Electrocatalytic bio-oil and wastewater treatment
An anode, a flow cell including the anode, and a method for electrocatalytic treatment of bio-oil and/or wastewater are disclosed. The anode comprises RuO 2 particles on a titanium support. The method includes flowing a process stream through the flow cell in the absence of added hydrogen, at a temperature of 0° C. to 50° C. and atmospheric pressure, and applying a potential across the flow cell such that the anode is positive with respect to the cathode, thereby electrocatalytically oxidizing compounds in the process stream to produce a treated process stream at the anode and generating hydrogen gas as a byproduct at the cathode.
1. An anode, comprising:
a titanium support; and
RuO 2 particles deposited directly onto a surface of the titanium support, the RuO 2 particles having an areal electrocatalytic decarboxylation rate to areal oxygen evolution reaction rate ratio of at least 5 and an average size of 12 nm to 40 nm.
2. The anode of claim 1 , wherein the titanium support comprises titanium foil.
3. The anode of claim 1 , further comprising a polymeric coating on the RuO 2 particles, the polymeric coating comprising poly(vinylidene fluoride) or a tetrafluoroethylene polymer.
4. The anode of claim 3 , wherein the tetrafluoroethylene polymer is a copolymer of tetrafluoroethylene and a perfluoro (vinyl ether) monomer comprising a sulfonic acid terminal group.
5. The anode of claim 1 , wherein:
(i) the RuO 2 particles have a specific surface area of 40 m 2 g RuO2 −1 to 100 m 2 g RuO2 −1 ; or
(ii) the anode has an electrochemical surface area of 25 m 2 g RuO2 −1 to 60 m 2 g RuO2 −1 ; or
(iii) both (i) and (ii).
6. The anode of claim 1 , wherein the RuO 2 particles have an areal electrocatalytic decarboxylation rate to areal oxygen evolution reaction rate ratio of at least 10, and an average size of 12 nm to 20 nm.
7. A flow cell, comprising:
an anode according to claim 1 ;
a cathode; and
a separator positioned between the anode and the cathode.
8. The flow cell of claim 7 , wherein the cathode comprises Pd/C or Cu/C.
9. An anode, comprising:
a titanium foil support having a thickness of 0.1 mm to 2 mm; and
RuO 2 particles deposited directly onto a surface of the titanium foil support, wherein
(i) the RuO 2 particles have an average size of 12 nm to 20 nm,
(ii) the RuO 2 particles have a specific surface area of 40 m 2 g RuO2 −1 to 100 m 2 g RuO2 −1 ,
(iii) the anode has an electrochemical surface area of 25 m 2 g RuO2 −1 to 60 m 2 g RuO2 −1 ,
(iv) the RuO 2 particles have an areal electrocatalytic decarboxylation rate to areal oxygen evolution reaction rate ratio of at least 10, and
(v) the anode has a RuO 2 loading on the titanium foil support of 0.5 mg cm −2 geo to 2 mg cm −2 geo .
10. A method, comprising:
flowing a process stream through the flow cell of claim 7 , in the absence of added hydrogen, at a temperature of 0° C. to 50° C. and at atmospheric pressure;
applying a potential across the flow cell such that the anode is positive with respect to the cathode, thereby electrocatalytically oxidizing compounds in the process stream to produce a treated process stream at the anode and generating hydrogen gas as a byproduct at the cathode.
11. The method of claim 10 , wherein the potential is from 2 V to 5 V vs. a reversible hydrogen electrode (RHE).
12. The method of claim 10 , wherein the temperature is 15° C. to 25° C.
13. The method of claim 10 , wherein the anode has:
(i) an areal electrocatalytic decarboxylation rate to areal oxygen evolution reaction rate ratio of at least 5; and
(ii) a hydrocarbon selectivity of at least 20%; both (i) and (ii).
14. The method of claim 10 , wherein:
(i) the process stream comprises a crude bio-oil, wastewater, or a combination thereof; or
(ii) the process stream is provided by hydrothermal liquefaction of a feedstock; or
(iii) both (i) and (ii).
15. The method of claim 10 , wherein electrocatalytically oxidizing the compounds in the process stream comprises decarboxylating of carboxylic acids, oxidizing nitrogen-containing compounds, oxidizing sulfur-containing compounds, or any combination thereof.
16. The method of claim 10 , wherein the process stream comprises organic compounds and electrocatalytically oxidizing the organic compounds produces aliphatic compounds, ketones, esters, alcohols, or a combination thereof.
17. The method of claim 16 , wherein the aliphatic compounds comprise C1-C8 aliphatic compounds, the method further comprising:
separating the C1-C8 aliphatic compounds from the treated process stream; and
using at least a portion of C1-C8 aliphatic compounds to generate heat.
18. The method of claim 10 , further comprising using at least a portion of the hydrogen gas to generate electricity.
19. The method of claim 10 , wherein the process stream comprises a crude bio-oil, the method further comprising using at least a portion of the hydrogen gas in a subsequent catalytic hydrotreatment of the treated process stream.
20. The method of claim 10 , wherein the process stream comprises wastewater and electrocatalytically oxidizing compounds in the process stream produces hydrocarbons and gases, the method further comprising:
separating the gases and the hydrocarbons from water in the treated process stream;
utilizing at least a portion of the hydrocarbons to generate heat; and
recycling at least a portion of the water to a hydrothermal liquefaction process.