Molten salt tests at Atomics International A place for social outcasts
water. Another might use producer gas as the reducing agent. Sulfur dioxide is a major air pollutant, and interest in removing it from stack gases is very high, particularly at coal- and oil-fired power plants (C&EN, July 10, page 2 8 ) . By the end of the year, Monsanto expects to b e selling units that oxidize the sulfur dioxide with vanadium pentoxide catalyst. Both the Bureau of Mines and the National Coal Association are working with alkalized alumina as an absorbent for the pollutant. Combustion Engineering uses dolomite to remove the sulfur dioxide, produces no by-product, but boasts lower capital costs. Dr. Oldenkamp emphasizes that it is too early to say anything definite about costs in the molten salt process. Preliminary estimates, though, indicate that they could b e as low as half the costs of other processes, even without crediting the by-products. Byproduct sales might result in a profit. If adopted on a large scale, the molten salt process would produce sulfur and sulfuric acid worth hundreds of millions of dollars each year, AI points out. Also, it would allow industry to use high-sulfur grades of coal and oil which are now social outcasts in the eyes of air pollution agencies from coast to coast. 12
C&EN AUG. 14, 1967
SNAM Progetti gives details of polymerization process First details of its recently developed stereospecific polymerization process for producing either polyisoprene or polybutadiene have been released by SNAM Progetti of Milan. T h e process for making the two elastomers is substantially the same in principle and operation. The primary difference, says SNAM Progetti, a company of Italy's government-owned oil firm E n t e Nazionale Idrocarburi ( E N I ) , is in the use of different catalyst systems. T h e process gives rubbers with a high cis content to more closely resemble natural rubber. For polymerizing isoprene, the catalyst system consists of titanium tetrachloride and a new polymeric aluminum hydride called Polylmino-Alane. A three-component catalyst system is used to polymerize butadiene. T h e catalyst system is m a d e u p of aluminum chlorohydride etherate, aluminum iodide, a n d titanium tetrachloride. In the first step of the process, fresh monomer is dried and separated from polymerization inhibitor. T h e n it is fed to polymerization reactors with recycle solvent and the catalyst sys-
tem, which is formed in situ. Polymerization takes three to six hours. Polymerization temperature is 5 ° to 4 0 ° C. T h e rubber solution obtained is blended with stopper and antioxidant, and washed with water to remove any residual catalyst. This wash step isn't necessary for polybutadiene, SNAM Progetti says, because the catalyst residue does not adversely affect properties of the finished product. The washed solution then goes to a steam stripper, which gives a crumb slurry of solvent-free rubber. Recovered solvent plus unreacted monomer is distilled to obtain dry solvent and to separate monomer and dimers. T h e rubber crumbs are separated from water on a vibrating screen and the crumbs dried. T h e dried product is weighed, baled, w r a p p e d with polyethylene film, and packed for shipment. T h e process gives 92 to 9 5 % cis-polybutadiene with a Mooney viscosity of M L ( 1 + 4) of 40 to 50; or it will produce 9 6 % cis-polyisoprene with a Mooney viscosity of M L ( 1 + 4 ) of 80 to 100. SNAM Progetti has several patents on the process, including U.S. 3,245,976 (issued to SNAM's Walter Marconi, Alessandro Mazzei, Alessandro Beranger, Mario Araldi, and Marcello de Malde) and 3,311,604 (issued to Mr. Marconi, Mr. Mazzei, Mr. de Malde, and Salvatore Cucinella), Belgian patent 675,406, and French patent 1,465,856. A N I C , another member of the E N I group, will use the process to produce polyisoprene in a plant scheduled to b e built soon at Ravenna.
Impact of surtax on spending by chemical firms uncertain Chemical company executives are not yet sure what effect the proposed 10% surcharge on corporate and personal income tax will have on their capital spending—or if they are, they aren't saying. But at least a couple of major chemical companies indicate that the tax boost could cause a cut in their future capital investments. Meanwhile, spending programs for this year for the bigger chemical companies seem to b e running at close to scheduled levels in spite of the so-called minirecession afflicting the U.S. economy. Carl A. Gerstacker, chairman of the board of D o w Chemical, says the proposed surcharge "certainly would not increase [Dow's] capital spending. If anything, it will reduce it." Monsanto says the surcharge will cause it to "take a close look" at capital investments, b u t the increase is unlikely to deflect it from worthwhile expansions.
