Patent GB-390845-A (GB)
Title: Improvements relating to the manufacture of aliphatic anhydrides
IPC: C07C51/56
Filed: 1931-09-30
Abstract: <PICT:0390845/IV/1> <PICT:0390845/IV/2> In the production of alyphatic anhydrides by thermal decomposition of the corresponding acids, the acid vapour is preheated and/or decomposed in the form of thin sheets which may be from a quarter to a twentieth of an inch in thickness and may be straight, curved, or annular.  The walls of the heating spaces may be heated in any suitable way such as by firing, by hot gases or superheated steam, or electrically, and preferably both walls are heated.  Preferably the acid vapour is preheated as described above and then decomposed in presence or absence of catalysts by the method described above or by passage through a body of molten catalytic material or molten material containing a catalyst.  The apparatus shown comprises annular spaces 1 .. 4 bounded by concentric walls 5, 5a .. 5g in a casing 6.  Adjacent spaces 1, 2 and 3, 4 are connected by annular chambers 7, 8 and 7a, 8a at the inlet and outlet ends respectively.  Hot acid vapour from a preheater 12 pass by way of a manifold 10 which contains a baffle 13, into the chambers 7, 8 and after passing through the narrow spaces 1 .. 4, are withdrawn through a manifold 10a connected to the chambers 7a, 8a, and then pass to the separation apparatus. The heating-gases enter at 14 and pass on both sides of the spaces 1 .. 4, passing through the chambers 7, 7a, 8, 8a by pipes 17, and thus pass by a pipe 18 to the preheater 12.  The spaces 1 .. 4 may contain a catalyst such as calcium tungstate.  Alternatively the apparatus described in Specifications 390,846 and 390,847 may be employed.  The anhydride may be separated from the water vapour as described in Specifications 256,663, 289,972, 298,667, 303,772, or 310,683, [all in Class 2 (iii), Dyes &c.].  Specification 279,916, [Class 2 (iii), Dyes &c.], also is referred to.ALSO:<PICT:0390845/III/1> <PICT:0390845/III/2> In the production of aliphatic anhydrides by thermal decomposition of the corresponding acids, the acid vapour is preheated and/or decomposed in the form of thin sheets which may be from a quarter to a twentieth of an inch in thickness and may be straight, curved, or annular.  The walls of the heating spaces may be heated in any suitable way such as by firing, by hot gases or superheated steam, or electrically, and preferably both walls are heated.  Preferably the acid vapour is preheated as described above and then decomposed in presence or absence of catalysts by the method described above or by passage through a body of molten catalytic material or molten material containing a catalyst.  The apparatus shown comprises annular spaces 1 .. 4 bounded by concentric walls 5, 5a .. 5g in a casing 6.  Adjacent spaces 1, 2 and 3, 4 are connected by annular chambers 7, 8 and 7a, 8a at the inlet and outlet ends respectively.  Hot acid vapours from a preheater 12 pass by way of a manifold 10 which contains a baffle 13, into the chambers 7, 8 and after passing through the narrow spaces 1 .. 4 are withdrawn through a manifold 10a connected to the chambers 7a, 8a, and then pass to the separation apparatus. The heating-gases enter at 14 and pass on both sides of the spaces 1 .. 4 passing through the chambers 7, 7a, 8, 8a by pipes 17, and then pass by a pipe 18 to the preheater 12.  The spaces 1 .. 4 may contain a catalyst such as calcium tungstate. Alternatively the apparatus described in Specifications 390,846 and 390,847 may be employed.