Process for recovering methane from a gas stream comprising methane and ethylene

• US 10,239,013 B2
• Filed: 04/20/2015
• Issued: 03/26/2019
• Est. Priority Date: 04/22/2014
• Status: Expired due to Fees

• Current Assignee: Shell Oil Company (Shell Plc)
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: Sadasivan Vijayakumari, Sivakumar, Sanders, Charles-Edouard, Shah, Vatsal Mukundlal
• Primary Examiner(s): Nguyen, Tam M
• Application Number:
  US15/305,523
• Publication Number:
  US 20170087501A1
• Time in Patent Office: 1,436 Days
• Field of Search: None
• CPC Class Codes: B01D 2253/102 Carbon
• CPC Class Codes: B01D 2253/108 Zeolites
• CPC Class Codes: B01D 2256/245 Methane
• CPC Class Codes: B01D 2257/102 Nitrogen
• CPC Class Codes: B01D 2257/108 Hydrogen
• CPC Class Codes: B01D 2257/502 Carbon monoxide
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2257/7022 Aliphatic hydrocarbons
• CPC Class Codes: B01D 53/047 Pressure swing adsorption
• CPC Class Codes: C07C 11/04 Ethylene
• CPC Class Codes: C07C 7/005 Processes comprising at least two steps in series
• CPC Class Codes: C07C 7/04 by distillation
• CPC Class Codes: C07C 7/12 by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with ion-exchangers
• CPC Class Codes: C07C 9/04 Methane production by treatment of sewage C02F11/04; natural gas, synthetic natural gas C10L3/06
• CPC Class Codes: C07C 9/06 Ethane
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y02P 20/151 Reduction of greenhouse gas [GHG] emissions, e.g. CO2
• CPC Class Codes: Y02P 20/50 Improvements relating to the production of bulk chemicals

Abstract

The invention relates to a process for recovering methane from a gas stream comprising methane and ethylene, comprising a sorption step which comprises contacting the gas stream comprising methane and ethylene with a sorption agent which has a lower affinity for methane than for ethylene, resulting in sorption of ethylene and 0 to 90% of the methane by the sorption agent and in a gas stream comprising methane in an amount of 10 to 100% based on the amount of methane in the gas stream that is subjected to the sorption step; and a desorption step which comprises desorbing sorbed ethylene and optionally sorbed methane resulting in a gas stream comprising ethylene and optionally methane.

Claims

1. A process for recovering methane from a gas stream comprising methane and ethylene, comprising:

a sorption step which comprises contacting the gas stream comprising methane and ethylene with a sorption agent which has a lower affinity for methane than for ethylene, resulting in sorption of ethylene and 0 to 25% of the methane by the sorption agent and in a methane gas stream comprising methane in an amount of 75 to 100% based on the amount of methane in the gas stream that is subjected to the sorption step; and

a desorption step which comprises desorbing sorbed ethylene and sorbed methane resulting in a gas stream comprising ethylene and methane,

a distillation step which comprises distilling the gas stream comprising ethylene and methane resulting from the desorption step, said distillation step resulting in a top stream comprising methane and a bottom stream comprising ethylene,

wherein the gas stream that is subjected to the sorption step is derived from an oxidative coupling of methane process.

2. A process according to claim 1, wherein the gas stream that is subjected to the sorption step comprises of 50 to 99 mol % of methane and 1 to 50 mol % of ethylene.

3. A process according to claim 1, wherein desorption in the desorption step is effected by reducing the pressure.

4. A process according to claim 3, wherein the pressure in the sorption step is in the range of from 5 to 15 bar, and the pressure in the desorption step is in the range of from 0.1 to 3 bar.

5. A process according to claim 1, wherein the gas stream comprising methane and ethylene that is subjected to the sorption step additionally comprises hydrogen, optionally nitrogen, carbon monoxide, carbon dioxide, ethane and hydrocarbons having 3 or more carbon atoms, which process comprises:

a sorption step which comprises contacting the gas stream comprising methane, ethylene, hydrogen, optionally nitrogen, carbon monoxide, carbon dioxide, ethane and hydrocarbons having 3 or more carbon atoms with a sorption agent which has a lower affinity for methane, hydrogen, nitrogen and carbon monoxide than for carbon dioxide, ethane, ethylene and hydrocarbons having 3 or more carbon atoms, resulting in sorption of hydrocarbons having 3 or more carbon atoms, ethane, ethylene, carbon dioxide and 0 to 25% of the methane by the sorption agent and in a gas stream comprising hydrogen, optionally nitrogen, carbon monoxide and methane wherein the amount of methane in said gas stream is 75 to 100% based on the amount of methane in the gas stream that is subjected to the sorption step; and

a desorption step which comprises desorbing sorbed carbon dioxide, ethylene, ethane and hydrocarbons having 3 or more carbon atoms and sorbed methane resulting in a gas stream comprising carbon dioxide, ethylene, ethane, hydrocarbons having 3 or more carbon atoms and methane.

6. A process according to claim 5, wherein the gas stream that is subjected to the sorption step comprises 40 to 90 mol % of methane, 0.5 to 45 mol % of ethylene, 0.01 to 3 mol % of hydrogen, 0 to 80 mol % of nitrogen, 0.1 to 5 mol % of carbon monoxide, 5 to 25 mol % of carbon dioxide, 0.1 to 25 mol % of ethane and 0.5 to 20 mol % of hydrocarbons having 3 or more carbon atoms.

7. A process according to claim 5, additionally comprising a distillation step which comprises distilling the gas stream comprising hydrogen, nitrogen, carbon monoxide and methane resulting from the sorption step, said distillation step resulting in a top stream comprising hydrogen, nitrogen and carbon monoxide and a bottom stream comprising methane.

8. A process according to claim 5, additionally comprising a carbon dioxide removal step which comprises removing carbon dioxide from the gas stream comprising carbon dioxide, ethylene, ethane, hydrocarbons having 3 or more carbon atoms and optionally methane resulting from the desorption step, resulting in a gas stream comprising ethylene, ethane, hydrocarbons having 3 or more carbon atoms and methane.

9. A process according to claim 8, wherein the sorption step results in sorption of hydrocarbons having 3 or more carbon atoms, ethane, ethylene, carbon dioxide and part of the methane by the sorption agent, which process additionally comprises a distillation step which comprises distilling the gas stream comprising ethylene, ethane, hydrocarbons having 3 or more carbon atoms and methane resulting from the carbon dioxide removal step, said distillation step resulting in a top stream comprising methane and a bottom stream comprising ethylene, ethane and hydrocarbons having 3 or more carbon atoms.

10. A process according to claim 9, additionally comprising a distillation step which comprises distilling a gas stream comprising ethylene, ethane and hydrocarbons having 3 or more carbon atoms resulting from the carbon dioxide removal step of the process of claim 8 or distilling the bottom stream comprising ethylene, ethane and hydrocarbons having 3 or more carbon atoms resulting from the distillation step of the process of claim 9, said distillation step resulting in a top stream comprising ethylene and a bottom stream comprising ethane and hydrocarbons having 3 or more carbon atoms.