Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
137 words
A method of recovering acetic acid by extracting an acetic acid-containing aqueous solution with an organic extracting agent and subjecting the extract to distillation, said method comprising the first step of performing extraction by using a tertiary amine having a boiling point higher than that of acetic acid and being capable of forming a non-aqueous phase as the organic extracting agent in combination with an oxygen-containing, high-boiling-point organic solvent selected from the group consisting of di-isobutyl carbinol, isophorone, methyl benzoate, tributyl phosphate, 3,3,5-trimethylcyclohexanone and 2-ethoxyethyl acetate, the second step of performing dehydration by subjecting the extract to distillation, and the third step of subjecting the dehydrated mixture to distillation in a reduced pressure distillation column at a column bottom temperature of 120° to 170° C. to distill acetic acid and separate it from the organic extracting agent.
Claim 2
Independent Claim
137 words
A method of recovering acetic acid by extracting an acetic acid-containing aqueous solution with an organic extracting agent and subjecting the extract to distillation, said method comprising the first step of performing extraction by using a tertiary amine having a boiling point higher than that of acetic acid and being capable of forming a non-aqueous phase as the organic extracting agent in combination with an oxygen-containing, high-boiling-point organic solvent selected from the group consisting of di-isobutyl carbinol, isophorone, methyl benzoate, tributyl phosphate, 3,3,5-trimethylcyclohexanone and 2-ethoxyethyl acetate, the second step of performing dehydration by subjecting the extract to distillation, and the third step of subjecting the dehydrated mixture to distillation in a reduced pressure distillation column at a column bottom temperature of 120° to 170° C. to distill acetic acid and separate it from the organic extracting agent.
Claim 3
Dependent Claim
37 words
A recovery method according to claim 1, wherein the organic extracting agent separated from acetic acid at the third step is used as a reflux liquid to be fed to the distillation column of the second step.
Claim 4
Dependent Claim
23 words
A recovery method according to claim 1, wherein the acetic acid concentration in the starting aqueous solution is 7 to 40% by weight.
Claim 5
Dependent Claim
26 words
A recovery method according to claim 1, wherein the extraction of the first step is carried out by using a mixer-settler type counter-current multi-stage extracting device.
Claim 6
Dependent Claim
50 words
A recovery method according to claim 1, wherein the tertiary amine has 12 to 40 carbon atoms and in the partial structure >N-CH 2 CR 1 R 2 - of said tertiary amine, R 1 is a hydrogen atom and R 2 is a hydrogen atom or a methyl group.
Claim 7
Dependent Claim
13 words
A recovery method according to claim 5, wherein the tertiary amine is tri-n-octylamine.
Claim 8
Dependent Claim
14 words
A recovery method according to claim 1, wherein the oxygen-containing organic solvent is 3,3,5-trimethylcyclohexanone.
Claim 9
Dependent Claim
29 words
A recovery method according to claim 1, wherein the oxygen-containing organic solvent is a member selected from the group consisting of isophorone, 2-ethoxethyl acetate, methyl benzoate and tributyl phosphate.
Claim 10
Dependent Claim
15 words
A recovery method according to claim 1, wherein the oxygen-containing organic solvent is di-isobutyl carbinol.
Claim 11
Dependent Claim
24 words
A recovery method according to claim 1, wherein the proportion of the tertiary amine in the extraction solvent is 10 to 80% by volume.
Claim 12
Dependent Claim
22 words
A recovery method according to claim 10, wherein the proportion of the tertiary amine in the extraction solvent is 50% by volume.
Claim 13
Dependent Claim
25 words
A recovery method according to claim 1, wherein the extraction of the first step is carried out at a temperature not higher than 50° C.
Claim 14
Dependent Claim
23 words
A recovery method according to claim 1, wherein the third step is conducted at a column bottom temperature of 120° to 150° C.