Patent GB-811500-A (GB)
Title: Method for manufacturing methyl-ethyl-ketone
Filed: 1955-07-05
Abstract: <PICT:0811500/III/1> Hydrogen, together with methyl ethyl ketone, is prepared by the catalytic dehydrogenation of vaporous sec. butanol by a process comprising passing the butanol into a catalysing furnace 1 (Fig. 1), suitably in the presence of a zinc-oxide catalyst at 300-500 DEG  C., fractionating directly and continuously the resulting vaporous mixture of organic products and inert non-condensable gases (mainly hydrogen and hereinafter so termed) by distillation in a column 2 under reflux and separating out, on the one hand, a vaporous mixture comprising hydrogen and substantially all of the methyl ethyl ketone, and, on the other hand, a liquid mixture comprising unchanged butanol and heavy organic by-products, returning part of this liquid mixture to the furnace 1 for retreatment, distilling the remainder of the liquid mixture in a subsidiary distillation column 6 and returning the butanol thus obtained to main distillation column 2 and recovering from column 6 as bottoms the heavy by-products, condensing the vaporous mixture from column 2 in a condenser 3 to recover the methyl ethyl ketone and further purifying at least part of the so-separated hydrogen to remove residual traces of ketone and alcohol by passing the gases to be treated first through a washing tower 4 in counter-current flow to a stream of sec.-butanol serving as primary feed to the catalysing furnace, and then through a second washing tower 5 in counter-current flow to a stream of heavy organic by-products supplied from distillation column 6, the wash-liquor thereafter being recycled to this column; the gases may then be given a final wash with water to remove any traces of the heavy by-products.  The hydrogen so obtained is suitable for use in hydrogenations.  The hydrogen not so purified is recycled to column 2 to facilitate fractionation.ALSO:<PICT:0811500/IV (b)/1> Methyl ethyl ketone is prepared from secondary butanol by catalytic dehydrogenetion in the vapour phase by a process comprising passing the butanol into a catalysing furnace, fractionating directly and continuously the resulting varporous mixture of organic products and inert non-condensable gases by distillation in a column under reflux and separating out, on the one hand, a vaporous mixture comprising substantially all of the methyl ethyl ketone and non-condensable inert gases and, on the other hand, a liquid mixture comprising heavy organic by-products and unconverted butanol; distilling part of this liquid mixture in a subsidiary distillation column and returning the butanol thus obtained to the first distillation column; returning the remainder of the liquid mixture comprising by-products and unconverted butanol to the catalysing furnace for retreatment and fractionally condensing the separated mixture of methyl ethyl ketone and non-condensable inert gases so as to separate out therefrom substantially the methyl ethyl ketone.  In one preferred method, the butanol in vapour form is dehydrogenated in a catalysing furnace 1 (Fig. 1) suitably maintained at 300-500 DEG  C. and containing, for example, a zinc-oxide based catalyst, the vaporous products are fed directly into a distillation column 2 having a bottom temperature of 95-100 DEG  C.  A vaporous mixture comprising methyl ethyl ketone and inert non-condensable gases is removed overhead and condensed in a condenser 3 wherein the methyl ethyl ketone is separated out and removed for, if desired, further purification.  A portion of the separated gases may be recycled to column 2.  The bottoms in column 2 comprises unchanged butanol, heavy by-products and some ketone.  Part of the bottoms is recycled to the furnace 1 and the remainder is fed to a distillation column 6 wherein the butanol and residual ketone are stripped off and returned to column 2, leaving a concentrate of heavy by-products at the bottom of column 6.  The inert gases separated in condenser 3 are fed to a washing tower 4 supplied with primary feed of secondary butanol which is subsequently passed to the catalysing furnace.  The washed gases are then fed into a second tower 5 where they are washed with part of the stripped heavy products from distillation column 6, the used wash liquor then being recycled to this column.  The remainder of the bottoms from column 6 are withdrawn from the system.  The gases from tower 5 comprising mainly hydrogen may be given a further washing using water.  The washing operations are preferably effected under an elevated pressure.  Figs. 2 and 3 (not shown) illustrate more detailed apparatus utilizable in the process, the latter figure illustrating suitable apparatus for further purification of the recovered ketone wherein the ketone is fed into a fractionating column from which pure methyl ethyl ketone is removed as bottoms and a light fraction comprising ketone and some water is removed overhead.  The light fraction is condensed and then passed into a column of salt from which a mixture of salt solution and light products is withdrawn. The organic phase is separated, vaporized and recycled to the fractionating column.