Chemistry of hydrocarbon compounds – Unsaturated compound synthesis – From nonhydrocarbon feed
Reexamination Certificate
2000-10-12
2003-07-15
Griffin, Walter D. (Department: 1764)
Chemistry of hydrocarbon compounds
Unsaturated compound synthesis
From nonhydrocarbon feed
C585S638000, C585S640000
Reexamination Certificate
active
06593506
ABSTRACT:
FIELD OF INVENTION
This invention relates to recovering ethylene from a polyethylene production process. In particular this invention relates to recovering ethylene from a polyethylene production process, converting the ethylene to ethanol, and converting the ethanol to olefin.
BACKGROUND OF THE INVENTION
Ethylene is one of the most important raw materials for organic chemical production. The present world demand for ethylene is about 80 million tons per year, with 57% of this demand attributable to the polyethylene industry. The preparation of polyethylene typically requires a highly purified ethylene raw material. An ethylene monomer concentration of 99.9 mole % is typically required for polyethylene production.
High purity olefin monomer is required throughout most polyolefin polymerization processes. During the typical olefin polymerization process, olefin monomer is charged to a reactor where some of the olefin monomer reacts to form polyolefins. Unreacted olefin monomer is recycled back into the reactor. Impurities in the monomer, such as methane, ethane, butylenes, and hydrogen can build up in the recycle stream requiring that a percentage of the recycle stream be purged.
The purge stream contains a high percentage of valuable olefin monomer, and recovery of this monomer is important for both economical and environmental reasons. However, the separation of impurities from light olefins such as ethylene and propylene typically requires expensive cryogenic distillation techniques.
Alternative techniques that do not require cryogenic temperatures have been explored. Dembicki et al. U.S. Pat. No. 4,623,704 discloses the use of membranes to recover the ethylene enriched gas in a polyethylene process. Mehra et al. U.S. Pat. No. 5,681,908 discloses an absorption process for the recovery of monomers in olefin polymerization processes.
The U.S. Environmental Protection Agency currently has a program to develop a process for recovering ethylene without the need for low process temperatures and with higher selectivities for purge stream impurities than offered by polymeric membranes.
Therefore, a need exists, for recovery of olefin, e.g., ethylene and propylene, during the polyolefin manufacturing process in order to reduce the loss of olefins. In particular, it is highly desirable to recover olefins in a highly pure and cost effective manner.
SUMMARY OF THE INVENTION
In order to recover olefins from a purge stream in a polyolefin production process, this invention provides for hydrating olefins in a purge stream to produce alcohols. The alcohol, after being separated from impurities in the purge stream, can then be used to make olefin products.
In one embodiment, the invention provides a method of purifying an olefin containing purge stream. The method comprises reacting a purge stream containing olefin and impurities with water in the presence of a hydrating catalyst to produce an alcohol containing stream. The alcohol from the alcohol containing stream is contacted with an olefin forming catalyst to form an olefin product stream.
Preferably, the impurities in the purge stream comprise at least one compound selected from the group consisting of methane, ethane, butylenes, and hydrogen. Preferably, the hydrating catalyst is a supported phosphoric acid catalyst. Preferably, the olefin forming catalyst is a silicoaluminophosphate molecular sieve catalyst. Preferably, the alcohol containing stream contains ethanol or propanol. Preferably, the reaction of a purge stream containing olefin and impurities with water in the presence of a hydrating catalyst is performed at a temperature of 180° C. to 300° C. and a pressure of 350 psig to 1000 psig.
In another embodiment, the invention provides a method of producing olefins from oxygenates. The method comprises mixing an oxygenate feed stream with an alcohol containing stream, the alcohol containing stream produced from a purge stream in a polyolefin production process. The mixed oxygenate and alcohol feed stream is converted in the presence of an olefin forming catalyst into an olefin product stream.
This invention will be better understood by reference to the Detailed Description of the Invention when taken together with the attached FIGURE and the appended claims.
REFERENCES:
patent: 2936303 (1960-05-01), Goins
patent: 3258455 (1966-06-01), Natta et al.
patent: 3305538 (1967-02-01), Natta et al.
patent: 3364190 (1968-01-01), Emrick
patent: 3450777 (1969-06-01), Mizutani et al.
patent: 3452106 (1969-06-01), Sato et al.
patent: 3635803 (1972-01-01), Binns et al.
patent: 3645992 (1972-02-01), Elston
patent: 3758615 (1973-09-01), Izumi et al.
patent: 3957448 (1976-05-01), Shepard et al.
patent: 3965083 (1976-06-01), Jezl et al.
patent: 3971768 (1976-07-01), Peters et al.
