The Effect of Bed Catalyst Design Variation on Catalytic Converter against Exhaust Emission Level of Carbon Monoxide ( CO ) and Hydrocarbon ( HC ) in Gasoline Engine

The increasing motor vehicle in Indonesia causes air pollution. Several gases that arise as pollutants are carbon monoxide (CO), hydrocarbon (HC), nitrogen oxides (NOx). This study aimed to determine the effect of catalyst bed design variation on catalytic converter on exhaust emissions of carbon monoxide and hydrocarbons in gasoline engine. The method used in this study was to compare the level of exhaust emissions with and without application of bed catalyst variation by putting hole on all of bed catalyst part, putting hole on the middle and side of bed catalyst part, and putting hole on the top and bottom part of bed catalyst part. The results showed that the lowest level of CO was on sample without catalyst, with value of 1.6%vol at 1500 RPM. While the result with variation hole on bed catalyst showed that the CO level on of full hole was 3.01%vol at 1500 RPM, hole on the middle and side was 3.19%vol at 1500 RPM, and hole on the top and bottom was 1.93%vol at 1500 RPM. Meanwhile, the lowest decreasing of HC level was found on the sample without catalyst, with the value of 155 ppm at 8000 RPM. Whereas the result with variation hole on the bed catalyst showed that the HC level on full hole variation was 543 ppm at 7500 RPM, hole on the middle and side was 459 ppm at 6500 RPM, and hole on the top and bottom was 509 ppm at 7500 RPM. Copyright © 2018Journal of Mechanical Engineering Science and Technology


I. Introduction
The increasing of motor vehicle in Indonesia caused serious problem such as the increasing of air pollution due to exhaust emission.The air pollutions that resulted by the exhaust emission were carbon monoxide (CO), hydrocarbon (HC), nitrogen oxides (NO x ).Besides that, the added material in the fuel would produce the other pollutants such as sulphur oxide and lead.These pollutants were extremely dangerous, especially for human health and the preservation of nature.Gasoline was hydrocarbon compound, so any hydrocarbons in exhaust result indicated incomplete combustion then discarded along with the residual gas [1]- [3].Hydrocarbon was very harmful to the environment and health.Hydrocarbons which reacted with nitrogen oxide and sunlight formed ozone.In addition, the pollutants contained in exhaust emission of motor vehicle were carbon monoxide (CO).This compound was extremely harmful to human health.This compound was very toxic because it was able to bind with the haemoglobin and inhibited the process of transporting oxygen to tissues.Carbon monoxide bond to 200 times stronger to haemoglobin than oxygen and therefore it become difficult to release it when it had been bond with the blood.One technology that could be used to reduce the level of emissions was making installation of catalytic converter that integrated with the exhaust emission system.Catalytic converter was device which used to control exhaust emissions which placed after the exhaust manifold in the exhaust system [4], [5].Installation of catalytic converters intended to transform the harmful pollutants such as CO, HC, and NO x into harmless gases such as carbon dioxide (CO 2 ), water (H 2 O) and nitrogen (N 2 ) through chemical reaction.The catalyst used was aluminium oxide (Al 2 O 3 ).Aluminium oxide (Al 2 O 3 ) had advantages such as thermal, chemical, and physical properties when compared to some ceramic material, and it was typically used for heat resistance.Because of the stability and strength at high temperatures, aluminium oxide was very appropriate as catalyst material at high temperatures or catalyst supports [6].

II. Methodology
This study was kind of experimental research that involved independent and dependent variables.This study aimed to compare the level exhaust emission with and without application of catalyst bed design variation.The catalyst used was aluminium oxide (Al 2 O 3 ).Aluminium oxide (Al 2 O 3 ) functioned as catalyst exhaust emissions of carbon monoxide and hydrocarbon.Meanwhile, hole plate functioned as the buffer of aluminium oxide (Al 2 O 3 ).Catalyst tube and exhaust neck were made of galvanized plate.The data analysis process was conducted to know how much potential percentage of catalyst bed design variations in reducing exhaust emissions (CO and HC).Data were analysed with descriptive method.

A. Catalyst bed design variations in reducing exhaust emissions of carbon monoxide (CO)
According to Figure 2, it showed the CO level without catalyst was recorded at 1.6%vol at 1500 RPM, and increased into 10.00%vol at 7500 RPM and 8000 RPM.While the application Al 2 O 3 used bed catalyst design variation with full hole showed the CO level was recorded at 3.01%vol at 1500 RPM, and increased into 9.43%vol at 6500 RPM, then decreased into 3.15%vol at 7500 RPM, and increased again into 4.05%vol at 8000 RPM.
Whereas the application Al 2 O 3 used bed catalyst design variation with hole in the middle and side showed that CO level was recorded at 3.19%vol at 1500 RPM, and increased into 10.00%vol at 7000 RPM to 8000 RPM.Then, the application Al 2 O 3 used bed catalyst design variation with hole in the top and bottom showed that CO level was recorded at 1.93%vol at 1500 RPM, and increased into 4.57%vol at 2500 RPM.Then, decreased into 4.62%vol at 3000 RPM.Then, increased again into 10.00%vol at 7500 RPM to 8000 RPM.

