GB692176A - Method of controlling exothermic catalytic gas reactions - Google Patents

Abstract

A substantially constant temperature is maintained in a reaction zone, particularly in the catalytic conversion of carbon monoxide and hydrogen to hydrocarbons, the hydrogenation of iso-octene to iso-octane and the oxidation of naphthalene to phthalic anhydride by passing through the reaction zone, countercurrent to the flow of gaseous reactants and in direct contact therewith, a liquid, heated to reaction temperature, consisting essentially of a volatile and a non-volatile component, inert under the reaction conditions, the volatile component being vaporizable under reaction conditions and the non-volatile component having a negligible vapour pressure under reaction conditions, absorbing the exothermic heat of the reaction by vaporization of the volatile component, and regulating the amounts of the components of the mixture so that the volatile component is completely vaporized during its passage through the reaction zone and so that a constant ratio is maintained throughout the reaction zone between the molal concentrations of the volatile component in the vapour and the liquid, thereby preventing a temperature gradient in the reaction zone. The volatile component leaves with and is separated from the reaction products and the non-volatile component is withdrawn from the bottom of the reactor. The two components may be pure compounds, preferably boiling at least 55 DEG C. apart, but the volatile component may be a narrow boiling liquid fraction, the non-volatile component in this case having an initial boiling point at least 55 DEG C. and preferably 85 DEG C. above the end boiling-point of the volatile component. In the Fischer-Tropsch synthesis employing a cobalt on kieselguhr catalyst at 190-210 DEG C., the desired temperature may be maintained constant, i.e. \sB 3 DEG C., at a temperature of 204 DEG C. and a superatmospheric pressure of 6.8 atmopheres, the volatile component may be a saturated hydrocarbon fraction boiling at 93-105 DEG C., having a vapour pressure of 9.7 atmospheres at 204 DEG C. The non-volatile component may be the gas oil fraction of the product. The process is applicable to stationary or moving beds.ALSO:A substantially constant temperature is maintained throughout a reaction zone during an exothermic catalytic reaction therein of gaseous reactants where there is a net decrease in the volume of the gases as the reaction proceeds by heating to the reaction temperature and passing through the reaction zone countercurrent to the flow of reactants and in direct contact therewith, a liquid mixture inert under the reaction conditions and consisting essentially of a volatile component and a relatively non-volatile component, the volatile component being vaporizable at the reaction temperature and the non-volatile component having a negligible vapour pressure under reaction conditions, absorbing the exothermic heat of the reaction by vaporization of the volatile component, and regulating the amounts of the components of the mixture so that the volatile component is completely vaporized during ing its passage through the reaction zone and so that a constant ratio is maintained throughout the reaction zone between the molal concentrations of the volatile component in the vapour and the liquid, thereby preventing a temperature gradient in the reaction zone. Reactions specified are the conversion of carbon monoxide and hydrogen to hydrocarbons, the hydrogenation of iso-octene to iso-octane, the oxidation of carbon monoxide to carbon dioxide, the conversion of hydrogen and nitrogen to ammonia and the oxidation of naphthalene to phthalic anhydride. The volatile component leaves with, and is separated from, the reaction products and the non-volatile component is withdrawn from the bottom of the reactor. The two components may be pure compounds, preferably boiling at least 55 DEG C apart, but the volatile component may be a narrow boiling liquid fraction, the non-volatile component in this zone having an initial boiling point at least 55 DEG C and preferably 85 DEG C above the end boiling point of the volatile component. Thus in a Fischer-Tropsch synthesis at 204 DEG C and a superatmospheric pressure of 6.8 atmospheres, the light component has a vapour pressure of 9.7 atmospheres at 204 DEG C and a normal B.P. of 99 DEG C. A saturated hydrocarbon fraction boiling at 93-105 DEG C is suitable. The non-volatile component could then be the gas oil fraction of the reaction product. The process is applicable to stationary or moving beds.