Gasoline specifications

On more than one occasion, tanks have overflowed because the contents were replaced by a liquid of lower specific gravity. The operators did not realize that the level indicator measured weight, not volume. For example, at one plant a tank that had contained gasoline (specific gravity 0.81) was used for storing pentane (specific gravity 0.69). The tank overflowed when the level indicator said it was only 85% full. The level indicator was a DP cell, which measures weight. 

Reformulated gasoline specifications require lower vapor pressure in the blended gasoline. It also requires maximum feed to the alkylation unit. This puts more pressure on the gas plant, particularly the debutanizer. Floating the tower pressure is often the best way to meet both constraints. 

Aromatics are typically included in gasolines to increase octane number. However, high aromatic content increases engine-out hydrocarbons and NOx emissions.16 Moreover, aromatics are the main precursors of exhaust benzene, a known carcinogenic, via dealkylation of substituted aromatics.17 Therefore, reduction of total aromatic content, together with olefin content, is an important part of California phase III reformulated gasoline specifications,18 with respect to the current allowed concentrations of benzene and total aromatics of 0.8 and 25 percent of volume, respectively. 

West European production capacity for MTBE is estimated at 3.61m tonne, unchanged since 1998. In 1999, west European production, at around 3m tonne, represented an 83% operating rate. Consumption was considerably lower at 2.2m tonne. Europe s new gasoline specification, which came into force in January 2000, has lifted consumption to an estimated 2.7m tonne in 2000. MTBE is used to boost octane in gasoline and to promote cleaner burning and reduce harmful vehicle emissions. Demand to meet 2000 gasoline specifications in Europe boosted prices from 250 US dollars/tonne mid-1999 to touch 600 US dollars/tonne fob Rotterdam briefly in June 2000. There is increasing likelihood that the California ban on the use of MTBE, due to come into effect end 2002, will lead to further bans in the US marketplace. 

The gasoline specification ASTM D-4814 requires gasoline which is marketed and sold to possess a minimum level of resistance to oxidative degradation. This resistance is determined by test method ASTM D-525 and is outlined below ... 

The ASTM D-4814 gasoline specification requiring an induction time of >240 minutes has been established for all gasoline sold in the United States. A similar induction time is maintained in the United Kingdom, Japan, and several other countries. Also, even higher induction time periods are required in some countries. 

The ASTM D-4814 gasoline specification states that an existent gum weight be measured. Existent gum is measured by ASTM D-381. This method is summarized by ASTM as follows ... 

The gasoline specification ASTM D-4814 states that gasoline must pass the ASTM D-130 test with a corrosion rating of lb or better before it can be sold. The addition of sweetening additives to fuels which do not meet this specification can often improve the corrosion rating. Additive treat rates of 25 to 1000 ppm are common. The following test conditions are recommended for various fuels and oils ... 

Heptenes. Heptenes, C7FL 7, are used for the preparation of isooctyl alcohol [26952-21-6] by hydroformylation (see Oxo process). The heptenes are prepared by very carefully controlled fractionation of polymer gasoline. Specifications generally call for >99.9% C content (including some paraffin that is also formed) to simplify processing. 

Table 4.2 Gasoline specifications proposed in the world-wide fuel charter...

Table 7.1 Gasoline specifications for Europe and the United States...

The 1974/75 slump in gasoline demand is over, the 1976 demand Is expected to top 6% while the 1977 demand will return to a more normal 3 to 5%. The question of lead phase-down appears relieved with an EPA postponement, but as a result of the steadily increasing number of vehicles that use unleaded gasoline (about 107o increase annually on the total number of automobiles in the United States) by 1980 some 62% of the total gasoline pool will have to meet no-lead gasoline specification. 

W.L. Backes at the National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, is studying the toxicological significance of the metabolism in rats and rabbits of alkylbenzenes (including toluene, xylenes, ethylbenzene, and />propylbenzene), which are major constituents of gasoline. Specifically, the identification of changes in the metabolic fate of the alkylbenzenes due to their prior administration, the effects of age, sex, and strain differences, the effects of exposure time and exposure to hydrocarbon mixtures, and the effect of hydrocarbon... 

Reformulated gasoline blends have several advantages over gasohol (gasoline-alcohol mixtures) and MTBE blends. REG blends evaporate less readily because they have a lower vapor pressure, and they have lower benzene and sulfur contents. Gasoline blends, as well as other petroleum distillates, are an inhalation hazard to humans. Hydrocarbon distillates have been shown to cause cancer in laboratory animals. The products from the combustion of gasoline, specifically carbon monoxide and nitrogen oxides, have been linked to the dissipation of the protective ozone layer... 

A more important deactivation aspect is poisoning. A diesel oxidation catalyst is poisoned by the same elements that poison three-way catalysts, except for lead, which is absent from diesel fuel and the diesel fuel supply chain. Table 25 compares the amount of sulfur, phosphorus and zinc offered to a diesel catalyst and to a three-way catalyst during their lifetime. From this table, it is apparent that a diesel oxidation catalyst has to deal with a considerably higher amount of sulfur during its lifetime than is the case with a three-way catalyst. This is because the diesel fuel specification allows for a higher sulfur content than the gasoline specification. Table 26 gives an overview of the maximum sulfur content in the diesel fuel specification of some selected countries. 

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