B. CO Level at Low Rotation
Figure 3 showed the CO level at low rotation ranged at 1500 RPM to 3500 RPM.According to Figure 3, could be understood that the CO level with application of bed catalyst design variation with full hole was above the line of CO level without using catalyst.
Figure 3 also showed the increasing of CO level was along the increasing of engine rotation.This was due to the mixture of fuel and air that was not ideal at low rotation being the factor that caused the CO level was high at low rotation.The CO level increasing at 2000 RPM to 2500 RPM, this was due to insufficient oxygen during combustion process.Then decreasing CO level was occurred at 2500 RPM to 3500 RPM, this happened because the air flow of exhaust gas into the catalyst inhibited, then causing air flow rate was reduced.This condition was utilized by aluminium oxide to bind the CO exhaust emission.

C. CO Level at Middle Rotation
The CO level was different at the middle rotation that ranged at 4000 RPM to 6000 RPM.The CO level at middle rotation without using catalyst had increased at 4000 RPM to 4500 RPM.Then, increased at 5500 RPM to 6000 RPM.The higher engine rotation, the mixture of fuel and air was also increasing which resulted the increment of CO level.This was in line with previous study, stated that the higher engine rotation, the higher CO level in exhaust emission by using premium, pertalite, and pertamax [7], [8].The CO level increased at 4000 RPM to 5000 RPM while applying bed catalyst design variation with full hole.This happened because the increasing motor power then the mixture of fuel and air was increasing which resulting in increased level of CO [9], [10].Furthermore, the application of bed catalyst design variations with full hole at 5500 RPM to 6000 RPM was decreased from the condition without using catalyst.This was due to the placement of aluminium oxide (Al 2 O 3 ) which was distributed evenly on bed catalyst design variations with full hole that caused the flow of exhaust emissions could be fastened easily by aluminium oxide (Al 2 O 3 ).The use of catalytic converter based on Al 2 O 3 could reduce exhaust emissions of CO level [11].According to Figure 4, the use of bed catalyst design variations with hole at middle and side showed that CO level increased from 4000 RPM to 6000 RPM.Based on observation, the using bed catalyst design variation with hole at middle and side coincided with the line that showed CO level result without catalyst, which meant there was no significant effect on the use of this variation in reducing the CO level.
Based on the Figure 4, the use of bed catalyst design variation with hole at top and bottom showed the increment CO level at 4000 RPM to 5500 RPM.However, line chart of CO level was under condition of CO level without catalyst.This factor was due to the design of bed catalysts that only had semi-circular hole this would inhibit the flow rate of exhaust gas emission, this condition would be utilized by aluminium oxide to bind CO exhaust emission.This meant that the used of this design variation with aluminium oxide (Al 2 O 3 ) could reduce emission level of CO at middle rotation.This was consistent with the chemical equation, the result of conversion of carbon monoxide (CO) by aluminium oxide (Al 2 O 3 ) was as follows Al 2 O 3(s) + 3 CO (g) 2 Al (s) + 3 CO 2(g).
Based on Figure 4, the used of bed catalyst design variation with full hole showed the CO level decreased at 6500 RPM to 7500 RPM.This was because the catalyst was able to bind at high temperature.Then, the alumina reacted with carbon monoxide (CO) into aluminium and carbon dioxide.Because of the stability and strength at high temperatures, aluminium oxide was very appropriate as catalyst material at high temperatures or catalyst supports [6].Subsequently, at 7500 RPM to 8000 RPM there was increased level of CO.This was due to the aluminium oxide (Al 2 O 3 ) which was wasted at high speed rotation.The residual aluminium oxide (Al 2 O 3 ) after treatment was 0.94 grams or 47% of 2 grams of aluminium oxide.Figure 5 also showed that the use of bed catalyst design variation with hole at the middle and side made the CO level increased at 6500 RPM to 8000 RPM.This was because aluminium oxide (Al 2 O 3 ) come out with exhaust emissions of CO inhibited at low speed and middle rotation due to high pressure of exhaust gases at high temperature.So aluminium oxide (Al 2 O 3 ) could not work optimally, then resulting CO level increased similarly with the condition without catalyst.The residual aluminium oxide (Al 2 O 3 ) after treatment equal to 0.86 grams or 43% of 2 grams of aluminium oxide.
According to Figure 5, the CO level increased at 6500 RPM to 8000 RPM by using bed catalyst design variation with hole at the top and bottom.The back pressure that occurred in the middle rotation caused CO level increased at high rotation speed.Due to the high speed, the pressure emissions would be higher which caused the CO level were inhibited in the middle rotation would drop out.In addition, same with the bed catalyst design variation with hole at middle and side.This design could not reduce the CO level because at high rotation speed, the aluminium oxide (Al 2 O 3 ) be carried out through the exhaust system so that CO level produced were similar to those without catalyst.The residual aluminium oxide (Al 2 O 3 ) after treatment was 0.43 grams or 21.5% of 2 grams of aluminium oxide.

