MARKETS
Gasoline Takes More Phosphorus Additives Newer compounds have now practically replaced tricresyl phosphate and their use grows steadily Petroleum companies have practically stopped using tricresyl phosphate as a gasoline additive. But other organophosphorus compounds, mostly phosphate esters, have replaced it, and the market for organophosphorus gasoline additives should continue to grow at about 2% per year for the next few years. Current U.S. consumption of these compounds for gasoline additives is about 19 million pounds a year. By 1970, the figure should hit about 28 million pounds. Organophosphorus additives modify deposits which form in the combustion chambers of automobile engines, and, thus, control preignition. These deposits contain high percentages of carbon and lead. During engine operation, such a deposit may start to glow continuously and, thus, ignite the gasoline charge in the cylinder at some time in the cycle other than the normal spark plug firing time. This causes preignition, "wild ping," or "rumble," in the engine. The result is power loss, overheating, inefficient operation, and sometimes engine damage. Organophosphorus additives con-
trol preignition by promoting a deposit that has less tendency to glow and cause preignition. The deposits formed from fuels containing organophosphorus also seem to have lower electrical conductivity than other deposits and, thus, reduce the tendency of spark plugs to short out and misfire. The chief organophosphorus compounds now used as gasoline additives are cresyl diphenyl phosphate, mixed methyl-phenyl phosphates, and trimethyl phosphate. Cresyl diphenyl phosphate (CDP) accounts for about 64% of all the phosphorus compounds added to gasoline. Mixed methylphenyl phosphates account for another 19%, and proprietary compounds of Humble and Standard Oil of Ohio for 14% of the market. Trimethyl phosphate accounts for 3 % of the market. Shell continues to use TCP as a trademark for its organophosphorus additive, although it is not necessarily tricresyl phosphate. Switch. The reason for the switch from tricresyl phosphate, tributyl phosphine, and other earlier organophosphorus compounds is largely one
ADDITIVES. Use of organophosphorous compounds in gasoline to reduce preignition will grow from the present 19 million pounds a year to 28 million by 1970 30
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of economics. The newer compounds can put more phosphorus into the gasoline for a lower price than the older ones can. In general, a phosphorus compound must sell at about $3.00 or less per pound of contained phosphorus to meet competition from the other organophosphorus additives. The amount of phosphorus additive in gasoline is usually stated in tenus of "theories of phosphorus." One "theory" of phosphorus can theoretically convert all the lead in a given gasoline into lead orthophosphate. In practice, petroleum refiners usually use between 0.2 and 0.3 "theory" in their premium gasolines. Any compound used must be soluble in gasoline. It should also be insoluble in water, because gasoline is often in contact with water, which would remove some of any water-soluble compound. Phosphorus additives may reduce the effectiveness of tetraethyllead as an antiknock agent, making it necessary to increase the amount of TEL used. Thus, any organophosphorus compound used must exhibit little tendency to counteract TEL's antiknock effect. Trimethyl phosphate finds a market as an additive despite the fact that it is water soluble and subject to alkaline hydrolysis. Generally, it is sold for use at gasoline terminals rather than for addition at the refinery, since the gasoline at a terminal is not so likely to come in contact with water during its relatively short storage period. Producers. Most of the companies that produce phosphate esters for plasticizers also sell phosphorus compounds as gasoline additives. The chief phosphate ester producers are FMC, Monsanto, Celanese, Ethyl Corp., Baldwin-Montrose, Union Carbide, Socony Paint Products (owned by Socony Mobil), Kolker Chemical (a subsidiary of Vulcan Materials), Eastman, and Dow. Generally, the different esters can be produced in the same equipment. Future growth for organophosphorus gasoline additives should be enhanced by increased compression ratios in automobile engines, higher levels of T E L in gasolines, a possible increase in levels of phosphorus addition to gasolines, and an increase in number of automobiles. Radical technological changes, such as a switch to turbine engines, would stall the growth of gasoline additives. But turbine engines will probably not appear in any great numbers before 1970.
