Controlling Lubricant-Derived Phosphorous Deactivation of the Three-Way Catalysts Part 2: Positive Environmental Impact of Novel ZDP Technology

Prior technical work by various OEMs and lubricant formulators has identified lubricant-derived phosphorus as a key element capable of significantly reducing the efficiency of modern emissions control systems of gasoline-powered vehicles ( 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ). However, measuring the exact magnitude of the detriment is not simple or straightforward exercise due to the many other sources of variation which occur as a vehicle is driven and the catalyst is aged ( 1 ).

This paper, the second one in the series of publications, examines quantitative sets of results generated using various vehicle and exhaust catalyst testing methodologies designed to follow the path of lubricant-derived phosphorous transfer from oil sump to exhaust catalytic systems ( 1 ). Data discussed include a survey of TWC technologies used currently by the passenger car and light duty truck market, catalyst compatibility testing, paired vehicle dynamometer tests, field trials and life cycle analysis. Finally, post-mortem analysis of aged catalysts is used to both quantify the level of phosphorus exposure from the oil as well as estimate the loss of performance resulting from phosphorus deposition within the catalyst. Results reveal a significant and beneficial impact of reduced lubricant-derived phosphorus exposure on the life and efficiency of various three-way catalyst technologies when utilized in numerous vehicle types and driving cycles. A novel statistical model was developed which provides a quantitative measure of the effect of lubricant-derived phosphorous contamination of TWC. The overall environmental benefits of the specific motor oil formulations in this study with the novel ZDP versus conventional ZDP are clearly defined by means of the life cycle analysis (LCA).