E. Catalyst bed design variations in reducing exhaust emissions of hydrocarbon (HC)
The following data was HC level in different bed catalyst design variation which presented in line chart According to line chart that presented in Figure 6, it could be understood that HC level without application catalyst (Al 2 O 3 ) was recorded at 710 ppm at 1500 RPM, then decreased maximally to 155 ppm at 8000 RPM.While HC level with application Al 2 O 3 using bed catalyst design variation with full hole recorded at 1942 ppm at 1500 RPM, and decreased to 977 ppm at 3500 RPM.Then, increased into1422 ppm at 6000 RPM, and decreased to 938 ppm at 6500 RPM.Then decreased to 596 ppm at 8000 RPM.HC level that recorded by using bed catalyst design variation with hole at middle and side was 1998 ppm at 1500 RPM, and decreased to 721 ppm at 2500 RPM.Then, increased into 1009 ppm at 3500 RPM, then decreased to 997 ppm at 4000 RPM.Then, increased into 1170 ppm at 4500 RPM.Then, decreased to 459 ppm at 6500 RPM, afterward had increased into 548 ppm at 8000 RPM.While HC level with application Al 2 O 3 by using bed catalyst design variation with hole at top and bottom was recorded at 963 ppm at 1500 RPM, and decreased to 801 ppm at 2500 RPM, and increased into 1174 ppm at 4000 RPM.Afterward decreased to 509 ppm at 7500 RPM, then increased into 654 ppm at 8000 RPM.

F. HC Level at Low Rotation
According to Figure 7, the use of bed catalyst design variation with full hole decreased from 1500 RPM to 3500 RPM, which meant aluminium oxide could bind hydrocarbon (HC).However, this variation was still far above the HC level without using catalyst, that meant this variation did not affect the level of HC exhaust emissions significantly.This happened because the engine already hot.Due to this treatment variation was conducted after treatment without catalyst, after application catalyst tube with hole at middle and sides, hole at top and bottom caused high level of HC at low rpm.
Furthermore, by observation after doing research, plug motorbike in dirty condition.Dirty spark plug electrode would inhibit the flow of electricity so that the stepping electricity from the negative electrode to the positive electrode was less then resulted incomplete combustion.This caused incomplete combustion process and hydrocarbon was increasing.Because most of fuel was not burned and wasted with exhaust gases from the combustion.So, when using full hole design, hydrocarbon (HC) was increasing due to the incomplete combustion.Based on Figure 7, the use of bed catalyst design variation with hole at the middle and side showed that HC level decreased at 1500 RPM to 2500 RPM.High level of HC at 1500 RPM due to the rich mixture of fuel and air.Then, leading to decrease level of HC exhaust emission flow was inhibited by the bed catalyst design variation with hole at the middle and side.This condition was utilized by aluminium oxide (Al 2 O 3 ) to bind the HC exhaust emission.The occurrence of problems was called back pressure in exhaust emission [12].Furthermore, there was increment HC level at 2500 RPM to 3500 RPM.It was caused by incomplete combustion.Because the plug in half-dead state that caused increased level of HC.While the use of bed catalyst design variation with hole at top and bottom showed that HC level increased at 2500 RPM to 3500 RPM, this was caused by incomplete combustion resulting in increasing level of hydrocarbon (HC).
According to Figure 8, the use of bed catalyst design variation with full hole showed that HC level increased from 4000 RPM to 6000 RPM.This was caused by incomplete combustion then resulted by the increasing HC level.Moreover, barrier that occurred which accumulated HC in the exhaust neck.This resulted into hot exhaust neck and increased HC level.The fuel split over the hot reaction turned into cluster of other HC emitted together with the exhaust gas [13].
Based on the line chart, the use of bed catalyst design variation with hole at the middle and side showed the HC level decreased at 4500 RPM to 5500 RPM.Decreased level of HC with the use of this design variation was above condition HC level without catalyst.In addition, the engine conditions did not work optimally.This was because the HC exhaust emission inhibited when through this design that made all of HC exhaust emission out through the exhaust system.The occurrence of problem was called back pressure in exhaust emissions [12].Based on the line chart, the use bed catalyst design variation with hole at the top and bottom showed the HC level decreased at 4000 RPM to 6000 RPM.Decreased level of HC with the use of this design variation was above condition HC level without catalyst.This was caused at low rpm, the mixture of fuel and air or AFR (Air Fuel Ratio) was rich that caused HC level increased.Then, the increasing fuel mixture in engine would make the HC level become ideal so that the HC level become lower accordingly.The rich mixture condition, HC level would be higher due to incomplete combustion in cylinder and HC level would be low on the condition of λ = 1.1 to 1.2 [14].

