A Systems Evaluation on the Effectiveness of a Catalyst Retrofit Program in China

Abstract

A low-cost, rare-earth oxide (REO) catalyst has been recommended as part of China's retrofit program for Chinese carbureted vehicles. This study evaluated: (1) the emission reduction efficiency of the REO catalyst during chassis dynamometer testing on the FTP cycle; (2) the effect that fuel properties had on tailpipe emissions and catalyst efficiency; (3) the importance of vehicle premaintenance as part of a retrofit protocol; and (4) the emission reductions obtained following implementation of the program.Results also show that current in-use Chinese noncatalyst, carbureted vehicles operate excessively rich, resulting in extremely high emissions of CO, gaseous toxic compounds, and other non-methane hydrocarbon species (NMHC). Preretrofit maintenance alone has the potential to reduce these emissions by ∼50%. Dynamometer emission tests showed emissions reductions of >95% for hydrocarbons, CO, and gaseous toxics after retrofit of the REO catalyst. In particular, the relative unit health risk associated with the decrease in emissions of airborne toxic compounds using unleaded Chinese fuel was reduced from 6.33 to 0.30. (Use of low-sulfur California Phase II gasoline rather than current in-use Chinese fuel reduced emissions further.) Following implementation of the program, a followup study showed that in-use emissions benefits were considerably less than anticipated, primarily because of poor quality control at the retrofit service centers, a less aggressive preretrofit maintenance procedure, and unauthorized modification to the recommended retrofit control system. Overall results indicate that a carefully controlled retrofit program using REO catalyst technology can reduce emissions significantly. However, welldefined implementation guidelines, and strict adherence to these guidelines are needed to achieve maximum benefits.

Evaluation of Real-World Gaseous Emissions Performance of Selective Catalytic Reduction and Diesel Particulate Filter Bus Retrofits

“…Emission control systems can be either integrated in the vehicle design phase (OEM) or retrofitted on in-use vehicles . Retrofit emission control efforts have shifted from light-duty petrol vehicles to heavy-duty diesel trucks and buses over time, , as diesel vehicles are the highest contributor of PM and NO x emissions in many urban environments around the world. − …”

Evaluation of the Vehicle Inspection/Maintenance Program in the Metropolitan Area of Mexico City

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