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EP-3452563-B1 - PROCESS FOR THE UTILIZATION OF C5 HYDROCARBONS WITH INTEGRATED PYGAS TREATMENT

EP3452563B1EP 3452563 B1EP3452563 B1EP 3452563B1EP-3452563-B1

Inventors

  • ALABBAD, Fares
  • ABDELGHANI, MOHAMED SABRI
  • UEHARA, Ernesto

Dates

Publication Date
20260506
Application Date
20170328

Claims (7)

  1. A process for treating pygas, the process comprising: a) depentanizing (101) the pygas (201) to produce a C 5 stream and a C 6 + stream (203); b) contacting the C 6 + stream (203) with a first catalyst to form one or more hydrotreatment products; c) separating the C 5 stream to form a product stream (213) comprising isoprene, piperylene, and cyclopentadiene, and a raffinate stream (209), including remaining C 5 and C 4 hydrocarbons; d) separating the raffinate stream (209) to produce a C 4 raffinate stream (212) comprising C 4 hydrocarbons and to produce a C 5 raffinate stream; e) contacting the C 5 raffinate stream with a second catalyst (210) in a hydrogenation reactor (210) to produce alkanes, wherein the second catalyst (210) comprises a C 4 /C 5 hydrogenation catalyst, wherein the contacting the C 5 raffinate stream (209) further comprises cracking the alkanes produced in the hydrogenation reactor (210) in a cracker furnace (211) to produce feedstock, the cracker furnace being coupled to the hydrogenation reactor (210); f) recycling the C 4 hydrocarbons from the C 4 raffinate stream (212) to the cracker furnace (211); and g) separating one or more of the one or more hydrotreatment products in a deoctanizer to produce a benzene, toluene, and/or xylene stream and a C 9 + hydrocarbon stream.
  2. The process of claim 1, further comprising contacting the raffinate stream (209) with a sulfur removal unit to remove sulfur containing compounds from the raffinate stream prior to contacting step e).
  3. The process of claim 1, further comprising contacting the C 6 + stream with a sulfur removal unit to remove sulfur containing compounds from the C 6 + stream prior to contacting step b).
  4. A system for processing pygas, the system comprising: a) a first distillation column (202) configured to separate pygas to produce a C 5 stream and C 6 + stream, wherein the first distillation column comprises a depentanizer column; b) a hydrotreatment unit (204), coupled to the first distillation column (202), configured to hydrotreat the C 6 + stream to form one or more hydrotreatment products; c) a deoctanizer that is a second distillation column (205), coupled to the hydrotreatment unit, configured to produce a benzene, toluene, and/or xylene stream and a C 9 + hydrocarbon stream; d) a separations unit (208), coupled to the first distillation column (202), configured to separating the C 5 stream to form a product stream (213) comprising isoprene, piperylene, and cyclopentadiene, and a raffinate stream (209), including remaining C 5 and C 4 hydrocarbons; e) a hydrogenation reactor (210), coupled to the separations unit (208), the hydrogenation reactor (210) comprising a C 4 /C 5 hydrogenation catalyst to convert at least a portion of the remaining C 5 in the raffinate stream into alkanes; and f) a cracker furnace (211) coupled to the hydrogenation reactor (210) for cracking the alkanes and recycled C 4 hydrocarbons from a C 4 raffinate stream (212).
  5. The system of claim 4, wherein the hydrogenation reactor comprises a three bed deep hydrogenation reactor.
  6. The system of claim 4, further comprising a sulfur removal unit coupled to and positioned between the separations unit and the hydrogenation reactor.
  7. The system of claim 4, further comprising a sulfur removal unit coupled to and positioned between the first distillation column and the hydrotreatment unit.

