Copper coated kitty litter

Cat litter boxes are stinky due to volatile sulfur-containing decomposition products of cat waste. Probably in nature these products help cats mark territory. In the home, they just stink.

Reduced sulfur compounds can be treated with oxidation, which kills the associated odors. This process can be catalyzed by copper ions (citation 1). In the petrochemical industry, molecules with reduced sulfur are removed by oxidation catalyzed by copper catalysts. Rather than invent something new for use in kitty litter, products currently on the shelf for this use could be added to kitty litter. These products would already be optimized for cost, surface area, toxicity and other properties all desirable in a kitty litter. Citation 2 is a link to a product brochure for the PERCO copper catalyst, which already has a more than passing resemblance to kitty litter to my eye. It is provided as an example of a commercial copper catalyst; there may be others better suited for the kitty litter application. I called and learned the PERCO copper catalyst costs $2.50/lb when bought in bulk which to me looks reasonable. One would do experiments to find the optimal ratio of catalyst to conventional kitty litter or filler.

An alternative would be to simply dope an existing kitty litter product with a solution of liquid copper sulfate then bake it dry. I suspect the PERCO product is probably something very like this. A zeolite type kitty litter would absorb the copper and so function as described above, in addition to the other advantages of zeolite litter. This would be very cheap and easy to test.

In addition to oxidizing sulfur molecules, an added benefit to the use of copper for kitty litter is that copper ion has strong antimicrobial properties, a quality which has been recognized and applied for over a century (citation 3). The presence of copper ion dissolved by the passage of cat urine should decrease the microbial propulations whose metabolism is responsible for the generation of malodorous sulfides.

As fortune would have it, in the months since devising this idea a cat has arrived at our house. I got to experience kitty litter smell for the first time and remembered this scheme. Preliminary tests (copper sulfate solution sprayed on litter during gentle mixing with trowel, no baking) suggest that it works well to reduce odor. Copper sulfate was obtained at HomeDepot where it is marketed as root killer. Cat seems healthy. I invite other bakers to give it a try and submit their results.