TECHNOLOGY
SNAM to Use Own Acrylonitrile Process Italian firm's plant will be first commercial operation of its process using propylene and ammonia Societa Nazionale (SNAM) will soon trile plant based on ammonia process.
Metandotti S.p.A. build an acryloniits own propyleneSNAM, a subsidi-
ary of Ente Nazionale Idrocarburi ( E N I ) , the Italian state-owned petroleum company with a hand in enterprises ranging from motels to textile
PILOT PLANT. SNAM has been using this pilot plant at Milan to produce up to 110 lb. per day of acrylonitrile. Its new plant at an as-yet-undisclosed location will be the first commercial use of the SNAM process 46
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factories, isn't disclosing the location of the plant that will inaugurate its acrylonitrile process. But it does say that the commercial unit will have a capacity of 30 to 40 million lb. a year. SNAM is also willing to license its propylene-ammonia route to other firms. It will thus vie with Britain's Distillers Co., Ltd., and with Standard Oil of Ohio for licensees. Distillers and Sohio are locked in a patent suit filed in U.S. District Court in Cleveland concerning their processes (C&EN, Nov. 4, 1963, page 2 9 ) . Most reservations about ENFs process center on the fact that it hasn't yet passed the test of full-scale plant operation. It has passed the pilotplant stage with flying colors, however. In cataloging the advantages of its process, SNAM stresses the fact that propylene feed purity is not critical. Linear butylènes can run higher than 2% of the feed without creating problems. This looseness in feedstock specifications has a corollary advantage of lowering capital investment. Important. Catalyst performance is all-important in determining the economics of plant production. The catalyst differs from those used in either the Sohio or Distillers processes, according to SNAM. Details are sketchy, but the catalyst is supported and is composed principally of oxides of vanadium, molybdenum, and bismuth. Process yields are high now and could climb higher. Pilot-plant performance indicates that 1.15 lb. of propylene and 0.5 lb. of ammonia will combine to give 1 lb. of acrylonitrile. New catalysts now in development should reduce these consumptions, SNAM says. SNAM is willing to cast some light on the general outline of its technology. The design of the reactor is veiy important, the firm explains. It uses a fixed-bed reactor. Chief problem in designing the reactor is process control of the exothermic reaction at proc-
ess temperatures between 450° and 550° C. Like most of the propylene-ammonia processes, SNAM obtains oxygen from air. The feed stream consists of 1 mole of ammonia and 1.5 moles of air per mole of propylene. The main by-products are acetonitrile and HCN. Small amounts of acetone, acrolein, carbon monoxide, and acetaldehyde are also formed. The distillation train following reaction is geared to recover fiber-grade acrylonitrile. Fiber-grade acrylonitrile, high-purity acetonitrile, and HCN are recovered by extraction distillation, according to SNAM. The pilot plant has a capacity of 110 lb. per day of acrylonitrile. Located at Milan, the unit has been operated since early 1963. Logical. The backward step to captive acrylonitrile production is a logical move for ENI, SNAM's parent company. The firm's mode of operation in recent years has been to integrate both forward and backward. In 1962, ENI gained control of Lanerossi, a textile company with eight factories near Vicenza. Another factory is being built at Foggia. It will soon have facilities for spinning acrylic fibers at a plant at Pisticci. The fiber plant uses a Japanese process based on nitric acid as a polyacrylonitrile solvent. ENFs acrylonitrile plant will be another in a series of developments in Europe that seem certain to draw the land-office business for U.S. exports of the material to a close. U.S. exports of the versatile chemical building block should near 200 million lb. this year. The bulk of this will find customers in western Europe. Erdoelchemie, the joint venture of Farbenfabriken Bayer and British Petroleum, said recently that it would build a second acrylonitrile plant at Dormagen, near Cologne. This will bring the planned and existing acrylonitrile capacity in Europe to 440 million lb. from its present level of about 75 million lb. Erdoelchemie has a 55 million lb.-per-year acrylonitrile plant at Dormagen set for startup in 1965 based on a Bayer-patented route using propylene and ammonia. Its new unit will use the Sohio process. The firm gives no reason for the switch. Patents on the SNAM process have been applied for in most of the industrial countries of the world. Belgian patent 643909 has already issued.
Phillips Offers Vulcanizable Polyethylene High-density polymers contain butadiene and a 1-olefin, and can be vulcanized with sulfur Vulcanizable high-density polyethylene has been developed by a group of research chemists at Phillips Petroleum. The materials are copolymers of ethylene and 0.1 to 0.5% butadiene, or terpolymers with a 1-olefin as the third component. Terpolymers with 5 to 10% 1-olefin are made for uses requiring lower hardness and more elongation than the copolymer has. At present, Phillips offers developmental quantities of the vulcanizable poly ethylenes. If demand develops for them, facilities can be converted to produce the polymers in commercial volume. Phillips has disclosed no details of the polymerization processes. The polymers can be vulcanized to a cross-linked product with sulfur and conventional accelerators used in rubber vulcanization. The product retains the hardness, crystallinity, solvent resistance, and abrasion resistance of high-density polyethylene and gains improved toughness and high-temperature performance of a cross-linked polymer, Dr. J. E. Pritchard of Phillips told the Southwest Regional Meeting of the American Chemical Society in Shreveport, La. The ethylene/butadiene polymers contain both trans and vinyl unsaturation, according to Dr. Pritchard and co-workers F. W. Bailey. and D. R. Witt. Trans unsaturation varies directly with the butadiene content of the polymer. This indicates that 1,4 addition of the butadiene predominates. Vinyl unsaturation depends slightly on butadiene content. It increases as polymer molecular weight
decreases—just as in other Phillips poly ethylenes. Significant. Copolymerization of ethylene and butadiene could have a big impact on the polyethylene industry. It could have an impact comparable to the discovery of copolymerization of isoprene with isobutylene which led to butyl rubber, according to Dr. James A. Reid, manager of Phillips' research division. Such a polymerization is especially novel because attempts to use butadiene as a "minor" comonomer generally have proved unsuccessful. Butadiene doesn't make a satisfactory butyl rubber when copolymerized with isobutylene, for example. In addition, no one apparently has succeeded in using butadiene to make a vulcanizable ethylene-propylene rubber. For ethylene-propylene rubbers, more expensive dienes such as dicyclopentadiene or 1,5-hexadiene are used to give a cross-linked product. Cross-linked polyethylenes have been available for some time for uses such as pipe, structural forms, and wire and cable coverings. These uses require a polyethylene that resists cracking well and does not flow above the normal melting point. To crosslink conventional polyethylenes, a peroxide is added which decomposes on heating during the cure. Properties. When vulcanized, the unsaturated polyethylenes develop levels of physical properties possible in very high-molecular-weight resins, Dr. Pritchard says. For example, a terpolymer of ethylene, butadiene, and 1-butène with an original melt index of 0.17 has stress-strain properties and
Terpolymer Shows How Vulcanizing Affects Stress-Strain Relationship Ethylene, 1-butène, butadiene terpolymer After vulcanizing
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