Olefin recovery in a polyolefin production process

• US 6,593,506 B1
• Filed: 10/12/2000
• Issued: 07/15/2003
• Est. Priority Date: 10/12/2000
• Status: Expired due to Fees

• Current Assignee: ExxonMobil Chemical Patents Inc. (Exxon Mobil Corporation)
• Original Assignee: ExxonMobil Chemical Patents Inc. (Exxon Mobil Corporation)
• Inventors: Searle, Ronald G.
• Primary Examiner(s): Griffin, Walter D.
• Assistant Examiner(s): NGUYEN, TAM M
• Application Number:
  US09/689,363
• Time in Patent Office: 1,006 Days
• Field of Search: 585/638, 585/639, 585/640
• US Class Current: 585/639
• CPC Class Codes: C07C 1/20 starting from organic compounds containing only oxygen atoms as heteroatoms
• CPC Class Codes: C07C 11/02 Alkenes
• CPC Class Codes: C07C 2529/85 Silicoaluminophosphates (SAPO compounds)
• CPC Class Codes: C07C 7/14866 water hydrate formation C07C7/152
• CPC Class Codes: Y02P 30/20 using bio-feedstock
• CPC Class Codes: Y02P 30/40 Ethylene production

Abstract

Disclosed is a method of recovering olefin from purge streams in a polyolefin production process. The method includes reacting a purge stream containing olefin and impurities with water in the presence of a hydrating catalyst to produce an alcohol containing stream. The impurities can include methane, ethane, butylenes, and hydrogen. The alcohol containing stream can be used to produce olefins in an oxygenate to olefin production process.

Claims

1. A method of producing olefins from oxygenates comprising:

converting olefins in a purge stream in a polyolefin production process to an alcohol thereby producing an alcohol containing stream;

mixing an oxygenate feed stream with the alcohol containing stream; and

converting the mixed oxygenate feed stream and alcohol containing stream in the presence of an olefin forming catalyst to form an olefin product stream.

2. A method as claimed in claim 1 wherein the alcohol containing stream contains ethanol or propanol.

3. A method as claimed in claim 1 wherein the oxygenate feed is methanol.

4. A method as claimed in claim 1 wherein the olefin forming catalyst is a silicoaluminophosphate molecular sieve catalyst.

5. A method as claimed in claim 4 wherein the olefin product stream is used to produce polyolefins.

6. A method as claimed in claim 5 wherein impurities are removed during the polyolefin production process in a purge stream.

7. A method as claimed in claim 6 wherein the impurities in the purge stream comprise at least one compound selected from the group consisting of methane, ethane, butylenes, and hydrogen.