Description

FIELD The disclosed subject matter relates to a process for treating pygas and a system for processing pygas. BACKGROUND Pygas, also known as pyrolysis gas, can be formed in the cracking furnaces of various refinery processes. Pygas can include alkanes, alkenes, alkynes, aromatics, naphthenes, alkyl aromatics and/or polyaromatics. After being formed in the cracking furnaces, pygas can be distilled through one or more fractional distillation columns to remove lighter hydrocarbons. C5 hydrocarbons can be separated from pygas while olefins are converted to alkanes. The separated C5 stream can be returned to the cracking furnace as feedstock. This process can cause the conversion of certain C5 hydrocarbons, e.g., isoprene and cyclopentadiene, to what can be less valuable chemicals such as isopentane and cyclopentane. Therefore, there remains a need for improved techniques for integrating the processing of pygas with the utilization of C5 hydrocarbons including isoprene and cyclopentadiene. Processes for the treatment of pygas are disclosed in US 2012/0203039 A1 and US 6090270. SUMMARY OF THE DISCLOSED SUBJECT MATTER The invention provides a process for treating pygas and a system for processing pygas according to the independent claims. Embodiments of the invention are disclosed in dependent claims and this description. The disclosed subject matter provides a process and system for recovering isoprene, pyperylene and cyclopentadiene from pygas. In certain instances, the pygas stream, the C5 stream, and/or the C6+ stream can be introduced into or contacted with a sulfur removal unit (e.g., a sulfur removal adsorption bed, amine treatment unit, etc.) to remove sulfur containing compounds (e.g., mercaptains, carbon sulfides, hydrogen sulfide, etc.) from these streams prior to coming into contact with the first and/or second catalysts. Removal of sulfur containing compounds from these streams can help protect the first and/or second catalysts from deactivation. In preferred instances, the sulfur removal unit can be positioned just before the C5 stream and/or the C6+ stream enter the hydrogenation reactor/unit or the hydrotreatment reactor/unit, respectively. In certain embodiments, the first catalyst is a hydrogenation catalyst. In certain aspects, the system can also include at least one, two, three, or more sulfur removal units (e.g., a sulfur removal adsorption bed, amine treatment unit, etc.) to remove sulfur containing compounds (e.g., mercaptains, carbon sulfides, hydrogen sulfide, etc.) from the pygas stream, the C5 stream and/or the C6+ stream. For example, a sulfur removal unit can be coupled to and positioned between the separations unit and the hydrogenation reactor. Alternatively, or additionally, a sulfur removal unit can be coupled to and positioned between the first distillation column and the hydrotreatment unit. Even further, a sulfur removal unit can be coupled to the first distillation column such that the pygas is first treated to remove (e.g., reduce) sulfur containing compounds prior to entering the first distillation column. In certain embodiments, the hydrogenation reactor can be a three bed deep hydrogenation reactor. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 depicts a method for recovering isoprene, piperylene, and dicyclopentadiene from pygas.FIG. 2 depicts a system for recovering isoprene, piperylene, and dicyclopentadiene from pygas according to the invention. DETAILED DESCRIPTION The presently disclosed subject matter provides methods and systems for recovering C5 hydrocarbons from pygas. The presently disclosed subject matter also provides methods for recovering isoprene and cyclopentadiene from pygas. For the purpose of illustration and not limitation, FIG. 1 is a schematic representation of an exemplary method. A method 100 for recovering isoprene and cyclopentadiene from pygas includes depentanizing the pygas to produce a C5 stream and a C6+ stream. The pygas of the presently disclosed subject matter can originate from various sources, for example other chemical processes, e.g., ethylene production or the cracking of naphtha, butanes, or gas oil. The pygas can include alkanes, alkenes, alkynes, aromatics, naphthenes, alkyl aromatics, and polyaromatics. For example, the pygas can include cyclopentadiene and/or dicyclopentadiene. As used herein, the term "about" or "approximately" means within an acceptable error range for the particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined, i.e., the limitations of the measurement system. For example, "about" can mean a range of up to 20%, up to 10%, up to 5%, and or up to 1% of a given value. The method includes separating a C5 stream from the pygas 101. The C5 fraction is recovered from the pygas by distillation, i.e., in a fractional distillation column. The distillation column is a depentanizer column. The C5 fraction can include aliphatic and aromatic hydroc