Sulfuric acid using copper electrocatalyst
copper sulfate solution and copper metal are placed in a cell with an inert counter electrode. The copper must be placed at the bottom flat.
First a positive potential is applied to the copper and enough current is applied that the copper bubbles oxygen gas. As this happens it will generate
copper hydroxide. When the solution has a dense composition of copper hydroxide, sulfur dioxide is bubbled into the solution which will generate
additional copper sulfate and various reduced copper forms including copper particles, copper (I) oxide nanopowders and copper sulfate. The current is
continually applied to keep oxidizing the reduced copper through the action of the bubbles coming off the copper. Eventually the sulfur dioxide runs
out, when it does the current is reversed, but applied at a much lower level so there is no bubbling at the copper surface. The oxidized copper ions
are reduced at the surface and rebuild the surface of copper. Any other forms of reduced copper are reincorporated back into the surface. Eventually
the solution will clear and leave nothing but pure water and sulfuric acid. Most of the solution is removed and the water boiled off to generate
sulfuric acid. The remaining sulfuric acid is left in the cell and the water level refilled to the top.
The cycle is repeated by applying a positive potential to the copper and regenerating the copper hydroxide.
This process is extremely slow but is a clean way of making sulfuric acid. |