GB726489A - Improved method of heating reaction apparatus for carrying out exothermic gas reactions - Google Patents

Abstract

A continuous catalytic process for the production of formaldehyde by oxidation of methanol or methane with air is initiated in a non-inflammable mixture of the reactant gases in which one gas is present in stoichiometric excess of the second gas, by passing the main stream of gas mixture through the cold reaction apparatus and introducing and igniting regulated quantities of the second gas through a separate gas inlet into the main gas stream in front of the actual reaction zone; the two gas streams react with the formation of flame, thus heating the reaction apparatus. In an example, a mixture of air and excess methanol vapour is passed through a catalytic reaction zone and air is introduced and ignited at a number of points in front of the reaction zone, flames being formed which do not reach to the catalyst. When the reaction temperature is attained the stream of air is shut off and the reaction continues automatically. Alternatively the main feed gas may contain excess air, in which case methanol vapour is introduced as the secondary stream.ALSO:A continuous exothermic catalyst reaction is initiated in a non-inflammable mixture of at least two gases in which a first gas is present in stoichiometric excess of a second gas, by passing the main stream of gas mixture through the cold reaction apparatus and introducing and igniting regulated quantities of the second gas through a separate gas inlet into the main gas stream in front of the actual reaction zone; the two gas streams react with the formation of flame, thus heating the reaction apparatus. Ignition may be effected by a spark gap or an incandescent wire. The secondary gas stream may be introduced perpendicular to the main stream in a tangential or radial direction. In modifications (1) the second gas is fed gradually into the main gas stream which contains initially only the first gas, and simultaneously the secondary gas stream is gradually reduced. (2) the main gas stream contains only the first gas, and when the required temperature is reached, the secondary gas stream is stopped to extinguish the flame, and then restarted. In an example, formaldehyde is formed from a mixture of methanol vapour and air (see Group IX (b)). The process is also applicable in the oxidation of ammonia to nitric acid and the production of hydrocyanic acid from methane and ammonia in the presence of air or oxygen.