H. HC Level at High Rotation
According to Figure 9, the use of bed catalyst design variation with full hole showed that HC level decreased at 6500 RPM to 7500 RPM.This was caused by the use of pertalite.The higher the engine rotation, the lower HC level produced by pertalite.The higher the engine rotation, the lower HC level [7].Moreover, barrier that occurred in the middle rotation caused the aluminum oxide (Al 2 O 3 ) managed to bind the HC because of the placement of aluminum oxide (Al 2 O 3 ) was evenly distributed on the hole of the catalyst so that the HC levels decreased.Furthermore, HC level increased at 7500 RPM into 8000 RPM.This was because aluminium oxide eroded and wasted through the exhaust due to high pressure.The residual aluminium oxide (Al 2 O 3 ) was 0.94 grams or 47% of 2 grams.Based on the diagram above, the use of bed catalyst design variation with hole at the middle and side showed the increasing HC level at 6500 RPM to 8000 RPM.This was occurred because the hydrocarbon was inhibited at the middle rotation the wasted due to the high pressure at the time of high rotation so that the hydrocarbon level increased.In addition, aluminium oxide (Al 2 O 3 ) was also wasted through the exhaust gas channel for highpressure exhaust gas emissions.The residual aluminium oxide (Al 2 O 3 ) was left at 0.86 grams or 43% of 2 grams.According to Figure 9, the use of bed catalyst design variation with hole at top and bottom showed the decreased at 6500 RPM to 7500 RPM.This happened due to the high speed of fuel mixture and air tends to be thin, causing HC level decreased.Subsequently, the increased HC level at 7500 RPM to 8000 RPM.It was caused HC which was inhibited at the middle rotation come out due to the high pressure at the time of high rotation so that the hydrocarbon level increased.Besides aluminium oxide (Al 2 O 3 ) also wasted through the exhaust channel for the high pressure so that aluminium oxide couldn't bind hydrocarbon gas.The residual aluminium oxide (Al 2 O 3 ) remaining of 0.43 grams or 21.5% of 2 grams.

IV. Conclusion
There was an effect of application bed catalyst design variation in catalytic converter in reducing exhaust emission of carbon monoxide (CO).It could be understood that bed catalyst design variation with full hole could reduce the CO levels in the middle rotation (4000 RPM to 6000 RPM) and high rotation (6500 RPM to 8000 RPM).The application of bed catalyst design variation with hole at top and bottom could reduce the CO level in the middle rotation (4000 RPM to 6000 RPM).While the application of bed catalyst design variation with hole at the middle and side couldn't reduce exhaust emissions of CO at low, middle, and high rotation.
There was significant effect in the use of bed catalyst design variation in catalytic converters in reducing exhaust emission of hydrocarbon (HC).In fact, the effect of the catalyst bed design variations increased the HC level.This could be understood according to line chart, the HC level in the application of three bed catalyst design variations were above HC level condition without applying catalyst.The bed catalyst design variations in catalytic converters against exhaust emissions of CO and HC were more effective in gasoline engine for reducing the exhaust emissions of carbon monoxide (CO) than to reduce exhaust gas emissions of hydrocarbon (HC).

Fig. 2 .Figure 2
Fig. 2. Comparison CO level without catalyst and catalyst bed design variation of RON 90 Figure 2 showed the detail CO level at different rotation of gasoline engine with different bed catalyst design.

Fig. 3 .
Fig. 3. CO level at low rotation with different bed catalyst design

Fig. 4 .
Fig. 4. CO level at middle rotation with different bed catalyst design D. CO Level at High Rotation

Fig. 6 .
Fig. 6.Comparison HC level without catalyst and catalyst bed design variation of RON 90

Fig. 7 .
Fig. 7. HC level at low rotation with different bed catalyst design

Fig. 8 .
Fig. 8. HC level at middle rotation with different bed catalyst design

Fig. 9 .
Fig. 9. HC level at high rotation with different bed catalyst design