GB472629A - Improvements in process and apparatus for carrying out exothermic reactions - Google Patents

Abstract

<PICT:0472629/IV/1> In the oxidation of olefines to olefine oxides in the gaseous phase according to the parent Specification by passage over catalytic material in thin layer form contained in a tube or tubes of good heat conducting material which are immersed in a liquid maintained at constant temperature, the temperature control is improved by providing within the tube or tubes a continuous or stepped gradation of one or more of the following reaction factors: surface area or thickness or activity of catalyst, velocity of gas flow, turbulence and cross-sectional area of the gas passage. The Figure shows a set of alternative reaction tubes with axial inserts. In the modification A, the conical support 2 is covered with a uniform layer of catalyst, so that the rate of transfer of heat from the catalyst is gradually decreased. In type B, the catalyst support is the reverse of that of A, but the effect may be to cause an even reaction, depending on type and activity of catalyst and other factors. In the type C, the thickness of the catalyst layer 3 progressively increases. In the modification D, tapering cavities are formed in the support, giving increasing cross-sectional area of the gas passage and decreasing turbulence with a substantially uniform catalytic area. D<1> and D<2> are end views. In type E, the surface area of the catalyst is uniformly increased in the direction of the gas flow. In type F, the surface area and thickness of catalyst are constant, but the rate of heat transfer from the catalyst is decreased by the tapering lining 4 of poor heat conducting material. In type G, the catalyst layer is uniform and is carried on the inner surface of the tube 1. The insert 2 acts as a conical baffle, giving increasing turbulence and gas velocity. Type H is a further modification of type E, giving an increasing catalytic surface. Alternatively, the tapering layer of type E may be wound round the support at constant pitch, or a uniform strip may be wound round in spirals of decreasing pitch. In type I, the catalyst is of uniform thickness and area, but of progressively increasing activity. The support may be hollow, and may be interiorly heated or cooled, or it may be used to preheat the incoming gases.ALSO:<PICT:0472629/III/1> In the oxidation of olefines to olefine oxides in the gaseous phase according to the parent Specification by passage over catalytic material in thin layer form contained in a tube or tubes of good heat conducting material which are immersed in a liquid maintained at constant temperature, the temperature control is improved by providing within the tube or tubes a continuous or stepped gradation of one or more of the following reaction factors: surface area, or thickness or activity of catalyst, velocity of gas flow, turbulence and cross-sectional area of the gas passage. The Figure shows a set of alternative reaction tubes with axial inserts. In the modification A, the conical support 2 is covered with a uniform layer of catalyst, so that the rate of transfer of heat from the catalyst is gradually decreased. In type B, the catalyst support is the reverse of that of A, but the effect may be to cause an even reaction, depending on type and activity of catalyst and other factors. In the type C, the thickness of the catalyst layer 3 progressively increases. In the modification D, tapering cavities are formed in the support, giving increasing cross-sectional area of the gas passage and decreasing turbulence with a substantially uniform catalytic area. D<1> and D<2> are end views. In type E, the surface area of the catalyst is uniformly increased in the direction of the gas flow. In type F, the surface area and thickness of catalyst are constant, but the rate of heat transfer from the catalyst is decreased by the tapering lining 4 of poor heat conducting material. In type G, the catalyst layer is uniform and is carried on the inner surface of the tube 1. The insert 2 acts as a conical baffle, giving increasing turbulence and gas velocity. Type H is a further modification of type E, giving an increasing catalytic surface. Alternatively, the tapering layer of type E may be wound round the support at constant pitch, or a uniform strip may be wound round in spirals of decreasing pitch. In type I, the catalyst is of uniform thickness and area, but of progressively increasing activity. The support may be hollow, and may be interiorly heated or cooled, or it may be used to preheat the incoming gases.