Method of preparing electrocatalysts for converting carbon dioxide to chemicals
View Patent ↗Electrocatalysts composed of single atoms or metal clusters dispersed over porous carbon support were prepared by a lithium-melt method. The new catalysts demonstrated high selectivity, high Faradic efficiency and low overpotential toward to the electrocatalytic reduction of carbon dioxide to chemicals such as glycerol or isopropanol.
1 . A method of synthesizing a catalyst comprising:
adding a catalytic metal selected from the group consisting of Sn and Cu in its metallic form to molten lithium metal, wherein a ratio of Cu to Li ranges from 0.5% to 2% or the relative ratio of Sn to Li ranges from 4% to 40%;
atomically dispersing the catalytic metal in the molten lithium metal;
forming a lithium catalytic metal-solid;
converting a portion of lithium in the lithium catalytic metal solid to lithium hydroxide forming a catalytic metal-lithium hydroxide solid;
mixing said catalytic metal-lithium hydroxide solid with a conductive support material to form a mixture, the conductive support material being carbonaceous with a porous network and having catalytic metal decorated throughout the porous network with a specific surface area of 1200 to 2000 m 2 /g;
removing lithium hydroxide from the mixture leaving a mixture of catalytic metal and the conductive support material; and
drying the mixture of catalytic metal and the conductive support material to produce the catalyst containing the catalytic metal atomically dispersed over the conductive support material.
2 . The method of claim 1 , wherein converting the portion of the lithium-catalytic metal solid to catalytic metal-lithium hydroxide solid comprises reacting lithium in the lithium catalytic metal solid with moist air.
3 . The method of claim 2 , further comprising mixing the catalytic metal-lithium hydroxide solid with the conductive support material using a mechanical method.
4 . The method of claim 1 , wherein the molten lithium metal has a temperature of 300° C. or less.
5 . The method of claim 1 , wherein removing the lithium hydroxide comprises a drop-wise washing of the catalytic metal-lithium metal hydroxide solid with water thereby removing lithium.
6 . The method of claim 5 , wherein the washing comprises forming an alkaline water solution and modifying the carbonaceous support with oxygenated species serving as anchoring sites for the catalytic metal.
7 . The method of claim 1 , wherein the catalytic metal comprises Cu.
8 . The method of claim 1 , wherein a loading range for the catalytic metal on the conductive support material is 0.2 wt % to 20 wt %.
9 . The method of claim 8 , wherein the loading range is 0.2 wt % to 1 wt %.
10 . The method of claim 8 , wherein the loading range is 0.4 wt % to 2 wt %.
11 . The method of claim 1 , wherein the catalytic metal comprises Sn.
12 . The method of claim 11 , wherein a loading range for the catalytic metal on the conductive support material is 0.5 wt % to 20 wt %.
13 . The method of claim 11 , wherein the loading range is 0.5 wt % to 2 wt %.
14 . The method of claim 11 , wherein the loading range is 10 wt % to 20 wt %.
15 . The method of claim 11 wherein the loading range is 10 wt % to 40 wt %.
16 . A process for forming glycerol comprising:
providing a catalyst having catalytic metal, comprising Sn or Cu, atomically dispersed as 0.2 wt % to 20 wt % over a carbonaceous conductive support material having a surface area of 1200-2000 m 2 /g;
exposing carbon dioxide to the catalyst; and
forming glycerol.
17 . The process of claim 16 , wherein the glycerol is formed at a Faradaic efficiency of at least 90%.
18 . A process for forming isopropanol comprising:
providing a catalyst having catalytic metal, comprising Sn atomically dispersed over a carbonaceous conductive support material having a surface area of 1200-2000 m 2 /g;
exposing carbon dioxide to the catalyst; and
forming isopropanol.
19 . The process of claim 18 , wherein the isopropanol is formed at a Faradaic efficiency of at least 80%.