GB873738A - A process for the production of carboxylic acids - Google Patents

Abstract

<PICT:0873738/IV (b)/1> <PICT:0873738/IV (b)/2> <PICT:0873738/IV (b)/3> <PICT:0873738/IV (b)/4> In a process for the production of a carboxylic acid in which an olefinic compound is reacted with carbon monoxide and water in the presence of a highly acidic inorganic compound as catalyst, the reaction mixture is separated into a phase comprising the carboxylic acid and a phase comprising the catalyst which is withdrawn from the separation zone, diluted with water or water-containing liquid, the organic material separated and removed, and the catalyst containing phase recycled to the system. Olefinically unsaturated compounds include propylene, butylene-1, and -2, isobutylene, branched or unbranched pentenes, hexenes, heptenes, octenes, nonenes, decenes, and higher alkenes, diisobutylenes and propylene tetramer, and cyclopentene and cyclohexene, and liquid hydrocarbon fractions from the thermal vapour phase steam cracking of paraffin wax, and in an example a mixture of 76% monoalkenes with 8 to 10 carbon atoms, with saturated hydrocarbons is used. The reaction may be continuous or batchwise at a temperature between for example, -10 DEG and 150 DEG C. with a carbon monoxide pressure above 20 atmospheres, and with pure carbon monoxide or carbon monoxide containing gases such as water gas, generator gas a coke oven gas. The catalysts specified are phosphoric, sulphuric, hydrated boron trifluoride and complexes of boron trifluoride with phosphoric or sulphuric acid. Flow diagrams show: Fig. I the separation of the reaction mixture, in vessel 6, into two layers, the bottom layer comprising catalyst and by-products, which is in part returned to the reaction vessel 1, and in part mixed, 11, with water, again separated and the catalyst layer returned to the reaction vessel; Fig. II an additional stage in which the diluted catalyst layer after separation is passed to the crude carboxylic acid, 18, separated, 21 and then returned to the reaction vessel 1, while the purified carboxylic acid is withdrawn 23; Fig. III as in Fig. II with further washing with water 25, and separation of the carboxylic acid 28, and the wash is then passed to mixer 11; and Fig. IV a modification in which the separated dilute catalyst, 14, is returned to the reactor effluent 32. Specification 871,278 is referred to.