Patent GB-373893-A (GB)
Title: Manufacture of acetaldehyde, acetone and acetic acid
Filed: 1931-09-23
Abstract: For the production of acetaldehyde acetone and acetic acid from acetylene and steam, molten catalysts are employed at a temperature at which they absorb less than 5 per cent of water, e.g. 300-550 DEG C.  Suitable catalysts are zinc chloride alone or mixed with iron, chromium, or other chloride.  The gases leaving the molten catalyst may be passed over a solid catalyst such as a mixture of zinc oxide and barium sulphate, and the solid catalyst loses its activity more slowly than would be the case with fresh gases.  Solid catalysts favouring the yield of acetone are cerium or manganese oxides or both or mixtures of them with zinc or titanium oxides with or without an activator such as an alkali. An example of a solid catalyst consists of 40 parts cerium oxide, 20 parts zinc oxide, 10 parts chromium oxide, 8 parts barium oxide, 8 parts titanium oxide, 2 parts potassium hydroxide, and 2 parts water glass.ALSO:The hydration of acetylene, to produce acetaldehyde, acetone, and acetic acid is effected by passing a mixture of acetylene and steam through a molten salt at a temperature at which the salt absorbs less than 5 per cent of water.  The temperature may be 300-550 DEG  C.  The acetylene steam mixture may be passed through the melt at a high velocity such as 1000 litres (measured at 100 DEG  C.) per litre of melt per hour. The gas mixture may be preheated, and hydrochloric acid may be added to prevent incrustation of the inlet pipe with basic salts.  Suitable salts are those which melt below 550 DEG  C. and whose concentrated aqueous solutions have an acid reaction; zinc chloride alone or mixed with iron, chromium, or other chloride is particularly suitable. Some of the catalyst may volatilize, and may be recovered by using for the production of the steam required, the residue of the condensate after the distillation of acetaldehyde and acetone therefrom; the acetic acid present is thus concentrated.  The gases leaving the molten catalyst may be passed over a solid catalyst such as a mixture of zinc oxide and barium sulphate to produce additional hydration products from the excess of acetylene; the solid catalysts lose their activity more slowly than would be the case with fresh acetylene and steam.  By selecting as the solid catalyst which promotes the conversion of acetaldehyde and acetic acid into acetone, the yield of acetone may be increased; such catalysts are cerium oxide, manganese oxide, or mixtures of these with zinc oxide, titanium oxide, or the like, in some cases with the addition of an activating agent such as an alkali or the like.  In examples (1) a mixture in molecular proportions of acetylene and steam preheated to 400-450 DEG  C. is passed through zinc chloride containing 10 per cent of chromium chloride at 420-435 DEG  C. at 1200-1400 litres per hour per litre of melt, (2) one volume of acetylene and two volumes of steam preheated to 400 DEG  C. are passed through zinc chloride at 445-450 DEG  C. at 1300-1500 litres per hour per litre of melt; (3) a speed of 2700-3300 litres per hour is employed; (4) hydrochloric acid is added to the gases; (5) the exit gases are passed through a tube containing a catalyst in the form of lumps consisting of 60 per cent zinc oxide and 40 per cent barium sulphate; (6) the solid catalyst employed is a mixture of 40 parts cerium oxide, 20 parts zinc oxide, 10 parts chromium oxide, 8 parts barium oxide, 8 parts titanium oxide, 2 parts potassium hydroxide, and 2 parts water glass, the temperature being 450-500 DEG  C.  Specification 313,864, [Class 2 (iii), Dyes &c.], is referred to.  The Specification as open to inspection under Sect. 91 (3) (a) is not limited to passing the vapours through the molten catalyst.