An improved method of supplying heat to endothermic and mildly exothermic gas-phase reactions

摘要

In the gas-phase reaction of chlorine and carbon monoxide to produce carbon tetrachloride, heat is supplied to the reaction by adding oxidizable gases containing hydrogen and/or carbon monoxide to the reactants and passing the mixture over an oxidizing agent arranged in front of the reaction zone in the direction of flow of the gas. The added gases are oxidized to carbon dioxide and/or water vapour with the production of heat. In a modification, only the oxidizable gases flow over the oxidizing agent, and the combustion products are used to preheat the reactants by mixture therewith before entry into the reaction zone. Suitable oxidizing agents are oxides of copper, manganese, silver, nickel, cobalt, or vanadium, which may be mixed with a heat-resisting material, e.g. magnesium oxide; oxides of copper or manganese may be activated with silver oxide.ALSO:PICT:0765455/III/1 Heat is supplied to endothermic or mildly exothermic gas-phase reactions by adding oxidizable gases containing hydrogen and/or carbon monoxide to the reactants and passing the mixture over an oxidizing agent arranged in front of the reaction zone in the direction of flow of the gas. The added gases are oxidized to carbon dioxide and/or water vapour with the production of heat. In a modification, only the oxidizable gases flow over the oxidizing agent, and the combustion products are used to preheat the reactants by mixture therewith before entering into the reaction zone; this method may be used for the cracking of oils in the vapour phase. Suitable oxidizing agents are oxides of copper, manganese, silver, nickel, cobalt, or vanadium, which may be mixed with a heat-resisting material, e.g. magnesium oxide; oxides of copper or manganese may be activated with silver oxide. As an example, in the conversion of a mixture of methane or other gaseous hydrocarbon and water vapour to a mixture of carbon monoxide and hydrogen, the reactants are mixed with carbon monoxide and hydrogen and passed over copper oxide before entering the reaction zone. When the oxidizing activity of the copper oxide is exhausted, reoxidation is effected by the passage of air. As shown in Fig. 1, methane and water vapour, mixed with carbon monoxide and hydrogen, enter at 1, pass through heat exchanger 2 to vessel 4 which contains an oxidizing bed 5 of copper oxide and magnesium oxide and a catalytic bed 6 of nickel, nickel oxide, and magnesium oxide. The product gas containing carbon monoxide and hydrogen is used to heat the reactants in heat exchanger 2. Meanwhile air is being passed through a similar vessel 11 in order to reoxidize the oxidizing agent; air entering at 8 is preheated by heat exchange at 9 with the exit gases. Vessels 4 and 11 are used alternately by adjustment of valves 3, 7, 10, 14. In the apparatus of Fig. 2 (not shown), the reactants flow in countercurrent to the oxidizing agent which is continuously removed, regenerated in a pneumatic conveyer by means of air, and recirculated. In another embodiment (Fig. 3, not shown), catalyst is arranged in the lower part of a vessel and in tubes in the upper part of the vessel, the tubes being surrounded by the oxidizing agent. Only the carbon monoxide and hydrogen pass over the oxidizing agent, the combustion products mixing in the tubes with the reactants which flow down into the lower catalyst bed. Other gas-phase reactions referred to are the preparation of hydrogen cyanide from carbon monoxide and ammonia, the preparation of carbon disulphide from carbon monoxide and sulphur vapour, and the preparation of hydrogen sulphide from sulphur vapour and hydrogen.