Process for the preparation of an olefinic product from an oxygenate

Patent metadata

Field	Value
Publication number	US-9878963-B2
Application number	US-201314655345-A
Country	US
Kind code	B2
Filing date	Dec 24, 2013
Priority date	Dec 28, 2012
Publication date	Jan 30, 2018
Grant date	Jan 30, 2018

Abstract

The invention relates to process for the preparation of an olefinic product comprising ethylene and/or propylene from an oxygenate, the process comprising the following steps: a) an oxygenate conversion step wherein a gaseous effluent comprising olefins and a water-soluble oxygenate is obtained; b) separation of water from the effluent; c) compression of the effluent; d) acid gas removal from the compressed gaseous effluent obtained in step c), wherein the compressed gaseous effluent is treated with a caustic solution in a caustic tower; and e) separating the olefinic product from the gaseous effluent treated in step d), wherein, in a final stage in the caustic tower, water-depleted compressed gaseous effluent is treated with a water stream that is essentially free of water-soluble oxygenate and a spent water stream comprising caustic and water-soluble oxygenate is obtained, which spent water stream is withdrawn from the process.

First claim

That which is claimed is:

1. A process for the preparation of an olefinic product comprising ethylene and/or propylene from an oxygenate, the process comprising the following steps:
a) contacting an oxygenate feedstock in an oxygenate conversion reaction zone with a molecular sieve-comprising catalyst at a temperature in the range of from 350 to 1000° C. to produce an oxygenate conversion effluent comprising olefins, water, carbon dioxide, unconverted oxygenate and oxygenate byproduct, wherein the unconverted oxygenate or the oxygenate byproduct is a water-soluble oxygenate;
b) separating water from the oxygenate conversion effluent to obtain a water-depleted gaseous oxygenate conversion effluent comprising olefins, carbon dioxide, unconverted oxygenate and oxygenate byproduct;
c) compressing the water-depleted gaseous effluent with the optional removal of any condensed phase to obtain a compressed water-depleted gaseous stream comprising olefins and carbon dioxide;
d) treating the compressed gaseous stream in a caustic tower, wherein the compressed gaseous stream is first countercurrently contacted with a caustic solution in one or more stages in series and is then countercurrently washed with a water stream in a final stage to obtain a washed gaseous stream comprising olefins; and
e) subjecting the washed gaseous stream to one or more separation steps such that at least an olefin product stream comprising ethylene and/or propylene is obtained,

wherein, in the final stage of the caustic tower, the water stream is a water stream that is essentially free of water-soluble oxygenate and a spent water stream comprising caustic and water-soluble oxygenate is obtained, which spent water stream is withdrawn from the process in the final stage.

2. A process according claim 1 , wherein the unconverted oxygenate or the oxygenate byproduct in the oxygenate conversion effluent is a water-insoluble oxygenate and the process further comprises the following step:
f) washing the water-depleted gaseous effluent or the compressed water-depleted gaseous stream with a water-soluble oxygenate to obtain a gaseous stream depleted in the water-insoluble oxygenate, the gaseous stream comprising olefins, carbon dioxide, and the water-soluble oxygenate used for washing.

3. A process according to claim 2 , wherein the water-insoluble oxygenate is dimethylether and the water-soluble oxygenate used for washing is methanol.

4. A process according to claim 1 , wherein the oxygenate feedstock comprises methanol.

5. A process according to claim 4 , wherein the oxygenate feedstock consists essentially of methanol.

6. A process according to claim 1 , wherein the oxygenate feedstock comprises dimethylether.

7. A process according to claim 1 , wherein the water stream that is essentially free of water-soluble oxygenate is an external water stream.

8. A process according to claim 1 , wherein the water stream that is essentially free of water-soluble oxygenate is boiler feed water.

9. A process according to claim 1 , wherein the process does not comprise washing the gaseous stream with water upstream of the caustic tower.

Assignees

• Shell Oil Co

Inventors

• Kloth Antonius Gijsbertus Johannes
• Vijayakumari Sivakumar Sadasivan
• Van Westrenen Jeroen

Classifications

• Y02P30/42

  Cross-Sectional Technologies · mapped topic

• C07C11/04

  Ethene · CPC title

• C07C2529/00

  Catalysts comprising molecular sieves · CPC title

• C07C7/005

  Processes comprising at least two steps in series · CPC title

• C07C11/06

  Propene · CPC title