Fuels additives

As an exception in the trends observed in the national market, the lead used to obtain tetraethyl lead has not only kept its level, but increased continuously (see Table 5) this is generally explained as due to the fact that this product is being exported to those countries that are still using it as a fuel additive (IMZPC 1987). However, it must not be forgotten that Mexico is also using large quantities of this substance. 

In 1984, the total number of vehicles registered in the country was 5,827,823, distributed as follows  

There was approximately one private automobile per 17 inhabitants the total number in Mexico City was 1,600,000 (Bruaux and Svartengren 1985). At present it is estimated that there are more than 2,500,000 in the city. Due to the difference in price of the unleaded gasoline and to the predominant type of motors, most of these vehicles use leaded gasoline. 

Year % of total lead Metric tons (lead) 

With information from the para-state Mexican oil company, Petroleos Mexi-canos (PEMEX), Bravo (1987) estimated that just in the area of Mexico City and surroundings (Metropolitan Zone of Mexico City, or MZMC) and due to the use of leaded gasoline (known as nova ), more than 32 metric tons of lead per day (approximately 12,000 metric tons per year) were emitted to the air. Before 1981, an annual emission of 19,600 tons/year of lead was calculated for the same area corresponding to a consumption of leaded gas of 20 million mVyr (Bruaux and Svartengren 1985). These authors estimated the emission of lead for 1982 in 12,800 metric tons and, based on the controls on lead in gas that were supposed to be established at that time, predicted that this amount would be reduced to 4000 metric tons/yr by 1984. 

In the late 1960s, new antipollution initiatives were enacted to reduce nitrogen oxides, carbon monoxide, and lead pollutants from automotive exhaust. Nitrogen oxides were responsible for the brown haze that hung over cities that can still be seen today. The advent of the catalytic converter, a small canister that contained heavy metal catalysts embedded on a ceramic support, helped oxidize carbon monoxide and reverse the reaction that produced nitrogen oxides. However, lead in the exhaust stream deactivated the catalysts in the catalytic converter. The only solution was to remove tetraethyllead from the gasoline. 

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 

---

Examples of biocide agents used as motor fuel additives. 

Although lubricant base stocks have been subjected to dewaxing processes, they still contain large amounts of paraffins that result in a high pour point for the oil. In the paragraph on the cold behavior of diesel fuels, additives were mentioned that modify the paraffin crystalline system and oppose the precipitation of solids. 

Coley, T.R. (1989), Diesel fuel additives influencing flow and storage properties . In Gasoline and diesel fuel additives (Owen, K. Ed.). John Wiley. 

Ranney, M.W. (1974), Fuel additives . Chemical Technology Review No. 26, Noyes Data Corporation, Park Ridge, NJ. 

In the first years of gasohol use some starting and driveabiUty problems were reported (19). Not all vehicles experienced these problems, however, and better fuel economy was often indicated even though the energy content of the fuel was reduced. Gasohol was exempted from the federal excise tax amounting to a 0.16/L ( 0.60/gal) subsidy. Without this subsidy, ethanol would be too expensive for use even as a fuel additive. 

Ben2otrifluoride has been recommended as a fuel additive for internal combustion engines (347). 

Petrochemicals Methyl Cellosolve Fuel Additive Grade, brochure. Union Carbide Canada Ltd., 1991. 

Some isopentane is dehydrogenated to isoamylene and converted, by processes analogous to those which produce methyl /-butyl ether [1634-04-4] (MTBE) to /-amyl methyl ether [994-05-8] (TAME), which is used as a fuel octane enhancer like MTBE. The amount of TAME which the market can absorb depends mostly on its price relative to MTBE, ethyl /-butyl ether [637-92-3] (ETBE), and ethanol, the other important oxygenated fuel additives. 

Pentanedione is widely used in extraction processes for the separation and purification of metals because of its abiUty to form covalent metal chelates. It is also used as an intermediate in the production of heterocycHc substances and dyes, as a fuel additive (324), and in metal plating and resin modification. 

