Patent GB-425550-A (GB)
Title: Improvements in or relating to the manufacture of acetaldehyde
IPC: C07C45/38
Filed: 1933-09-18
Abstract: Acetaldehyde is produced by the oxidation and/or dehydrogenation of alcohol in presence of a catalyst mass comprising silver deposited or supported upon another metal which metal may advantageously be a catalyst for the reaction.  The silver may be electrodeposited upon the other metal, for instance, from a solution of silver and potassium cyanides or silver thiocyanate, especially when employing a silver anode, or such solutions may be caused to deposit silver on copper even without the passage of a current.  Alternatively, silver or a reducible compound thereof may be deposited from a suspension on the other metal, for instance silver oxide may be precipitated from a salt such as silver nitrate and be caused to settle on copper turnings and subsequently reduced, or reduced during the process, especially when effected above 300 DEG  C.  The silver need not completely cover the copper which may be in the form of gauze, foil or other form of large surface or even masses of relatively small surface.  The alcohol may be admixed with inert diluents such as steam, nitrogen or carbon dioxide, whether oxygen is present or not and the temperature of reaction may be 250--450 DEG  C., the pressure being preferably near atmospheric.  The catalyst may be employed together with other catalysts for the reaction or with promoters, such as silver or copper oxides.  The reaction mixture may be preheated, and the oxygen may be admitted at various points along the reaction zone.  The reaction may be effected as described in Specification 391,444 in which the reaction gases are introduced at a number of points along the reaction zone, and the temperature may be controlled by means of "climbing films" as described in Specification 390,504.  Or it may be effected in apparatus having narrow annular spaces, the copper walls of which may be lined on the inside with silver, as described in Specification 390,847.  In examples: (1) apparatus as described in Specification 391,444 containing silvered copper gauze is preheated by passing steam through it, and alcohol vapour mixed with steam and air is led through, a further quantity of air being admitted by the perforated tube; the temperature, 350--400 DEG  C. is controlled by "climbing films" of water; (2) a paste of silver oxide and water is spread thinly on roughened copper foil, which is then heated to dry and decompose the oxide; the foil is then corrugated and used as the catalyst in example 1; (3) alcohol vapour with a fifth of its volume of air is passed through a narrow copper tube lined with silver and packed with silvered copper gauze.ALSO:Acetaldehyde is produced by the oxidation and/or dehydrogenation of alcohol in presence of a catalyst mass comprising silver deposited or supported upon another metal which metal may advantageously be a catalyst for the reaction.  The silver may be electrodeposited upon the other metal for instance from a solution of silver and potassium cyanides or silver thiocyanate, especially when employing a silver anode or such solutions may be caused to deposit silver on copper even without the passage of a current. Alternatively silver or a reducible compound thereof may be deposited from a suspension on the other metal, for instance silver oxide may be precipitated from a salt such as silver nitrate and be caused to settle on copper turnings and subsequently reduced, or reduced during the process, especially when effected above 300 DEG  C.  The silver need not completely cover the copper, which may be in the form of gauze, foil or other form of large surface or even masses of relatively small surface.  The alcohol may be admixed with inert diluents such as steam, nitrogen or carbon dioxide, whether oxygen is present or not and the temperature of reaction may be 250--450 DEG C., the pressure being preferably near atmospheric.  The catalyst may be employed together with other catalysts for the reaction or with promoters, such as silver or copper oxides.  The reaction mixture may be preheated, and the oxygen may be admitted at various points along the reaction zone.  The reaction may be effected as described in Specification 391,444 in which the reaction gases are introduced at a number of points along the reaction zone, and the temperature may be controlled by means of "climbing films" as described in Specification 390,504.  Or it may be effected in apparatus having narrow annular spaces the copper walls of which may be lined on the inside with silver, as described in Specification 390,847.  In examples (1) apparatus as described in Specification 391,444, containing silvered copper gauze is preheated by passing steam through it, and alcohol vapour mixed with steam and air is led through, a further quantity of air being admitted by the perforated tube; the temperature, 350--400 DEG  C., is controlled by "climbing films" of water; (2) a paste of silver oxide and water is spread thinly on roughened copper foil, which is then heated to dry and decompose the oxide; the foil is then corrugated and used as the catalyst in example 1; (3) alcohol vapour with a fifth of its volume of air is passed through a narrow copper tube lined with silver and packed with silvered copper gauze.