GB343947A - Improvements in or relating to the production of organic compounds containing oxygen - Google Patents

Abstract

Acetic acid; methyl acetate.-In the production of oxygenated organic compounds, particularly acetic acid and other carboxylic acids and esters thereof, by the action of carbon monoxide on alcohols either in the free or combined state in the presence of inorganic acid catalysts of the type defined in Specification 283,989, [Class 2 (iii), Dyes &c.], promoters comprising vanadium, chromium, manganese, iron, nickel, cobalt, or compounds of these metals, or mixtures thereof with one another or with copper or copper compounds are incorporated in the catalysts. The process is particularly applicable to the production of acetic acid and methyl acetate by the action of carbon monoxide on methyl alcohol or compounds capable of decomposing under the conditions of the reaction with the separation of a methoxy group or methyl alcohol. Such compounds include dimethyl ether or methyl esters such as methyl formate or acetate. When methyl formate is employed carbon monoxide is formed by its decomposition, and in this case the addition of further carbon monoxide, although preferable, may be dispensed with. The proportion of methyl acetate in the product depends on the relative proportions of methyl alcohol, carbon monoxide, and water vapour present in the starting materials. The reaction is preferably carried out at temperatures between 250 DEG and 400 DEG C., and pressure up to 300 atmospheres or more may be employed. Inert gases may be present. The main catalyst may consist of any of the phosphoric acids or a mixture thereof, acid phosphates, or aromatic sulphonic acids. The phosphoric acid may be employed in the liquid form or on an inert solid carrier. The promoter is preferably a compound of iron or manganese, for example, the hydroxide, acetate, or formate of either metal. The apparatus in contact with phosphoric acids may be lined with gold, platinum, or graphite, or made of or lined with copper. According to an example a vapour mixture of methyl alcohol, water, and carbon monoxide obtained by passing carbon monoxide through liquid methyl alcohol at 50-56 DEG C. and afterwards through water at 80 DEG C. is passed at 120-160 atmospheres pressure over a catalyst consisting of pyrophosphoric acid with 0,5-1,0 per cent of iron or manganese formate maintained at 290-315 DEG C. in a gold-lined reaction vessel. The products are separated by condensation, the condensate containing methyl acetate and acetic acid, and the uncondensed gases are returned to the reaction. Hydrocarbon and other undesired products may be removed from the circulating gases by means of absorbents such as active carbon, absorbent charcoal, or silica gel. Specification 317,867, [Class 2 (iii), Dyes &c.], also is referred to.