Uses. Magnesium alkyls are used as polymerization catalysts for alpha-alkenes and dienes, such as the polymerization of ethylene (qv), and in combination with aluminum alkyls and the transition-metal haUdes (16—18). Magnesium alkyls have been used in conjunction with other compounds in the polymerization of alkene oxides, alkene sulfides, acrylonitrile (qv), and polar vinyl monomers (19—22). Magnesium alkyls can be used as a Hquid detergents (23). Also, magnesium alkyls have been used as fuel additives and for the suppression of soot in combustion of residual furnace oil (24). 

This excess hydrogen is normally carried forward to be compressed into the synthesis loop, from which it is ultimately purged as fuel. Addition of by-product CO2 where available may be advantageous in that it serves to adjust the reformed gas to a more stoichiometric composition gas for methanol production, which results in a decrease in natural gas consumption (8). Carbon-rich off-gases from other sources, such as acetylene units, can also be used to provide supplemental synthesis gas. Alternatively, the hydrogen-rich purge gas can be an attractive feedstock for ammonia production (9). 

Methyl tert-Butylluther Methyl /-butyl ether (MTBE) is an increasingly important fuel additive. Platinum—tin and other PGM catalysts are used for the dehydrogenation of isobutane to isobutene, an intermediate step in MTBE manufacture. 

Monofunctional, cyclohexylamine is used as a polyamide polymerization chain terminator to control polymer molecular weight. 3,3,5-Trimethylcyclohexylamines ate usehil fuel additives, corrosion inhibitors, and biocides (50). Dicyclohexylamine has direct uses as a solvent for cephalosporin antibiotic production, as a corrosion inhibitor, and as a fuel oil additive, in addition to serving as an organic intermediate. Cycloahphatic tertiary amines are used as urethane catalysts (72). Dimethylcyclohexylarnine (DMCHA) is marketed by Air Products as POLYCAT 8 for pour-in-place rigid insulating foam. Methyldicyclohexylamine is POLYCAT 12 used for flexible slabstock and molded foam. DM CHA is also sold as a fuel oil additive, which acts as an antioxidant. StericaHy hindered secondary cycloahphatic amines, specifically dicyclohexylamine, effectively catalyze polycarbonate polymerization (73). 

These mixed phosphate ester titanium complexes or their amine salts are useful as fuel additives to help maintain cleanliness of carburetors and inhibit surface corrosion. Chloride-free mixed alcohol phosphate esters can be obtained if a tetraalkyl titanate is used (101). 

K. Pattas and co-workers, Cordierite Filter Durability with Cerium Fuel Additive 100,000 km of Revenue Service in Athens, SAE Technical Paper 920363, Society of Automotive Engineers, Warrendale, Pa., 1992 U.S. Pat. 4,522,631 (June 11, 1985), A. M. Mourao and C. H. Falst. 

Chlorotoluene isomer mixtures, especially those containing a relatively high amount of o-chlorotoluene, are widely used as solvents in industry for such purposes as metal-cleaning formulations, railroad industrial cleaners, diesel fuel additives, carbon removal procedures, paint thinners, and agricultural chemicals. Halso 99 andHalso 125 are examples of such solvents. 

With the increasing emphasis on energy conservation and environmental considerations, additives for fuels that can correct combustion-related problems have aroused considerable interest. Many commercial fuel additives are combinations of organometaHics, dispersants, emulsifiers, and carrier solvents. The organometaHic, often a metal soap, acts as a combustion catalyst, increasing efficiency with reduction of smoke, deposits, and corrosion. 

In addition to MTBE, two other ethers commonly used as fuel additives ate /n/f-amyl methyl ether (TAME) and ethyl in/f-butyl ether [637-92-3] (ELBE). There ate a number of properties that ate important in gasoline blending (see Gasoline and OPHER MOTOR fuels) (Table 3). 

Oxygenates and Chemicals A whole host of oxygenated products, i.e., fuels, fuel additives, and chemicals, can be produced from synthesis gas. These include such produc ts as methanol, ethylene, isobutanol, dimethyl ether, dimethyl carbonate, and many other hydrocarbons and oxyhydrocarbons. Typical oxygenate-producing reactions are ... 

On fuel, fuel additives, ingredients in fuel, pollution-producing equipment... 

---