Appendix D.   Construction of a Catalytic Converter  from a Used Automotive Catalyst

     An alternative catalytic device as shown in the above figure can be constructed from a used automobile catalytic converter.  The catalyst is coated onto either a brittle ceramic honeycomb material or onto beads.  The honeycomb form is required for these experiments.  The device can be constructed as follows.  A machine shop can cut the converter apart with the use of a band saw or equivalent.  Pieces should be cut into segments of about 1 x 1 x 5 cm as shown in the figure.  The honeycomb ceramic material is fairly brittle.  You will also need two 4-cm lengths of 5-mm diameter glass tubing, epoxy glue, and a plastic bag.

    With a 5-mm (3/16-inch) drill bit, bore a 6-mm deep hole into the center of each end of the honeycomb.  Clean up all dust with a moist paper towel as it contains heavy metals.  Cut two 3 x 3-cm squares of polyethylene from a plastic bag.  Make a small hole in the center of the plastic square with a pencil and then poke one of the pieces of glass tubing through the hole.  Only 5-mm of the tubing should protrude through the plastic square.  Make a 2-cm diameter mound of freshly mixed epoxy glue on the plastic square around the base of the glass tubing — be careful not to get glue inside the glass tubing.  Slip the honeycomb onto the glass tubing and into the glue.  The glue should fill all of the holes in the end of the honeycomb.  To prevent the glue from seeping into the honeycomb, keep the device positioned with the honeycomb on top of the tubing until the epoxy hardens.  After the first piece of glass tubing has hardened, repeat with the other tubing.  Allow the apparatus to cure for at least a day or two before use.
 
    Test for leaks:  Lubricate two syringes with plenty of silicone oil.  The plungers must move freely.  Use two short pieces of latex tubing to connect the syringes, one empty and one filled with air, to the two ends of the catalytic converter.  Push air back and forth through the catalyst.  No volume loss should occur.  Locate leaks at the ends of the honeycombed with a cotton swab soaked with soapy water — bubbles will appear when air is pushed through the converter.