The performance of natural zeolites in a catalytic converter to reduce the emission contents of diesel engine was studied in this research. Diesel engines are engines that use a high compression ratio to carry out a combustion process that will produce high contents of carbon monoxide (CO), nitrogen oxides (NOx), and sulfur oxide (SO2) in diesel engine exhaust gases. One solution to reduce the contents of exhaust gas compounds in diesel engines is to use catalytic converter technology. In this study, the catalytic converter used natural zeolite as an emission filter. The catalytic converter was designed in the form of a pipe made from iron plates and hollow balls that were used as natural zeolite holders. A diesel engine emission test was conducted using a gas analyzer with engine speed variations. The results show the highest reduction efficiency in the emission contents of diesel engine (carbon monoxide (CO), nitrogen oxides (NOx), and sulfur dioxide (SO2)) of 46.14%, 22.77%, and 90.56%, respectively.

The emission of nitrogen oxide (NOx), nitrogen monoxide (NO) and carbon monoxide (CO) from vehicle exhaust gas generates an adverse effect to the environment as well as the human health. Therefore, the need to reduce such emission is urgent. The decrease of the emission can be achieved through the use of catalytic converter. This study explains the application of catalytic converter prepared from activated carbon to enhance the activity through its adsorption ability. The activated carbon was derived from banana peels after heating them up at 400 ºC for 1.5 hours and activation using natrium hydroxide (NaOH). Several techniques including N2 adsorption-desorption, X-Ray Diffraction (XRD), Scanning Electron Microscopy-Electron Dispersive X-ray (SEM-EDX), and Fourier Transform Infrared (FTIR) were adopted to characterize the activated carbon properties. The activated carbon formed was then coated with copper. The activity of the catalytic converter using activated carbon coated with copper was then tested for its performance on diesel engine Yanmar TF 70 LY-DI with variations in the number of catalyst layers, namely 1 layer (C1), 2 layers (C2) and 3 layers (C3). Sample with three layers (C3) of catalyst exhibited the highest activity with the percentage efficiency in reducing emissions concentration of 48.76 %; 31.27 % and 29.35 % for NOx, NO and CO, respectively.