The cost of platinum and rhodium in the three-way catalyst accounts for a major fraction of the cost associated with the treatment of automotive exhaust. Therefore, striving to achieve a higher level of pollutant removal by increasing the platinum and rhodium contents in the way catalyst is not economically attractive. In this, an alternative method for achieving a higher level of pollutant removal is proposed, in which by using yttria-stabilized-zirconia (YSZ) as the support material, instead of alumina at the present time, the activity of the three-way catalyst can be nearly doubled. In Phase I of the proposed study, the magnitude of the beneficial effects of YSZ as a support material will be studied. Phase II of the study will be devoted to the development of a converter in the form of a washcoated layer of YSZ on a conrdierite monolith, with the platinum and rhodium crystallite deposited in the YSZ layer.It is anticipated that this work will lead to the development of an improved three-way catalyst for the treatment of automobile exhaust. The catalyst will achieve a substantially higher level of pollutant removal for the same concentration of active metals. Furthermore, the oxygen-ion conductive supports which is responsible for the enhanced performance of the new catalyst, will be used only sparingly, Consequently, the new catalyst will cost essentially the same as the currently-used three-way catalysts. Hence, the new catalyst is expected to be readily marketable.
