound distillation unit comprising one or more distillation columns, wherein the process comprises, after the step of washing one or more distillation columns, a step of passivating at least one distillation column, wherein in the passivation step, a flux comprising a passivation mixture passes through at least one distillation column under passivation conditions comprising a temperature of at least 90°C, and the passivation mixture comprises a component A which is one or more polymerization inhibitors; and a component B selected from one or more vinyl group-free hydrocarbons and/or steam. The present disclosure also relates to a process for purifying and producing one or more vinyl aromatic compounds comprising the washing process.

Inventors

  • 펠라티 조
  • 또레 보셰 장-피에르

Assignees

  • 토탈에너지스 원테크

Dates

Publication Date
20260508
Application Date
20230221
Priority Date
20220223

Claims (15)

  1. A washing process for a vinyl aromatic compound distillation unit comprising one or more distillation columns (1), wherein the process comprises a step of washing one or more distillation columns (1), and after the step of washing one or more distillation columns (1), a step of passivating at least one distillation column (1) is followed, wherein in the passivation step, a flux comprising a passivation mixture passes through at least one distillation column (1) under passivation conditions comprising a temperature of at least 90°C and a pressure ranging from 90 kPa to 300 kPa, and the passivation mixture comprises component A which is one or more polymerization inhibitors, and component B selected from steam, one or more vinyl group-free hydrocarbons, or steam and one or more vinyl group-free hydrocarbons, wherein one or more vinyl group-free hydrocarbons are one or more aliphatic saturated hydrocarbons, one or more aromatic compounds, or one or more aliphatic saturated hydrocarbons and one or more aromatic compounds.
  2. A cleaning process according to claim 1, characterized in that the passivation mixture comprises component A in an amount of 0.01% to 2.00% by weight and the remainder being component B, based on the total weight of the passivation mixture.
  3. A washing process according to claim 1, characterized in that the passivation condition includes a temperature in the range between a temperature 10°C higher than the boiling point of the vinyl aromatic compound and a temperature up to 20°C higher than the boiling point of the vinyl aromatic compound; or the passivation condition includes a temperature of at least 100°C and up to 250°C, or at least 100°C and up to 250°C.
  4. A cleaning process according to claim 1, characterized in that the passivation condition includes a pressure in the range of 98 kPa to 120 kPa; the passivation step is performed under an atmosphere provided with one or more inert gases; or the passivation condition includes a pressure in the range of 98 kPa to 120 kPa, and the passivation step is performed under an atmosphere provided with one or more inert gases.
  5. A washing process according to claim 1, wherein at least one vinyl group-free aromatic compound is selected from benzene, toluene, o -xylene, m -xylene, p -xylene, ethylbenzene, mixtures of benzene/ethylbenzene, and any mixtures thereof; one or more aliphatic saturated hydrocarbons are selected from heptane, octane, nonane, decane, and any mixtures thereof; or at least one vinyl group-free aromatic compound is selected from benzene, toluene, o -xylene, m -xylene, p -xylene, ethylbenzene, mixtures of benzene/ethylbenzene, and any mixtures thereof, and one or more aliphatic saturated hydrocarbons are selected from heptane, octane, nonane, decane, and any mixtures thereof.
  6. In claim 1, component A is at least one polymerization inhibitor selected from molten sulfur, phenyl- p -phenylenediamine, phenothiazine, tert -butyl catechol, diethyl-hydroxylamine, quinone methide, 2-(3,5-di- tert -butyl-4-oxocyclohexa-2,5-diene-1-ylidene)acetonitrile, 2,6-di- tert -butyl-4-(methoxymethylene)cyclohexa-2,5-dienone, 4-benzylidene-2,6-di- tert -butylcyclohexa-2,5-dienone, butylated hydroxytoluene, butylated hydroxyanisole, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and any mixture thereof; A washing process characterized by comprising at least one polymerization inhibitor selected from tert -butyl catechol, diethyl-hydroxylamine, and any mixture thereof.
  7. A washing process according to claim 1, characterized in that the flux containing a passivation mixture passing through at least one distillation column (1) during the passivation step is free of vinyl aromatic compounds.
  8. A washing process according to claim 1, wherein the vinyl aromatic compound is selected from styrene, alpha-methyl styrene, divinylbenzene, polyvinylbenzene and any mixture thereof; or wherein the vinyl aromatic compound is styrene or comprises styrene.
  9. A cleaning process according to claim 1, characterized in that the passivation step is performed for a time ranging from 1 hour to 24 hours; or from 5 hours to 15 hours.
  10. A cleaning process according to claim 1, characterized in that the step of cleaning one or more distillation columns (1) is mechanical cleaning or includes the same, or includes pressure cleaning of one or more distillation columns (1), or includes mechanical cleaning of one or more distillation columns (1).
  11. A purification process for one or more vinyl aromatic compounds, or one or more vinyl aromatic compounds that are styrene or include styrene, wherein the process comprises the step of distilling one or more vinyl aromatic compounds using a vinyl aromatic compound distillation unit comprising one or more distillation columns (1), wherein the process comprises the step of interrupting the distillation of one or more vinyl aromatic compounds at least once to perform a washing process of the vinyl aromatic compound distillation unit, and wherein the washing process of the vinyl aromatic compound distillation unit conforms to any one of claims 1 to 10.
  12. A purification process according to claim 11, characterized in that the washing process includes a passivation step performed at a temperature higher than the temperature at which distillation is performed.
  13. As a process for producing a vinyl aromatic compound from a corresponding saturated aromatic compound, the process comprises: a) a step of providing a catalyst composition comprising one or more zeolites; b) a step of providing a stream containing a saturated aromatic compound; d) a step of contacting the stream containing the saturated aromatic compound with the catalyst composition under dehydrogenation reaction conditions including a temperature of at least 550°C to obtain a stream rich in vinyl aromatic compounds; e) a step of performing a purification process of at least one vinyl aromatic compound according to claim 11 in a stream rich in the vinyl aromatic compound; f) Optionally, a production process characterized by including a step of recovering a vinyl aromatic compound from a vinyl aromatic compound-rich stream.
  14. A production process according to claim 13, wherein the produced vinyl aromatic compound is styrene and the corresponding saturated aromatic compound is ethylbenzene; or wherein the produced vinyl aromatic compound is styrene and the corresponding saturated aromatic compound is ethylbenzene, and the stream provided in step (b) further comprises diethylbenzene, and the process further comprises step (c) of removing said diethylbenzene from said stream provided in step (b) before contacting the stream with a catalyst composition.
  15. A production process according to claim 13, wherein one or more zeolites are selected from the FAU, MFI, or MOR series; the catalyst composition further comprises at least one transition metal; or one or more zeolites are selected from the FAU, MFI, or MOR series and the catalyst composition further comprises at least one transition metal.