patent: 4008290 (1977-02-01), Ward
patent: 4012456 (1977-03-01), Chaplits
patent: 4041095 (1977-08-01), Kuo
patent: 4046822 (1977-09-01), Severino
patent: 4068136 (1978-01-01), Minami
patent: 4076698 (1978-02-01), Anderson et al.
patent: 4101289 (1978-07-01), Jezl et al.
patent: 4172099 (1979-10-01), Severino
patent: 4187278 (1980-02-01), Clifford
patent: 4243691 (1981-01-01), Mohlenkamp, Jr. et al.
patent: 4244892 (1981-01-01), Guseinov et al.
patent: 4263212 (1981-04-01), Hong et al.
patent: 4287091 (1981-09-01), Selman
patent: 4302565 (1981-11-01), Goeke et al.
patent: 4310440 (1982-01-01), Wilson et al.
patent: 4318800 (1982-03-01), Woebcke et al.
patent: 4340769 (1982-07-01), Brandes et al.
patent: 4343957 (1982-08-01), Sartorio et al.
patent: 4404095 (1983-09-01), Haddad et al.
patent: 4419221 (1983-12-01), Castagnos, Jr. et al.
patent: 4426449 (1984-01-01), Geigert et al.
patent: 4433188 (1984-02-01), Hoelderich et al.
patent: 4440871 (1984-04-01), Lok et al.
patent: 4463207 (1984-07-01), Johnson
patent: 4471147 (1984-09-01), Owen et al.
patent: 4474647 (1984-10-01), Asselineau et al.
patent: 4482687 (1984-11-01), Noshay et al.
patent: 4499327 (1985-02-01), Kaiser
patent: 4504691 (1985-03-01), Hsia et al.
patent: 4508842 (1985-04-01), Beran et al.
patent: 4521631 (1985-06-01), Nishimura et al.
patent: 4524229 (1985-06-01), Johnson
patent: 4554392 (1985-11-01), Leuck et al.
patent: 4558167 (1985-12-01), Riegel et al.
patent: 4567029 (1986-01-01), Wilson et al.
patent: 4623704 (1986-11-01), Dembicki et al.
patent: 4629484 (1986-12-01), Kister
patent: 4659685 (1987-04-01), Coleman, III et al.
patent: 4677242 (1987-06-01), Kaiser
patent: 4677243 (1987-06-01), Kaiser
patent: 4710482 (1987-12-01), Job
patent: 4721824 (1988-01-01), McWilliams et al.
patent: 4749817 (1988-06-01), George et al.
patent: 4752651 (1988-06-01), Kaiser
patent: 4861743 (1989-08-01), Flank et al.
patent: 4861939 (1989-08-01), Debras et al.
patent: 4956426 (1990-09-01), Ardell et al.
patent: 4992608 (1991-02-01), Cavani et al.
patent: 5019143 (1991-05-01), Mehrta
patent: 5055627 (1991-10-01), Smith, Jr. et al.
patent: 5068475 (1991-11-01), Schmidhammer et al.
patent: 5096684 (1992-03-01), Guth et al.
patent: 5102841 (1992-04-01), Cann et al.
patent: 5126308 (1992-06-01), Barger et al.
patent: 5144090 (1992-09-01), Honda et al.
patent: 5183936 (1993-02-01), Etzkorn et al.
patent: 5198578 (1993-03-01), Etzkorn et al.
patent: 5235088 (1993-08-01), Paparizos et al.
patent: 5238892 (1993-08-01), Chang
patent: 5240894 (1993-08-01), Burkhardt et al.
patent: 5243115 (1993-09-01), Smith, Jr. et al.
patent: 5243116 (1993-09-01), Lee et al.
patent: 5258543 (1993-11-01), Suresh et al.
patent: 5262575 (1993-11-01), Dianis
patent: 5262576 (1993-11-01), Smith, Jr.
patent: 5274138 (1993-12-01), Keating et al.
patent: 5280074 (1994-01-01), Schreck et al.
patent: 5288473 (1994-02-01), Shaw et al.
patent: 5300707 (1994-04-01), Caillod et al.
patent: 5326465 (1994-07-01), Yongqing et al.
patent: 5326929 (1994-07-01), Mehra et al.
patent: 5349072 (1994-09-01), Preston et al.
patent: 5364915 (1994-11-01), Benham et al.
patent: 5432243 (1995-07-01), Bodart
patent: 5504166 (1996-04-01), Buchelli et al.
patent: 5523502 (1996-06-01), Rubin
patent: 5608123 (1997-03-01), Inoue et al.
patent: 5609734 (1997-03-01), Streicher e
ExxonMobil Chemical Patents Inc.
Griffin Walter D.
Lavoie Paul T.
Nguyen Tam Minh
LandOfFree
Olefin recovery in a polyolefin production process does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Olefin recovery in a polyolefin production process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Olefin recovery in a polyolefin production process will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3107600