Electrochemical conversion of hydrocarbons

Patent metadata

Field	Value
Publication number	US-10865487-B2
Application number	US-201815910112-A
Country	US
Kind code	B2
Filing date	Mar 2, 2018
Priority date	Oct 31, 2013
Publication date	Dec 15, 2020
Grant date	Dec 15, 2020

Abstract

An electrochemical conversion method for converting at least a portion of a first mixture comprising hydrocarbon to C 2+ unsaturates by repeatedly applying an electric potential difference, V(τ 1 ), to a first electrode of an electrochemical cell during a first time interval τ 1 ; and reducing the electric potential difference, V(τ 1 ), to a second electric potential difference, V(τ 2 ), for a second time interval τ 2 , wherein τ 2 ≤τ 1 . The method is beneficial, among other things, for reducing coke formation in the electrochemical production of C 2+ unsaturates in an electrochemical cell. Accordingly, a method of reducing coke formation in the electrochemical conversion of such mixtures and a method for electrochemically converting carbon to C 2+ unsaturates as well as an apparatus for such methods are also provided.

First claim

What is claimed is:

1. An electrochemical conversion method, comprising:
(a) providing an electrochemical cell, the electrochemical cell comprising a first electrode, a second electrode, and at least one membrane located therebetween;
(b) providing a first mixture comprising >1.0 wt. % hydrocarbon based on the weight of the first mixture to the first electrode of the electrochemical cell;
(c) applying an electric potential to the cell to establish an electric potential difference V 1 , across the cell during a first time interval, the first time interval having a duration τ 1 ;
(d) changing the applied electric potential to (i) establish a second electric potential difference, V 2 , across the cell for a second time interval τ 2 , and (ii) produce C 2+ unsaturates proximate to the first electrode, wherein V 2 is more negative or less positive than V 1 , τ 2 <τ 1 , and τ 1 is in the range of from 1×10 −1 ° sec. to 1.0 sec.; and
(e) repeating steps (c) and (d).

2. The method of claim 1 , wherein step (c) and/or step (d) are carried out in the substantial absence of oxygen, the hydrocarbon is methane, and wherein the process further comprises conducting at least a portion of the C 2+ unsaturates away from the first electrode at a rate >1.0×10 −7 mole min· −1 cm −2 for >100.0 minutes.

3. The method of claim 1 , wherein during at least step (c) the first mixture is exposed to a temperature in the range of from 1.0×10 2 ° C. to 5.0×10 2 ° C. at a pressure in the range of from 0.1 bar to 100.0 bar.

4. The method of claim 1 , further comprising conducting an oxygen-containing mixture to the second electrode during at least step (c), the oxygen-containing mixture comprising ≥10.0 wt. % molecular oxygen, based on the weight of the oxygen-containing mixture, and conducting water away from the second electrode.

5. The method of claim 1 , wherein the first electrode and/or the second electrode comprises ≥1.0 wt. % of at least one noble metal.

6. The method of claim 1 , wherein a current density through the membrane during step (c) achieves a value in the range of from 1.0 mA cm −2 to 100.0 mA cm −2 .

7. The method of claim 1 , wherein V 1 is in the range of from 0.1 to 20 volts.

8. The method of claim 1 , wherein V 1 and V 2 satisfy at least one of: (i) V 1 >0, V 2 >0, and V 2 =A 1 ⋅V 1 , wherein A 1 is in the range of from about 0.00 to about 0.99; (ii) V 1 ≥0 and V 2 <0; or (iii) V 1 <0, V 2 <0, and |V 2 |=A 2 |V 1 |, wherein A 2 ≥1.01.

9. The method of claim 1 , wherein τ 2 is in the range of from 0.01 ⋅τ 1 to 0.9⋅τ 1 .

10. The method of claim 1 , further comprising a step of oligomerization, polymerization, hydroxylation, or hydrogenation of at least a portion of the C 2+ unsaturates.

11. The method of claim 1 , wherein, the first electrode is an anode and the second electrode is a cathode.

12. The method of claim 1 , wherein applying an electric potential to the cell includes applying an external positive voltage to the first electrode.

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Weissman Walter
• Raman Sumathy
• Greaney Mark A

Classifications

• B01D53/326 Primary

  in electrochemical cells · CPC title

• C25B3/29

  Coupling reactions · CPC title

• C25B3/25 Primary

  Reduction · CPC title

• C25B3/23

  Oxidation (halogenation C25B3/27) · CPC title

• B01D2257/7022

  Aliphatic hydrocarbons · CPC title