Description

Washing process of a vinyl aromatic compound distillation unit and a process including such washing process The present disclosure relates to a process for processing a distillation column suitable for distilling vinyl aromatic compounds, a process for purifying at least one vinyl aromatic compound, and a process for producing vinyl aromatic compounds from corresponding saturated aromatic compounds, in particular a process for producing styrene from ethylbenzene. If the components being distilled contain polymerizable groups such as vinyl groups, the distillation unit is susceptible to contamination by polymers. For example, when purifying styrene, the presence of divinylbenzene can clog the distillation column during polymerization. After maintenance for cleaning, living chain polymer residues that act as polymer seeds always remain. When the distillation unit is restarted, these polymer seeds are reactivated, causing contamination to reoccur and reducing distillation efficiency. U.S. Patent 3,476,656 discloses that because styrene tends to polymerize when heated, various styrene polymerization inhibitors, such as molten sulfur and tert -butyl catechol (TBC), can be used. Other styrene polymerization inhibitors, such as diethyl-hydroxylamine (DEHA), phenyl -p -phenylenediamine, and phenothiazine, may be used. However, using polymerization inhibitors during distillation incurs costs, and a solution to reduce these costs has not yet been found. WO 00/14039 discloses a composition suitable for inhibiting the polymerization of vinyl aromatic compounds. Such a composition comprises a di-hydroxy-arene, a hydrogen transfer agent, and a stable nitrate. These components are used to keep polymerization levels low while purifying styrene using distillation techniques. However, even after the styrene distillation unit is stopped, the styrene distillation column still contains polymer seeds. In this regard, KR101299781 discloses a method for cleaning internal components of a fractionation column or a distillation column applicable to the fractionation, purification, and distillation processes of petrochemicals. The method uses ultrasound to bring the material to be cleaned into contact with a cleaning solution containing isopropyl alcohol. This physical cleaning by means of ultrasonic vibration cannot completely clean the distillation column. For heat exchangers, thermal cleaning was developed to replace traditional high-pressure cleaning. High-pressure cleaning has the disadvantage that the sprayed water does not reach every nook and cranny around the heat exchanger, leaving dirt and dust behind. On the other hand, thermal cleaning can restore the heat exchanger and restore its original performance. Accordingly, the object of the present disclosure is to provide a method for efficiently cleaning a distillation unit for vinyl aromatic compounds, in particular a distillation unit for styrene. According to a first embodiment, the present disclosure provides a washing process for a vinyl aromatic compound distillation unit comprising one or more distillation columns, which is notable in that the process comprises a step of washing one or more distillation columns, and after the step of washing one or more distillation columns, a step of passivating at least one distillation column is followed, wherein in the passivation step, a flux comprising a passivation mixture passes through at least one distillation column under passivation conditions comprising a temperature of at least 90°C and a pressure of up to 300 kPa, and the passivation mixture comprises component A which is one or more polymerization inhibitors, and component B which is selected from one or more aliphatic saturated hydrocarbons and/or one or more aromatic compounds, or comprising the same, and one or more hydrocarbons and/or steam that are not vinyl groups. Advantageously, the passivation mixture comprises component A in an amount of 0.01 wt% to 2.0 wt%, or component A in an amount of 0.01 wt% to 1.0 wt%, or component A in an amount of 0.01 wt% to 0.80 wt%, or component A in an amount of 0.01 wt% to 0.50 wt%, or component A in an amount of 0.01 wt% to 0.10 wt%, preferably component A in an amount of 0.02 wt% to 0.08 wt%, more preferably component A in an amount of 0.03 wt% to 0.07 wt%, based on the total weight of the passivation mixture, and the remainder consists of component B. Surprisingly, it was found that chemical passivation performed during the washing process can reduce or at least maintain the amount of polymer inhibitor used during the purification process of one or more vinyl aromatic compounds at a low level. Without being bound by theory, the process of the present disclosure enables the deactivation of polymer seeds remaining in the column after washing the column using a passivation step. Thus, the process deactivates the inner surface of the distillation column for the life of the distillation column, said deactivation being performed in t