ASSESSING CATALYTIC CONVERTER DEGRADATION IN EMISSION REDUCTION: COMPARATIVE STUDY OF CO, THC, AND NOx ACROSS MILEAGE, ENGINE CAPACITY, AND TRANSMISSION TYPE

Environmental problems are a global concern, prompting all countries to implement increasingly strict emission regulations. For motorized vehicles with combustion engines, exhaust emissions are a primary concern. Catalytic converters in gasoline-powered cars are designed to reduce emissions of carbon monoxide (CO), total hydrocarbons (THC), and nitrogen oxides (NOx) throughout the vehicle's operational lifespan. This study evaluates the emission performance of various catalytic converter types after prolonged use. In this study, a comprehensive analysis was performed on 20 passenger vehicles from different models, such as AMPV, BMPV, SUV, and Van that varied in catalytic converter type, engine capacity, transmission model, and mileage. Emission tests were conducted using the New European Driving Cycle (NEDC) method to assess compliance with both Indonesian regulations and EURO-4 standards. This study presents differences in performance between types of catalytic converters regarding CO, THC, and NOx emissions. In particular, type D catalytic converters exhibited the lowest CO emissions, while type B showed higher average CO and NOx emissions compared to the other types. Analysis of variance (ANOVA) statistically showed across all converter types significant differences in THC emissions (p < 0.05), but no significant differences in CO and NOx emissions (p > 0.05). We found that catalytic converter Type D performed better in reducing CO and THC emissions, although it did not significantly reduce NOx emissions compared to other types. Consequently, Type D is recommended for optimal emission reduction. Conversely, Type B requires further investigation due to its higher emission levels over time. Materials like alumina, cerium oxide, and zirconia are typically used in wash coats to improve catalytic oxidation and reduce THC emissions. The exact impact on THC reduction depends not only on the choice of wash coat material but also on the catalyst formulation and engine conditions. Enhanced performance can be achieved by combining these materials with the appropriate active metals, optimizing conditions for hydrocarbon oxidation. Future research should explore the performance of catalytic converters concerning the detailed composition and structure of the substrate material and wash coat. Additionally, vehicle operational variables and periodic maintenance should be considered as factors that influence performance.