Science/Technology yield of ethylene, with naphtha and gas-oil cracking following in that or AUTONOM handles complex structures der. Cracking has the lowest produc tion cost. The Eindhoven study is aimed at comparing ethylene production via methane coupling with convention ο 0=CN Λ „ . ,c-o al naphtha cracking from technical and economic viewpoints. This was o=c.^\^_y ^c v ^ C - c * ° C done in connection with the prelim inary design for a new process based c on methane coupling that is expect l l V x c / i / -° ° Q N C=0 C ed to be available in the next few years. C Among the coupling catalysts that C-c/S C have been proposed in the open lit erature, two groups can be distin AUTONOM-generated name: 5-Methoxy-3-(2-methoxy-4,5-bis-methoxycarbonyl-furan-3guished. The first group contains yl)-6-(1,2,3-tris-methoxycarbonyl-cycloprop-2-enyl)-8-oxa-tricyclo[3.2.1.02'4]oct-6-ene1,2,3,4,7-pentacarboxylic acid pentamethyl ester those with metal ions changing va lence states. During the reaction, they are reduced by methane and Ltd. ROSDAL is the standard query search & Technology. But we're cer reoxidized by oxygen. The second format used for the 3.5 million Beil- tain that we will recover our costs so group requires a cofeed of methane stein structures on DIALOG, a major far as internal use goes. From that and oxygen because these catalysts are only active w h e n oxygen is U.S. vendor of on-line databases, as point of view, I have no worries." well as being widely used by orga Lawson points out that through present. Catalysts in this second nizations other than Beilstein. use of AUTONOM, Beilstein Insti group are neither oxidized nor re It's still too early to put an esti tute's nomenclature department has duced. Generally speaking, the sec mated price on AUTONOM. "I don't improved its operating efficiency by ond group of catalysts exhibits the think we'll recover our costs from a factor of almost three. "We have better performance. Hoebink also notes that all of the the sales," Lawson comments. "It kept the same complement of staff took several million dollars to devel while essentially tripling output," coupling catalysts that have been re ported in the literature have a short op, with some funding coming from he says. the West German Ministry of ReDerrnot O'Sullivan run time. The longest runs are with lithium/magnesium oxide catalysts that last about two weeks but show steadily decreasing activity. Hoe bink believes it realistically can be Industrial ethylene is expected by or lack of it, of natural gas some assumed that a process can be devel some industry observers to become times makes it cheaper to burn off oped with a 30% methane conver available from natural gas in the than to transport. Hence, it is in the sion and an 80% selectivity with re near future. The general perception interests of conservation to look into spect to C 2 products and/or a 50% is that some sort of oxidative cou the possibility of converting the gas conversion and a 50% selectivity. pling of methane will be developed. to higher value products such as There is a natural trade-off in these To achieve success, any oxidative methanol, ammonia, or distillate- two cases. The Eindhoven study an coupling process must compete with range products. Ethylene is another alyzed both cases. Three reactor types were consid either cracking of higher hydrocar attractive possibility, both because bons from gas wells (the preferred of its intrinsic value and because it ered: tubular fixed beds, multistage process in the U.S.) or n a p h t h a can be oligomerized to gasoline or packed beds, and fluid beds. In ev cracking (preferred in Europe). That otherwise converted to petrochemi ery case, the reactors were fed mix competition has been examined in a cals. The present world production tures of pure oxygen and methane. new study by Dutch researcher Josef of ethylene is estimated by Hoebink Oxygen was adjusted to achieve the 6 desired methane conversion levels G. B. J. Hoebink and a group of in to be 34 Χ 10 tons per year. vestigators at the Laboratory of At present, most of the ethylene is and was completely consumed with Chemical Process Technology of obtained by cracking other, higher in the catalyst bed. Total ethylene Eindhoven University of Technolo hydrocarbons. Because cracking is production was taken as 350,000 gy, the Netherlands. The outlook for highly endothermic, it is usually tons of methane processed per year methane coupling is rather promis done in tubular reactors. The reac in the single plant. Upon analysis, the tubular reactor ing. tion mechanism is essentially a freeIn some places, natural gas re radical mechanism creating hydro is not considered to be attractive— sources greatly exceed crude oil re gen abstraction and chain fracture. there is a serious problem with run serves. However, the intrinsic value, Ethane cracking has the highest away extinction of the reaction. It
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