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Average effects of reformulated gasoline on emissions from catalyst equipped cars are compared with those from a regular conventional unleaded gasoline on Fig. 8.3. These effects are primarily due to leaning effect caused by presence of oxygenates. The CO and HC emissions are reduced significantly while a small increase in NO_x emissions is observed.

Figure 8.3

Comparison of effects of reformulated gasoline on emissions for catalyst equipped cars with those with regular grade unleaded gasoline

Trends in Gasoline Specifications

As the effect of gasoline properties on engine out emissions and on performance of catalytic converters is quite significant, fuel specifications all over the world have been progressively revised. Engine and vehicle manufacturers in Europe, America and Japan are making efforts to harmonize fuel quality through out the world. They have come out on fuel quality recommendations based on the level of emission control technology and customer satisfaction, which are referred as Worldwide Fuel Charter. As an example of current day gasoline properties, Indian Specifications of Euro IV emission compliant fuel are given in Table 8.9

Table 8.9

Indian Specifications for Euro IV/Bharat Stage IV Emmission Norms Compliant Motor Gasoline

	Characteristics	Limits
	Characteristics	Gasoline 91 RON	Gasoline 95 RON
1	Density @ 15°C, kg/m3	720-775	720-775
2	Distillation:
	a) % evaporated at 70°C (E-70), v/v	10-45	10-45
	b) % evaporated at 100°C (E-100), v/v	40-70	40-70
	c) % evaporated at 150°C (E-1500), v/v , min	75	75
	d) Final boiling point, ºC, max	210	210
	e) Residue, percent by volume, max	2	2
3	Research Octane Number (RON), min	91	95
4	Motor Octane Number (MON), min	81	85
5	Existent gum, g/m3, max	40	40
6	Sulphur, total, mg/kg, max	50	50
7	Lead content (as Pb), g/1, max	0.005	0.005
8	Reid vapour pressure (RVP) at 38ºC, kPa,	60 (67)	60 (67)
9	Benzene content, percent by volume, max	1	1
10	Olefin content, percent by volume, Max	21	18
11	Oxidation stability, minutes, Min	360	360
12	Aromatic content, percent by volume, Max	35	35
13	Oxygen content, percent by mass, Max	2.7	2.7
14	Oxygenates, percent by volume, Max
	a) Methanol	Nil	Nil
	b) Ethanol	5	5
	c) Iso-Propyl alcohol	10	10
	d) Iso-butyl alcohol	10	10
	e) Tertiary-butyl alcohol	7	7
	f) Ethers containing 5 or more 'C' atoms per molecule	15	15
	g) Other Oxygenates	8	8