Electrochemical conversion of hydrocarbons

Patent metadata

Field	Value
Publication number	US-9932679-B2
Application number	US-201414516934-A
Country	US
Kind code	B2
Filing date	Oct 17, 2014
Priority date	Oct 31, 2013
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

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. A method of reducing coke formation in the electrochemical production of C 2+ unsaturates in an electrochemical cell comprising a first electrode, a second electrode, and at least one membrane situated between the first and second electrodes, the method comprising:
(a) providing to the first electrode of the electrochemical cell a first mixture comprising≥1.0 wt. % methane based on the weight of the first mixture;
(b) applying an electric potential difference to the electrochemical cell to establish a first electric potential V 1 across the electrochemical cell sufficient to convert at least a portion of the methane during a first time interval of duration τ 1 , wherein (i) the conversion is carried out substantially without oxidant, and (ii) τ 1 is in the range of from 1×10 −10 sec. to 1.0 sec.;
(c) establishing a second electric potential difference V 2 across the cell during a second time interval of duration τ 2 , wherein τ 2 ≤τ 1 ; and
(d) repeating steps (b) and (c), and at least during step (c) producing C 2+ unsaturates.

2. The method of claim 1 , further comprising 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 step (c) the first mixture is exposed to a temperature in the range of from 100° C. to 500° C. at a pressure in the range of from 0.1 bar to 100.0 bar.

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

5. The method of claim 1 , wherein the 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 .

6. The method of claim 1 , wherein V 1 achieves a value in the range of from 0.1 Volts to 20 Volts during step (b).

7. 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; (iii) V 1 <0, V 2 <0, and |V 2 |=A 2 |V 1 |, wherein A 2 ≥1.01; (iv) V 2 is more negative or less positive than V 1 ; or (v) V 1 ≥0, and |V 2 |<|V 1 |.

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

9. 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.

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Weissman Walter
• Raman Sumathy
• Greaney Mark A

Classifications

• C08F2/00

  Processes of polymerisation · CPC title

• C25B15/02

  Process control or regulation · CPC title

• C25B3/04 Primary

  Chemistry & Metallurgy · mapped topic

• B01D2257/7022

  Aliphatic hydrocarbons · CPC title

• C07C29/04

  by hydration of carbon-to-carbon double bonds · CPC title