Carbon-vapor reactor

Cannulation, low-temperature, 186 Carbon liner, 170 Carbon monoxide, 85 Carbonyl ligands, 99-100 Carbon-carbon bond, 287 Carbon-vapor reactor, 159 Catalytic system... 

Apparatus and Procedure - The experiments with the solid feedstocks and the initial experiments on liquid samples were carried out in the apparatus shown in Figure 1A. The vapors from a stainless steel, stirred-bed carbonizer/vaporizer at 873°K were cracked at atmospheric pressure in a tube reactor heated in a platinum-wound furnace. The reactor was 30 mm ID and had a 100 mm long hot zone within 20°K of the maximum reactor temperature. Solid feedstocks were introduced at about 1 g min. from a vibratory table through a water-cooled port. Liquids were injected at the same point from a mechanically driven syringe at 0.1-0.8 ml min. The amount fed was determined by weighing the feeders. 

Although the selectivity of isopropyl alcohol to acetone via vapor-phase dehydrogenation is high, there are a number of by-products that must be removed from the acetone. The hot reactor effluent contains acetone, unconverted isopropyl alcohol, and hydrogen, and may also contain propylene, polypropylene, mesityl oxide, diisopropyl ether, acetaldehyde, propionaldehyde, and many other hydrocarbons and carbon oxides (25,28). 

Aqueous formaldehyde is corrosive to carbon steel, but formaldehyde in the vapor phase is not. AH parts of the manufacturing equipment exposed to hot formaldehyde solutions must be a corrosion-resistant alloy such as type-316 stainless steel. Theoretically, the reactor and upstream equipment can be carbon steel, but in practice alloys are required in this part of the plant to protect the sensitive silver catalyst from metal contamination. 

In the heating and cracking phase, preheated hydrocarbons leaving the atomizer are intimately contacted with the steam-preheated oxygen mixture. The atomized hydrocarbon is heated and vaporized by back radiation from the flame front and the reactor walls. Some cracking to carbon, methane, and hydrocarbon radicals occurs during this brief phase. 

Mercury vapor discharge from vents of reactors or storage tanks at normal atmospheric pressure is controlled readily by means of activated carbon. Standard units (208-L (55-gal) dmms) of activated carbon equipped with proper inlet and outlet nozzles can be attached to each vent. To minimize the load on the carbon-absorbing device, a small water-cooled condenser is placed between the vent and the absorber. 

The predominant process for manufacture of aniline is the catalytic reduction of nitroben2ene [98-95-3] ixh. hydrogen. The reduction is carried out in the vapor phase (50—55) or Hquid phase (56—60). A fixed-bed reactor is commonly used for the vapor-phase process and the reactor is operated under pressure. A number of catalysts have been cited and include copper, copper on siHca, copper oxide, sulfides of nickel, molybdenum, tungsten, and palladium—vanadium on alumina or Htbium—aluminum spinels. Catalysts cited for the Hquid-phase processes include nickel, copper or cobalt supported on a suitable inert carrier, and palladium or platinum or their mixtures supported on carbon. 

Pyrolysis. Benzene undergoes thermal dehydrocondensation at high temperatures to produce small amounts of biphenyls and terphenyls (see Biphenyl AND terphenyls). Before the 1970s most commercial biphenyl was produced from benzene pyrolysis. In a typical procedure benzene vapors are passed through a reactor, usually at temperatures above 650°C. The decomposition of benzene iato carbon and hydrogen is a competing reaction at temperatures of about 750°C. Biphenyls are also formed when benzene and ethylene are heated to 130—160°C ia the presence of alkaH metals on activated AI2O3 (33). 

The reactor effluent is rapidly quenched with aqueous mother Hquor in specially designed equipment operating at pressures essentially equal to the reactor pressure. This operation yields an off-gas consisting of ammonia and carbon dioxide vapor and a crystalline melamine slurry saturated with ammonia and carbon dioxide. The slurry is concentrated in a cyclone mill. The mother Hquor overflow is returned to the quenching system. The concentrated slurry is redissolved in the mother Hquor of the crystallization system, and the dissolved ammonia is stripped simultaneously. 

The per pass ethylene conversion in the primary reactors is maintained at 20—30% in order to ensure catalyst selectivities of 70—80%. Vapor-phase oxidation inhibitors such as ethylene dichloride or vinyl chloride or other halogenated compounds are added to the inlet of the reactors in ppm concentrations to retard carbon dioxide formation (107,120,121). The process stream exiting the reactor may contain 1—3 mol % ethylene oxide. This hot effluent gas is then cooled ia a shell-and-tube heat exchanger to around 35—40°C by usiag the cold recycle reactor feed stream gas from the primary absorber. The cooled cmde product gas is then compressed ia a centrifugal blower before entering the primary absorber. 

It is important to produce HCl rather than elemental chlorine, CI2, because HCl can be easily scmbbed out of the exhaust stream, whereas CI2 is very difficult to scmb from the reactor off-gas. If the halogenated hydrocarbon is deficient in hydrogen relative to that needed to produce HCl, low levels of water vapor may be needed in the entering stream (45) and an optional water injector may be utilized. For example, trichloroethylene [79-01 -6] C2HCI2, and carbon tetrachloride require some water vapor as a source of hydrogen (45). 

Tibbetts, G.G., Gorkiewicz, D.W., and Alig, R.A. A new reactor for growing carbon fibers from liquid- and vapor-phase hydrocarbons, Carbon, 993, 31(5), 809 814. Tibbetts, G.G., Bernardo, C.A., Gorkiewicz, D.W. and Alig R.L. Role of sulfur in the production of carbon fibers in the vapor phase. Carbon, 1994, 32(4), 569 576. 

The stripped catalyst is picked up by a stream of air and carried into the regenerator where the carbon is burned at temperamres about 1100-1300°F. Entrained catalyst is again removed by cyclones and the flue gas goes out the stack. The hot, regenerated catalyst leaves the regenerator and takes with it much of the heat of combustion. This is carried over to the reactor to vaporize the feed and to balance the endothermic heat of cracking. Thus, the process is heat balanced. 

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